Why am I getting blurry images with a Sigma 35mm Art and Canon EOS 77D?

Question

I recently got the Canon EOS 77D and the Sigma 35mm Art 1.4 I notice in my pictures stuff where i'm a little distance away I comes out blurry. My setting on here were ISO 800 f/1.4 1/160sec I do know with such a wide aperture and a high ISO stuff is gunna be blurry But I focused on my daughter on the right (brunette) right over her eye and even that was pretty blurry when I magnify it at 100% Is it that i'm expecting too much for such a high ISO. We took this shot pretty early in the day (10am) with the windows open. I recently just got the Sigma 35mm and was expecting pretty sharp photos but was kinda let down. Am I just putting my expectations to high? And also what would be the best fix? I use lightroom and applied the Reduce Noise and sharpened but it still seemed pretty poopy.

Answer 1

This question, Why are my photos not crisp?, covers a multitude of possible reasons why images may not be as sharp as we might want them to be. How do I diagnose the source of focus problem in a camera? addresses how one might determine what the specific reason for a particular case is. This answer discusses ways to improve getting sharp results on the intended subject when shooting at large apertures.

In the case of the example photo, the image is slightly front focused. Notice that the hands of the boy and the girl are sharper than their faces. This could be due to user error in using the camera's AF system, or it might be due to a camera and lens combination where the manufacturing tolerances of each work to pull the focus forward of where the AF system is instructing the lens to focus.

Putting the camera on a stable tripod and triggering the shutter via timer or remote (wired cable release or wireless) will probably result in an even sharper image, but it will do nothing for a front or back focus issue. For that the camera and lens need to be calibrated to each other. Since the 77D does not offer Autofocus Micro Adjust, that would require a trip to a Canon Service Center to adjust the camera to the lens or the use of the Sigma USB dock to adjust the lens to the camera.

I do focus and recompose a lot.

Focus and recompose is susceptible to missed focus when using wide apertures for two reasons:

• The camera can be moved closer/further from the subject as you recompose. Ideally instead of rotating the camera around the center of the photographer's body - which is what usually happens - you should rotate the camera around the optical center of the lens (the so-called 'nodal point')
• Even when rotating the camera around the optical center, depending on the shape of the lens' field of focus, you can move the subject in front of or behind the field of focus

Answer 2

There are a few things to unpack in your question – but I want to start by saying that the shot looks good!

I used a depth of field calculator which, given a subject distance of 5 feet, yields a depth of field that is only 4 inches wide. That’s not a lot of wiggle room. There’s potential for you to move slightly between obtaining autofocus lock and taking the shot or your daughter to move as well.

With your image processing, reducing noise can soften an image. So, it’s important that you don’t try to reduce it too much. Additionally, if you were shooting RAW, then you’re working on an image that has had no sharpening applied – something that can feel very foreign if you’re coming from cell phone cameras or Point and Shoots. You may simply need to just increase the sharpening.

I haven’t used the Sig, and can’t comment to its inherent sharpness. But, something I’d recommend you do with any lens is put it on a tripod and shoot some tests. Test at ISO 100 and run through all full stops from f/1.4 to 22 to get a feel for the lens.

If you are inexperienced with photo processing, then go ahead and shoot Large JPEG and let the camera do the work so that you are comparing apples to apples. From everything that I’ve read, the Sig is a pretty sharp lens, even wide open.

So, I’d run through the list of other factors (movement, autofocus issue, post processing) before circling back to the lens. If you can rule out everything else, then it may be that you just got stuck with a bad copy and need to put in a warranty claim.

Answer 3

I agree with the general assessment here: first, this is a nice image, and pixel-peeping the sharpness doesn't really add anything. And second, if you do pixel-peep, the results are reasonable for the situation. You have narrow depth of field, not that fast of shutter speed, you're hand-holding, and your subjects are not static. This image is great for sharing online as is, and will make a perfectly wonderful 8×10 print.

But, if you do want to get sharper results in situations like this, there's a really easy and relatively affordable option. Get a low-cost radio-controlled flash (Godox, Flashpoint, Yongnou — there are lots of options). It doesn't need to have TTL or fancy features, because you're not going to be changing the distance or the general lighting situation much — you can take a test shot or two to get it right.

• Don't put the flash on your camera — put it on a shelf or on top of bookshelves, pointed right at the ceiling, or angled to catch the ceiling and a wall — "bounce flash".
• Set your ISO to 200 or 400, so you don't need to use the flash at full power (which will make recharge time faster)
• Set the shutter to your camera's sync speed (which happens to be ¹⁄₂₀₀th for your camera). The flash impulse will be much faster than that, even — see Why does the flash freeze a picture?
• Set aperture to f/5.6 or f/8. Then you don't need to worry about getting focus super-super precise, and your kids can move around. (And don't worry that you're "wasting" that f/1.4 — even fast lenses are better in terms of sharpness and aberration control stopped down.)

With this setup, you can get consistently sharp indoor images, and the

Some more on this in this earlier question: Prime lens or flash: which upgrade will most improve baby photos?

Answer 4

I agree with all that has been said here. That is a good photo, and the slight out of focus doesn't hurt it in the least. My thought was that maybe you just leaned back very slightly after focusing, and before shooting. I've been known to do that.

As you commented earlier it is possible that the lens/body combination is front focusing a bit. This is not something that generally a software update from the dock will clear up.

You should be able to tell the camera how to adjust the focusing for that lens, to make it work better. Jeff Harmon did a really good podcast earlier this year explaining how to test, and how to adjust the fine focus on your camera. He goes over three different methods for testing and also even did a followup talking about how well it worked in the longer run for him.