Lenses on a crop sensor

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The Great Poobar

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Right so, as a noob I've gotten my head around the fact that using a lens on a crop sensor DSLR Vs a Full Frame will give very different different results. All well and good.

What I'm struggling with a little is the actual results it'll give. Can someone please check my understanding here?

Say, for example, we use a 35mm on both. On the crop it's not actually altering the focal length, it's simply giving a cropped image which would be the equivalent of tighter lens on the Full Frame (50mm-ish I believe?). This would be the same as applying a bit of digital zoom (I'm sure there's a more Pro name for it, but I'm not aware of that yet) PP with the FF results. That's my understanding so far anyway, is it even remotely close?

Leading on from that, as I currently own a crop sensor (d5100), what difference would I see in a side by side comparison of images taken using both a DX 35mm and a non DX 35mm?

As I said, noob. Your answers are very much appreciated.
 
if you take your focal length and multiply by 1.6 (Canon crop) it will give you the length your image will show.

E.g. 35mm EF lens on a crop sensor will be 35x1.6=56mm

So in effect your 35mm lens will be a 56mm lens
 
The Great Poobar said:
Say, for example, we use a 35mm on both. On the crop it's not actually altering the focal length, it's simply giving a cropped image which would be the equivalent of tighter lens on the Full Frame (50mm-ish I believe?). This would be the same as applying a bit of digital zoom (I'm sure there's a more Pro name for it, but I'm not aware of that yet) PP with the FF results. That's my understanding so far anyway, is it even remotely close?
Click to expand...
Yes, this is correct. Lenses do not change focal lengths, it is the fields of view that change with different sensor sizes.

Barring pixel differences, you would get exactly the same image if you cropped the FF image in post processing.
 
http://www.cambridgeincolour.com/tutorials/digital-camera-sensor-size.htm

Focal length stays the same 35mm lens is a 35mm lens, but on a crop because its a smaller sensor you introduce a crop factor, it's all to do with the path of the light to the lens. A 35mm on a 1.5x crop is equivalent to a 53mm lens on a full frame camera. There are advantages and disadvantages to crop sensors, it depends what you're taking photos of.

So to sort of see the equivalent you would need a 53mm lens on a FF v 35mm on a crop to get similar results but you would also have to take settings into account in terms of you aperture settings.
 
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The Great Poobar said:
Right so, as a noob I've gotten my head around the fact that using a lens on a crop sensor DSLR Vs a Full Frame will give very different different results. All well and good.

What I'm struggling with a little is the actual results it'll give. Can someone please check my understanding here?

Say, for example, we use a 35mm on both. On the crop it's not actually altering the focal length, it's simply giving a cropped image which would be the equivalent of tighter lens on the Full Frame (50mm-ish I believe?). This would be the same as applying a bit of digital zoom (I'm sure there's a more Pro name for it, but I'm not aware of that yet) PP with the FF results. That's my understanding so far anyway, is it even remotely close?

Leading on from that, as I currently own a crop sensor (d5100), what difference would I see in a side by side comparison of images taken using both a DX 35mm and a non DX 35mm?

As I said, noob. Your answers are very much appreciated.
Click to expand...

None.
 
if the image below was taken on FF the image inside the black lines is what you would see on a crop sensor using the same lens at the same focal length only straighter as i did it quickly! (basically)

blueriverscenerywallpapers_zps8b779a5a.jpg


It essentially 'crops' the image - the same way you would in PP
 
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