Lenses matter: You better invest in glass than the body – we all know this. But, does the same lens perform equally on an APS-C (or DX in Nikon’s terms) and full frame camera? To answer this question, I’ll share below some photos taken with the same 50mm lens on crop and full frame body – namely D3400 and D750. Before seeing the samples, let’s look at some technicalities.
Technicalities
- All photos are edited to taste.
- The cameras use the same sensor (Expeed 4) and have equal image size (24MP), making the comparison more “real” and reliable.
- I shoot RAW with D750 and JPEG with D3400, yet I don’t sharpen the images.
- 50mm on 1.5 crop factor becomes 75mm, needs to be kept in mind.
Not a technicality but a note: I use 50mm on full frame practically only for portraits, hence there’s a limited amount of photos available. But don’t worry, there’s enough in the tank.
50mm on Full Frame D750
Let’s start with what matters the most: f/1.8 performance on a not-so-close subject. The shoes were around 4 metres away from me and here is the result an a sunny day – hence bright background. The shadows are recovered, whites are lowered, and the result is a perfectly usable photo. It is sharp enough, colours are as they were, and no vignetting – alles guten.
Now it’s f/2.8. The birds were again around 3-4 metres away from me, enjoying their time – especially the guy on the centre-left. The shadows are recovered again, yet the “pool” appears yellower and darker than it needs to be. The harsh summer light made the frame bit hard for me to fix properly, and I can’t say I did a good job.
Simply perfect. I couldn’t ask for more.
f/2.8 again, and come the problems: The centre is razor sharp, but go halfway from the centre and things start getting nasty. The edges of the building are already bad, needless to add the trees. You see that the sun is on the right side and in the frame, but the problems aren’t from the light, it’s the glass: The centre is amazingly sharp, but only the centre %25 or so. The rest, oh the rest…
At f/5.6, though, it’s a wholly different story: Now everything is darn sharp – even the lady on the left’s feelings when she looks at the girls.
The frame is darker than it should be, but you still can get the idea. It needn’t be put even after the photo above, but I did. Now it’s f/8, no aberrations, no vignetting, no lack of sharpness anywhere and no nothing. As brilliant as it can get.
I realized that I skipped f/4 and here it is. Needless to wait until f/5.6, at f/4 the lens already is sharp almost edge to edge, with f/5.6 making it even better.
Now that we’ve seen how the lens fared on full frame D750, let’s see its performance on a crop body, D3400.
50mm on APS-C D3400
At f/1.8, albeit the balls are around 5-6 metres away from me, we find some subject separation. Well done, Nikon! But, that is all. There’s no sharpness and tons of fringing. Needed harsher editing than with that of D750, not only at this particular photo or aperture but all of them, and the output still isn’t half as close to what I’d want it to be.
But when you don’t need “critical” sharpness, as in the photo above, f/1.8 always is good to have for lower ISO. Here the lens worked a lot better compared to the daylight photo above, and I’m happy with the result.
Narrowing the aperture a bit, at f/2.8, we find the image quality dramatically improved. CAs are a lot less and sharpness is more – just as we’d expect. Still, the lens doesn’t perform as good as it did on D750. Remember the birds? Look again and see for yourself.
Like most if not all other lenses, we see it starting to shine at f/4, but still something is missing. No, colours are just right and there is no fringing. It’s that the quality of the centre doesn’t hold up with the corners, not only the edges. It’s f/4, with D750 we practically had edge-to-edge critical sharpness, but not here. Not good, Nikon!
f/5.6 and almost the same story. The image keeps improving but, for me, it’s not comparable with how it performed on the full frame. Before coming to conclusions, let’s see an f/8 sample:
Conclusion
With every test we have a dull and alternative hypothesis. My dull hypothesis, “right until proven wrong”, was that the lens should work better on smaller sensor. Why? Because at the centre we have the highest quality. Crop sensor bodies use the central are of the lens, leave the lesser-quality sides aside, and provide better photos than full frames.
And what happened? The opposite. Full frame worked (a lot) better with the lens, gave less CAs and more sharpness and detail. I can’t tell its physics but I can say two things on the potential reasons:
- Crop body magnifies everything at the centre. A 2px CA on FF, for example, becomes 3px on the crop body. This is why quality dropped on D3400: Albeit it has the same sensor and image size, because the glass is the same, hence the flaws of the lens, they grew larger.
- Scooters are easy to ride, for which many beginners use them – as those that don’t want to mess with the machine too much. But motorcycles are lot more forgiving of mistakes: You can slip easier with a motorcycle than with a scooter. Similarly, full frame bodies are more forgiving. This goes against the custom, yet that’s my experience – and for you to check if right or wrong.
I’ll do another version of this test, Tokina 16-28, and, here comes the spoiler, my conclusion will be the same: Full frame gives better images than crop body. One of the main takeaways of yet another forthcoming post, FF vs APS-C, will be this.
At this point you may ask: Of course a full frame lens will work better with full frame body! What about crop lens on crop body? Well, albeit not a comparison like this, I used 18-55 Lens on Full Frame Camera and you can see the results there. Also find the Flickr gallery for D750 and 50mm here, and D3400 and 50mm here to see full size images to look closer if you like.
