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pandreas68
Joined: 24 Jan 2020
Posts: 96
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 Posted: Sun Feb 02, 2020 4:34 pm Post subject: Analogue lense resolution in pixel by circle of confusion |
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pandreas68 wrote:
Hi,
I thought about how to estimate the quality of an old analogue lense by pixel counting and ended in the idea of expressing the circle of confusion by a number of pixels:
The resolution of an "analogue" lense may be defined by a maximum number of pixels in within the lense may produce e.g. unsharp pictures or chromatic errors.
This maximum number of pixels may be derived from the maximum diameter of the so called circle of confusion (CoC). The circle of confusion is used in order to achieve a defined depth of field in analogue photography. In general the bigger a film format is the bigger is the allowed maximum CoC diameter. For 24mmx36mm format the diameter is 0.029mm, for 6x6 middle format the diameter is 0.053 mm.
From this diameter, the used resolution of the digital camera and the sensor size the CoC diameter can be calculated as a number of pixels in within the lense may produce unsharpness or chromatic errors.
In general the bigger the film format a lense was calculated for, the bigger the used digital resolution and the smaller the sensor size the bigger is the number of pixels in within the unsharpness and lense errors may be.
The following data show the CoCiPx (CoC in pixel) for different sensor sizes, digital pixel resolutions and film formats respectively CoC the lense originally was calculated for.
For full size sensors (24mmx36mm):
Analogue lenses for full format (CoC: 0.029mm):
10MPx: 3.1Px
12MPx: 3.4Px
24MPx: 4.8Px
42MPx: 6.4Px
50MPx: 7.0Px
Analogue lenses for 6x6 (CoC: 0,053mm):
10MPx: 5.7Px
12MPx: 6.2Px
24MPx: 8.8Px
42MPx: 11.7Px
50MPx: 12.7Px
For APS-C sensors (23.6mm x 15.8mm):
Analogue lenses for full format (CoC: 0.029mm):
10MPx: 4.7Px
12MPx: 5.2Px
24MPx: 7.4Px
42MPx: 9.7Px
50MPx: 10.6Px
Analogue lenses for 6x6 (CoC: 0.053mm):
10MPx: 8.7Px
12MPx: 9.5Px
24MPx: 13.4Px
42MPx: 17.8Px
50MPx: 19.4Px
For MicroFourThird sensors (17.3mm x 13mm):
Analogue lenses for full format (CoC: 0.029mm):
10MPx: 6.1Px
12MPx: 6.7Px
24MPx: 9.5Px
42MPx: 12.5Px
50MPx: 13.7Px
Analogue lenses for 6x6 (CoC: 0.053mm):
10MPx: 11.2Px
12MPx: 12.2Px
24MPx: 17.3Px
42MPx: 22.9Px
50MPx: 25.0Px
All these numbers are calculated using the formula:
CoCiPx = CoCinMillimeter * squareRoot( resolutionInPixel/sensorAreaInSquareMillimeter)
When assuming that 3Pixel is the minimum number of Pixels in within unsharpness and errors may occur due to the nature of digital fotography (sampling, averaging, etc) and that good lenses should have a resolution better than half of the CoC diameter then it can be derived, that good analogue lenses for full format should be useable on full format cameras for at least up to 24MPx resultion while staying within a limit of some 3 Pixels of unsharpness.
Analogue lenses for 6x6 medium format however should be useable for at least 10MPx resolution when using full format sensors.
In reality deviations are reported. Beside the quality of a lense design, the quality of a specific lense copy and the parameters of the particular shot such as e.g. whether a lense shade was used, two other influences are reported:
The quality of a lense may be better than expected by CoCiPx because only the center area of the film format the lense is calculated for is used. This holds true when e.g. a medium format lense is used on full format.
The quality of the lense may be worse than expected by CoCiPx because the lense was calculated for projection on film directly rather than through a flat glass before an sensor. The latter seems to mainly affect lenses calculated for analogue view finder cameras.
I hope this may help in deciding about the quality of a lense and its usability for digital photography.
Andreas |
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Lightshow
Joined: 04 Nov 2011
Posts: 3666
Location: Calgary
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| Posted: Mon Feb 03, 2020 10:12 pm Post subject: |
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Lightshow wrote:
Those seem to be some broad assumptions, lens resolution can vary wildly between brands and even within the brand.
I have a few FF lenses that should handle 100MP FF sensor with ease, and a few that struggle with 36MP FF.
I'm still not to sure about the MP war going for much longer, at some point soon most shooters will be asking for smaller resolution options in the menu, I've already started seeing an increased number of requests for it with the A7rIV release.
There are a few that will take every pixel they can get, but I think most will be happy at 50MP, I know a few that think 24MP is the sweet spot.
I know I'm quite happy with 36MP in my A7r for file size vs resolution, I don't covet the sensors in any other camera, only the firmware updates.
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pandreas68
Joined: 24 Jan 2020
Posts: 96
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| Posted: Tue Feb 04, 2020 6:08 pm Post subject: |
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pandreas68 wrote:
| Lightshow wrote: |
| Those seem to be some broad assumptions, lens resolution can vary wildly between brands and even within the brand. |
I'd say no and yes.
Yes because lenses are reported being excellent also at more than 50MPx as you do. No manufacterer would have made a lens worse by intent without purpose.
No because it is not an assumption but a calculation what a lens must fulfill (in pixel) to fit into specification for which originally it was calculated for.
I came on that by my thoughts about a Zebra respectively NON-MC 4/300 Sonnar for the Pentacon Six. Marco Kroeger found out that it is better than the later so called MC 4/300 Sonnar and from my own trials I can state that for my impression the NON-MC version not only outperforms the MC version but also the Prakticar 4/300 from 1981 calculated for analogue full format.
How did it come? Originally the Olympia Sonnar 300 was calculated for full format. In 1963 they recalculated it for the Pentacon Six while using almost the same optical formula (and obviously the quality of a good full format lense); see Marco Kroeger.
In 1974 they invented the MC 4/300 with a different optical formula, which allowed cheaper production by less glass (see Marco Kroeger). Also the quality seemingly went down but stayed within definition of the Circle of Confusion.
| Lightshow wrote: |
| sweet spot |
: The numbers show that good lenses which have been calculated for analogue full format cameras should be useable for up to 50MPx and beeing within definition until 24MPx. That would support the sweet spot with lens numbers. I don't know how much better modern lenses are. I guess there will be some limits in quality as long as the price shouldn't be exorbitantly high even in modern time.
Reusing lenses may be a contribution to "circular economy"!-) |
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visualopsins
Joined: 05 Mar 2009
Posts: 11067
Location: California
Expire: 2025-04-11
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| Posted: Tue Feb 04, 2020 9:13 pm Post subject: |
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visualopsins wrote:
I think you are on the right track. Coc is specified, however, for a standard size enlargement (8x10) viewed from a standard distance (arm's length), the eye's resolution limit. You have simply calculated pixel coverage for different density sensors given coc used for format size, however, actual minimum coc produced by the lens on a sensor can be much smaller.
This reminds me why I have to sit so close to see 4k video improvement over 1080p. But if my eyes had greater resolution more megapixels...
_________________
☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮ like attracts like! ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮
Cameras: Sony ILCE-7RM2, Spotmatics II, F, and ESII, Nikon P4
Lenses:
M42 Asahi Optical Co., Takumar 1:4 f=35mm, 1:2 f=58mm (Sonnar), 1:2.4 f=58mm (Heliar), 1:2.2 f=55mm (Gaussian), 1:2.8 f=105mm (Model I), 1:2.8/105 (Model II), 1:5.6/200, Tele-Takumar 1:5.6/200, 1:6.3/300, Macro-Takumar 1:4/50, Auto-Takumar 1:2.3 f=35, 1:1.8 f=55mm, 1:2.2 f=55mm, Super-TAKUMAR 1:3.5/28 (fat), 1:2/35 (Fat), 1:1.4/50 (8-element), Super-Multi-Coated Fisheye-TAKUMAR 1:4/17, Super-Multi-Coated TAKUMAR 1:4.5/20, 1:3.5/24, 1:3.5/28, 1:2/35, 1:3.5/35, 1:1.8/85, 1:1.9/85 1:2.8/105, 1:3.5/135, 1:2.5/135 (II), 1:4/150, 1:4/200, 1:4/300, 1:4.5/500, Super-Multi-Coated Macro-TAKUMAR 1:4/50, 1:4/100, Super-Multi-Coated Bellows-TAKUMAR 1:4/100, SMC TAKUMAR 1:1.4/50, 1:1.8/55
M42 Carl Zeiss Jena Flektogon 2.4/35
Contax Carl Zeiss Vario-Sonnar T* 28-70mm F3.5-4.5
Pentax K-mount SMC PENTAX-A ZOOM 1:3.5 35~105mm, SMC PENTAX ZOOM 1:4 45~125mm
Nikon Micro-NIKKOR-P-C Auto 1:3.5 f=55mm, NIKKOR-P Auto 105mm f/2.5 Pre-AI (Sonnar), Micro-NIKKOR 105mm 1:4 AI, NIKKOR AI-S 35-135mm f/3,5-4,5
Tamron SP 17mm f/3.5 (51B), Tamron SP 17mm f/3.5 (151B), SP 500mm f/8 (55BB), SP 70-210mm f/3.5 (19AH)
Vivitar 100mm 1:2.8 MC 1:1 Macro Telephoto (Kiron)
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pandreas68
Joined: 24 Jan 2020
Posts: 96
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| Posted: Wed Feb 05, 2020 12:43 pm Post subject: |
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pandreas68 wrote:
| visualopsins wrote: |
| ...actual minimum coc produced by the lens on a sensor can be much smaller. |
Yes. I still struggle to find something EASY which transforms either MTFs or the old LP/mm (line pairs per mm) to pixel. My current feeling is that there is nothing easy.
The best explanation about that I found here.
With respect to LP/mm according to that link they were accepted with a MTF of 5% or less. So that makes no sense for me even to think about those LP/mm even if they would be available.
MTFs for full format however are usually measured at 30lines per mm which means a line distance of 0.033mm which is slightly above CoC. And MTFs do not take care for chromatic errors. So how to get out of this dilemma?
My idea is to simply count the pixels. A measure of quality of a lens could be by the factor of pixels which it is sharper than expected by CoC. For that also chromatic errors could be taken into account. That would be quite an easy measure which everebody could count on a full frame camera with e.g. 42MPx. By using the factor the sensor size should be "reduced" in the fraction. For a good lens I would assume a factor of 0.5 or better; that is what I meant in my originally text.
Maybe a question would be to use full format values only regardless of sensor size AND the film format a lense has originally been calculated. It would be easier to be interpreted when doing so. On the other hand it could omit important dependencies. |
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pandreas68
Joined: 24 Jan 2020
Posts: 96
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| Posted: Wed Feb 05, 2020 2:00 pm Post subject: |
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pandreas68 wrote:
| pandreas68 wrote: |
| For a good lens I would assume a factor of 0.5 or better |
When looking on those lens MTFs it seems that modern lenses make up to 80 LP / mm over the full format sensor when using a MTF of 50% as boundary which would be reasonable for me. That would translate into a factor of 0.21 according CoC of 0.029mm which they resolve better than required by full format CoC.
With Rodenstock giving the lines for 80 40 20 and 10LP/mm it is possible to interpolate. For e.g. the HR Digaron-S 23 mm f/5.6 at f/8 it can be seen that it resolves with approx 50LP/mm over the complete full format which means a factor of 0.35.
Andreas |
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pandreas68
Joined: 24 Jan 2020
Posts: 96
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| Posted: Sun Jan 17, 2021 5:59 pm Post subject: Rethinking resolution and sharpness |
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pandreas68 wrote:
Having a problem with resolution respectively sharpness using a Pentacon auto 2.8 200 its time again for me to think about circle of confusion, dpi and so on.
So far I understand the main idea of circle of confusion is, that the human eye can resolve some 1500 lines per the diagonal of the picture held in appropriate distance, that one can see the picture in one view. Therefor in theory it does not really matter how big a picture is printed as long as the appropriate distance is kept to see the picture with one gaze of the eyes.
Looking e.g. on Din A4 it has a format of 297mm times 210mm and a diagonal of sqrt(210^2+297^2)mm = 264mm = 14,32 inch. In turn a resolution of 1500 dots/(14,32inch) = 105 dpi. Of course 150dpi print resolution could yield a better quality for people with over average eyes, while 300 dpi or even 600 dpi should mainly allow for better quality when looking into details but not when looking to the whole picture in one gaze of the eyes.
When it comes now to the sensor or film the 1500 lines per diagonal is calculated to the film or sensor size, and for the standard 1500 lines we yield 0.029mm for 35mm format respectively 0.053mm for square medium format as the diameter of the circle of confusion.
If we want to achieve a higher resolution than 105dpi on A4 or in general more than 1500lines per length of diagonal a smaller diameter of the circle of confusion must be chosen.
In some photographs it is intended to have a maximum depth of field from lowest possible distance to the maximum distance, e.g. infinity, in the picture when the aperture is given. In this case the classical setting is to focus on the most distant point, and to turn this setting now visible at the setting mark to the mark of the intended aperture so that now a smaller distance is at the distance mark.
In other cases a certain depth of field is intended from a minimum distance to a maximum distance, e.g. to catch two faces. In this case the classical setting is to set the minimum distance and "save" it by a pencil mark or in brain, or feeling by the hand, set to the maximum distance, again "save" it, and turn the focus setting ring back in the middle. Now the necessary aperture can be read at the two saved marks (take the bigger aperture value, if two are neighboring).
So far the theory. In practice however it depends how the lens manufacturer has chosen the aperture marks. Setting the Pentacon auto 4/200 (P 4/200au) on the distance mark of 15m according to the aperture marks the depth of field (dof) goes from some 11m to 25m at aperture 22. When using the formulas for depth of field or a respective calculatur, for 35mm film however the dof should only reach from some 12m to 20m. Whats wrong? Obviously they did not use a circle of confusion of 0.029mm but more like 0.053mm which would be leading to some 10,5m to 26m. For the Pentacon Auto therefor an about 1,5 higher aperture setting would be needed. If e.g. for a certain depth of field according to the aperture scale of the P 4/200au an aperture of 8 would be needed an aperture of in between 11 and 16 or higher must be set to achieve a minimum required sharpness in the depth of field.
These considerations should be true for all lenses, also wide angle lenses, and there may be not only Pentacon which did not use the standard circle of confusion for their aperture marks. Knowing about that for the respective lens may help to correct the settings and avoid disappointments especially for pictures which can't be easily repeated.
Last edited by pandreas68 on Tue Jan 26, 2021 6:56 pm; edited 1 time in total |
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pandreas68
Joined: 24 Jan 2020
Posts: 96
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| Posted: Mon Jan 18, 2021 3:05 pm Post subject: Required lens resolution |
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pandreas68 wrote:
While in the beginning I thought about what to expect from a lens as minimum required quality and how to proove this by pixel counting, the question of this post is, which minimum resolution of lines I need from a lens and what I may expext from a lense which has a higher resolution at a given aperture and in turn which resolution I should use at the camera.
Here I think about what lens resolution I need and what I can do with lenses which support higher resolution that actually needed.
Coming from the circle of confusion I'd expect to have a minimum resolution of 1/0.053mm = 19 lines/mm for 6x6 and 1/0.029mm =35lines/mm for 35mm film / FF.
If I'd have a lens with 70lines/mm then it would mean that I could create crops of a quarter of the area of the original picture and having still the standard resolution defined by the circle of confusion.
It means also that according to the ability of a lens and to the intended resolution the resolution of a digital camera may be selected appropeately: When assuming that it makes sense to use twice the x and y resolution in the sensor than the signal has then we'd achieve 24*2*36*2/(0.029^2) = 4Mx as sensful Minimum resolution. When the lens is sharp enough to allow for a circle of confusion of 0.015mm we'd achieve a necessary resolution of some 16MPx.
In turn it means that if using a camera as a Sony 7S with some 12MP a lens (and aperture) which supports sqrt(12MPx/(4*24*36))= 60lines/mm is sufficient and this even allows for a certain "cropability" while still staying in standard quality definition.
60 lines then corresponds to 30 line pairs. Next step is how to correspond this to MTF charts... |
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DConvert
Joined: 12 Jun 2010
Posts: 921
Location: Essex UK
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| Posted: Mon Jan 18, 2021 5:06 pm Post subject: |
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DConvert wrote:
| visualopsins wrote: |
I think you are on the right track. Coc is specified, however, for a standard size enlargement (8x10) viewed from a standard distance (arm's length), the eye's resolution limit. You have simply calculated pixel coverage for different density sensors given coc used for format size, however, actual minimum coc produced by the lens on a sensor can be much smaller.
This reminds me why I have to sit so close to see 4k video improvement over 1080p. But if my eyes had greater resolution more megapixels... |
That is the usual use of CoC, but I note here the same CoC is used for all three sensor sizes despite the different enlargement needed to produce prints at 8x10.
on-line DOF calculators generally use different CoC values for the different formats... |
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visualopsins
Joined: 05 Mar 2009
Posts: 11067
Location: California
Expire: 2025-04-11
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| Posted: Mon Jan 18, 2021 5:54 pm Post subject: |
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visualopsins wrote:
| DConvert wrote: |
| visualopsins wrote: |
I think you are on the right track. Coc is specified, however, for a standard size enlargement (8x10) viewed from a standard distance (arm's length), the eye's resolution limit. You have simply calculated pixel coverage for different density sensors given coc used for format size, however, actual minimum coc produced by the lens on a sensor can be much smaller.
This reminds me why I have to sit so close to see 4k video improvement over 1080p. But if my eyes had greater resolution more megapixels... |
That is the usual use of CoC, but I note here the same CoC is used for all three sensor sizes despite the different enlargement needed to produce prints at 8x10.
on-line DOF calculators generally use different CoC values for the different formats... |
Exactly...
_________________
☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮ like attracts like! ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮
Cameras: Sony ILCE-7RM2, Spotmatics II, F, and ESII, Nikon P4
Lenses:
M42 Asahi Optical Co., Takumar 1:4 f=35mm, 1:2 f=58mm (Sonnar), 1:2.4 f=58mm (Heliar), 1:2.2 f=55mm (Gaussian), 1:2.8 f=105mm (Model I), 1:2.8/105 (Model II), 1:5.6/200, Tele-Takumar 1:5.6/200, 1:6.3/300, Macro-Takumar 1:4/50, Auto-Takumar 1:2.3 f=35, 1:1.8 f=55mm, 1:2.2 f=55mm, Super-TAKUMAR 1:3.5/28 (fat), 1:2/35 (Fat), 1:1.4/50 (8-element), Super-Multi-Coated Fisheye-TAKUMAR 1:4/17, Super-Multi-Coated TAKUMAR 1:4.5/20, 1:3.5/24, 1:3.5/28, 1:2/35, 1:3.5/35, 1:1.8/85, 1:1.9/85 1:2.8/105, 1:3.5/135, 1:2.5/135 (II), 1:4/150, 1:4/200, 1:4/300, 1:4.5/500, Super-Multi-Coated Macro-TAKUMAR 1:4/50, 1:4/100, Super-Multi-Coated Bellows-TAKUMAR 1:4/100, SMC TAKUMAR 1:1.4/50, 1:1.8/55
M42 Carl Zeiss Jena Flektogon 2.4/35
Contax Carl Zeiss Vario-Sonnar T* 28-70mm F3.5-4.5
Pentax K-mount SMC PENTAX-A ZOOM 1:3.5 35~105mm, SMC PENTAX ZOOM 1:4 45~125mm
Nikon Micro-NIKKOR-P-C Auto 1:3.5 f=55mm, NIKKOR-P Auto 105mm f/2.5 Pre-AI (Sonnar), Micro-NIKKOR 105mm 1:4 AI, NIKKOR AI-S 35-135mm f/3,5-4,5
Tamron SP 17mm f/3.5 (51B), Tamron SP 17mm f/3.5 (151B), SP 500mm f/8 (55BB), SP 70-210mm f/3.5 (19AH)
Vivitar 100mm 1:2.8 MC 1:1 Macro Telephoto (Kiron)
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kymarto
Joined: 30 Nov 2016
Posts: 409
Location: Portland, OR and Milan, Italy
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| Posted: Mon Jan 18, 2021 6:50 pm Post subject: |
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kymarto wrote:
There is a lot more to lens performance than raw resolution. Lens designers have to balance design for resolution vs contrast. A lens with good microcontrast will often appear better than one with higher resolution, before we even begin to talk about Seidel aberrations. There are very few situations when any viewer can actually tell any difference in raw resolution between two lenses under normal viewing conditions.
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visualopsins
Joined: 05 Mar 2009
Posts: 11067
Location: California
Expire: 2025-04-11
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| Posted: Mon Jan 18, 2021 7:00 pm Post subject: |
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visualopsins wrote:
| kymarto wrote: |
| There is a lot more to lens performance than raw resolution. Lens designers have to balance design for resolution vs contrast. A lens with good microcontrast will often appear better than one with higher resolution, before we even begin to talk about Seidel aberrations. There are very few situations when any viewer can actually tell any difference in raw resolution between two lenses under normal viewing conditions. |
Raw resolution, then, becomes an important factor under abnormal viewing conditions.
My decades old mpeg-1 videos on full HD monitor don't look quite as silly as on 8K monitor.
_________________
☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮ like attracts like! ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮
Cameras: Sony ILCE-7RM2, Spotmatics II, F, and ESII, Nikon P4
Lenses:
M42 Asahi Optical Co., Takumar 1:4 f=35mm, 1:2 f=58mm (Sonnar), 1:2.4 f=58mm (Heliar), 1:2.2 f=55mm (Gaussian), 1:2.8 f=105mm (Model I), 1:2.8/105 (Model II), 1:5.6/200, Tele-Takumar 1:5.6/200, 1:6.3/300, Macro-Takumar 1:4/50, Auto-Takumar 1:2.3 f=35, 1:1.8 f=55mm, 1:2.2 f=55mm, Super-TAKUMAR 1:3.5/28 (fat), 1:2/35 (Fat), 1:1.4/50 (8-element), Super-Multi-Coated Fisheye-TAKUMAR 1:4/17, Super-Multi-Coated TAKUMAR 1:4.5/20, 1:3.5/24, 1:3.5/28, 1:2/35, 1:3.5/35, 1:1.8/85, 1:1.9/85 1:2.8/105, 1:3.5/135, 1:2.5/135 (II), 1:4/150, 1:4/200, 1:4/300, 1:4.5/500, Super-Multi-Coated Macro-TAKUMAR 1:4/50, 1:4/100, Super-Multi-Coated Bellows-TAKUMAR 1:4/100, SMC TAKUMAR 1:1.4/50, 1:1.8/55
M42 Carl Zeiss Jena Flektogon 2.4/35
Contax Carl Zeiss Vario-Sonnar T* 28-70mm F3.5-4.5
Pentax K-mount SMC PENTAX-A ZOOM 1:3.5 35~105mm, SMC PENTAX ZOOM 1:4 45~125mm
Nikon Micro-NIKKOR-P-C Auto 1:3.5 f=55mm, NIKKOR-P Auto 105mm f/2.5 Pre-AI (Sonnar), Micro-NIKKOR 105mm 1:4 AI, NIKKOR AI-S 35-135mm f/3,5-4,5
Tamron SP 17mm f/3.5 (51B), Tamron SP 17mm f/3.5 (151B), SP 500mm f/8 (55BB), SP 70-210mm f/3.5 (19AH)
Vivitar 100mm 1:2.8 MC 1:1 Macro Telephoto (Kiron)
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kymarto
Joined: 30 Nov 2016
Posts: 409
Location: Portland, OR and Milan, Italy
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| Posted: Mon Jan 18, 2021 7:04 pm Post subject: |
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kymarto wrote:
Well, what is the resolution of your mepg-1 vids? 480x640 pixels?
I has some exhibitions a few years ago with photos taken with a 12mp Canon powers hot and a 36mp Nikon D800 with pro lenses. The photos were about 60x90cm. At a viewing distance of one meter there was no noticeable difference. If you got really close you could see a bit more detail in the Nikon images.
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visualopsins
Joined: 05 Mar 2009
Posts: 11067
Location: California
Expire: 2025-04-11
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| Posted: Mon Jan 18, 2021 7:26 pm Post subject: |
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visualopsins wrote:
| kymarto wrote: |
Well, what is the resolution of your mepg-1 vids? 480x640 pixels?
I has some exhibitions a few years ago with photos taken with a 12mp Canon powers hot and a 36mp Nikon D800 with pro lenses. The photos were about 60x90cm. At a viewing distance of one meter there was no noticeable difference. If you got really close you could see a bit more detail in the Nikon images. |
320x240, and some 240x180 wmv, stuff like that, varies...
Obviously, your example is within the range of normal viewing conditions, which has more range than expected, for now.
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☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮ like attracts like! ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮
Cameras: Sony ILCE-7RM2, Spotmatics II, F, and ESII, Nikon P4
Lenses:
M42 Asahi Optical Co., Takumar 1:4 f=35mm, 1:2 f=58mm (Sonnar), 1:2.4 f=58mm (Heliar), 1:2.2 f=55mm (Gaussian), 1:2.8 f=105mm (Model I), 1:2.8/105 (Model II), 1:5.6/200, Tele-Takumar 1:5.6/200, 1:6.3/300, Macro-Takumar 1:4/50, Auto-Takumar 1:2.3 f=35, 1:1.8 f=55mm, 1:2.2 f=55mm, Super-TAKUMAR 1:3.5/28 (fat), 1:2/35 (Fat), 1:1.4/50 (8-element), Super-Multi-Coated Fisheye-TAKUMAR 1:4/17, Super-Multi-Coated TAKUMAR 1:4.5/20, 1:3.5/24, 1:3.5/28, 1:2/35, 1:3.5/35, 1:1.8/85, 1:1.9/85 1:2.8/105, 1:3.5/135, 1:2.5/135 (II), 1:4/150, 1:4/200, 1:4/300, 1:4.5/500, Super-Multi-Coated Macro-TAKUMAR 1:4/50, 1:4/100, Super-Multi-Coated Bellows-TAKUMAR 1:4/100, SMC TAKUMAR 1:1.4/50, 1:1.8/55
M42 Carl Zeiss Jena Flektogon 2.4/35
Contax Carl Zeiss Vario-Sonnar T* 28-70mm F3.5-4.5
Pentax K-mount SMC PENTAX-A ZOOM 1:3.5 35~105mm, SMC PENTAX ZOOM 1:4 45~125mm
Nikon Micro-NIKKOR-P-C Auto 1:3.5 f=55mm, NIKKOR-P Auto 105mm f/2.5 Pre-AI (Sonnar), Micro-NIKKOR 105mm 1:4 AI, NIKKOR AI-S 35-135mm f/3,5-4,5
Tamron SP 17mm f/3.5 (51B), Tamron SP 17mm f/3.5 (151B), SP 500mm f/8 (55BB), SP 70-210mm f/3.5 (19AH)
Vivitar 100mm 1:2.8 MC 1:1 Macro Telephoto (Kiron)
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Ernst Dinkla
Joined: 30 Nov 2016
Posts: 412
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| Posted: Tue Jan 19, 2021 12:50 pm Post subject: |
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Ernst Dinkla wrote:
| kymarto wrote: |
Well, what is the resolution of your mepg-1 vids? 480x640 pixels?
I has some exhibitions a few years ago with photos taken with a 12mp Canon powers hot and a 36mp Nikon D800 with pro lenses. The photos were about 60x90cm. At a viewing distance of one meter there was no noticeable difference. If you got really close you could see a bit more detail in the Nikon images. |
I am using a 44" wide format inkjet printer, HP Z3200-PS, 12 inks. For customers and what I need myself. The whole concept of CoC, DoF, is shaken when viewing distance / eye resolution is not seen as absolute. Check how often people in a gallery go close to an image and backwards. They see another image when they return to the viewing distance. This applies to lithography, intaglio prints as well, whether abstract of figurative. Even the paper texture itself may have an influence on how we appreciate a print and not just on the haptic character of texture. So is the graduation in images, no detail there and on viewing distance it may be smooth enough but close by there could be irregularity seen. Not to mention a desire to create a kind of noise there like the grain in William Klein's images of the 60's.
Viewing distance has also an arbitrary aspect, WA images at different sizes versus Tele images at different sizes, subject distance close or far away, all that can deliver more abstraction if we do not create a display point of view in the display that more or less represents the viewing angle of the used lens/sensor combination. Of course the display size chosen can be intentional to create that effect. Bill Brandt's images come to mind.
There is another thing; today we have superior upsampling routines, sharpening routines without halo's and more refinements. 16 bit input for printers, inkjet droplet size variations, 4 to 12 ink printers, droplet weaving algorithms, GCR/UCR, excellent inkjet paper coatings. I estimate that the best prints today have a resolution that is equal to 450 PPI at the scale of the print. What we feed the printer is often way lower or higher in PPI resolution at print scale. At 180 PPI input most prints are still acceptable at viewing distance, thanks to good algorithms, not the ones in the printer driver though. I use Qimage Ultimate for that but there are better but more laborious workflows. Depending on the subject and a desire to create as much realistic information in the print you could feed that printer up to 450PPI information and that print improves in view of that intention. Printer drivers however ask for 360/720/1440 PPI or 300/600/1200 PPI, depending on the print quality setting. To create that 450PPI print image quality a printer quality setting that asks for 600 or 720 PPI input is at least needed. Inkjet printing's droplet weaving in stochastic style on paper already has an anti-aliasing effect so there is no penalty by aliasing in the print when too much information is fed.
Half the population in many countries is at an age where vision gets impaired, this process goes on. That aim at increasing print quality may not be important for them. Nevertheless I think it would not be unwise to use the 450 or 500 PPI in print as an absolute standard to relate MTF measurements to, or what the OP here tries to create a quality pixel number for lenses. It is pity that little is done on MTF measurements in prints as that would be an even better standard in relation to lens+sensor MTF measurements.
This is a route to an absolute reference number, in no way it says that a lousy lens with character should not be used or someone's creative process from scene to output should take into account a max print quality.
An older discussion on the subject: https://www.dpreview.com/forums/thread/4155685
_________________
Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
March 2017 update, 750+ inkjet media white spectral plots |
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kymarto
Joined: 30 Nov 2016
Posts: 409
Location: Portland, OR and Milan, Italy
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| Posted: Tue Jan 19, 2021 8:20 pm Post subject: |
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kymarto wrote:
Just to add to the discussion: New software algorithms like Topaz Sharpen AI and the discontinued but powerful Piccure Plus can improve sharpness and microcontrast greatly with few artifacts. I have not tested them for absolute resolution using charts, but the effects are striking.
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Vintage lens aficionado |
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visualopsins
Joined: 05 Mar 2009
Posts: 11067
Location: California
Expire: 2025-04-11
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| Posted: Wed Jan 20, 2021 1:46 am Post subject: |
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visualopsins wrote:
 https://www.discovery.com/science/mexapixels-in-human-eye
_________________
☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮ like attracts like! ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮
Cameras: Sony ILCE-7RM2, Spotmatics II, F, and ESII, Nikon P4
Lenses:
M42 Asahi Optical Co., Takumar 1:4 f=35mm, 1:2 f=58mm (Sonnar), 1:2.4 f=58mm (Heliar), 1:2.2 f=55mm (Gaussian), 1:2.8 f=105mm (Model I), 1:2.8/105 (Model II), 1:5.6/200, Tele-Takumar 1:5.6/200, 1:6.3/300, Macro-Takumar 1:4/50, Auto-Takumar 1:2.3 f=35, 1:1.8 f=55mm, 1:2.2 f=55mm, Super-TAKUMAR 1:3.5/28 (fat), 1:2/35 (Fat), 1:1.4/50 (8-element), Super-Multi-Coated Fisheye-TAKUMAR 1:4/17, Super-Multi-Coated TAKUMAR 1:4.5/20, 1:3.5/24, 1:3.5/28, 1:2/35, 1:3.5/35, 1:1.8/85, 1:1.9/85 1:2.8/105, 1:3.5/135, 1:2.5/135 (II), 1:4/150, 1:4/200, 1:4/300, 1:4.5/500, Super-Multi-Coated Macro-TAKUMAR 1:4/50, 1:4/100, Super-Multi-Coated Bellows-TAKUMAR 1:4/100, SMC TAKUMAR 1:1.4/50, 1:1.8/55
M42 Carl Zeiss Jena Flektogon 2.4/35
Contax Carl Zeiss Vario-Sonnar T* 28-70mm F3.5-4.5
Pentax K-mount SMC PENTAX-A ZOOM 1:3.5 35~105mm, SMC PENTAX ZOOM 1:4 45~125mm
Nikon Micro-NIKKOR-P-C Auto 1:3.5 f=55mm, NIKKOR-P Auto 105mm f/2.5 Pre-AI (Sonnar), Micro-NIKKOR 105mm 1:4 AI, NIKKOR AI-S 35-135mm f/3,5-4,5
Tamron SP 17mm f/3.5 (51B), Tamron SP 17mm f/3.5 (151B), SP 500mm f/8 (55BB), SP 70-210mm f/3.5 (19AH)
Vivitar 100mm 1:2.8 MC 1:1 Macro Telephoto (Kiron)
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Ernst Dinkla
Joined: 30 Nov 2016
Posts: 412
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| Posted: Wed Jan 20, 2021 12:26 pm Post subject: |
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Ernst Dinkla wrote:
https://plex.page/The_Equivalent_Megapixels_Of_The_Human_Eye
for international members.
_________________
Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
March 2017 update, 750+ inkjet media white spectral plots |
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pandreas68
Joined: 24 Jan 2020
Posts: 96
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| Posted: Sun Jan 24, 2021 5:33 pm Post subject: |
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pandreas68 wrote:
| Ernst Dinkla wrote: |
https://plex.page/The_Equivalent_Megapixels_Of_The_Human_Eye
for international members. |
Thanks for the link! Is there a conclusion?
I hope that I understood everything in the posts before as non native English speaker.
So far I understand some of you are professional photographers. For myself I am a hobby-fotographer who has some old lenses, many of them since a long time when I was a student which I'd still like to use. Many of them from Zeiss Jena for the Pentacon Six and the Praktica BC1.
Being an electrical engineer I thought before using them more serious on a digital camera I should make some calculations. First I started in this thread with thinking which sharpness I may expect from these lenses on different sensor formats, so that I am not disappointed using these lenses. Since I do not have MTFs from those lenses I simply assumed that they at least fulfill the CoC requirement of the respective original film format.
My newer post was now about how to use them to achieve best possible quality. I forgot to write that I use them now on a Sony Alpha II, so a full format sensor.
Does it make sense to stick with the to my knowledge 1500 lines per diagonal and thus with the circle of confusion as originally defined? Zeiss states, that the human eye can distiguish 1600 lp/picture height.
http://userfiles.rf-webworld.de/ec8e1dcc-6735-4d5f-9900-7320e47a7e43/Dokumente/Sonstige/cln30_de_web_special_mtf_01.pdf
http://evtifeev.com/wp-content/files/manual/cln__30_mtf_kurven_en.pdf
Does this make sense and to calculate the CoC from this which would result in a much smaller CoC than usually used for the different sensor formats?
How to work then with depth of field (and its scales) on the old lenses?
From my current practical experience I'd say that I am more than satiesfied with a CoC of about 0.015mm for full format so that crops are possible - on the other hand this reduces the achievable depth of field. Playing with this I found that at least on some lenses from German Democratic Republic, The depth of field scales are not calculated to the "official" CoC of the respective film format but a bigger diameter.
Best regards
Andreas
PS: In my last post series I thought that I could come at least to any link between these thoughts and the MTFs but somehow I got stuck in my findings by that the lens provider use different definitions and sometimes it is even not clear for me whether they use lines or linepairs, though for my taste the latter make more sense though for advertisement the lines may make more sense. Thats why I stopped to write... |
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pandreas68
Joined: 24 Jan 2020
Posts: 96
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| Posted: Sun Jan 24, 2021 6:29 pm Post subject: |
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pandreas68 wrote:
| Ernst Dinkla wrote: |
Half the population in many countries is at an age where vision gets impaired, this process goes on. That aim at increasing print quality may not be important for them. Nevertheless I think it would not be unwise to use the 450 or 500 PPI in print as an absolute standard to relate MTF measurements to, or what the OP here tries to create a quality pixel number for lenses. It is pity that little is done on MTF measurements in prints as that would be an even better standard in relation to lens+sensor MTF measurements.
This is a route to an absolute reference number, in no way it says that a lousy lens with character should not be used or someone's creative process from scene to output should take into account a max print quality.
An older discussion on the subject: https://www.dpreview.com/forums/thread/4155685 |
Dear Ernst, I am not sure whether I got you right. especially I wonder for which print size you'd suggenst the 450 ppi. Generally? But if generally how then to map this to a lens reolution if the sensor format is fixed?
Best regards
Andreas |
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Ernst Dinkla
Joined: 30 Nov 2016
Posts: 412
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| Posted: Mon Jan 25, 2021 9:18 am Post subject: |
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Ernst Dinkla wrote:
Andreas,
The discussion I gave a link to shows quite well that this is complex field to explore. I am more interested in the data of print quality that would add to the total chain of reproduction quality. Replacing MTF measurements of lenses with what looks to me as a simpler but less telling rating is not something I am interested in.
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Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
March 2017 update, 750+ inkjet media white spectral plots |
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Ernst Dinkla
Joined: 30 Nov 2016
Posts: 412
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| Posted: Mon Jan 25, 2021 12:47 pm Post subject: |
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Ernst Dinkla wrote:
| pandreas68 wrote: |
| Ernst Dinkla wrote: |
Half the population in many countries is at an age where vision gets impaired, this process goes on. That aim at increasing print quality may not be important for them. Nevertheless I think it would not be unwise to use the 450 or 500 PPI in print as an absolute standard to relate MTF measurements to, or what the OP here tries to create a quality pixel number for lenses. It is pity that little is done on MTF measurements in prints as that would be an even better standard in relation to lens+sensor MTF measurements.
This is a route to an absolute reference number, in no way it says that a lousy lens with character should not be used or someone's creative process from scene to output should take into account a max print quality.
An older discussion on the subject: https://www.dpreview.com/forums/thread/4155685 |
Dear Ernst, I am not sure whether I got you right. especially I wonder for which print size you'd suggenst the 450 ppi. Generally? But if generally how then to map this to a lens reolution if the sensor format is fixed?
Best regards
Andreas |
Would it not be simpler to state that a certain lens/sensor MTF result is good for a specific size print with 450ppi information? And forget about viewing distance etc. Of course the ideal solution would be a transfer function covering the whole chain from test target shot to print.
Whether a print is still relevant as output is another question. For me I am quite happy with MTF graphs to get an idea of a lens/sensor combination. I would like the extension of that to the max quality possible in a print and not a simplification of the lens/sensor combination measurement.
_________________
Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
March 2017 update, 750+ inkjet media white spectral plots |
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pandreas68
Joined: 24 Jan 2020
Posts: 96
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| Posted: Mon Jan 25, 2021 6:16 pm Post subject: |
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pandreas68 wrote:
Which specific size of print would you suggest to support with 450ppi, Ernst? |
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Ernst Dinkla
Joined: 30 Nov 2016
Posts: 412
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| Posted: Tue Jan 26, 2021 1:26 pm Post subject: |
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Ernst Dinkla wrote:
| pandreas68 wrote: |
| Which specific size of print would you suggest to support with 450ppi, Ernst? |
A specific size per MTF testing result, so not a fixed size. So a small size print with a mediocre vintage lens on an old Olympus E-PL1 with M4/3 sensor. There is probably nowhere an MTF made for that combination and there is also no algorithm yet for linking that transfer function to a digital image<>print transfer function, not to mention an MTF for the total chain. Anyway a modern larger and better sensor with more pixels + a modern native lens will allow a larger print.
You could read some articles written by Norman Koren, this is more than a decade old and could use an update as technology in cameras, printers, paper coatings, improved again: https://www.imatest.com/support/docs/5-2/sharpness/interpreting-mtf50/ Last lines could be interesting for you.
on SQF:
https://www.imatest.com/docs/sqf/
If I could understand all that is written on Norman Koren's pages I might think of making my own solution for this all, I simply can't. I will not contribute further here as I am also not that interested in what you propose.
An H.L. Mencken quote "For every complex problem there is an answer that is clear, simple, and wrong."
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Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
March 2017 update, 750+ inkjet media white spectral plots |
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pandreas68
Joined: 24 Jan 2020
Posts: 96
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| Posted: Tue Jan 26, 2021 4:23 pm Post subject: |
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pandreas68 wrote:
Thanks Ernst for the links.
Yes it is not that easy. Maybe I missunderstood you with the 450ppi. I thought you mean it directly as print resolution.
I guess I need to find some more time to think about; I will start with https://www.imatest.com/support/docs/5-2/sharpness/interpreting-mtf50/
So far I understand with not too much of additional thinking and thus the strong risk of making a mistake is that the 150 line withs/inch in the left column actually is the print resolution. And the example with the EOS 10 D with coming from 2048Px picture hight when printing on 12.3inch high paper results in 167 dpi print resulution which is seen as high print resolution. This results in the sentence: "There’s little reason go to a 12+ megapixel camera likie the EOS 5D, unless you plan to print larger" which I can support from both my observations and calculations. So my Sony Alpha II is usually switched to 10MPx, but I have no professional requirements. A3 paper size is maybe too small for professional application and/or if stronger crops are required.
"MTF50" of 150lines/inch I would interpret, that 150lines per inch are assumed, if its transfer function is 50%. The problem with calculating this down to pixel resolution of lenses and MTFs may be that digital pictures always somehow interpolate some three pixels in one dimension, but for this issue there may be those algorithms mentioned above. If we use now the 2048 on a sensor height of 24mm then we achieve some 2048/24 = 85 lines/mm respectively some 40lp/mm. I guess there are some vintage lenses which deliver 40lp/mm with a MTF at or better than 50.
Vintage lenses: When trying to take vintage style photographs, for my taste somehow also the original rules of taking pictures somehow need to be applied; but this requires that the old theory still holds true which somehow hardly relies on the diameter of the circle of confusion (CoC). Since the 80ies however when the MTF charts got chick there were some hobby photographers which looked upon their negative film stripes or slides with some 10x magnifiers, but not using anymore the depth of field in their pictures because they hunted for absolute sharpness.
So maybe there is a need to come to new definitions of CoC, or even different sets of CoC for different applications.
Best regards, Andreas
Last edited by pandreas68 on Tue Jan 26, 2021 5:36 pm; edited 1 time in total |
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