Lens on cropped sensor?

BIGEYE

BIGEYE

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Jim
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Just watched a wedding photography video and the photographer used an 85mm f1.4 prime a lot of the time which produced some stunning photos. He was using this lens on a full size sensor. If I were to use a 50mm f1.4 on a cropped sensor, could I expect similar results (all othere things being equal)?
 
I think so :D but I don't think you'll be able to match the 85mm f1.4 aperture DoF unless you shoot slightly tighter framing with the crop and 50mm. My own little real world experiments show me that the crop factor should be applied to aperture as well as focal length if you are going for the exact same framing, but step forward just a little with the crop camera and you'll get there or there abouts :D
 
BIGEYE said:
Just watched a wedding photography video and the photographer used an 85mm f1.4 prime a lot of the time which produced some stunning photos. He was using this lens on a full size sensor. If I were to use a 50mm f1.4 on a cropped sensor, could I expect similar results (all othere things being equal)?
Click to expand...

Not quite the same DoF, but the angle of view is fairly close. Not identical mind, just close. Personally I love the 85 on a crop, but then I loved 135 on film for portraits.
 
If you organise a meet Jim you can try my 85 to see how you like that on a crop.
 
Barrysprout said:
If you organise a meet Jim you can try my 85 to see how you like that on a crop.
Click to expand...

Bit short notice as I need it for a couple of weeks time, and march is a really busy month for me.
Now a meet in April sounds a good idea, any ideas/preferences?
 
As WW says above, multiply focal length by crop factor for framing, and aperture by crop factor for DoF, though of course the aperture remains unchanged for exposure.

Eg, 50mm f/1.4 is equivalent to 80mm f/2.24 for framing and DoF, but stays at f/1.4 for exposure.
 
Hoppy, that helped clear things in my head which I thought I was clear on. Many thanks.

Jim, I set up a comparison to give you an image to compare.

Shots taken using 500D crop sensor with Sigma 50mm f/1.4 and a 5DMk II with Sigma 85mm f/1.4

First up is the crop shot at 50mm f/1.4
crop_1_4.jpg


Next the Full frame at 85mm f/1.4
full_1_4.jpg


And last the full frame at f/2.2 (to compare bokeh to crop at f/1.4)
full_2_2.jpg
 
Thanks Colin for that, any chance you could post one with the 85mm f1.4 on the cropped sensor?
Thanks Richard for explaining the DOF.
 
I've put the scary doll back in a bag under the stairs. Freaks me out she does. If I don't get a chance later I'll do another couple of shots tomorrow.
 
BIGEYE said:
Thanks Colin for that, any chance you could post one with the 85mm f1.4 on the cropped sensor?
Thanks Richard for explaining the DOF.
Click to expand...

You're welcome :)

Just to add, with lenses like this, DoF and bokeh (appearance of the out of focus background) often get confused.

Bokeh is about much more than DoF and focal length is just as important. In particular, with a longer lens you will have to move back to get the same subject framing with the narrower field of view. This has the effect of enlarging the background relative to the foreground subject, and while DoF will remain the same f/number for f/number, the background usually looks less cluttered and more attractive as smaller details are rendered as larger and more simple shapes.

As here, 70mm f/4
IMG_3410.jpg


And moving back at 200mm f/4
IMG_3411.jpg
 
OK Jim I got the scary doll back out,she had already crawled out of the bag on her own!
did a whole new batch to match positions.

First shot on full frame 85mm f/1.4
full_85_1_4.jpg


second on full frame again 85mm f/2.2
full_85_2.jpg


Then onto crop:
50mm f/1.4
crop_50_1_4.jpg


85mm f/1.4
crop_85_1_4.jpg


And this last one is 85mm f/1.4 again but with the camera to subject distance increased from 1.2m to 1.9m (roughly)
crop_85_1_4_distance.jpg


Shooting distance will be the other thing to take into account for lens choice.
 
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