DOF for same FOV in FF vs APS-C

[jmahto]

Advertisement (gone after registration)

Well, I was kind of bored and it was raining continuously. My Christmas tree has to be brought down and before I did that, I wanted to do a small test comparing APS-C and FF for out of focus blur.

 

Conclusion: The 28mm @f/2 on Nex-6 (APS-C sensor) has the similar out of focus blur as in 40mm @f/2.8 on M240.

 

Not surprising and we all know why we use FF instead of smaller sensors. ... what is indeed surprising is that how good cheapo 40 summicron-C in real world situations. I love this tiny lens.

 

The 1:1 screenshot is self explanatory with the captions.

 

Both at f/2 (L: Nex-6, R: M240)

 

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

 

 

40 summicron-c at 2.8 (L: Nex-6, R: M240)

 

The cameras

[vanGeist]

You could have done this with simple mathematics in much shorter time.

[Advertisement]

The Leica Q3 is available for pre-order at B&H Photo Video and Adorama

[jmahto]

You could have done this with simple mathematics in much shorter time.

Photographs look more beautiful than formulas and numbers. I do get your point though.

 

My intention was to illustrate a simple rule of thumb that with APS-C you loose DOF worth 1 stop (for same FOV). Similarly, you loose DOF worth 2 stops with micro thirds. Therefore a f/1.4 lens on micro thirds has similar rendering (DOF wise, not the quality) to a f/2.8 lens on FF.

[michaelwj]

Beauty is in the eye of the beholder. Mathematics can be very beautiful, elegant and profound. It can also be applied to every lens and format. Whereas a test shot is simply a test shot...

[Exodies]

It's even more beautiful to see mathematics in action.

[luigi bertolotti]

... and notoriously, the little Summicron C 40 is a lens which always proves to be a little gem of its own

 

(fine hood on it, btw...)

Edited January 10, 2017 by luigi bertolotti

[jaapv]

Advertisement (gone after registration)

You could have done this with simple mathematics in much shorter time.

Not really. Mathematics tells only half the story. It can tell you the basic relationship of DOF to subject distance and magnification ( related to its derivative: focal length), sensor/film size, print size, viewing distance and aperture, but it does not take subject contrast, subject frequency, lens design, resolving power of the observer's eye, subjective perception of sharpness by the observer, film or sensor, etc. into account.

[jmahto]

I love taking test shots all the time because it helps me to understand which equipment is suitable for my purposes. For example I can use 40summucron c in place of 50lux if I am shooting f4 or narrower with no penalty. And 40mm gives better sun stars than 50lux!

Edited January 11, 2017 by jmahto

[michaelwj]

Not really. Mathematics tells only half the story. It can tell you the basic relationship of DOF to subject distance and magnification ( related to its derivative: focal length), sensor/film size, print size, viewing distance and aperture, but it does not take subject contrast, subject frequency, lens design, resolving power of the observer's eye, subjective perception of sharpness by the observer, film or sensor, etc. into account.

You *could* do all that with mathematics (maybe not the lens design?), indeed most of those variables are what the MTF measures or are just numbers rather than variables (eg. resolving power), but it would get very complicated very quickly and no longer take half the time of the test shots...