Commons:Photography critiques/July 2021

Question regarding QI

As I'm learning how to improve my photography skills by nominating images for COM:QIC, sometimes other users said my nominations are "not sharp enough". I'd like to ask is it associated with the shutter speed? But I also remembered that some failed nominations actually have quite high shutter speed actually (like this file with 1/800). Can someone explain further? Many thanks.廣九直通車 (talk) 09:21, 22 July 2021 (UTC)

I should mention that I'm also in the same boat, trying to improve my photography skills by nominating photos for COM:QIC, and I've also had some questions about judgement of sharpness. One thing to pay attention to is the aperture; you shot this in shutter priority mode, so it used a plenty fast shutter speed (probably faster than you need), but a fairly wide aperture of f/4. A wide aperture means a shallower depth of field, so less of the scene is in focus. In the case of this image, with the truck at an angle, that means that even if part of the truck is in focus, the rest is not. Since 1/800 is faster than you need, assuming that there's nothing fast moving in the scene, you could reduce the shutter speed. The rule of thumb is that the slowest viable shutter speed for handheld shots is 1/(focal length), so that would be about 1/30 of a second for this lens. Image stabilization can reduce that minimum, or you could increase it to be on the safe side.

A lens has its greatest depth of field when it has the smallest aperture, at f/22 in the case of the lens you were using for the above image. However, at the very smallest apertures, there's another effect, diffraction, which can limit sharpness. Usually the sweet spot for a lens in terms of sharpness for a single subject is in the middle range, around f/8 to f/11.

One additional factor I notice in this image is a bit of chromatic aberration; different colors can be refracted to different places on the sensor by the lenses, leading to slight colored fringes around objects. This can also lead to a bit of loss of sharpness. Stopping the aperture down can help with this as well, and there's also software that can correct for this. Sony's own software might have an option, or other RAW processing software or photo editing tools like Darktable, Lightroom, DxO, or Photoshop will likely have tools to correct this.

My recommendation is to first try doing a better balance between shutter speed and aperture, rather than a very fast shutter speed and fairly wide aperture. Stay at ISO 100 for bright sunny days, you should be able to get a good balance of shutter speed and aperture for optimum sharpness at ISO 100. Also try seeing if any "chromatic abberation" or "color fringing" correction filters help improve your image. And of course, you could always shoot with a tripod, allowing for even longer exposures of still subjects, but that's more cumbersome to carry around. --Lambda (talk) 00:39, 23 July 2021 (UTC)

Thanks for your useful information! And I've think I also managed the tip of staying ISO low when taking photographs, many thanks!廣九直通車 (talk) 06:22, 16 August 2021 (UTC)

This section is resolved and can be archived. If you disagree, replace this template with your comment. 廣九直通車 (talk) 06:22, 16 August 2021 (UTC)

Lincoln Center with rainbow fountain

A couple days ago I spent about an hour at Lincoln Center in New York, where they set up rainbow lighting in their fountain for Pride (and painted their large steps). I got there just before the sun went down (behind the central building, roughly opposite the camera). While the sun was out, the colors of the fountain weren't visible enough, but I didn't want the light to be gone completely because I wanted to capture this public space and the buildings, not just the fountain. Setting up a tripod is not allowed here anyway (there are security guards which make this perhaps the most tripod-unfriendly outdoor space in the city), so night shoots aren't realistic anyway.

This is the result. It's ok, but I was hoping for something better. Maybe there's no way to get a sufficiently illuminated building + public space while also being dark enough to see the colors of the fountain, but I'm posting here for ideas from more experienced photographers. — Rhododendrites ^talk |  13:21, 2 July 2021 (UTC)

I think one major problem of this is the unattractive, blown-out sky. Maybe this is a stupid idea, but how about trying again in the morning when you've got the sun at your back? Even with it being below the horizon, that might still make a difference … --El Grafo (talk) 12:23, 4 July 2021 (UTC)

I agree, the blown sky was probably the first thing I noticed looking at this photo Buidhe (talk) 17:04, 4 July 2021 (UTC)

Pre-dawn Blue Hour might be lovely. For those who intend to be afoot then. Jim.henderson (talk) 14:56, 6 July 2021 (UTC)

@El Grafo, Buidhe, and Jim.henderson: Thanks for the suggestions. At this point, with Pride over, a new shoot will have to wait until next year. We'll see if I feel like going to Manhattan before dawn... :)

But I did look back through the various shots I got, looking for one with decent color but also a better sky. Here's what I came up with. It's not the big scene, but the sky isn't blown out (would be better with clouds, but an improvement anyway)... — Rhododendrites ^talk |  22:27, 8 July 2021 (UTC)

Follow-up: There are some technical shortcomings, but I think it captures the special scene well enough that I nominated it at FPC: Commons:Featured picture candidates/File:Lincoln Center during pride at dusk (93381p).jpg. I guess the critique moves there now. :) — Rhododendrites ^talk |  04:30, 9 July 2021 (UTC)

Sufficient sharpness?

I posted this image to Quality images candidates, and got an opposition saying that it's out of focus. As far as I can tell, the subject is in the peak focus region of the image; it was a handheld nighttime shot with long exposure, aperture as wide as this lens will go, and somewhat high ISO, so the overall image is slightly soft, but the detail resolution is considerable better than the minimal 2 MP recommendation for quality images; if you look at the half resolution image, you see the resolution become the limiting factor of image sharpness, and that's still well above the 2 MP minimum. You can only really see the softness if you enlarge the image considerably, and things like the lettering on the tank badge and air intake are readable. Am I missing something? What level of sharpness is considered acceptable? I can improve the apparent sharpness in post a bit, with some further contrast tweaking and sharpening, but that doesn't do anything to actually increase the amount of detail in the image. Or I could downscale it by a linear factor of 2. But I'd like some more detailed feedback on what's wrong so that I can correct it or avoid the problem in the future. Thanks! --Lambda (talk) 05:02, 22 July 2021 (UTC)

I've made those suggested changes, tweaked the tone curve a bit as I had a bit of leeway to brighten the highlights and thus enhance the contrast, and turned up the sharpening filter. There may not be any more detail present, but the image at least looks a bit better. --Lambda (talk) 05:10, 22 July 2021 (UTC)

There's a diffuse but quite evident halo around a lot of the top of the motorcycle. I'm not sure what's causing it, but it shouldn't be there. Ikan Kekek (talk) 10:12, 22 July 2021 (UTC)

Ah, I'm guessing that's a mask I used to darken the background but leave the motorcycle bright; there were some distracting things in the background, and darkening them helped reduce their prominence. Unfortunately, it looks like my monitor is missing a shade or two at the bottom end, according to the monitor test graphic, so it looks fine to me; it had also been prominent to me, so I tweaked it until it wasn't, but if my monitor is missing a shade or two on the bottom end then it may still be prominent on other monitors. Anyhow, thanks, now I have a direction to look into to improve it. --Lambda (talk) 15:31, 22 July 2021 (UTC)

OK, turns out that I could see it if I turned up my brightness all the way, and took off my glasses, because my glasses were actually causing a bit of bloom that masked it. I'm using an OLED display, which has very dark darks and very bright brights, so the bloom from the bright parts was enough to overpower the halo effect you mentioned; and unlike an LCD, changing the viewing angle didn't make it more apparent. I've addressed this by reducing the amount of darkening I was doing, tightening up the masks, and reducing their feathering. There's still a slight effect in a couple of places that I can only see if I zoom in and know where to look, but I'd appreciate if someone with a different display could take a look as what was apparently obvious on other screens is quite hard for me to see. --Lambda (talk) 18:57, 22 July 2021 (UTC)

@Ikan Kekek and Hillopo2018: Ikan, thanks for the note on the halo; that is fixed now. But you have still voted the image insufficiently sharp. Can either of you explain what is insufficiently sharp about this image? What level of sharpness you are expecting? As mentioned, to my eye, this is about as sharp as a 5 MP image could get; the fact that there's some softness if zoomed in further, because I didn't downscale it, doesn't seem like it should be a problem, if 5 MP is within the quality image guidelines. I'm really trying to get a better understanding of the guidelines, and how you're evaluating them; in photography, there are a number of tradeoffs, and how much sharpness is needed depends on what level of enlargement you need an image to be usable at. To my eye, this is sharp enough to be enlarged to about 8"x10" (or about A4 paper size) at 300 DPI without noticeable lack of sharpness. Is it necessary that images remain sharp when enlarged even further than that? If so, should the minimum image size for a quality image be increased to reflect that? --Lambda (talk) 02:24, 25 July 2021 (UTC)

Ah, just found this nice essay which explains the issue better than I did. I like the distinction it makes between "bold subjects" and "detailed subjects"; bold subjects are ones where once magnified to full screen or a full page in a magazine, there's no real impetus to zoom in further or look closer at tiny details, while detailed subjects are things like architectural photos of ornate architecture, where there may be good reason to zoom in as far as possible to try to see tiny details. The picture I took clearly falls into the "bold subject" category, so I think evaluating it at around full page print size is the right way to evaluate it. --Lambda (talk) 02:59, 25 July 2021 (UTC)

It's really unsharp at full size but also not that sharp at 300% of my 13-inch screen. I believe that the level of expected sharpness for these kinds of photos is greater at QIC. You are free to disagree. -- Ikan Kekek (talk) 06:34, 25 July 2021 (UTC)