Time and again you’ll hear photographers with a case of G.A.S. bemoan their crop sensor cameras, longing for the day they upgrade to full frame. But is there a good reason to prefer a crop sensor? Photographer Steve Perry has an answer in this YouTube video.
Crop sensors add a multiplier effect to the focal length of a lens. When you need some extra reach, say about 1.5 or 1.6 times as much, cameras with crop sensors have a leg up over full frame. Of course, if you have frame camera you can always add a teleconverter to get 1.4x the reach, but at a cost. You lose a stop of precious light and some sharpness on top of that. So, which is better?
The first comparison is the full frame the Nikon D5 with Nikon AF-S Teleconverter TC-14E III against the crop sensor D500. The two cameras have virtually identical resolutions at 20.8 and 20.9 megapixels, respectively. The D500 should be a hair sharper against the D5 without adding the teleconverter, since it doesn’t have an anti-aliasing filter.
But what if you put the D500 head to head with the D810 and a teleconverter? The D810’s significantly higher resolution should make it the clear winner on its own, what happens when the teleconverter is added and the images are down-sampled to virtually standardize file sizes?It’s close, but the D810 still looks a little sharper. But all this is just pixel peeping. For most practical uses, the difference is negligible as long as the teleconverter is quality. What about real-world use?
Full frame cameras will usually outperform crop sensor cameras from the same generation and manufacturer in ISO tests, but when you’re subtracting a stop of light in order to get that extra reach you negate this full frame advantage. If you’re shooting something that moves, like wildlife, with a long lens you will want every millisecond of shutter speed you can grasp so this is a definite minus.
The forced stop-down of a teleconverter doesn’t play nice with autofocus points. The example shown here is only one way that autofocus can be crippled by a teleconverter, watch the video for more explanation. As with the last example, if you’re trying to photograph a moving subject from a distance autofocus is not a great sacrifice.
REDUCED IMAGE QUALITY
Sharpness isn’t the only way image quality can suffer when using a teleconverter. Images taken using a teleconverter will often lack contrast compared to those taken without. Additionally, teleconverters make other image detracting anomalies, like heat waves, more pronounced.
The takeaway? If you want to get a little more out of the lenses you already have, get another body if you can. Who was I kidding, G.A.S. prevails. Though, there is one definite upside to teleconverters: they will take a much smaller bite out of your wallet. Weigh the price difference to the performance difference to decide which gear you should acquire next.