I own a D800 and the Nikon 50mm 1.4. I'm wondering, what if I bought the new beast Sigma 35mm f1.4 (sell my nikon) and if I need a 50mm, I just enable crop mode, which roughly give me a 50mm.

The question is, will I get better image quality or sharpness from the 35mm shooting in DX crop mode versus shooting with the 50mm in full frame? If so, why?


if you use a 35mm lens in place of a 50mm with the intent to crop for the same FOV, you do get the same perspective, but you sacrifice the shallow DOF used to separate subject from the background.

Example 35mm vs 50mm in NikonD800, at 1.5meters distance (typical portrait setting): 50mm 1.4 gives 7cm DOF, while 35mm gives 15cm DOF.

That can be both good or bad, ofc.

I just wanted to make sure you know that you wont be making the same images with your "hack".

Secondly, a 16MP image resized from a 36MP image will be better quality, retaining more details, even if you sharpen the 16MP crop. You will see more textures from the resized 36MP image, and then sharpen that.

So you should only get the 35mm for wide angle usage.

  • Right, that makes a hell lot of a difference, even a cheaper 50mm 1.8 would give me better DOF.
    – Bastien974
    Apr 21 '13 at 18:21
  • well you can stop your 1.4 down to 1.8 if you need more DOF. I was talking in the opposite diretion, that when you strive for less DOF, the 50mm is an advantage. Apr 21 '13 at 18:24
  • By better I meant, even a 50 1.8 would give me a shallower DOF vs 35mm 1.4 in crop.
    – Bastien974
    Apr 21 '13 at 19:11
  • @Bastien974 Right; the change in depth of field is roughly the same as changing the aperture by the amount you crop. (More on this here.)
    – mattdm
    Apr 21 '13 at 20:35

Well, nobody can answer this question than you. The first thing that comes to mind is: if 16MP is more than enough, why on earth did you go and buy a 36MP camera?! Besides that, the obvious thing to say is this: Don't fool yourself. A cropped 35mm (to "simulate" 50mm) is not the same as using a 50mm lens. You're throwing away tons of resolution. Either you "don't need it" (which takes us to the original question, 'why the D800?'), or you acknowledge that, and realize you need the 50mm lens to have 50mm POV. I think you need to clarify your priorities before you take another step buying/selling lenses...

  • Well, the subject is not whether 36MP is needed or not, all new FF have massive amount of MP, there was no choice about that. What I'd like is to get a fairly wide fast lens, but can't really afford a 1000$ lens but if I can sell the 50mm, that would help and I can still get a good 52mm on DX mode.
    – Bastien974
    Apr 21 '13 at 17:17

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