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09-05-2020, 03:47 PM - 4 Likes   #1
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Moonlight shot with K-70 at ISO 25,600

I recently got my K-70 repaired by Precision Camera, under the Pentax extended 3-year warranty, for the aperture block failure. I still haven't re-done all my custom settings, like my custom noise reduction settings at high ISO. However, here is a shot I took illuminated only by a shaft of moonlight coming through the skylight in my master bath. I'm posting two shots, one correctly exposed for the moonlight, the other at ISO 100 with some adjustment in Lightroom to get the image to resemble how the scene looked to me by eye. First shot: ISO 25,600, 10s at F4, with Pentax-DA 50mm F1.8 autofocus lens. In Lightroom I took 0.5 stop off the exposure and pulled in the highlights 5%. Second shot (actually took this before the first shot, then decided to switch lenses): This is pretty close to what the scene looked like to the naked eye. Pentax K-70, ISO 100, 8s at F3.5, Pentax-DA 18-135 zoom. Had to give it +0.5 exposure, +70 white and black in Lightroom to get anything to show at all.

The low light capability of the Pentax K-70 continually amazes me. This scene looked nearly totally dark, just a shaft of moonlight coming in the skylight. Too dark to manually focus, but the camera was able to autofocus with the AF assist light. I used a little table-top tripod for both shots, and did the exposure by trial and error.

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09-06-2020, 08:59 AM - 1 Like   #2
dms
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It would be informative (for your future use) to adjust in pp the iso 100 image, and compare it to the high iso image. The iso 100 will preserve highlights better. Perhaps the problem (for a comparison) is the high iso has noise removal done in camera, so it will look better than it "should" in the comparison.

I have done iso 80 vs 1600 in my K-5 and there is no difference, except the iso 80 preserves highlights than can be blown out. And at iso 3200 the iso 80 is better. However since the post shot display on camera is tough to view if (about) 4 stops underexposed I usually use iso 400.
09-06-2020, 09:13 AM - 1 Like   #3
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QuoteOriginally posted by dms Quote
It would be informative (for your future use) to adjust in pp the iso 100 image, and compare it to the high iso image. The iso 100 will preserve highlights better. Perhaps the problem (for a comparison) is the high iso has noise removal done in camera, so it will look better than it "should" in the comparison.

I have done iso 80 vs 1600 in my K-5 and there is no difference, except the iso 80 preserves highlights than can be blown out. And at iso 3200 the iso 80 is better. However since the post shot display on camera is tough to view if (about) 4 stops underexposed I usually use iso 400.
Thanks for your comment. You may be right, I've not tried to compare low vs high ISO with each getting enough exposure. I'm not going to try that though, I'm not sure if it would be worth my time. I can't see spending the time to allow enough exposure at ISO 100 in such a low light situation, even if it gives an improvement in image quality. It took 10 seconds to get a good exposure at ISO 25,600, and I'm not going to wait around many times longer at lower ISO.

The point I was trying to make was that I get pretty good results at the high ISO settings, much better than I expected. I've taken other shots handheld at ISO 10,000 or so that were perfectly usable. For an old film guy (who still uses film very often) this is quite amazing and pleasing to know it can be done in a practical way.

Richard.
09-06-2020, 12:38 PM - 1 Like   #4
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QuoteOriginally posted by OldChE Quote
The point I was trying to make was that I get pretty good results at the high ISO settings
I'll say! Though the first image has some noise blotches in the shadows, the overall result is quite good. I have yet to put my KP to the test in this regard.

09-06-2020, 12:42 PM   #5
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QuoteOriginally posted by Apet-Sure Quote
I'll say! Though the first image has some noise blotches in the shadows, the overall result is quite good. I have yet to put my KP to the test in this regard.
Well, I suppose I can live with some noise in the shadows if I get some kind of usable image vs. none. Try some things with your KP, it is supposed to have even better low light capability than the K70, no?
09-06-2020, 01:16 PM - 1 Like   #6
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QuoteOriginally posted by OldChE Quote
Try some things with your KP, it is supposed to have even better low light capability than the K70, no?
I don't know about 'better', but it is supposed to be quite good. I currently have my auto-ISO set to top out at 6400, and I've seen a shot taken at 10,000 here on PF that was amazingly good. It will be fun to experiment, when I get around to it.
09-07-2020, 07:28 PM - 1 Like   #7
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QuoteOriginally posted by OldChE Quote
Thanks for your comment. You may be right, I've not tried to compare low vs high ISO with each getting enough exposure. I'm not going to try that though, I'm not sure if it would be worth my time. I can't see spending the time to allow enough exposure at ISO 100 in such a low light situation, even if it gives an improvement in image quality. It took 10 seconds to get a good exposure at ISO 25,600, and I'm not going to wait around many times longer at lower ISO.

The point I was trying to make was that I get pretty good results at the high ISO settings, much better than I expected. I've taken other shots handheld at ISO 10,000 or so that were perfectly usable. For an old film guy (who still uses film very often) this is quite amazing and pleasing to know it can be done in a practical way.

Richard.
I meant you take the shot at the same exposure time but at the lower iso!** (If you could increase the exposure time, that is always better than higher iso.) The reasoning is when you have a minimum shutter speed to use, and maximum aperture, and the exposure is not sufficient, you have two choices: up the iso, or take the shot at a low iso and increase exposure in pp. (But this only works if using RAW.)

_____
** You already have the lower iso shot--you showed it. If it is a RAW capture, Just up the exposure in pp and then compare them.

I have this issue in my theatre photography all the time. E.g., I want 1/60 sec to stop motion blur, and want f/4 to get adequate DOF. And this exposure is fine for iso 1600. If instead I use iso 400 I need to increase the exposure 2 stops in pp. Comparing using iso 1600 and iso 400, the result w/ K-5 is the shadows and midtones are the same, but the iso 1600 may have blown the highlights, but w/. the iso 400 the highlights are fine.

Again since your camera does noise reduction automatically at higher iso, the comparison will favour the higher iso, but you can do noise reduction to the lower iso for the comparison--but then it depends on how you do the noise reduction. In any event noise reduction has a penalty of reduced resolution.

09-07-2020, 07:47 PM   #8
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QuoteOriginally posted by dms Quote
I meant you take the shot at the same exposure time but at the lower iso!** (If you could increase the exposure time, that is always better than higher iso.) The reasoning is when you have a minimum shutter speed to use, and maximum aperture, and the exposure is not sufficient, you have two choices: up the iso, or take the shot at a low iso and increase exposure in pp. (But this only works if using RAW.)

_____
** You already have the lower iso shot--you showed it. If it is a RAW capture, Just up the exposure in pp and then compare them.

I have this issue in my theatre photography all the time. E.g., I want 1/60 sec to stop motion blur, and want f/4 to get adequate DOF. And this exposure is fine for iso 1600. If instead I use iso 400 I need to increase the exposure 2 stops in pp. Comparing using iso 1600 and iso 400, the result w/ K-5 is the shadows and midtones are the same, but the iso 1600 may have blown the highlights, but w/. the iso 400 the highlights are fine.

Again since your camera does noise reduction automatically at higher iso, the comparison will favour the higher iso, but you can do noise reduction to the lower iso for the comparison--but then it depends on how you do the noise reduction. In any event noise reduction has a penalty of reduced resolution.
That is quite interesting. I only save to RAW occasionally, these were jpegs, and I was in no way experimenting with the best way to capture the image. The only reason I posted the low ISO shot was to give people an impression of how the scene looked to my eye, how dimly lit it really was. Actually, when I took that image at ISO 100 and reviewed it on the back of the camera, I thought it was solid black. I only saw a faint image once I brought it into Lightroom.

What you said about exposing at low ISO to RAW and then increasing exposure in post is quite interesting. It is almost like you are "push developing" the RAW image, similar to what you might do with film. I'll have to remember that. Thanks.
12-10-2020, 01:31 AM - 1 Like   #9
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Thats amazing. I sometimes shoot pictures up to ISO 12800, but they get some serious noise from there (last safe step is ISO 6400). So Im impressed seeing you shot look like that I have a lot more of noise going on there at ISO 25600.
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