I've been thinking again... Full frame glass on a cropped sensor camera.

stu_the_flat

stu_the_flat

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Stuart
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I've got my self confused again. I was thinking about full frame lenses on a cropped frame camera. So obviously there will be light entering the lens and not hitting the sensor. however I am confused as to how its effects the aperture? Is f2.8 the same on a FX lens as a DX lens? Or is there a multiplication factor for FX lenses as there is light lost?

Cheers Stuart
 
I agree makes no difference, there is still the same amount of light coming through the lens regardless of DX or FX.

The sampling area for matrix metering on a crop sensor is smaller, on account of the smaller sensor size, but thats it

Hugh
 
Stuart,

think of the DX sensor as a cropped FX sensor...all that happens with a DX frame is the centre portion of the image is th eonly bit that it isused. Think of it as a full frame image that is transmitted by the lens, but part of it fals outside the edges of the DX sensor. That is what actually happens.

I can see where you get the idea from though, and certainly what happens on DX bodies is the viewfinder appears darker than a full frame one, even if it isn't.
 
I want a Nikon 24-70 f2.8 but there is no way I'll ever be able to afford one.

So I'm trying to convince EVERYBODY they don't want there's, I started with the D700 owners pointing out that there where not nearly enough pixels to for them to sample the resolution from there 24-70mm but they were unconvinced, So then I stared this thread trying to convince the D200 and D300 owners that they would be much better off with the 17-55mm f2.8. But I have failed

I will go back to darkly brooding my evil plans.

Stuart
 
17-55 is a perfectly good DX lens .
 
I like the style, and I have to give you 11/10 for effort. I'll keep my 24-70 though thanks :razz:
 
I think I'll end up buying a 3rd party lens. As all these Nikon users seem very reluctant to give me there 24-70 lenses.

the only problem is it has to autofocus with my bloomin D60. I have learnt the hard way that the best optics in the world don't count for toffee if they are out of focus.

I think I'll get the Sigma 18-50, I know Tamron get a good write up but I really like Sigma HSM system.

Cheers I wasn't aware that Tokina had an offering I find out about that.

Stuart (the dark lord of nothing in particular)
 
the multiplication factor comes as a result of the sensor, not the lens. As stated numerous times above two f/2.8 lens will perform identically from an exposure and DoF perspective on the same camera.

BUT a FF and a crop BODY will obviously provide very different results with the same F/2.8 lens, even at "equivalent" focal lengths (if it's a zoom of course).

HTH
 
I think most have got it right above. What you have to remember though is that the same amount of light enters a FF lens, irrespective of whether the sensor is FF or crop. Once there only a certain amount of the available light is captured by the crop sensor. The remaining light falls to the bottom of the body and needs to be drained every few months.
 
condyk said:
What you have to remember though is that the same amount of light enters a FF lens, irrespective of whether the sensor is FF or crop. Once there only a certain amount of the available light is captured by the crop sensor. The remaining light falls to the bottom of the body and needs to be drained every few months.
Click to expand...
Indeed. That's one of the reasons why FF bodies are so big, or course. There needs to be space for the bucket.
 
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