View previous topic :: View next topic |
Author |
Message |
rbelyell
Joined: 13 Oct 2009 Posts: 4269 Location: somewhere in the mountains of central NY
Expire: 2014-01-31
|
Posted: Mon Aug 15, 2011 9:30 pm Post subject: how to compute medium format lens FL in 35mm terms? |
|
|
rbelyell wrote:
in reading about medium format lenses, their focal lengths are often described in 35mm terms to make their field of view more generally understandable. for example, an 80mm lens for a 6x6 cam is often referred to as 'like a 50mm lens' used on a 35mm cam. this same lens on a 6x9 cam would be 'something like a35mm lens' on your 35mm film cam.
my question is does anyone know the formula for computing the 35mm FOV equivalent for lenses used on medium format cams? with so many different size MF cams--6x6, 6x7, 6x8, 6x8 and even 6x12 and 6x17--i think it would be helpful to know how to interpret different lenses used on these systems in the 35mm terms with which we are most familiar.
any light anyone can shed on this would be appreciated!
tony _________________ Epson RD1 + Elmarit 21/2.8; Summarit 50/1.5; Summarit 75/2.5; Elmar-c 90/4; Sankyo Komura 135/2.8, Hektor 135/4.5; Braun Paxina 29 6x6; Photax Boyer Paris; Holga 120 Pano
GREAT STUFF FOR SALE:
Contax T
Hasselblad XPan + 45/4, 90/4
Kodak Retina Reflex IV + full set of Schneider Krueznach lenses
Mercury 2 half frame 35mm
Kodak Pro slr/n
Fuji GM670+100/3.5+65/8!
Praktisix 6x6 medium format + ZeissBiometar 120/2.8
Bessa T 101 Anniversary Edition in Navy Blue
Mamiya Six Folder with Zuiko 75/3.5
Adaptall: Tamron SP 28-85 macro
Cameras: Canon IX
PM for more complete descriptions/pix. All in great shape!
_________________________
'buy me a drink, sing me a song,
take me as i come 'cause i can't stay long' |
|
Back to top |
|
|
Orio
Joined: 24 Feb 2007 Posts: 29545 Location: West Emilia
Expire: 2012-12-04
|
Posted: Mon Aug 15, 2011 9:40 pm Post subject: |
|
|
Orio wrote:
I don't have a scientific formula, only a practical one for 6x6
Divide by 1.6 the MF focal lenght to obtain the SF equivalent.
Example:
80mm : 1.6 = 50mm
45mm : 1.6 = 28,1 mm
hope this helps _________________ Orio, Administrator
T*
NE CEDE MALIS AUDENTIOR ITO
Ferrania film is reborn! http://www.filmferrania.it/
Support the Ornano film chemicals company and help them survive!
http://forum.mflenses.com/ornano-chemical-products-t55525.html |
|
Back to top |
|
|
visualopsins
Joined: 05 Mar 2009 Posts: 10543 Location: California
Expire: 2025-04-11
|
Posted: Mon Aug 15, 2011 10:44 pm Post subject: |
|
|
visualopsins wrote:
Crop factor is simply the ratio of the diagonal lengths of two formats.
Remember Pythagoras' Theorem, for a rectangle the diagonal is the square root of the sum of the squared lengths of two adjacent sides.
=============================================
For APS-C of 15.7mm x 23.7mm, is 15.7^2 + 23.7^2 = 808 and 808^0.5 = 28.4mm diagonal
For FF/35mm of 24mm x 36mm, is 24^2 + 36^2 = 1872 and 1872^0.5 = 43.3mm diagonal
So, for APS-C compared to FF/35mm is 43.3 / 28.4 = 1.53 crop factor.
=============================================
For 6x6 of 60mm x 60mm, is 60^2 +60^2 = 7200 and 7200^0.5 = 84.8mm diagonal.
So, for FF/35mm compared to 6x6 is 84.8 / 43.3 = 1.96 crop factor. _________________ ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮ 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 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 (51BB), SP 500mm f/8 (55BB), SP 70-210mm f/3.5 (19AH)
Vivitar 100mm 1:2.8 MC 1:1 Macro Telephoto (Kiron)
|
|
Back to top |
|
|
ludoo
Joined: 18 Sep 2009 Posts: 1397 Location: Milan, Italy
Expire: 2011-12-05
|
Posted: Tue Aug 16, 2011 5:58 am Post subject: |
|
|
ludoo wrote:
For square formats, just multiply one side by 1.41 _________________ My galleries
Digital: Samsung EX-1
Past Digital: Samsung NX10, Sigma SD9, Sigma SD10, SD14, DP2, Pentax *istD, Kx, Fuji S2 Pro, Canon 5D
Analog: packfilm Polaroids, 6x9 Kodak folders, Pentacon Taxona half-frame, Fujica ST605n, Walz Envoy, Olympus 35 S-II, Olympus Wide S
Past Analog: Polaroid 600se, Polaroid 110B, Canon IIF, various fixed-lens and Russian rangefinders, ...
Past Lenses: Nikkor 24/2.8, Nikkor SC 50/1.4, Nikkor 50/2, Nikkor H 85/1.8, Nikkor P 105/2.5, Nikkor Q 135/3.5, Fujinon 100/2.8, Fujinon EBC 100/2.8, Fujinon EBC 135/3.5, Fujinon EBC 200/4.5, Mamiya SX 135/2.8, CZJ Flektogon 35/2.4, CZJ Pancolar 50/1.8 zebra, CZJ Sonnar 135/3.5, ...
altroformato
|
|
Back to top |
|
|
rbelyell
Joined: 13 Oct 2009 Posts: 4269 Location: somewhere in the mountains of central NY
Expire: 2014-01-31
|
Posted: Tue Aug 16, 2011 2:08 pm Post subject: |
|
|
rbelyell wrote:
thanks to all, but it seems we have a pretty big discrepancy even with one format, 6x6. orio says the crop factor is 1.6, V says its 1.9 and ludoo says its 1.4!
because i am not comfortable with math generally, i have a very healthy respect for it and i do actually (to my surprise) understand the mathematical underpinnings of V's equation. orio and ludoo, how do you each feel about your crop factors in light of V's math equations? it basically changes orio's 80>50 to 80>43mm. it would obviously have a bigger impact on ludoo's method of determining equivalence. _________________ Epson RD1 + Elmarit 21/2.8; Summarit 50/1.5; Summarit 75/2.5; Elmar-c 90/4; Sankyo Komura 135/2.8, Hektor 135/4.5; Braun Paxina 29 6x6; Photax Boyer Paris; Holga 120 Pano
GREAT STUFF FOR SALE:
Contax T
Hasselblad XPan + 45/4, 90/4
Kodak Retina Reflex IV + full set of Schneider Krueznach lenses
Mercury 2 half frame 35mm
Kodak Pro slr/n
Fuji GM670+100/3.5+65/8!
Praktisix 6x6 medium format + ZeissBiometar 120/2.8
Bessa T 101 Anniversary Edition in Navy Blue
Mamiya Six Folder with Zuiko 75/3.5
Adaptall: Tamron SP 28-85 macro
Cameras: Canon IX
PM for more complete descriptions/pix. All in great shape!
_________________________
'buy me a drink, sing me a song,
take me as i come 'cause i can't stay long' |
|
Back to top |
|
|
ludoo
Joined: 18 Sep 2009 Posts: 1397 Location: Milan, Italy
Expire: 2011-12-05
|
Posted: Tue Aug 16, 2011 2:11 pm Post subject: |
|
|
ludoo wrote:
rbelyell wrote: |
thanks to all, but it seems we have a pretty big discrepancy even with one format, 6x6. orio says the crop factor is 1.6, V says its 1.9 and ludoo says its 1.4! |
Nope, I just said that instead of computing the diagonal using powers and square roots, for square formats the diagonal is simply side*1.41. Then apply the same rules to get to the ratio compared to 35mm. The diagonal for 6x6 is 60mm * 1.41 = 84.6mm. _________________ My galleries
Digital: Samsung EX-1
Past Digital: Samsung NX10, Sigma SD9, Sigma SD10, SD14, DP2, Pentax *istD, Kx, Fuji S2 Pro, Canon 5D
Analog: packfilm Polaroids, 6x9 Kodak folders, Pentacon Taxona half-frame, Fujica ST605n, Walz Envoy, Olympus 35 S-II, Olympus Wide S
Past Analog: Polaroid 600se, Polaroid 110B, Canon IIF, various fixed-lens and Russian rangefinders, ...
Past Lenses: Nikkor 24/2.8, Nikkor SC 50/1.4, Nikkor 50/2, Nikkor H 85/1.8, Nikkor P 105/2.5, Nikkor Q 135/3.5, Fujinon 100/2.8, Fujinon EBC 100/2.8, Fujinon EBC 135/3.5, Fujinon EBC 200/4.5, Mamiya SX 135/2.8, CZJ Flektogon 35/2.4, CZJ Pancolar 50/1.8 zebra, CZJ Sonnar 135/3.5, ...
altroformato
|
|
Back to top |
|
|
Orio
Joined: 24 Feb 2007 Posts: 29545 Location: West Emilia
Expire: 2012-12-04
|
Posted: Tue Aug 16, 2011 4:58 pm Post subject: |
|
|
Orio wrote:
Like I said, I have no scientific foundation for my calculation.
I have always read that 80mm equals 50mm on small format, 45mm equals 28mm, 35mm equals 21mm, and 120mm equals 75mm.
The division factor to obtain these figures is 1.6, so that's how I figure out the corresponding focal lenghts.
Of course, I have no way to tell if the 1.6 division factor gives a precise value or only an approximation. _________________ Orio, Administrator
T*
NE CEDE MALIS AUDENTIOR ITO
Ferrania film is reborn! http://www.filmferrania.it/
Support the Ornano film chemicals company and help them survive!
http://forum.mflenses.com/ornano-chemical-products-t55525.html |
|
Back to top |
|
|
visualopsins
Joined: 05 Mar 2009 Posts: 10543 Location: California
Expire: 2025-04-11
|
Posted: Tue Aug 16, 2011 5:12 pm Post subject: |
|
|
visualopsins wrote:
Wikipedia: Crop Factor _________________ ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮ 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 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 (51BB), SP 500mm f/8 (55BB), SP 70-210mm f/3.5 (19AH)
Vivitar 100mm 1:2.8 MC 1:1 Macro Telephoto (Kiron)
|
|
Back to top |
|
|
visualopsins
Joined: 05 Mar 2009 Posts: 10543 Location: California
Expire: 2025-04-11
|
Posted: Tue Aug 16, 2011 6:05 pm Post subject: |
|
|
visualopsins wrote:
The math above, while the method is sound, uses figures that are not quite accurate, rather estimations of film size. Using this Film Size Chart for more accurate measurements, here are the most accurate crop factors related to 35mm film size:
The column FL shows the FL lens for that format with angle of view same as 50mm lens on 35mm camera.
Interesting the crop factor for 645 is 1.62, same as Orio gives. _________________ ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮ 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 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 (51BB), SP 500mm f/8 (55BB), SP 70-210mm f/3.5 (19AH)
Vivitar 100mm 1:2.8 MC 1:1 Macro Telephoto (Kiron)
|
|
Back to top |
|
|
rbelyell
Joined: 13 Oct 2009 Posts: 4269 Location: somewhere in the mountains of central NY
Expire: 2014-01-31
|
Posted: Tue Aug 16, 2011 7:50 pm Post subject: |
|
|
rbelyell wrote:
ludoo: like i said, math is not my thing! frankly, i was amazed i comprehended V's equations at all.
orio: thank you for your help as there is no substitute for a great photographers real world experience.
V: that chart is super! ive made a copy and if it helps anyone, using these calculations the crop factor on 6x9 is approximately 2.5, and for 6x12 is approxiately 3.
this has been immensely helpful, thank you to all!
tony _________________ Epson RD1 + Elmarit 21/2.8; Summarit 50/1.5; Summarit 75/2.5; Elmar-c 90/4; Sankyo Komura 135/2.8, Hektor 135/4.5; Braun Paxina 29 6x6; Photax Boyer Paris; Holga 120 Pano
GREAT STUFF FOR SALE:
Contax T
Hasselblad XPan + 45/4, 90/4
Kodak Retina Reflex IV + full set of Schneider Krueznach lenses
Mercury 2 half frame 35mm
Kodak Pro slr/n
Fuji GM670+100/3.5+65/8!
Praktisix 6x6 medium format + ZeissBiometar 120/2.8
Bessa T 101 Anniversary Edition in Navy Blue
Mamiya Six Folder with Zuiko 75/3.5
Adaptall: Tamron SP 28-85 macro
Cameras: Canon IX
PM for more complete descriptions/pix. All in great shape!
_________________________
'buy me a drink, sing me a song,
take me as i come 'cause i can't stay long' |
|
Back to top |
|
|
peterqd
Joined: 28 Feb 2007 Posts: 7448 Location: near High Wycombe, UK
Expire: 2014-01-04
|
Posted: Tue Aug 16, 2011 8:43 pm Post subject: |
|
|
peterqd wrote:
I have no argument with the maths, but could someone explain why the length of the diagonal is significant? How do you get from a 43mm diagonal to the "normal" 50mm FL on 135?
When I look through any 135 viewfinder with a 50mm lens mounted, the image is larger than I see with the other eye. I'd need a lens of about 43mm to make them appear similar, which is remarkably similar to the 135 diagonal. Why is that? _________________ Peter - Moderator |
|
Back to top |
|
|
visualopsins
Joined: 05 Mar 2009 Posts: 10543 Location: California
Expire: 2025-04-11
|
Posted: Tue Aug 16, 2011 10:19 pm Post subject: |
|
|
visualopsins wrote:
peterqd wrote: |
I have no argument with the maths, but could someone explain why the length of the diagonal is significant? How do you get from a 43mm diagonal to the "normal" 50mm FL on 135?
When I look through any 135 viewfinder with a 50mm lens mounted, the image is larger than I see with the other eye. I'd need a lens of about 43mm to make them appear similar, which is remarkably similar to the 135 diagonal. Why is that? |
In spreadsheet, 50mm lens was chosen for 35mm/FF, only for illustrative purpose, to compare the 'equivalent' focal lengths of other formats giving the same angle of view. It could have been any focal length lens, the crop factors remain the same regardless of lens chosen to compare.
'Normal' is different. (no there's an oxymoron ) Meaning 'normal' has nothing to do with crop factors, but only with focal length equal to diagonal measurement of format.
Eye angle of view is 180 degrees, same as ultra-wide of around 16mm (on 35mm). The foveal region (best focus) angle of view is around the same as 135mm lens on (35mm).
'Normal' lens angle of view retains relative perspective of objects at different distances. A wider lens increases the apparent distances. A longer lens reduces the apparent distances. _________________ ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮ 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 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 (51BB), SP 500mm f/8 (55BB), SP 70-210mm f/3.5 (19AH)
Vivitar 100mm 1:2.8 MC 1:1 Macro Telephoto (Kiron)
|
|
Back to top |
|
|
peterqd
Joined: 28 Feb 2007 Posts: 7448 Location: near High Wycombe, UK
Expire: 2014-01-04
|
Posted: Tue Aug 16, 2011 11:12 pm Post subject: |
|
|
peterqd wrote:
visualopsins wrote: |
'Normal' lens angle of view retains relative perspective of objects at different distances. A wider lens increases the apparent distances. A longer lens reduces the apparent distances. |
I once thought the same but was corrected by Rick Oleson, and a few years ago I did a little test. It's an optical illusion - the apparent distances between near and far actually appear exactly the same whether with a telephoto or a wide angle.
http://forum.mflenses.com/perspective-and-focal-lengths-t12219,highlight,%2Bperspective.html
I still don't see what the diagonal length of the frame has to do with the focal length of a "normal" lens, or "standard" if you prefer. Perhaps it's just a coincidence? _________________ Peter - Moderator |
|
Back to top |
|
|
visualopsins
Joined: 05 Mar 2009 Posts: 10543 Location: California
Expire: 2025-04-11
|
Posted: Tue Aug 23, 2011 4:53 am Post subject: |
|
|
visualopsins wrote:
peterqd wrote: |
visualopsins wrote: |
'Normal' lens angle of view retains relative perspective of objects at different distances. A wider lens increases the apparent distances. A longer lens reduces the apparent distances. |
I once thought the same but was corrected by Rick Oleson, and a few years ago I did a little test. It's an optical illusion - the apparent distances between near and far actually appear exactly the same whether with a telephoto or a wide angle.
http://forum.mflenses.com/perspective-and-focal-lengths-t12219,highlight,%2Bperspective.html
I still don't see what the diagonal length of the frame has to do with the focal length of a "normal" lens, or "standard" if you prefer. Perhaps it's just a coincidence? |
There is so much confusion surrounding the term 'perspective'. Yes some of it is 'optical illusion', but that's not what I refer to. Check Rauschenbach's Theory of Perspective and Photography for explanations of all types.
By definition, a 'normal' lens is focal length equal to the length of diagonal of the film/sensor. On apug, Viewing distance and perspective -- what's the basis? Roger Hicks gives the basis, "The logic is that the angle subtended by each element in the picture should be the same as the angle subtended at the camera by the same element in the original scene. " _________________ ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮ 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 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 (51BB), SP 500mm f/8 (55BB), SP 70-210mm f/3.5 (19AH)
Vivitar 100mm 1:2.8 MC 1:1 Macro Telephoto (Kiron)
|
|
Back to top |
|
|
doomed-forever
Joined: 09 Aug 2014 Posts: 239
|
Posted: Thu Mar 17, 2016 4:09 pm Post subject: |
|
|
doomed-forever wrote:
Orio wrote: |
Like I said, I have no scientific foundation for my calculation.
I have always read that 80mm equals 50mm on small format, 45mm equals 28mm, 35mm equals 21mm, and 120mm equals 75mm.
The division factor to obtain these figures is 1.6, so that's how I figure out the corresponding focal lenghts.
Of course, I have no way to tell if the 1.6 division factor gives a precise value or only an approximation. |
Only Canon APS-C is Cropfactor x1.6 Orio, Pentax, Nikon & Sony is x1.5, the Sensors are a little bigger.
(but differ also in very neglible points) |
|
Back to top |
|
|
visualopsins
Joined: 05 Mar 2009 Posts: 10543 Location: California
Expire: 2025-04-11
|
Posted: Sat Mar 19, 2016 1:13 am Post subject: |
|
|
visualopsins wrote:
Now I see I misunderstood what Peter was talking about -- he is correct, if the two lenses are used from the same position the perspective does not change. However, I was talking about using lenses from different positions, which does change the perspective, when used to obtain images with the same magnification...
I should also clarify why comparison of diagonals is used for determining crop factors -- the diagonal is the maximum the lens image circle must cover, for each format, no matter if one is square and one rectangular...
Lastly, something should be said about what is a "Normal" lens for any format -- again, this is the length of the diagonal, with a caveat.
Gerald wrote: |
CBokeh wrote: |
I was always under the impression that "normal" was 43mm on 35mm format but 50mm was "close enough." |
The conventional definition of a normal lens is that one whose focal length is equal to the diagonal of the format. This gives a focal length of 43.3mm for 35mm and 79.2mm format for 6x6 format.
I prefer another definition: a normal lens is the one whose angle of view matches the angle of view of the person viewing a print of a picture taken with that lens. This definition can be extended to pictures viewed on a screen of a computer, TV or cinema.
I will try to explain with a simple example. Suppose an image captured by a FF sensor is enlarged by a factor M equal to, say, 10x to produce a print with dimensions 24 x 30 cm. If the print is to be viewed at a distance of 50cm, the normal lens is the one with a focal length of 50cm / M = 50 mm. However, if the print is viewed at a distance of 40 cm, the normal lens has focal length of 40 mm. And if the viewer is a young person that prefers to see the print at 20 cm, the normal lens is the 20 mm!
According to the second definition, the focal length of a normal lens is always given by:
FL = D / M
where:
D = distance of visualization
M = magnification of the displayed image relative to the sensor size |
_________________ ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮ 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 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 (51BB), SP 500mm f/8 (55BB), SP 70-210mm f/3.5 (19AH)
Vivitar 100mm 1:2.8 MC 1:1 Macro Telephoto (Kiron)
|
|
Back to top |
|
|
480sparky
Joined: 16 Apr 2013 Posts: 355 Location: Iowa
|
Posted: Sat Mar 19, 2016 2:19 pm Post subject: |
|
|
480sparky wrote:
I don't feel the need to convert FL to the fourth decimal point. A factor of 2 is close enough for me.
50mm on a 35 is 100mm for my 6x7. |
|
Back to top |
|
|
Gott23
Joined: 10 Dec 2018 Posts: 250
|
Posted: Wed Jan 30, 2019 12:16 am Post subject: |
|
|
Gott23 wrote:
Orio wrote: |
I don't have a scientific formula, only a practical one for 6x6
Divide by 1.6 the MF focal lenght to obtain the SF equivalent.
Example:
80mm : 1.6 = 50mm
45mm : 1.6 = 28,1 mm
hope this helps |
I've just started shooting MF, though I've dabbled before, but I'm also currently using the lenses on a DSLR.
With this in mind, I take it that a full-frame DSLR would mimic a 35mm in terms of the focal length then? |
|
Back to top |
|
|
visualopsins
Joined: 05 Mar 2009 Posts: 10543 Location: California
Expire: 2025-04-11
|
Posted: Wed Jan 30, 2019 1:52 am Post subject: |
|
|
visualopsins wrote:
35mm film size is the same as FF sensor size.
To get same angle of view on MF camera as on 35mm or FF camera requires a longer focal length lens.
However any focal length lens for any camera is the same focal length on 35mm or FF camera.
Not sure that answers your question. To get the same angle of view seen on MF camera on 35mm or FF camera requires a shorter focal length lens. DOF, however is more complicated, however. There's another thread here someplace that gives all the relationships. Also refer to the article by Zeiss about bokeh for explanation and a table of how dof is affected.
I'll try to find links to thread here and at Zeiss. ... _________________ ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮ 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 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 (51BB), SP 500mm f/8 (55BB), SP 70-210mm f/3.5 (19AH)
Vivitar 100mm 1:2.8 MC 1:1 Macro Telephoto (Kiron)
|
|
Back to top |
|
|
visualopsins
Joined: 05 Mar 2009 Posts: 10543 Location: California
Expire: 2025-04-11
|
Posted: Wed Jan 30, 2019 2:04 am Post subject: |
|
|
visualopsins wrote:
Link to Zeiss document Depth of Field and Bokeh by Dr. Hubert Nasse, Carl Zeiss AG on
https://lenspire.zeiss.com/photo/en/article/overview-of-zeiss-camera-lenses-technical-articles _________________ ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮ 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 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 (51BB), SP 500mm f/8 (55BB), SP 70-210mm f/3.5 (19AH)
Vivitar 100mm 1:2.8 MC 1:1 Macro Telephoto (Kiron)
|
|
Back to top |
|
|
visualopsins
Joined: 05 Mar 2009 Posts: 10543 Location: California
Expire: 2025-04-11
|
Posted: Wed Jan 30, 2019 2:22 am Post subject: |
|
|
visualopsins wrote:
And here's the thread here http://forum.mflenses.com/anyone-try-a-pentax-67-105f2-4-on-any-fullframe-dslr-t78604.html _________________ ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮ 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 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 (51BB), SP 500mm f/8 (55BB), SP 70-210mm f/3.5 (19AH)
Vivitar 100mm 1:2.8 MC 1:1 Macro Telephoto (Kiron)
|
|
Back to top |
|
|
|