Do you want to know the difference between a full frame lens on APS-C vs APS-C lens on full frame? Do you want to know which lenses can mount on which cameras and whether various camera/lens combinations are compatible?
That’s what this article is all about.
I’m going to explain whether you can use a
full frame lens on an APS-C body. I’m going to explain whether you can use an
APS-C lens on a full-frame body.
And you’ll come away knowing all about your
camera and lens compatibility.
Sound good?
Let’s get started.
What Happens When You Attach a
Full Frame Lens on APS-C Cameras?
A full-frame lens is designed for full-frame
cameras. But what happens if you take that full-frame lens…
…and mount it onto an APS-C camera body?
In truth, not much at all.
Focal Length
First, the focal length of the lens doesn’t change. You see, the focal length of the lens is a physical property – it’s already fixed from the moment the lens is created. Focal length is the distance from a point inside the lens to the camera sensor, and this isn’t changed by a smaller, APS-C sensor.
Depth of Field (DoF)
Second, the depth of field doesn’t change. The
depth of field is determined by the aperture, the focal length, and the
distance from the lens to the point of focus; none of these are altered by an
APS-C sensor.
Image Quality
Third, the quality of the lens stays the same. The optics of the lens remain constant no matter what camera you mount it on.
However, there is one feature that changes
with an APS-C sensor size:
Lens’s Field of View
You see, whenever you mount a lens onto a
camera, the lens projects a circular image onto the camera sensor.
(This is known as the circle of projection.)
That circular image is always the same size, no matter the camera sensor. But the camera sensor doesn’t always use this entire projected image. A full-frame lens is designed to project an image that’s perfect in size for a full frame camera sensor.
But when a full-frame lens is mounted onto a
crop-sensor camera, the smaller sensor essentially crops the image projected by
the full-frame lens. And you end up with a narrower field of view–that is, you
end up with a narrower portion of the scene captured by the sensor.
Make sense?
Advantages of Using Full-Frame
Lens on APS-C Camera
Now that you know how a full-frame lens works
on an APS-C camera, you can see that there is one big advantage to using this
combination:
The narrower field of view increases lens reach, so you’re able to photograph more distant subjects with ease. This increased field of view is often referred to as a crop factor, where a 100mm lens is cropped to a 150mm lens on an APS-C camera.
See also: Best Fujifilm APS-C X Mount Lenses
(Despite this method of referring to APS-C
cameras, the focal length doesn’t actually change! Only the field of view is
affected.)
This is important for wildlife and sports photographers because they often need to capture images of subjects far off in the distance. It increases their lens’s reach, even though the focal length doesn’t change.
Disadvantages of Using Full-Frame
Lens on APS-C Camera
There are a few important disadvantages to
using this combination.
See also: Top Rated Lenses for Bird Photography
For one, full frame lenses tend to be bigger and more expensive than their APS-C counterparts.
Plus, while the extra reach is useful for sports and wildlife photographers, it makes wide-angle landscape photography a lot harder, because it nixes the ultra-wide field of view. That’s one of the reasons why many landscape photographers prefer to shoot full-frame, especially if their style involves creating ultra-wide, sweeping landscape photos.
What Happens When You Attach an
APS-C Lens on a Full-Frame Camera?
In many ways, attaching an APS-C lens on a full frame camera is just like attaching a full-frame lens to an APS-C camera.
Focal Length
For instance, the lens focal length doesn’t change – because just like a full-frame lens, the APS-C lens’s focal length is fixed from the moment it’s produced. Focal length is an optical property of the lens, completely unaffected by the sensor size.
Depth of Field (DoF)
And the lens’s depth of field doesn’t change,
either, because the focal length of the lens remains constant.
Image Quality
Even the quality of the lens doesn’t change;
as I explained above, a lens’s image quality isn’t influenced by the sensor
size.
There is one issue with mounting an APS-C lens
on a full-frame camera, however:
Image Projection
The image that’s projected by the lens is designed for APS-C sensors, not full-frame sensors. So it’s smaller than required and doesn’t cover the entire full-frame sensor.
Now, if you’re using Sony or Nikon cameras and
lenses, then you can still mount an APS-C lens onto a full-frame camera. But
you’ll often see vignetting (i.e., darkening) around the edges of the frame,
which can easily ruin an image–unless you crop it out.
If you mount an APS-C lens on a full-frame
Nikon and Sony camera and you don’t see vignetting, this is probably because
the camera automatically identified the lens as APS-C and switched into a crop
mode that uses only part of the sensor. This is a viable way of taking photos,
but you’re going to lose some resolution. After all, the camera is cropping out
megapixels!
Canon EF-S Lenses Issue
Note that things get a bit trickier when it comes to native Canon lenses. If you mount a Canon APS-C lens (labeled as an EF-S lens) onto a Canon full-frame camera, the lens mount will ram into the mechanism inside the camera, which you want to avoid at all costs. This won’t be a problem with third-party lenses for Canon APS-C cameras, but native EF-S lenses simply should not be mounted on Canon full-frame cameras.
Advantages of Using an APS-C Lens
on a Full-Frame Camera
Here’s the main advantage of mounting APS-C
lenses on full-frame cameras:
You can take advantage of smaller, cheaper
APS-C lenses offered by manufacturers. These are often high-quality, but they
cost much less than their full-frame equivalents.
For instance, Nikon users often mount the
(APS-C mount) 35mm f/1.8 lens on full-frame bodies. This lens offers excellent
quality and a compact build for an impressively low price.
Disadvantages of Using an APS-C
Lens on a Full-Frame Camera
When you use an APS-C lens with a full-frame
camera, you’re only using part of the sensor. This, in turn, reduces the
resolution of the final image. You’ll be forced to crop, or your camera will
crop for you–so that a 24 megapixel sensor produces a 10 megapixel image.
Conclusion
Now that you’ve finished this article, you
know all about using APS-C lenses on full-frame sensors, as well full-frame
lenses on APS-C sensors.
And you know the pros and cons of each option.
Just remember:
You don’t need to be afraid of mounting full-frame
lenses on APS-C cameras, nor do you need to be afraid of the reverse.
(Unless you’re using a Canon EF-S lens on a
full-frame camera–which you should never do!)
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