Understanding Full Frame

[HDNitehawk]

If I apply this logic and look at the equivalent of 24-105 f/4 crop equivalence when shot on full frame I get a 15-66 f/2.5. That not very fast on a crop lens is now surpassing the very highly regarded 17-55 f/2.8 in both speed and versatility while also getting better image quality! Also, a great prime like the 35mm f/1.4 L is now an equivalent 56mm f/2.2 lens. Still nice, but not nearly as nice as the real thing and probably equivalent to the much cheaper 50mm 1/4 now.

Most of what you said is correct. Daniel's comparisons were for a crop camera with a 100mm lens. I am not sure of your logic in your statement, are you saying that the 35mm F/1.4 on a crop frame vs a 56mm on a full frame?

The 35mm F/1.4 shot at F/1.4 on both cameras is going to have low IQ no matter if it is shot on a FF or a Crop Camera. It may have a deeper DOF and narrower FOV but the quality will still be lacking, until you tighten the aperture a bit.

[Dave Throgmartin]

I am not sure of your logic in your statement, are you saying that the 35mm F/1.4 on a crop frame vs a 56mm on a full frame?

Sorry, my intent was that the awesome 35L when used on a crop doesn't appear like it would be quite so awesome any more, given Daniel's work up it would now be:

35 x 1.6 = 56mm focal length
56mm focal length / 25mm pupil = f/2.2 aperture

compared to full frame. It appears the 50mm f/1.4 that is much cheaper would be able to provide the similar (maybe better) results on a full frame camera than what could be achieved on the crop with the 35L.

Dave

[ahab1372]

Sorry, my intent was that the awesome 35L when used on a crop doesn't appear like it would be quite so awesome any more, given Daniel's work up it would now be:

35 x 1.6 = 56mm focal length
56mm focal length / 25mm pupil = f/2.2 aperture

compared to full frame. It appears the 50mm f/1.4 that is much cheaper would be able to provide the similar (maybe better) results on a full frame camera than what could be achieved on the crop with the 35L.

Dave

I think your math is correct for focal length and aperture, but other attributes that affect IQ of a lens won't change (bokeh, CA, etc.)
I'm sure I will be corrected if I'm wrong

Arnt

[HDNitehawk]

Sorry, my intent was that the awesome 35L when used on a crop doesn't appear like it would be quite so awesome any more, given Daniel's work up it would now be:

35 x 1.6 = 56mm focal length
56mm focal length / 25mm pupil = f/2.2 aperture

compared to full frame. It appears the 50mm f/1.4 that is much cheaper would be able to provide the similar (maybe better) results on a full frame camera than what could be achieved on the crop with the 35L.

Dave

I think this logic for the 35mm works, butto a less extent for many other lenses.

The 35mm L is a great lens on a FF camera. What makes the 35mm a great lens, and a very creative tool is its high image quality at the wider apertures. On a full frame camera it can be used to really set individuals or your subject apart and gives a fair bokeh. Because of the deeper DOF with the crop camera you lose some of the 35mm's creative ability. Keep in mind that the 35mm shot at F/1.4 on either body, the IQ will be very low. You need to get up to F/2.0 or better, and of course the higher you go the deeper DOF you get.

But the same scenario has less impact the longer the lens, even though it is still there.

I think given the choice, a 7D with a 35mm or a 5D II or III with a 50mm I would go with the 50mm on a FF. However I wouldn't go with the 50mm F/1.4.