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02-01-2014, 12:57 PM   #1
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What does it mean when a lens is "made for the aps-c sensor"

Hi. I've read ads and reviews of lenses that say the lense is "made for the aps-c sensor". What does that really mean? Is it expected to not be optimal for (future?) full frame cameras?

02-01-2014, 01:04 PM   #2
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QuoteOriginally posted by Kurt Euler Quote
Hi. I've read ads and reviews of lenses that say the lense is "made for the aps-c sensor". What does that really mean? Is it expected to not be optimal for (future?) full frame cameras?
It's supposed to mean that they're built from the bottom up to work well with APS-C cameras. So they should be more compact than FF lenses but still cover the APS-C image circle properly. The focal lengths might also be different to take into account the cropped field of view.

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02-01-2014, 01:04 PM   #3
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APS-C Sensors are smaller, so if you take an APS-C lens and mount it to full frame/film camera there is a very good chance that the image will have a vignette as the lens does not cover the full sensor.
02-01-2014, 01:05 PM   #4
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it just means that the image circle on the back is made to cover the smaller aps-c sensor and will not cover a FF sensor at least that is what I was told

02-01-2014, 01:06 PM   #5
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in dslr's there are a few types of sensors. the most common are Full frame and APS-C. Full frame captures the same area as a 35mm analog camera, and aps-c is 1.6x and 1.5x times the size, so it is smaller. it ends up like this:

So, for example in canon, you can use a full frame lens in both bodies, but you can't use a apsc lens in a full frame. I really don't know why they do that, might be economy, but those lenses' area is more squrare than the full frames which are more like a rectangle... also, remember that a 28mm in a full frame ends up being like a 58mm, so they might adjust those numbers for the apsc so you don't have to calculate and avoid you having a lense not as wide as you wanted it,.
02-01-2014, 01:07 PM   #6
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It means that Pentax is guaranteeing that it will cover the APS-C sensor well but not making any promises for FF. Some lenses have been tested to work on film cameras. Until there is a FF camera though it will be hard to tell if they really cover anything more than APS-C and provide sufficient sharpness across the frame.
02-01-2014, 01:44 PM   #7
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So yes, its about the size of the projected image circle. A bigger sensor needs a bigger image circle, plus a little spare room for SR.
A lens made for APSC is marketing talk for "It will work great on your crop camera! Buy it!"
Such a lens would have a smaller projected image circle (since it needs to cover a smaller sensor), but in practice that is often not the case. Many "crop only" lenses actually project an image circle big enough for FF. These were tested on film and there is a thread with a list of such lenses, please just search for it. Either way, a FF camera would still allow the use of crop lenses, you would simply need to crop the dark edges. The real differences are that APSC lenses tend to be smaller, lighter, and more automated (missing DoF scales, missing aperture ring), though this is just a general rule. There are some great APSC lenses that actually produce dark corners on FF cameras.
Field of view for a APSC 35mm and FF 35mm lens will be exactly the same on your camera btw. Only if you put the APSC lens on a FF camera, the quality of the edges might be poor or they might even be blacked out.
Oh, and lens hood also crop the image circle.

Last edited by Na Horuk; 02-01-2014 at 02:28 PM.
02-01-2014, 03:05 PM   #8
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In general the shorter focal lengths will not work on a FF camera whereas longer focal lengths often will.


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