K-70 low light banding issues

**MossyRocks** · 07-08-2019, 10:59 AM

Originally posted by rigger

I also would like to try astrophotography in the future, but don't want to spend out on the required equipment if all my night shots end up like this?

If you want to try astro just go out out and start with what you have. Stick the camera on a tripod, use what ever lenses you have, use the rule of 200 for shutter speed (focal length/200 = longest shutter speed), and use the 2 second mirror up delay. Take a bunch of photos play with stacking, and then post your first effort over in the astrophotography group for feedback, we don't bite. If you want to get pointed in somewhat the right direction read this on shooting the moon and then read this on shooting things farther away.

As far as the banding goes I almost wonder if it is just that you were approaching the dynamic range limit of shooting at ISO 3200 as it is only showing up in the darkest areas that were brought and you mentioned that you were underexposing things even at ISO 3200. If that is the case then you may just be picking up systematic noise in the system in these areas. I would probably have upped the ISO more and done what BigMackCam suggest with stacking and averaging to deal with the noise.

**Just1MoreDave** · 07-08-2019, 11:49 AM

I was surprised that the K-70 has 14 bits in its RAW files. I was going to suggest that you ran into the limitation of 12 bits, but that's wrong.

Maybe it's a problem created by the RAW converter. You can try the Pentax software or post the RAW file somewhere for others to try it in other converters.

reh321 · 07-08-2019, 12:50 PM

Originally posted by rigger

Hi all, I was hoping to get some assistance with an issue that I'm experiencing with my K-70. I recently went on a trip to White scar caves in Yorkshire and manged to take a few shots in the caves. As you can probably imagine the light levels were low, as a novice I opted to limit my auto ISO to 6400 to try to keep noise low, I shot in Aperture priority mode and underexposed the images in the hope that I could shoot in RAW and recover the shadow data later in post... Unfortunately a large majority of the pictures I took appear to have quite significant banding issues (I have not noticed these on any pictures before, although I suppose I have not shot in similar conditions before either) and I was wondering if anyone could help me diagnose the cause of these horizontal bands?

I will endeavour to attach a picture that I have edited (I have just upped the exposure in Rawtherapee a large amount to emphasise the issue, but I can still notice the banding even when trying to expose the photo properly)

I have tried and failed to recreate the banding at home by taking a photo with the same settings and the lens cap on, so I'm not sure what the issue could be?

If anyone could offer assistance, or has experienced similar issues I would be very grateful!

I don't have any experience with a K-70, so my comments will be based on my experience with a KP. I notice that this photo was taken at 1/15th second, using an ISO of 3200. Was this 1/15-th second using the mechanical shutter or the so-called 'electronic shutter'?

Under the same circumstances, with my KP I regularly limit ISO to 12800.
Iso 25600! - PentaxForums.com
With that setting you should be working with a shutter speed that the IBIS system could provide adequate detail even when using the focal shutter hand held.

When I first got the KP, I took several photos during evening hours
First photo with KP - PentaxForums.com
Iso 204800 - PentaxForums.com

so I could become more familiar with how this camera performed at higher ISO values.
I would suggest that you use a similar procedure to investigate this phenomenon.

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07-08-2019, 10:59 AM	#16
MossyRocks Loyal Site Supporter Join Date: Nov 2017 Location: Minnesota Photos: Gallery \| Albums Posts: 2,982	Originally posted by rigger I also would like to try astrophotography in the future, but don't want to spend out on the required equipment if all my night shots end up like this? If you want to try astro just go out out and start with what you have. Stick the camera on a tripod, use what ever lenses you have, use the rule of 200 for shutter speed (focal length/200 = longest shutter speed), and use the 2 second mirror up delay. Take a bunch of photos play with stacking, and then post your first effort over in the astrophotography group for feedback, we don't bite. If you want to get pointed in somewhat the right direction read this on shooting the moon and then read this on shooting things farther away. As far as the banding goes I almost wonder if it is just that you were approaching the dynamic range limit of shooting at ISO 3200 as it is only showing up in the darkest areas that were brought and you mentioned that you were underexposing things even at ISO 3200. If that is the case then you may just be picking up systematic noise in the system in these areas. I would probably have upped the ISO more and done what BigMackCam suggest with stacking and averaging to deal with the noise.

07-08-2019, 11:49 AM	#17
Just1MoreDave Site Supporter Join Date: Feb 2007 Location: Aurora, CO Photos: Gallery \| Albums Posts: 6,340	I was surprised that the K-70 has 14 bits in its RAW files. I was going to suggest that you ran into the limitation of 12 bits, but that's wrong. Maybe it's a problem created by the RAW converter. You can try the Pentax software or post the RAW file somewhere for others to try it in other converters.

07-08-2019, 12:50 PM	#18
reh321 Pentaxian Join Date: Nov 2014 Location: South Bend, IN, USA Photos: Gallery \| Albums Posts: 23,185	Originally posted by rigger Hi all, I was hoping to get some assistance with an issue that I'm experiencing with my K-70. I recently went on a trip to White scar caves in Yorkshire and manged to take a few shots in the caves. As you can probably imagine the light levels were low, as a novice I opted to limit my auto ISO to 6400 to try to keep noise low, I shot in Aperture priority mode and underexposed the images in the hope that I could shoot in RAW and recover the shadow data later in post... Unfortunately a large majority of the pictures I took appear to have quite significant banding issues (I have not noticed these on any pictures before, although I suppose I have not shot in similar conditions before either) and I was wondering if anyone could help me diagnose the cause of these horizontal bands? I will endeavour to attach a picture that I have edited (I have just upped the exposure in Rawtherapee a large amount to emphasise the issue, but I can still notice the banding even when trying to expose the photo properly) I have tried and failed to recreate the banding at home by taking a photo with the same settings and the lens cap on, so I'm not sure what the issue could be? If anyone could offer assistance, or has experienced similar issues I would be very grateful! I don't have any experience with a K-70, so my comments will be based on my experience with a KP. I notice that this photo was taken at 1/15th second, using an ISO of 3200. Was this 1/15-th second using the mechanical shutter or the so-called 'electronic shutter'? Under the same circumstances, with my KP I regularly limit ISO to 12800. Iso 25600! - PentaxForums.com With that setting you should be working with a shutter speed that the IBIS system could provide adequate detail even when using the focal shutter hand held. When I first got the KP, I took several photos during evening hours First photo with KP - PentaxForums.com Iso 204800 - PentaxForums.com so I could become more familiar with how this camera performed at higher ISO values. I would suggest that you use a similar procedure to investigate this phenomenon.