Full and crop sensor, which part of the lens does it use?

Robbo

Robbo

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not a clue how to try and explain this....so here goes

If I had a 50mm on a full frame sensor, I am assuming it will use the full width of the lens.

If it was on a 1.6 sensor, would it still use the full width of the lens and the sonsor increases the size over the full frame......or will it use more of the centre of the lens, making it bigger than the full frame.

hope that doesnt sound like a really pathetic question lol

:thinking:
 
I don't think I understand the question but the center of a image has used the center of the lens.

I do not believe that a 50mm on a full frame camera would use the full width of the lens as you get medium format cameras which have larger sensor or film than full frame.
 
A smaller sensor will use a smaller central part of the lens.

This is why Canon EF-S lenses (designed for crop sensor models) are smaller and lighter than the equivalent EF lenses, and why they wouldn't work on a full-frame sensor - if you did manage to mount one, you'd get heavy vignetting at the edges of the frame.

Also why compact cameras have small lenses compared to SLRs.

This is all completely independent of the resolution of the sensor - I think this the second part of your question! A Canon 7D with a 18mp 1.6x crop sensor will give you 18mp images, regardless of what lens you put on it.

A.
 
Anorakus said:
A smaller sensor will use a smaller central part of the lens.

This is why Canon EF-S lenses (designed for crop sensor models) are smaller and lighter than the equivalent EF lenses, and why they wouldn't work on a full-frame sensor - if you did manage to mount one, you'd get heavy vignetting at the edges of the frame.

Also why compact cameras have small lenses compared to SLRs.

A.
Click to expand...

So say I had an EF lens of 200mm, my camera would mainly use the centre part of the lens?

Really cant explain lol

e.g.

On a blur index of a 200mm len on a full frame sensor, the middle is pin sharp and blurs off towards the sides.

on a 1.6 crop sensor would the blur edges be slightly less because of the crop ratio, as it would focus more on the centre of the lens?

:bonk::thinking:
 
Robbo said:
So say I had an EF lens of 200mm, my camera would mainly use the centre part of the lens?

Really cant explain lol

e.g.

On a blur index of a 200mm len on a full frame sensor, the middle is pin sharp and blurs off towards the sides.

on a 1.6 crop sensor would the blur edges be slightly less because of the crop ratio, as it would focus more on the centre of the lens?

:bonk::thinking:
Click to expand...

Yes.

So you can get away with using crap lenses on a crop sensor because you won't ever see those darker, fuzzier corners.
 
Here you go the circle represents the lens.

008d1j-18482184.jpg
 
A crop sensor (APS-C for Canon) is smaller than the full frame, it uses the centre part of the lens, whereas the full frame uses as much as it can.

Remember that lenses are circle whereas sensors are rectangles, so there are some parts of the lens that the sensor can't use.

Dogfish_magnet said:
Here you go the circle represents the lens.

008d1j-18482184.jpg
Click to expand...

The grey circle being a full frame lens (EF mount) the green circle being a crop lens (EF-S). Also I was looking for one of those, decided to make one then found out I couldn't attach it to the reply :(.
 
thanks for helping everyone :-) and that diagram explain what I was trying to say! lol
 
trencheel303 said:
Yes.

So you can get away with using crap lenses on a crop sensor because you won't ever see those darker, fuzzier corners.
Click to expand...

I don't agree with this conclusion. Crop cameras have far higher pixel density and require very sharp glass in the centre and the middle of the frame. FF is more forgiving in that respect and things generally come out sharper with the same lens. While vignetting is a smaller issue on crop, fuzzy corners full of CA are still pretty common. Hence, the latest generation cameras both FF and crop really need only the best, not the crappiest lenses. Otherwise Canon 10D / Nikon D40 is all you need.
 
trencheel303 said:
Yes.

So you can get away with using crap lenses on a crop sensor because you won't ever see those darker, fuzzier corners.
Click to expand...

Except, the pixel density of the crop sensors tends to be higher, so they are more demanding of the lens (albeit in the lens's best are, the middle).

E.g. 10MP full-frame, vs 10MP APS-C Canon crop. The crop sensor is packing 10MP over 1/2.56 of the area - so the pixels are smaller and the lens has to produce more detail to obtain pixel-level sharpness.

So any tests of 'blur', although they will tend to be uneven on full frame, the sharpness, per pixel, for the same lens, will appear better on the full frame.

This is part of the reason for the EF-S lenses - they have a smaller image circle than full frame lenses and tend to have better resolution over that smaller area.

Andy
 
them last two posts make sense....that for that handy bit of info :-)

I would purchase 'rubbish' glass anways....well what I see as not rubbish anyways lol

Would you say these are ok for my 450D
canon 60mm F2.8macro USM
canon 70-300mm F4-5.6 IS USM
canon 10-22mm F3.5-5
 
Robbo said:
them last two posts make sense....that for that handy bit of info :-)

I would purchase 'rubbish' glass anways....well what I see as not rubbish anyways lol

Would you say these are ok for my 450D
canon 60mm F2.8macro USM
canon 70-300mm F4-5.6 IS USM
canon 10-22mm F3.5-5
Click to expand...

They look fine to me, but I would opt for 100mm macro whenever possible. It will work on FF and is a far better macro.
 
daugirdas said:
They look fine to me, but I would opt for 100mm macro whenever possible. It will work on FF and is a far better macro.
Click to expand...

I have ran out of money at the min but I like the 60mm at the moment it gives me best of both worlds.

My next macro upgrade is the Mp-E65
 
Robbo said:
.......My next macro upgrade is the Mp-E65
Click to expand...

The MP-E65 isn't really an upgrade from an EF-S60, it's complimetary to it. One lens will focus from infinity down to 1:1 whilst the other starts at 1:1 and goes to 5:1

Bob
 
Canon Bob said:
The MP-E65 isn't really an upgrade from an EF-S60, it's complimetary to it. One lens will focus from infinity down to 1:1 whilst the other starts at 1:1 and goes to 5:1

Bob
Click to expand...

yes I know, I mean my next upgrade will be specific for macro work, thats why I would rather pay high price for specific like the MP e 65 over the 100mm macro
 
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