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Pancolart
Joined: 04 Feb 2008 Posts: 3702 Location: Slovenia, EU
Expire: 2013-11-18
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Posted: Fri Feb 24, 2012 8:07 pm Post subject: Connection between speed of lens and DOF |
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Pancolart wrote:
I am sure this is well explained somewhere but i'd like to point to specific question. F-number means evaluation of how much light intensity is delivered to the focal plane. But does it strictly say anything about DOF?
I will exaggerate: you can have a F2.0 fast lens that gives you wide (deep) DOF like F8.0 lens. On the other hand you can have F4.0 slow lens that has thin DOF like F2.0 lens. Is that possible?
I know there are differences in DOF with different 2.8/28mm lenses. I guess it is a product of optical design. It's definetly harder to achieve thin DOF when object is far. Any similar experiences? _________________ ---------------------------------
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hoacker
Joined: 01 May 2011 Posts: 89 Location: Germany, S�dhessen
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Posted: Fri Feb 24, 2012 8:57 pm Post subject: |
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hoacker wrote:
DOF depends on focal length, aperture, focussing distance and "circle of confusion", but NOT on the optical design.
See:
Wikipedia: Depth of field
DOF-Calculator _________________ Holger
Cameras: Canon EOS 5D, 7D, 1000Da, M
Manual lenses: Zeiss Distagon 3,5/18 ZE, Nikon PC-Nikkor 28mm 1:3.5, Olympus OM 28 f/2,0, Zeiss Distagon 2/35 ZE, Leitz Summicron-R 1:2/50, Minolta MC ROKKOR 1:1.2 f=58mm (EOS-Mod), LZOS MC Jupiter-9 2/85, Meyer-Optik G�rlitz Trioplan 1:2.8/100 V (Exa), Zeiss Macro Planar 2/100 ZE, Nikon Nikkor-P.C Auto 1:2.5 f=105mm, Schneider-Kreuznach Componar 1:4,5/105, Porst Tele 1:1,8/135mm MC AUTO (M42), Cosina Auto Cosinon 135mm/2.8 (M42), Makinon MC 1:5.6 300mm Reflex, LZOS MTO 1000A 10,5/1100
AF lenses: Canon EF-S 17-55 f/2,8 IS USM, Canon EF-M 22mm 1:2 STM, Canon EF 40 f/2,8 STM, Canon EF-S 60 f/2,8 USM, Canon EF 200 1:2.8L II USM, Canon EF 500 f/4L IS USM, Canon Extender 1,4x III, Sigma 50-150/2,8 EX DC APO HSM II, Sigma 150 f/2,8 HSM, Sigma APO Tele Converter 1.4x EX DG, Sigma APO Tele Converter 2x EX DG, Kenko Extension Tubes
For sale (PM me): E.Zuiko Auto-T 1:3,5 f=100mm (Pen F), Zeiss Planar 85 f/1,4 (C/Y)
Some pictures at Flickr |
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atomstitcher
Joined: 26 Nov 2011 Posts: 67 Location: Oxford, England
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Posted: Fri Feb 24, 2012 9:01 pm Post subject: |
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atomstitcher wrote:
I'm not sure I quite understand your question, but here goes.
Depth of field is a product of three things: focal length, aperture and focal distance. These are physical laws. As I understand it, any perceived difference in DOF between lenses where all three factors are nominally identical can only be due to slight variations in the true focal length, aperture calibration, rendering characteristics of the lens and so on. In practice I cant see this making much more than a tiny difference.
edit: was typing this during the above reply. |
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Ymmot
Joined: 24 Sep 2011 Posts: 168
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Posted: Fri Feb 24, 2012 9:10 pm Post subject: |
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Ymmot wrote:
I am certainly not an expert, however as circle of confusion also seems to be affected by lens properties (see for instance http://en.wikipedia.org/wiki/Spherical_aberration) this (and with it depth of field) would be affected to some degree by lens design/glass type? |
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hoacker
Joined: 01 May 2011 Posts: 89 Location: Germany, S�dhessen
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Posted: Fri Feb 24, 2012 9:18 pm Post subject: |
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hoacker wrote:
Ymmot wrote: |
however as circle of confusion also seems to be affected by lens properties |
No, not at all. The circle of confusion in this context is the "amount of unsharpness" that is perceived as sharp. A point out of the focal plane becomes a circle on the image. Depending on image output/printing size and viewing distance these circles may still be perceived as sharp points.
See:
Wikipedia: Circle of confusion _________________ Holger
Cameras: Canon EOS 5D, 7D, 1000Da, M
Manual lenses: Zeiss Distagon 3,5/18 ZE, Nikon PC-Nikkor 28mm 1:3.5, Olympus OM 28 f/2,0, Zeiss Distagon 2/35 ZE, Leitz Summicron-R 1:2/50, Minolta MC ROKKOR 1:1.2 f=58mm (EOS-Mod), LZOS MC Jupiter-9 2/85, Meyer-Optik G�rlitz Trioplan 1:2.8/100 V (Exa), Zeiss Macro Planar 2/100 ZE, Nikon Nikkor-P.C Auto 1:2.5 f=105mm, Schneider-Kreuznach Componar 1:4,5/105, Porst Tele 1:1,8/135mm MC AUTO (M42), Cosina Auto Cosinon 135mm/2.8 (M42), Makinon MC 1:5.6 300mm Reflex, LZOS MTO 1000A 10,5/1100
AF lenses: Canon EF-S 17-55 f/2,8 IS USM, Canon EF-M 22mm 1:2 STM, Canon EF 40 f/2,8 STM, Canon EF-S 60 f/2,8 USM, Canon EF 200 1:2.8L II USM, Canon EF 500 f/4L IS USM, Canon Extender 1,4x III, Sigma 50-150/2,8 EX DC APO HSM II, Sigma 150 f/2,8 HSM, Sigma APO Tele Converter 1.4x EX DG, Sigma APO Tele Converter 2x EX DG, Kenko Extension Tubes
For sale (PM me): E.Zuiko Auto-T 1:3,5 f=100mm (Pen F), Zeiss Planar 85 f/1,4 (C/Y)
Some pictures at Flickr |
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spoilerhead
Joined: 25 Jan 2012 Posts: 68 Location: Austria
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Posted: Fri Feb 24, 2012 9:58 pm Post subject: |
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spoilerhead wrote:
Well, the F-Stop actually specified the DOF (in context of focal length of course)
but the T-Stop actually gives the speed (i.e. light on the focal plane), but it's usually not specified for photographic lenses as it's quite close anyways. Cine lenses usually get a T-stop rating
http://en.wikipedia.org/wiki/T-stop#T-stops
--> F-Stop defines the look, T-stop the speed. _________________ Eos (A/D) + M42 |
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Nesster
Joined: 24 Apr 2008 Posts: 5883 Location: NJ, USA
Expire: 2014-02-20
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Posted: Fri Feb 24, 2012 10:07 pm Post subject: |
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Nesster wrote:
In that aberrations affect the perceived image, yes, they may affect what we see as 'in focus'. If the most-in-focus point is not incredibly sharp, it may not be as distinguishable from the nearly-in-focus?
One common situation is with e.g. wide angle lenses when we're going for extreme DOF: we trade some absolute sharpness (due to diffraction) for the greater depth of perceived sharpness... quality for quantity.
This is of course in perceptual, utilitarian, terms, not in precise optical ones (i.e. I'm not overthrowing optics here ) _________________ -Jussi
Camera photos
Print Photographica
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hoanpham
Joined: 31 Jan 2011 Posts: 2575
Expire: 2015-01-18
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Posted: Fri Feb 24, 2012 10:29 pm Post subject: |
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hoanpham wrote:
Tilt (changing focus plan) makes the DOF seem thicker.
nikkor 35/1.4 at f1.4, about 60cm distance:
nikkor 35/1.4 at f1.4, about 40-45cm distance:
_________________ La migliore cura di LBA � imparare una nuova lingua. Le meilleur rem�de de LBA est d'apprendre une nouvelle langue. La mejor cura del LBA es aprender una nueva lengua. |
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Pancolart
Joined: 04 Feb 2008 Posts: 3702 Location: Slovenia, EU
Expire: 2013-11-18
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Posted: Fri Feb 24, 2012 10:46 pm Post subject: |
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Pancolart wrote:
One has to distinguish the result and how (with what) this result is achieved. You can say to have 2m of sharp area / DOF; after and before that it slowly degrades (circle of confusion), using 28mm lens (angle of view) and at the focal distance of 5m. Plus F2.8 (absolute value).
But using some other 2.8/28mm lens wide-open, and at focal distance 5m, you get 3m thick DOF. That is 1m deeper then previous lens. I think it's possible. Is it? Why? Lens properties has to be the factor. _________________ ---------------------------------
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hoacker
Joined: 01 May 2011 Posts: 89 Location: Germany, S�dhessen
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Posted: Fri Feb 24, 2012 10:57 pm Post subject: |
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hoacker wrote:
Pancolart wrote: |
You can say to have 2m of sharp area [..] But using some other 2.8/28mm lens wide-open, and at focal distance 5m, you get 3m thick DOF. [..] I think it's possible. Is it? Why? Lens properties has to be the factor. |
No, this is not possible if you use the same camera (film/sensor size) and same image output size. The lens design itself has no influence on DOF (unless you count lens flaws on the DOF side). _________________ Holger
Cameras: Canon EOS 5D, 7D, 1000Da, M
Manual lenses: Zeiss Distagon 3,5/18 ZE, Nikon PC-Nikkor 28mm 1:3.5, Olympus OM 28 f/2,0, Zeiss Distagon 2/35 ZE, Leitz Summicron-R 1:2/50, Minolta MC ROKKOR 1:1.2 f=58mm (EOS-Mod), LZOS MC Jupiter-9 2/85, Meyer-Optik G�rlitz Trioplan 1:2.8/100 V (Exa), Zeiss Macro Planar 2/100 ZE, Nikon Nikkor-P.C Auto 1:2.5 f=105mm, Schneider-Kreuznach Componar 1:4,5/105, Porst Tele 1:1,8/135mm MC AUTO (M42), Cosina Auto Cosinon 135mm/2.8 (M42), Makinon MC 1:5.6 300mm Reflex, LZOS MTO 1000A 10,5/1100
AF lenses: Canon EF-S 17-55 f/2,8 IS USM, Canon EF-M 22mm 1:2 STM, Canon EF 40 f/2,8 STM, Canon EF-S 60 f/2,8 USM, Canon EF 200 1:2.8L II USM, Canon EF 500 f/4L IS USM, Canon Extender 1,4x III, Sigma 50-150/2,8 EX DC APO HSM II, Sigma 150 f/2,8 HSM, Sigma APO Tele Converter 1.4x EX DG, Sigma APO Tele Converter 2x EX DG, Kenko Extension Tubes
For sale (PM me): E.Zuiko Auto-T 1:3,5 f=100mm (Pen F), Zeiss Planar 85 f/1,4 (C/Y)
Some pictures at Flickr |
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sichko
Joined: 20 Jun 2008 Posts: 2475 Location: South West UK
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Posted: Fri Feb 24, 2012 11:53 pm Post subject: Re: Connection between speed of lens and DOF |
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sichko wrote:
Pancolart wrote: |
I know there are differences in DOF with different 2.8/28mm lenses. |
Do you have particular examples in mind ?
Quote: |
I guess it is a product of optical design. |
DOF calculations assume a flat field. In practice lenses might have curved fields, with two different lenses having different degrees of curvature. Field curvature will reduce DOF so these two lenses will, under similar conditions, give different DOFs. I don't know how big the difference might be. However, for example, the Nikon Nikkor 28mm f/2.8 Ais is often reported as not being suitable for landscapes because of softening, in the corners, attributed to to field curvature. The Nikkor 28 mm f/3.5 Ai(s) is thought to be more suitable - presumably due to its flatter field. _________________ John |
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Pancolart
Joined: 04 Feb 2008 Posts: 3702 Location: Slovenia, EU
Expire: 2013-11-18
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Posted: Sat Feb 25, 2012 12:14 pm Post subject: |
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Pancolart wrote:
I opened this topic due to my experience with PB Prakticar 2.8/28mm. When shooting i remember checking many times if aperture didn't close accidentally so very deep DOF it seemed after i crossed 1m focusing barrier.
Finally i can show my assumptions make sense: Yashica DSB 2.8/28mm & PETRI (Cosina) 2.8/28mm & Prakticar 2.8/28mm with it's DOF scale.
You can see how much DOF you will get with the same adjustments of focus and aperture. It's way different.
Yashica & PETRI
Prakticar & Yashica
With selected aperture F8.0 and focusing distance 2m (the same on all lenses) you will get approximate DOF values:
PETRI: 1.75m - 2.3m = 55cm
YASHICA: 1.2m - 4.2m = 3m
Prakticar: 1.2m - infinity = very deep _________________ ---------------------------------
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hoacker
Joined: 01 May 2011 Posts: 89 Location: Germany, S�dhessen
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Posted: Sat Feb 25, 2012 2:16 pm Post subject: |
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hoacker wrote:
Pancolart wrote: |
With selected aperture F8.0 and focusing distance 2m (the same on all lenses) you will get approximate DOF values:
PETRI: 1.75m - 2.3m = 55cm
YASHICA: 1.2m - 4.2m = 3m
Prakticar: 1.2m - infinity = very deep |
A DOF calculator gives the following for 28mm, F8, 2m distance:
Near limit 1.25 m
Far limit 5.05 m
Total 3.8 m
This is about what the yashica and prakticar show.
For me It looks like the petri has the dof scale of a 50mm lens:
Near limit 1.68 m
Far limit 2.46 m
Total 0.78 m _________________ Holger
Cameras: Canon EOS 5D, 7D, 1000Da, M
Manual lenses: Zeiss Distagon 3,5/18 ZE, Nikon PC-Nikkor 28mm 1:3.5, Olympus OM 28 f/2,0, Zeiss Distagon 2/35 ZE, Leitz Summicron-R 1:2/50, Minolta MC ROKKOR 1:1.2 f=58mm (EOS-Mod), LZOS MC Jupiter-9 2/85, Meyer-Optik G�rlitz Trioplan 1:2.8/100 V (Exa), Zeiss Macro Planar 2/100 ZE, Nikon Nikkor-P.C Auto 1:2.5 f=105mm, Schneider-Kreuznach Componar 1:4,5/105, Porst Tele 1:1,8/135mm MC AUTO (M42), Cosina Auto Cosinon 135mm/2.8 (M42), Makinon MC 1:5.6 300mm Reflex, LZOS MTO 1000A 10,5/1100
AF lenses: Canon EF-S 17-55 f/2,8 IS USM, Canon EF-M 22mm 1:2 STM, Canon EF 40 f/2,8 STM, Canon EF-S 60 f/2,8 USM, Canon EF 200 1:2.8L II USM, Canon EF 500 f/4L IS USM, Canon Extender 1,4x III, Sigma 50-150/2,8 EX DC APO HSM II, Sigma 150 f/2,8 HSM, Sigma APO Tele Converter 1.4x EX DG, Sigma APO Tele Converter 2x EX DG, Kenko Extension Tubes
For sale (PM me): E.Zuiko Auto-T 1:3,5 f=100mm (Pen F), Zeiss Planar 85 f/1,4 (C/Y)
Some pictures at Flickr |
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sichko
Joined: 20 Jun 2008 Posts: 2475 Location: South West UK
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Posted: Sat Feb 25, 2012 2:36 pm Post subject: |
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sichko wrote:
In the first picture, the lens on the left (Yashica) is set at 2 meters, whereas the lens on the right (PETRI) appears to be set at 2 feet.
EDIT In the second picture the scales are similar if not identical. Maybe it's possible that the two manufacturers (one Japanese, one German) used different values for the Circle of Confusion (CoC) when calculating the scales. Remember that the CoC is somewhate arbitrary. If you do a search you will find debates about which value to use. _________________ John
Last edited by sichko on Sat Feb 25, 2012 2:44 pm; edited 2 times in total |
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hoacker
Joined: 01 May 2011 Posts: 89 Location: Germany, S�dhessen
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Posted: Sat Feb 25, 2012 2:38 pm Post subject: |
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hoacker wrote:
sichko wrote: |
In the first picture, the lens on the left (Yashica) is set at 2 meters, whereas the lens on the right (PETRI) appears to be set at 2 feet. |
Good point! DOF for 2 ft distance:
Near limit 1.84 ft
Far limit 2.2 ft
Total 0.36 ft _________________ Holger
Cameras: Canon EOS 5D, 7D, 1000Da, M
Manual lenses: Zeiss Distagon 3,5/18 ZE, Nikon PC-Nikkor 28mm 1:3.5, Olympus OM 28 f/2,0, Zeiss Distagon 2/35 ZE, Leitz Summicron-R 1:2/50, Minolta MC ROKKOR 1:1.2 f=58mm (EOS-Mod), LZOS MC Jupiter-9 2/85, Meyer-Optik G�rlitz Trioplan 1:2.8/100 V (Exa), Zeiss Macro Planar 2/100 ZE, Nikon Nikkor-P.C Auto 1:2.5 f=105mm, Schneider-Kreuznach Componar 1:4,5/105, Porst Tele 1:1,8/135mm MC AUTO (M42), Cosina Auto Cosinon 135mm/2.8 (M42), Makinon MC 1:5.6 300mm Reflex, LZOS MTO 1000A 10,5/1100
AF lenses: Canon EF-S 17-55 f/2,8 IS USM, Canon EF-M 22mm 1:2 STM, Canon EF 40 f/2,8 STM, Canon EF-S 60 f/2,8 USM, Canon EF 200 1:2.8L II USM, Canon EF 500 f/4L IS USM, Canon Extender 1,4x III, Sigma 50-150/2,8 EX DC APO HSM II, Sigma 150 f/2,8 HSM, Sigma APO Tele Converter 1.4x EX DG, Sigma APO Tele Converter 2x EX DG, Kenko Extension Tubes
For sale (PM me): E.Zuiko Auto-T 1:3,5 f=100mm (Pen F), Zeiss Planar 85 f/1,4 (C/Y)
Some pictures at Flickr |
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ForenSeil
Joined: 15 Apr 2011 Posts: 2726 Location: Kiel, Germany.
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Posted: Sat Feb 25, 2012 4:00 pm Post subject: |
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ForenSeil wrote:
The transition of sharp and unsharp is with some lenses very harsh while with others it's very smooth causing a sligthly wider looking DOF. This has something to do with the bokeh which depends on the optical design. _________________ I'm not a collector, I'm a tester
My camera: Sony A7+Zeiss Sonnar 55/1.8
Current favourite lenses (I have many more):
A few macro-Tominons, Samyang 12/2.8, Noritsu 50.7/9.5, Rodagon 105/5.6 on bellows, Samyang 135/2, Nikon ED 180/2.8, Leitz Elmar-R 250/4, Celestron C8 2000mm F10
Most wanted: Samyang 24/1.4, Samyang 35/1.4, Nikon 200/2 ED
My Blog: http://picturechemistry.own-blog.com/
(German language) |
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AhamB
Joined: 22 Jun 2008 Posts: 733 Location: Germany
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Posted: Sat Feb 25, 2012 4:10 pm Post subject: |
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AhamB wrote:
The circle of confucion depends on the magnification/display size of the captured image, so in that sense you could say that DOF does depend on optical design, because different designs can have very different amounts of background blur and rate of focus transition. For example, the Zeiss Makro-Planar has been shown to have significantly less background blur than the Planar 50/1.4 at the same apertures. In web sized images, the DOF of the Planar definitely looks more shallow, because it has a faster focus transition.
Edit: So I agree with Forenseil. |
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visualopsins
Joined: 05 Mar 2009 Posts: 10959 Location: California
Expire: 2025-04-11
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Posted: Sat Feb 25, 2012 4:56 pm Post subject: |
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visualopsins wrote:
ForenSeil wrote: |
The transition of sharp and unsharp is with some lenses very harsh while with others it's very smooth causing a sligthly wider looking DOF. This has something to do with the bokeh which depends on the optical design. |
+1 my thinking too. I still wonder about effect similarity to focal length change -- perhaps two 28mm lenses are really 27.5mm and 28.4mm, to account for different dof measurement.
Field curvature can cause dof measurement error -- dof is same for both lenses, but in the region measured, the two dof are not in the same place. _________________ ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮ 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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Pancolart
Joined: 04 Feb 2008 Posts: 3702 Location: Slovenia, EU
Expire: 2013-11-18
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Posted: Sat Feb 25, 2012 9:03 pm Post subject: |
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Pancolart wrote:
Sorry about Petri mistake. Darn. It seemed too easy to be true. I'll check other 28mm tomorrow. And then give up my case . _________________ ---------------------------------
The Peculiar Apparatus Of Victorian Steampunk Photography: 100+ Genuine Steampunk Camera Designs https://www.amazon.com/dp/B0B92829NS |
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AhamB
Joined: 22 Jun 2008 Posts: 733 Location: Germany
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Posted: Sun Feb 26, 2012 1:02 pm Post subject: |
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AhamB wrote:
visualopsins wrote: |
I still wonder about effect similarity to focal length change -- perhaps two 28mm lenses are really 27.5mm and 28.4mm, to account for different dof measurement.
Field curvature can cause dof measurement error -- dof is same for both lenses, but in the region measured, the two dof are not in the same place. |
The Zeiss MP50/2 is 51.6mm and the P50/1.4 is 51.7mm, so no significant difference in my example of these lenses. Field curvature has an effect but not in the center, only near the edges and in the corners.
Anyway, I wasn't talking about DOF "measurement" -- the images from these lenses can look radically different w.r.t. background blur and perceived DOF. |
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