Crop vs FF for Landscape

existent said:
It's getting a bit confusing now.. :D

I know that dof is smaller on full frame. Is it one stop difference?
So lets take 10mm (crop) / 16mm (ff) for example.

10mm crop fov will be equivalent to 16mm on FF.

Now, what about dof.. Is the same f-stop going to give the same dof? or do you need smaller aperture (higher f number)?
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The smaller the image, the more DoF. The difference between full-frame and crop format is f/number x crop factor, ie 1.6x in the case of Canon.

That translates to 1.28 stops - eg f/4 on crop format delivers the same DoF as f/6.4 on full-frame. Call it a stop and a bit for both Canon and Nikon. It's two stops for the yet smaller 4/3rds format.

Check it all out here www.dofmaster.com
 
HoppyUK said:
The smaller the image, the more DoF. The difference between full-frame and crop format is f/number x crop factor, ie 1.6x in the case of Canon.

That translates to 1.28 stops - eg f/4 on crop format delivers the same DoF as f/6.4 on full-frame. Call it a stop and a bit for both Canon and Nikon. It's two stops for the yet smaller 4/3rds format.

Check it all out here www.dofmaster.com
Click to expand...


so what I wrote above was correct then.. for the same dof you would need to have 1.28 stops smaller aperture.

even though the sensor/lens allows you to go down to f/22 on ff with minimal loss in IQ, you do need to go that small to get the same dof with f/16 on a crop.

So the real advantage of ff is on the larger apertures... when the crop can't possibly reach to the max aperture of the lens..
 
existent said:
so what I wrote above was correct then.. for the same dof you would need to have 1.28 stops smaller aperture.

even though the sensor/lens allows you to go down to f/22 on ff with minimal loss in IQ, you do need to go that small to get the same dof with f/16 on a crop.

So the real advantage of ff is on the larger apertures... when the crop can't possibly reach to the max aperture of the lens..
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Yes :thumbs:
 
"So the real advantage of ff is on the larger apertures..."

Plus you start out with a bigger recording medium.

That dof master site states that longer lenses give less dof but current thinking which I tend to agree with is that this simply isn't true.
 
woof woof said:
"So the real advantage of ff is on the larger apertures..."

Plus you start out with a bigger recording medium.

That dof master site states that longer lenses give less dof but current thinking which I tend to agree with is that this simply isn't true.
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I'm not sure the DoFmaster site says that. Basically, if you change magnification, either by moving closer/further or by altering focal length, the DoF changes. But if you change both, eg by doubling the shooting distance but also doubling the focal length at the same time to maintain magnification, then DoF stays the same.

What changing the format is doing is effectively changing the magnification also, ie crop sensor records a smaller image for the same field of view, so DoF changes accordingly.

To be strictly accurate, focal length does shift DoF by itself, but in practise the difference is tiny. You can only really measure it if you compare extremes like a 20mm lens against a 200mm lens, but you would never do that in practise and even then the dramtic changes in field of view and perspective would again make any slight DoF shift irrelevant.
 
woof woof said:
"So the real advantage of ff is on the larger apertures..."

Plus you start out with a bigger recording medium.

That dof master site states that longer lenses give less dof but current thinking which I tend to agree with is that this simply isn't true.
Click to expand...

well yea.. I meant aperture / dof wise. :D
 
existent said:
Being a digi-noob (:D), why does 16mm on FF looks better than a 10mm on a crop? It surely is similar field of view. But as you said, I never looked through the viewfinder of a FF, so I can only go by what people say about it :)
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Maybe because the Canon 16-35 (or Nikon 17-35) is a better piece of glass than a Sigma 10-20? I wouldn't find that hard to believe...

Focal length is one thing, but the glass itself is a whole different game.

Barrel distortion and corner sharpness come into play...
 
desantnik said:
Maybe because the Canon 16-35 (or Nikon 17-35) is a better piece of glass than a Sigma 10-20? I wouldn't find that hard to believe...

Focal length is one thing, but the glass itself is a whole different game.

Barrel distortion and corner sharpness come into play...
Click to expand...

That is a fair point. Some of the crop-only lenses are made for a less monied audience and often aren't as good. On fourthirds, the Sigma 10-20 is the least good option, followed by the ZD 9-18 and then the ZD 7-14, which gives amazing results as a super-wide-angle. But then the 7-14 is about £1300!

Andy
 
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