Wide Angle with Cropped Sensor

dazzajl said:
At the risk of making more friends in this thread ;) ......

That's not right. Depth of Field is purely an affect of the lens and not changed by using a FF, crop, large format camera or whatever. :)
Click to expand...

is it just that the DOF would seem shallower on a ff camera because there is no crop and you see more oof area?
 
Yeah, I guess you could have a larger OOF area but technically, the DoF isn't changing.

What would affect the DoF, is if you moved closer to the subject to get the same field of view from a FF camera that a small sensor would give. By moving closer to the subject, the DoF would get smaller. Also, if you were to put a longer lens to create that same field of view, again that would reduce the DoF.

So, yes there are times that the same shot could have a different DoF but it's brought about from either changing distance or changing lens.

If you just took the same shot from the same place, with the same lens and cropped it afterwards, the DoF would be identical.

Hopefully, some of this will make sense and be useful to someone. :LOL:
 
dazzajl said:
At the risk of making more friends in this thread ;) ......

That's not right. Depth of Field is purely an affect of the lens and not changed by using a FF, crop, large format camera or whatever. :)
Click to expand...

Surely Dof is determined by the circle of confusion which is determined by the sensor type?

Edit: scientific explanation here
And online DOF calculator here - punch in the numbers for yourself.
 
Hmmm.
Looks like I got it the wrong way round.
The dof is shallower with the crop body for the same focal length, aperture, and distance to subject.
Doh!
 
Are you sure??

I thought you got more dof with a smaller sensor given a certain F number.
 
yes.
have a go on the DOF calculator two posts back.
Change the drop down list between 5D and 30D and look at the total depth of field change.
 
ooh, now were getting into another of my favourite debates and that's the one of does DoF actually exist.

There are those that say the plane of focus exists in one place and something in a shot is either on that plane and therefor sharp or it's not on it and therefore isn't.

There are degrees of softness moving away from the focal plane but what we call DoF is just a combination of circle of confusion and enlargement size. For example, in a small print at 2x3 inches lots more of a shot will appear to be sharp than in a 20x30 print. Is the DoF different in each print?

You can also add viewing distance to mixing pot too, if you like your head hurting. ;):LOL:
 
:help: :LOL:

I think the key phrase is 'within acceptable limit of sharpness'

If DoF didn't exist then pictures would have no form or depth.

And we'd be talking about PoF!
 
hmmm, that's very flattering Tom but I think it just means that we both need to get out more. ;)

It also means that now I know someone's actually reading the stuff I write, I should go back and put in all the words I miss out. Just cant type as fast as I think.

.... and no, that doesn't mean I think fast, just type very slowly. :LOL:
 
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