DOF FF vs Crop

yjt · 19th of December 2010 (Sun)

Why do people say that FF has shallower depth of field than crop in the same conditions?

JeffreyG · 19th of December 2010 (Sun)

Because to take the same image (same perspective, same framing) a FF camera must be shot with a lens focal length that is 60% longer.

That's really all it is, longer focal length (for the same photo) = shallower DOF.

yjt · 19th of December 2010 (Sun)

Quote:

Originally Posted by JeffreyG

Because to take the same image (same perspective, same framing) a FF camera must be shot with a lens focal length that is 60% longer.

That's really all it is, longer focal length (for the same photo) = shallower DOF.

They have the same focal length it's just cropped, but when I crop my images I don't really see a loss in the depth of field.

mury · 19th of December 2010 (Sun)

If you use same FL, to get equivalent field of view on both you have to either move closer with the FF camera (less DOF) or back off with the crop (increased DOF).

yjt · 19th of December 2010 (Sun)

Quote:

Originally Posted by mury

If you use same FL, to get equivalent field of view on both you have to either move closer with the FF camera (less DOF) or back off with the crop (increased DOF).

Yes, i know that distance is a factor in DOF, but this doesn't explain why FF has shallower DOF as other people said

JeffreyG · 19th of December 2010 (Sun)

Quote:

Originally Posted by yjt

They have the same focal length it's just cropped, but when I crop my images I don't really see a loss in the depth of field.

Suppose you take a picture with a 7D using a focal length of 50mm.

Now take the 7D off the tripod and mount a 5D. To take the same picture using the 5D you will have to use a lens with a focal length of 80mm. This change (from 50mm to 80mm) is why the FF camera has less DOF.

If you take both pictures using a 50mm lens, the field of view from the 5D photo will be much larger and the pictures will not be the same (but will have essentially the same DOF).

Staszek · 19th of December 2010 (Sun)

This is the best post regarding FF vs Crop DOF. http://photography-on-the.net/forum/...6&postcount=10

Read through the thread as well.

amfoto1 · 19th of December 2010 (Sun)

Quote:

Originally Posted by JeffreyG

Because to take the same image (same perspective, same framing) a FF camera must be shot with a lens focal length that is 60% longer.

That's really all it is, longer focal length (for the same photo) = shallower DOF.

This....

Or, use the same focal length in both cases and you have to move 60% closer to your subject to get the same framing....

Either way, the effective DOF is reduced with full frame.

It's approx. one stop worth... i.e., f2.8 on a cropper equals f4 on FF, etc.

mury · 19th of December 2010 (Sun)

Quote:

Originally Posted by JeffreyG

Suppose you take a picture with a 7D using a focal length of 50mm.
If you take both pictures using a 50mm lens, the field of view from the 5D photo will be much larger and the pictures will not be the same (but will have essentially the same DOF).

Not exactly, because the Circle of Confusion is different for FF and crop. If you open a DOF calculator and put for example FL 50mm and subject distance 5 feet, @f/2.8 you
will have 0,5 ft DOF for FF sensor and 0,32 ft on 1.6x crop, which is actually the other way around (less DOF on the crop).
The difference in the DoF comes only because to frame the same subject with the same FoV you need to move (change subject distance) or use shorter/wider lens on the crop.

JeffreyG · 19th of December 2010 (Sun)

Quote:

Originally Posted by mury

Not exactly, because the Circle of Confusion is different for FF and crop. If you open a DOF calculator and put for example FL 50mm and subject distance 5 feet, @f/2.8 you
will have 0,5 ft DOF for FF sensor and 0,32 ft on 1.6x crop.

Yes, I know. For the same everything (focal length, subject distance and aperture) FF will have slightly more DOF due to being enlarged less from sensor to print.

But this difference is really small and totally swamped by the effect of focal length needed to frame the shot the same.

IMO since you would never use the same focal length on each format, this information winds up being just a bit of trivia.

LBI · 19th of December 2010 (Sun)

This is why I got rid of my crop (40D) and moved to FF. Couldn't be happier!

yjt · 19th of December 2010 (Sun)

Quote:

Originally Posted by Staszek

This is the best post regarding FF vs Crop DOF. http://photography-on-the.net/forum/...6&postcount=10

Read through the thread as well.

thanks, that was really helpful

TeamSpeed · 19th of December 2010 (Sun)

Here is a sample I did comparing the DOF between the 7D and 5D2

xarqi · 19th of December 2010 (Sun)

Quote:

Originally Posted by TeamSpeed

Here is a sample I did comparing the DOF between the 7D and 5D2

Not so. What you have demonstrated marvellously is the effect of focal length on DoF (assuming you did not change f ratio or distance).

TeamSpeed · 20th of December 2010 (Mon)

True, I was trying to show Jeffrey's point that assuming you want the same image across both, then only changing the FL gives that DOF difference. I really don't get the OP's question because I wouldn't really ever want to crop out a 1.6 crop's image from a FF, and lose all that resolution, I would rather zoom in a bit more (or foot zoom) at least so I don't crop as much.

19th of December 2010 (Sun)	#1
yjt Member Join Date: Nov 2010 Posts: 359 IMAGE EDITING OK	DOF FF vs Crop Why do people say that FF has shallower depth of field than crop in the same conditions? __________________ 7D (Gripped) \|\| 24-70 f2.8L \|\| 50 f1.4 \|\| 70-200mm f4L Flickr Last edited by yjt : 19th of December 2010 (Sun) at 18:24.

19th of December 2010 (Sun)	#2
JeffreyG "my bits and pieces are all hard" Join Date: Jan 2007 Location: Detroit, MI Posts: 13,485	Re: DOF FF vs Crop Because to take the same image (same perspective, same framing) a FF camera must be shot with a lens focal length that is 60% longer. That's really all it is, longer focal length (for the same photo) = shallower DOF. __________________ My personal stuff:http://www.flickr.com/photos/jngirbach/ Commercial sports:http://girbach.zenfolio.com/ I use a Canon 5D and 1DIV and a Panasonic GF-1 Gear List: http://photography-on-the.net/forum/...postcount=1550

19th of December 2010 (Sun)	#4
mury Member Join Date: Sep 2010 Posts: 87	Re: DOF FF vs Crop If you use same FL, to get equivalent field of view on both you have to either move closer with the FF camera (less DOF) or back off with the crop (increased DOF). __________________ Canon 5D, 50D EF 20mm f/2.8, EF 28mm f/1.8, EF 50mm f/1.4, EF 85mm f/1.8, EF 100mm f/2.8 Macro EF 24-85mm f/3.5-4.5, EF 70-210mm f/3.5-4.5 Mir-1B 37/2.8, Helios 44-2 - 58/2, Jupiter 11A - 135/4

19th of December 2010 (Sun)	#7
Staszek Goldmember Join Date: Mar 2010 Location: San Jose, CA Posts: 3,177 IMAGE EDITING OK	Re: DOF FF vs Crop This is the best post regarding FF vs Crop DOF. http://photography-on-the.net/forum/...6&postcount=10 Read through the thread as well. __________________ SOSKIphoto \| Blog \| facebook! 5D3 \| EF 24-70 \| EF 70-200 II \| EF 28 f/1.8 \| EF 50 f/1.4 \| 600EX-RT's \|

19th of December 2010 (Sun)	#11
LBI Member Join Date: Oct 2009 Location: Honolulu, HI Posts: 126	Re: DOF FF vs Crop This is why I got rid of my crop (40D) and moved to FF. Couldn't be happier! __________________ 5D \| 7D \| 50 1.4 \| 24-105L \| 70-200 2.8L \| 580EX

19th of December 2010 (Sun)	#13
TeamSpeed Cream of the Crop Join Date: May 2002 Location: Cow and Corn Country, Indiana Posts: 19,677 IMAGE EDITING OK	Re: DOF FF vs Crop Here is a sample I did comparing the DOF between the 7D and 5D2 __________________ 7D \| 100L \| 24-70L \| 70-200L f2.8 IS \| Σ 50-500 OS \| Σ 50 1.4 \| Tok 11-16 \| 18-55 IS \| 55-250 IS Past Equipment \| My Gallery \| My Mini-Reviews Resources For Sale: Focus Genie MicroAdjustment Chart \| Gel Genie Flash Gel Holder \| High ISO Denoiser Action

20th of December 2010 (Mon)	#15
TeamSpeed Cream of the Crop Join Date: May 2002 Location: Cow and Corn Country, Indiana Posts: 19,677 IMAGE EDITING OK	Re: DOF FF vs Crop True, I was trying to show Jeffrey's point that assuming you want the same image across both, then only changing the FL gives that DOF difference. I really don't get the OP's question because I wouldn't really ever want to crop out a 1.6 crop's image from a FF, and lose all that resolution, I would rather zoom in a bit more (or foot zoom) at least so I don't crop as much. __________________ 7D \| 100L \| 24-70L \| 70-200L f2.8 IS \| Σ 50-500 OS \| Σ 50 1.4 \| Tok 11-16 \| 18-55 IS \| 55-250 IS Past Equipment \| My Gallery \| My Mini-Reviews Resources For Sale: Focus Genie MicroAdjustment Chart \| Gel Genie Flash Gel Holder \| High ISO Denoiser Action

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