skimmel Posted November 18, 2015 Share #1 Posted November 18, 2015 Advertisement (gone after registration) The Leica S sensor is about 56% bigger than "full frame." Given that, for the same field of view and f-stop, I'm trying to get a sense for the DOF with the S compared with full frame. (Please note, I am specifying using a different focal length to get the same field of view at the same distance -- I realize that DOF is not directly due to sensor size or focal length). I borrowed an S last week and it seemed to me (totally a gut sense) that DOF with the S was substantially less than I expected. This site has a great calculator for DOF equivalent, but it doesn't include the S sensor size: http://www.cambridgeincolour.com/tutorials/digital-camera-sensor-size.htm If one used 6x4.5 the DOF is about 1 and 2/3 stop different compared with full frame. What would be the estimate for the S sensor size? Thanks. Quote Link to post Share on other sites More sharing options...
Advertisement Posted November 18, 2015 Posted November 18, 2015 Hi skimmel, Take a look here Depth of Field vs 35mm frame. I'm sure you'll find what you were looking for!
mgrayson3 Posted November 18, 2015 Share #2 Posted November 18, 2015 (edited) The S sensor is 1.25x the linear dimensions of "FF". To a good approximation, getting "the same" picture from, say, an SL and an S, the S would need 1.25x the focal length (to get the same FoV), 1.25x the f-number (to get the same DoF), and 1.25x the ISO (to compensate for the smaller aperture given that the shutter speeds would have to be equal to match motion blur). This is getting "the same" in the sense of "difficult to distinguish at the same print size" NOT "looking the same at 100% on a monitor". --Matt Edited November 18, 2015 by mgrayson3 2 Quote Link to post Share on other sites More sharing options...
DucatiTerminator Posted November 18, 2015 Share #3 Posted November 18, 2015 (edited) Not questioning your math, Matt, but why is it that a 70mm S lens is the equivalent of a 50mm FF lens (1.4x). Do they not have the same FoV, or am I missing something here? Alvin Edited November 18, 2015 by DucatiTerminator Quote Link to post Share on other sites More sharing options...
Daedalus2000 Posted November 18, 2015 Share #4 Posted November 18, 2015 Not questioning your math, Matt, but why is it that a 70mm S lens is the equivalent of a 50mm FF lens (1.4x). Do they not have the same FoV, or am I missing something here? Alvin It is not the equivalent of a 50mm, it is the equivalent of a 56mm (56 = 70 * 0.8 or 70 = 56 * 1.25) as Matt explained. 1 Quote Link to post Share on other sites More sharing options...
DucatiTerminator Posted November 18, 2015 Share #5 Posted November 18, 2015 It is not the equivalent of a 50mm, it is the equivalent of a 56mm (56 = 70 * 0.8 or 70 = 56 * 1.25) as Matt explained. Thank you for the clarification. 1 Quote Link to post Share on other sites More sharing options...
skimmel Posted November 18, 2015 Author Share #6 Posted November 18, 2015 The S sensor is 1.25x the linear dimensions of "FF". To a good approximation, getting "the same" picture from, say, an SL and an S, the S would need 1.25x the focal length (to get the same FoV), 1.25x the f-number (to get the same DoF), and 1.25x the ISO (to compensate for the smaller aperture given that the shutter speeds would have to be equal to match motion blur). This is getting "the same" in the sense of "difficult to distinguish at the same print size" NOT "looking the same at 100% on a monitor". --Matt Thanks Matt, so f 2.5 with an S-lens would be similar to f 2.0 on full frame, all else being equal (FoV, etc)? Quote Link to post Share on other sites More sharing options...
pico Posted November 18, 2015 Share #7 Posted November 18, 2015 Advertisement (gone after registration) Confusing, isn't it? The nominal normal for FF 35mm is 43.3, (not 51mm) and for 30x45 it is 54mm. We actually use a lens of ~51mm for FF 35, and 70mm for the S. I especially appreciate that each sensor is proportioned alike - same ratios. 1 Quote Link to post Share on other sites More sharing options...
mgrayson3 Posted November 18, 2015 Share #8 Posted November 18, 2015 It *should* be - in that the size of an OOF distant light will be the same in both *prints*. How the two lenses handle the transition to OOF might be different. I have not done the study of real lenses - it's just math. And while math may not be the whole story, it's a good starting point. Quote Link to post Share on other sites More sharing options...
skimmel Posted November 18, 2015 Author Share #9 Posted November 18, 2015 Thanks. My sense - it seemed to me that DOF with the S was narrower than I would expect. Maybe it's the way the lenses handle transition to OOF. For example, I have found that the 50 Apo for the M seems to have a different DOF-feel from shooting a summilux at f/2.0. Quote Link to post Share on other sites More sharing options...
Guest chipcarterdc Posted November 18, 2015 Share #10 Posted November 18, 2015 (edited) I have no idea about the underlying math, but I find from experience that I need an aperture 1.5 stops smaller to get the equivalent DOF look on the Leica as as on a full-frame 35mm camera. Thus, if aiming for the look of F8 on 35mm, I use F13 on the Leica S. If I'm shooting at 5.6, I can pre-visualize that the DOF will look like F3.5(ish). Etc. Edited November 18, 2015 by chipcarterdc Quote Link to post Share on other sites More sharing options...
John McMaster Posted November 18, 2015 Share #11 Posted November 18, 2015 Yes, the M 50 APO has a different DoF cutoff to the Summilux (asph or not) at f2.0. john Quote Link to post Share on other sites More sharing options...
mgrayson3 Posted November 18, 2015 Share #12 Posted November 18, 2015 (edited) I'm surprised that I've never seen a measurable test of OOF transition. You could take a row of small shiny spheres arranged from near to far and have one distant light. You'd get specular reflections from which you could see the dependence of CoC on distance from the focal plane. Even more abstract than brick walls! --Matt Edited November 18, 2015 by mgrayson3 Quote Link to post Share on other sites More sharing options...
pico Posted November 19, 2015 Share #13 Posted November 19, 2015 I'm surprised that I've never seen a measurable test of OOF transition. You could take a row of small shiny spheres arranged from near to far and have one distant light. Yes, that would be good for those who shoot a row of small shiny spheres arranged from near to far and have one distant light. Quote Link to post Share on other sites More sharing options...
albertknappmd Posted November 26, 2015 Share #14 Posted November 26, 2015 If I understand David Farkas' recent review, the issue of DOF is resolved very nicely on the 007. Just depress shutter release slightly and it will the limits of DOF will be readily seen on the top display. According to the "math", the correct compensation for DOF should be about ONE stop, not 1.5... Albert Quote Link to post Share on other sites More sharing options...
peterv Posted November 27, 2015 Share #15 Posted November 27, 2015 As much as I like the idea of the DOF indicator on the top deck display, until now I haven't come across any official word from Leica as to how this is being calculated. For what print size/dpi? At what COC? Does anyone know? Quote Link to post Share on other sites More sharing options...
xiaubauu2009 Posted November 28, 2015 Share #16 Posted November 28, 2015 Just do a 0.8x muplication to the focal lengh of S lens. You get the 135 equivalent... Quote Link to post Share on other sites More sharing options...
jip Posted November 28, 2015 Share #17 Posted November 28, 2015 Yes but this discussion is about depth of field differences not field of view. Quote Link to post Share on other sites More sharing options...
RVB Posted November 28, 2015 Share #18 Posted November 28, 2015 The aperture equivalent of the S 70mm is f2. 70 x .8 = 56/28 (70/2.5=28mm) = 2. Quote Link to post Share on other sites More sharing options...
jaapv Posted November 29, 2015 Share #19 Posted November 29, 2015 Is it not simpler to use DOFMaster? The Pentax 645 setting? http://www.dofmaster.com/dofjs.html Quote Link to post Share on other sites More sharing options...
RVB Posted November 29, 2015 Share #20 Posted November 29, 2015 Is it not simpler to use DOFMaster? The Pentax 645 setting? http://www.dofmaster.com/dofjs.html Not really... I mean its a pretty simple equation and can be done on a iPhone calculator or even without a calc,but the site seems useful!! 1 Quote Link to post Share on other sites More sharing options...
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