Using an APS-C Lens on a Full-Frame Camera #
A7C2, Sigma 56mm #
Normally, crop lenses with a smaller image circle tend to reveal frustrating black edges when used on full-frame cameras. However, some lenses have an unusually large image circle, making them usable even on full-frame bodies. One of my favorite lenses in this category is the Sigma 56mm.
The shape of the image circle becomes more defined as you stop down the aperture, so I tried shooting at the maximum aperture to see the effect.
Explaining this in words is not very meaningful, so all the explanations are replaced with sample photos.
Without Post-Editing… #
Even if you try to avoid it, cropping during post-processing can be really tedious. I try to preserve the full field of view when shooting, but in the end, I often end up cropping anyway. Since the amount of vignetting varies from photo to photo, I used to adjust each one individually. However, I recently discovered the aspect ratio tool in Lightroom, and I’ve been using it frequently.
On Nikon cameras, there’s not just the x1.5 crop mode but also an x1.2 option, so you don’t even have to worry about this. But what could work on the C2? While thinking about it, I remembered that the aspect ratio feature I mentioned earlier in Lightroom is also available on Sony bodies under the name “Screen Ratio.” By adjusting the screen ratio like this, I thought it would be much better than blindly using crop mode.
Ratio | W | H | Pixels | Pixels (MP) | Crop Ratio |
---|---|---|---|---|---|
3:2 | 7,008 | 4,672 | 32,741,376 | 33MP | 100% |
4:3 | 6,224 | 4,672 | 29,078,528 | 29MP | 89% |
16:9 | 7,008 | 3,944 | 27,639,552 | 28MP | 84% |
1:1 | 4,672 | 4,672 | 21,827,584 | 22MP | 67% |
crop-mode | 4,608 | 3,072 | 14,155,776 | 14MP | 43% |
Test #
Here’s what the simulation looks like.
3:2
4:3
16:9
1:1
Unfortunately, the screen ratios provided by the camera body are limited to this. It would have been nice if custom options were included, but I wonder how many people are really going to go through the trouble of using a crop lens.
Also, I’ve occasionally read online that cropping the sensor can be harmful to it. Personally, I think that’s nonsense—but I can’t help but wonder if such creative claims came completely without any basis.
In conclusion… using what you already have is fine, but buying one specifically for this purpose seems unnecessary. It might be better to invest in a cost-effective lens like a Viltrox instead.
With Post-Editing #
If you’re using an editing program like Lightroom, cropping to a 5:4 or 4:5 aspect ratio is quite simple. This adjustment helps minimize vignetting.
Ratio | W | H | Pixels | Pixels (MP) | Crop Ratio |
---|---|---|---|---|---|
5:4 | 5,841 | 4,672 | 27,289,152 | 27MP | 87% |
On the camera, you can preview a 5:4 crop using the guideline option. Fortunately, the guideline feature includes a 5:4 aspect ratio.