White Noise Long exposure

[tjompen1968]

Hi there! New on the forum and to Fuji. Just got myself a X-T20 with the 18-55. Really nice little camera. Coming from Pentax FF.

Did some long exposure, 400 seconds long and there is alot of "snow" or white noise in the image. ISO200. Not using the Long Exposure NR.

Anyone else seen this?

The bright image is from RAW brightened 2.5 stops

 

The darker image is SOOC.

Both heavily cropped.

 

The D810 and Pentax K-1 had this "white dot" issue.

 

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Edited August 18, 2017 by tjompen1968

[BobJ]

I have never tried an exposure as long as that, so maybe I shouldn't be commenting, but there are probably two things at play here. Firstly they are both seriously underexposed. If you have to brighten the raw by 2.5 stops then what you have done is to take the image at 1200 iso, not 200 iso. Secondly, with such a long exposure heat becomes a problem leading to "hot" pixels. That is what the long exposure noise reduction deals with. With very long exposures it becomes tedious to use long exposure nr but it is possible to take an image with the lens cap on and subtract it in Photoshop.

[Rand47]

I shoot long exposure. I'd suggest that that is exactly what the long exposure noise reduction is for. LOL

 

This one was 3 minutes 15 seconds:

 

 

Rand

Edited August 21, 2017 by Rand47

[tjompen1968]

Coming from Pentax 24 MP APS-C models I never have used the LENR because this problem did not exist. Only a few dots to clean out in post. I really was surprised to find the problem on the X-T20.

If I shoot the Pentax K-1 which is FF with LENR there is no noise in the image even if underexposed like the image above, also if I shoot for 2-3 minutes or less without LENR there is no noise to talk about. 

I still get noise when using LENR and have to push a few stops. I will give it a try to get a good exposure to see if that works better.

 

On the note that I lifted the exposure, the noise is still visible without lifting the image 2.5 stops.

Edited August 21, 2017 by tjompen1968

[tjompen1968]

I shoot long exposure. I'd suggest that that is exactly what the long exposure noise reduction is for. LOL

 

This one was 3 minutes 15 seconds:

 

 

Rand

How does a 100% crop look like from this image? I ask because the noise in my images is not visible unless zooming in. 

[Rand47]

How does a 100% crop look like from this image? I ask because the noise in my images is not visible unless zooming in.

 

Clean as a whistle. No "shot noise" at all.

 

Rand

[tjompen1968]

Clean as a whistle. No "shot noise" at all.

 

Rand

Well, I guess I try another for 3:15 with LENR.

[tjompen1968]

5:25 min with long exposure NR on. Still getting the "dust" in the shadows. So it is not just hot pixels that a dark frame can remove. It is something else.

Here a tight crop

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Edited August 21, 2017 by tjompen1968

[CDBC]

I liked Rand's picture way better. 

[tjompen1968]

I liked Rand's picture way better. 

Now you are hurting my feelings

Edited August 22, 2017 by tjompen1968

[tjompen1968]

Ok, I will go out and do some real life images instead. I think that is much more fair. The white noise will be consealed by things like sand and bright things. This may or may not be an actual problem. I just remember how my images looked from my first outing with the Pentax K-1. They were horrible. Had to send the camera back to be fixed.
 

 

 

I ask if someone else is having the same noise from their sensor so that I can determine if I need to send it back for repair or not.

[BobJ]

If you have to zoom in to 100% to see the noise then there is no problem. The average monitor is about 100 pixels per inch so at 100% you are looking at an image that is five feet wide! Pixel peeping is bad for your health.

[tjompen1968]

If you have to zoom in to 100% to see the noise then there is no problem. The average monitor is about 100 pixels per inch so at 100% you are looking at an image that is five feet wide! Pixel peeping is bad for your health.

The noise is visible before 100%, maybe already at 50% but it is there and it is degrading the IQ.

 

I hear what you say and I hear this comment alot but I think that is as wrong as saying that you can zoom with your feet.

 

Maybe I have to crop heavily, then it will be visible. Maybe I make a large print and people stand close, then it will be visible. If I wanted just to look at a 24 inch HD-monitor or a 4K-monitor in full size I really do not need 24 MP, 10 MP would be more than enough but I have 24 MP and i want them all to contribute to the final image and give me the possibility to print large with alot of detail or to crop alot.

 

 

 

(p.s I ask if someone else is having the same noise from their sensor so that I can determine if I need to send it back for repair or not. d.s)

[BobJ]

Well I make prints for exhibitions that are about 50cm on the long edge max, occasionally from a heavy crop. My previous camera was a Sony Alpha 99. I don't find the X-t2 files any noisier than the A99 ones, in fact they are better. I use raw normally. I don't use any noise reduction at all at 200 iso, maybe a touch at 400. At 800 some nr becomes more necessary and at 1600 is essential. I hope this helps a bit.

[BobJ]

I am sorry, I should have added that my last comments apply to "normal" exposure lengths and I use an X-t2. Oh and by the way, counter intuitively, a small amount of luminance noise will usually improve the image. This doesn't apply to the "snow" that you are experiencing of course.

[tedgoudie]

I came here to start a thread about LE noise (both white and color) that I'm seeing when shooting astro with both X-T2 and X-T20. But since this thread is here, I'll jump in.

 

I only see the noise in shadow areas, and I see much more of it in Capture One than with Lightroom. But I prefer Capture One, so hopefully I'm doing something wrong and someone can point out a way to fix this. I'm honestly looking for help here, not complaining about Fuji or Adobe or Phase One.

 

I'm shooting (lossless compressed) RAW, and usually in time-lapse, so I do not use LENR.

 

This particular file is a 20 second exposure on the X-T20 at ISO3200 from a TL sequence, taken on a 50-degree night last week. If I can figure out how, I'll share the RAW file with anyone who wants it (here it is in Dropbox).

 

I'm posting screenshots, but the noise is present in the final exported JPEGs as well - I've had to use Median NR in Photoshop to get rid of it, which is a huge pain when working with motion TL sequences. Here's a full-size, unedited JPEG export from C1: http://www.tedgoudie.com/wp-content/uploads/2017/08/Aug_22_2017_DSCF0681.jpg

 

 

First, the Capture One screenshots:

 

 

 

Zoomed in one step on the left side:

 

 

400% zoomed in the same area:

 

 

To me, those could be hot pixels (or blocks of them), but I'm no technical wiz. The shadows are packed with those.

 

Now a similar comparison from Lightroom. 

 

First the normal view:

 

 

Then a similar 1x zoom:

 

Finally, a 400% zoom into a different part of the picture (the road near the bottom center), because there is no noise in most of the shadows. There are 4 or so of these pixel groups in the whole picture:

 

 

 

Any ideas how I can avoid this? 

 

I can certainly also post to the C1 forum, but figured I'd check with the Fuji crowd first. Thanks y'all.