Focus peak mode, AKA is this eye sharp?

My first mistake was posting this photo to home of the pedants on the internet, Reddit, but it started making me wonder.

Immediately I got hit with “the eye’s not sharp, please always get the eye in focus when taking a portrait” comments from a 1200px wide image. That made me look again in darktable at 100% and check with focus peak mode. From there it looks like the camera hit the plane of plane of her eye just fine it’s just the iris looks cloudy? As if it focused on the cornea maybe? At any rate this was taken with a Fuji 35mm 1.4 prime wide open which is a notoriously smooth, beautifully buttery, gradient-luscious lens. I love the lens myself but it seems to get panned online for being “soft.” If I want sharp I usually go for the 80mm f2.8.

Anyway, the photos looks OK to me but the pixel peepers over there got me to thinking about this. What does the community think? This was shot in 2019 and I cannot remember if our friend here was wearing contacts that might have clouded her iris, but it doesn’t look like a contact was present in the photos. I checked a few other photos in the set from different angles and her iris just always looks cloud even when it’s obviously in focus. From my understanding of focus peak mode blue is a sharper edge, green is less sharp and yellow is softest.

The image Reddit found unsharp:

darktable screenshots, 100% and with focus peak mode on:

For comparison here’s a shot straight on with focus peak mode as well, the eye is clearly visually in focus but the iris still shows as unsharp, only the catchlight registers:

This is not meant to start a debate over the role of your favorite or least favorite technical quality in a good photo. It’s just a curiosity moment. Have some fun thinking about it! I did add some sharpening/brightened the hair a bit in darktable so maybe that’s distracting from the eye?

I still find the photo acceptable myself, it’s not going to win any awards , but I’m taking pictures not curing cancer here.


I think this is fine. It isn’t out of focus and it isn’t unsharp. I have this lens as well and shoot it pretty regularly, and if you want sharpness, this probably isn’t the lens for you. How can you even judge critical sharpenss from a 1200px jpeg? People…


Yeah I guess in my insanity up there I didn’t get to the point of my thought here: does the focus peaking tool in darktable see the iris as a smoothish gradient? It kinda looks like it. I know focus peaking is looking at delta in gradient, the larger the delta the sharper the edge so it makes sense if a person has a softer or more uniform tone in the iris. Tools have limits in what they can do obviously.

I’m not into what Reddit thinks it just kicked off this thought process.

Fun fact. On my tiny mobile screen, the image looks really soft. On the laptop, it is much better. Not magazine tack sharp but entirely acceptable. Another thing is that the dt’s preview appears to be sharper than your output. Remarks about focus/sharpness:

1 Image 1’s eyes are not in focus. To me, the place of prominence would be around the cheekbone and temple region. You may be right about the cornea edge but I don’t think it is as sharp as the aforementioned area.

2 Image 2’s right eye (our left) is definitely in focus. Perhaps, leave some leeway so that the other eye may be in range next time…?

3 I am curious how you did your focusing and what was your decision making process. I wanted to say something else related to that but I forgot… ha ha. I will let you respond first.

4 RT’s capture sharpening would do wonders on such an image. Coupled with AP’s work in dt, one could reduce the criticism. But most of it happens at the time of capturing.

PS 5 I remember something else. I wonder if your friend’s eye moved during the shot.

Thought process? Planning? That’s probably asking a bit much from the likes of me …

I was going for a thin depth of field and with portraiture I’m ok with things leaning to the soft side as it tends to be more flattering on skin and faces. I generally put the AF-S focus point on the eye, near the iris but at this distance the AF box is so large it would catch some of the eyelid as well I think.

I did paint in some sharpening from the new diffusion or sharpening module in darktable but only on the hair. I also lightened it a bit. I could paint some more in the eye area too, but I thought it was fine until I started this investigation.

The reason why I think the eye has to be in focus is you can see my lighting grid clearly in the catch light and if you look at the bottom eyelid it’s pretty sharp from the far side to the near side. There’s probably about 2-2.5 cm there that would pass through the eyeball. The iris looking cloudy is what throws me off the most.

Edit: yes it’s interesting the exported JPEG is that much softer looking. When I get back to my desktop I’ll export it a higher quality and resolution and see if that helps. This was 1200px tall and 95% JPEG I believe.

In my earlier assessment, I did trace the eyelids and lashes. To me, they aren’t the sharpest part of profile. The resolution of the ends of the lashes and the ones closer to the nose is lower than the sharpness potential demonstrated in the second image. Still, that doesn’t explain your point and people’s problem with the iris: it is softer than the lids and lashes. That is where my eye movement remark comes in, or another speculation is that it is the result of refraction of the cornea (and the contacts that you aren’t sure if she had on or not).

The side of the eye closest to the view (and associated eye lids/lashes) are indeed sharper looking to me too. Trying to impose a 3D space as DoF is really a slice through the image and not a specific point is tricky, especially when you start talking viewing angles with it. Effects of the lens not being sharpest at the edges of the frame not withstanding.

There is some minute distance between the iris and cornea but I wouldn’t think it’s enough to cause softness if you AF system decided to focus on the cornea. I’m trying to think about movement and if that would also blur the reflection of the softbox and grid in the eyeball as it reflected against different surfaces during the shot. Corneas are pretty smooth across so maybe not.

I keep coming back to the contact lens or refraction theory myself too. If say you had allergies or your eyes were inflamed from some irritant would that cause the eye to not look as clear? That could change the refraction properties of the cornea/lens. If she is wearing contacts you’ve got two more interfaces between mediums that would also lend to diffraction. I’ve got other photos of people with similar settings/lighting and sharper looking irises. Again in all of these shots her iris does look soft, although softer in some shots than in others. Outside of obvious blatant AF errors they’re all acceptable to me.

Oh, come on. It’s a beautiful photo :smiley: . I wonder what Reddit would say if you posted similar photo shot on film, where you could never achieve pixel-perfect-razor-sharp deatails :face_with_peeking_eye:

As if the tack-sharpness was the deciding factor for the quality of the image… :relieved:


Exactly… I think because of the advancement of crazy auto focus and high res digital, people focus too much on those tiny things that really add nothing to the picture (this one at least). The woman is clearly in focus and you get a detailed view of her face.


And I remember reading the manual from one of my earlier Canon cameras. “100% accurate all the time autofocus” is just a marketing talk. The manual said that the camera should deliver images looking sharp when printed 15 x 10 cm and viewed from 40 cm :wink:

Nobody promises that pixel-peepers will be pleased.


Lovely photo of a beautiful woman. I think the difficulty here might be the wafer thin depth of field with f1.4. Maybe if you had stopped the lens down a couple of stops for slightly increased DoF there would have been more of her eye/face in sharp focus and less for some to complain about. Alternatively if you really want that thin DoF, try using the smallest possible single point focus and place it on her eyeball.

Lovely photo. Even without pixelpeeping I’m left with the impression that the cheekbone is sharper. It’s really interesting because I can’t really judge actual resolution on my phone but the over all impression I get is that she’s receding into softness from the cheek back. Could be that the lighting etc is bringing out the mildly sub optimal focus?

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My opinion, FWIW: the nearest catchlight looks soft, viewed at 1:1. The pixels can be gently hacked in Gimp to (IMHO) improve the image.

It seems to me that the cheekbone is sharper than the nose. But maybe the nose has more makeup, or whatever made the JPEG has smoothed it, perhaps influenced by the steep gradient with the black background.

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I think there is a somewhat irritating blurriness in the right eye. No idea what the cause is.
If you correct it with e.g. diffuse and sharpen in darktable, you can see it even in the posted resolution.

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would be interested in seeing the raw if you didn´t mind sharing it

I think for portraits like this you dont really need to shoot wide open. you have the background controlled with light. so step down the aperture and give yourself an easier time with the sharpness.

I would only use wide open for portraits if you want to control the background with that.


Thanks for all the input. I’m not that concerned about the eye, the photo is fine for its intent. This was always just more of a curiosity around the iris being soft. Yeah, I know I can stop down but I like exploiting the thin DoF and look of those lenses.

Unfortunately I cannot share the RAW due to other obligations, I did get back to my desk and was able to paint in some diffuse or sharpen over the iris. I think Reddit is unfortunately right and the focus is just slightly off and the DoF plane just grazes the side of the eye closest to the viewer and the IRIS lies just slightly outside the plane. Again doesn’t overly bother me. It’s good enough for the deliverable.

Diffuse or sharpen didn’t exist when I initially edited this but it does seem to help.

TFW you’re such an incompetent photographer and editor you Reddit corrects you. Feels bad man.

Edit: uploaded wrong image.

Reddit may never be satisfied. Now that the eye is sharper, how about the lips? :stuck_out_tongue_closed_eyes:


Because wafer thin DoF, perhaps it’s a cope for mediocre skill and no artistic vision and fair enough. But I’ve never claimed to be an artist either.

However, I’m also of the mind of “why buy fast glass if you just shoot at f/5.6 all the time?” “f/8 and be there” is part of why I got out of doing weddings.

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