Does my camera/lens need repair, or are iPhones just better?
September 18, 2022 12:48 PM   Subscribe

Someone asked me to photograph a painting for them, since I have a "good" camera. I used a Canon 80D with a Canon EF 24-70mm f/2.8L lens, set to f11 with a shutter speed of 125. All focus points lit up when I auto-focused on the canvas. I also took a snapshot with my iPhone 12 mini, using whatever the camera settings decided. The iPhone image is clearly sharper and shows more detail in the texture of the paint and the canvas.

You can compare the two images here. Is it just the auto-sharpening of the iPhone image? Later I did some sharpening with Photoshop but it feels like the Canon didn't capture the information in the first place, particularly in the white shirt.
posted by xo to Computers & Internet (10 answers total) 4 users marked this as a favorite
 
Best answer: Phones do a lot of post processing (brightness, contrast, sharpening), so you shouldn't compare an unprocessed camera photo with a phone photo. But:

• It doesn't look like the camera focused perfectly. I would try shooting on manual focus to see if you can get it sharper. That lens should be a quality lens, but there's certainly a chance that it's just not sharp. Also, look up to see if it's sharpest at any particular aperture and focal length, and try those.

• Was it on a tripod? Try a shorter exposure at F8.

• It looks like the shot with the camera is a little overexposed, which is causing the whites to blow out. It it the same lighting for both? It doesn't look like a camera flash was used, but that certainly would cause a big difference in texture.
posted by jonathanhughes at 12:59 PM on September 18 [4 favorites]


Best answer: The photo on the left looks like it's been heavily JPEG compressed as well (fine detail missing, weird colour noise). Was the camera perhaps set up for small file sizes rather than high photo quality?

Modern iPhones have very good cameras in them and they also leverage the phone's accelerometer to do image stabilization. If these shots were taken without a tripod, that might help explain why the camera one looks so poor by comparison.
posted by flabdablet at 1:07 PM on September 18


You're stopping down your lens to f/11; the iPhone 12 Mini's main camera (aka 1x aka Wide) is at f/1.6. That alone would produce almost a 7x improvement in lateral resolution.

I would also do a comparison with both cameras shooting in RAW, if possible, to help eliminate differences in the processing pipelines.
posted by Maecenas at 1:08 PM on September 18 [2 favorites]


Best answer: A few possibilities:
  • F/11 is above the diffraction limit for your camera, try a wider open aperture, just below f/7.1
  • Manual focus the camera carefully with the aperture fully open, and then step down to f/6.7 to take the photo. If focus peaking is an option with the rear LCD screen, enable it to help nail the middle of the focus sweet spot and also utilize the focus zoom feature if it has one. One of the classic problems with DSLRs is that they can off-focus from the actual sensor location at times because they are using a mirror, so focus peaking/zoom via the rear screen will increase the chances of nailing the focus.
  • Make sure that optical stabilization is on, or turn off OIS and use a tripod - 125th of a second is probably slow enough to catch hand held motion blur.
  • Shoot raw, and see if the highlights are blown. Any decent photo editor will let you recover them if they were blown. (You can also check the clipping if you enable the histogram in the live view.)
  • If using a photo editor, try adjusting the clarity/micro-contrast if it is offered.
It can be worthwhile to try shooting it a few times at each aperture, refocusing each time, and then pick the one that nails it all the best...
posted by rambling wanderlust at 1:12 PM on September 18 [1 favorite]


I think johnathanhughes is right on the money with the comment on overexposure.

The Canon photo is definitely overexposed in the shirt area which to me looks like the main reason why detail is lost there. Try a faster shutter speed and do some post-processing to lighten the shadows if needed. The newer iPhones do some funky auto-HDR processing where by default they take multiple photos at different exposure levels and automatically merge them together. It’s pretty impressive — and also unsurprising that you can’t get the same dynamic range out of the box with the Canon.

Some info about HDR on the iPhone
posted by mekily at 4:45 PM on September 18 [1 favorite]


I would also double check the ISO setting on the camera, higher ISO will give less detail/more noise.

For a situation like this, where the subject is stationary and literally in a single plane, you should use a much wider aperture, as others have mentioned. This will give you three benefits:

- Better resolving power of the lens at a wider aperture
- You can use a faster shutter speed which will make stabilization less of an issue
- You can use a lower ISO which will improve the performance of your sensor
posted by goingonit at 6:01 PM on September 18


Best answer: F11 is a small aperture for distance or way too much light. 125 is too slow for an f11 take. Try F7 at 250 iso, and use a tripod. Don't try to get the image edge to edge, leave a border so there is play to take out any optical bending. Take the picture in the morning with north at your back. Out door light will deliver on more color range and detail, phone cams are so handy, but the color is often off in the reds. Make sure the art is as perpendicular as you can get it, and is in shadow, line your camera up to be parallel with what you are shooting. Make sure there are no strong colors nearby ie, a magenta Ferrari.

I used to shoot other artist's art. I set up against a white outside wall, with the east light behind my building, I let the sky light, of morning illuminate. Morning is a much more neutral light.

Lenses sometimes have to be taken apart and cleaned. It isn't the lens. Best to you.
posted by Oyéah at 7:45 PM on September 18


Best answer: You're stopping down your lens to f/11; the iPhone 12 Mini's main camera (aka 1x aka Wide) is at f/1.6. That alone would produce almost a 7x improvement in lateral resolution.

Um, what? That makes no sense.

Also, I disagree that it's caused by front-focusing. Yes, DSLRs with uncalibrated lenses can front/backfocus, but the DoF at f/11 should be like two feet and you're shooting a painting that's millimeters thick.

I would agree with others saying that the 1/125s exposure time was too long, especially with a body and lens without image stabilization. You'd get better results on a tripod or if your exposure time were closer to 1/400s. You could easily get away with f/5.6-8.

Also, you don't mention what focal length you were at. You'd probably get better results if you were to stand back and shoot at ~50mm rather than stand up close and shoot at 28mm.
posted by alidarbac at 8:42 PM on September 18 [1 favorite]


Best answer: The first picture looks like the ISO is set far too high, most camera sensor hardware has a fixed ISO of 800, the other ISO settings are all made available through software trickery, the further you get from 800 the worse the quality gets (more noise and more noise reduction). In an iPhone the ISO setup is similar but is restricted to a lower range of around 25-2000.
posted by Lanark at 1:43 AM on September 19 [2 favorites]


alidarbac, maecenas' comment refers to a fundamental optical relationship between the F-number of a lens (which is not really always the aperture setting) and the theoretical resolution. As the f-number goes down, the theoretical resolution goes up. However, this situation is a practical one, not theoretical, and so their comment doesn't really offer much to the poster in terms of understanding what happened, especially in a case that is so apples-to-oranges.

OP, the defects others have listed here are correct.
*Your image has noise - ISO is too high.
*You may be slightly misfocused - double check
*Your camera should be on a tripod for best result
*Your image is overexposed
*Set aperture to F/8 or less - you may be seeing softening due to diffraction
*Work with raw files and do your own sharpening in photoshop or similar as a final step

It's invisible to the user, but the iPhone camera takes multiple images every time you press the shutter. It does an incredible amount of computational work to produce a very high quality image from many source images. It's really not comparable to a single image from a single camera anymore. The same is true for all smartphone cameras, but the iPhone is particularly computationally enhanced.
posted by fake at 9:08 AM on September 19 [1 favorite]


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