[jonathanastro]

Hi all, I'm looking forward to your help, I bought the pentax k-1, I take a lot of night shots, after I bought the camera I went to photograph the Milky Way I had parameters of iso 4500, 20 sec, f 2.8 and the picture came with a lot of noise, I would like to know if the problem is known or it is a configuration problem, the lens I took with it Pentax 15-30 f2.8 I also put the focus to infinity and there were places in the picture that were not in focus
I would be happy for help, thank you

[pschlute]

I don't do astrophotography but a few thoughts come to mind.

There is not a single infinity setting on that lens, it can focus past infinity.

Did you use astrotracer ? Light trals can cause streaks which will appear like blur.

iso 4500 seems high to me (no expert). A long exposure where there is a lot of dark areas surely calls for much lower iso.

I would also suggest stopping down more from the maximum aperture which is always the softest setting.

[jonathanastro]

I don't do astrophotography but a few thoughts come to mind.

There is not a single infinity setting on that lens, it can focus past infinity.

Did you use astrotracer ? Light trals can cause streaks which will appear like blur.

iso 4500 seems high to me (no expert). A long exposure where there is a lot of dark areas surely calls for much lower iso.

I would also suggest stopping down more from the maximum aperture which is always the softest setting.

i didn't use astrotracer
i used iso 4500 in very dark place and olso i used this iso with my old camera and there was not a problem with noise

[clackers]

Hi all, I'm looking forward to your help, I bought the pentax k-1, I take a lot of night shots, after I bought the camera I went to photograph the Milky Way I had parameters of iso 4500, 20 sec, f 2.8 and the picture came with a lot of noise, I would like to know if the problem is known or it is a configuration problem, the lens I took with it Pentax 15-30 f2.8 I also put the focus to infinity and there were places in the picture that were not in focus
I would be happy for help, thank you

How did you know it was infinity Jonathan?

The way I've done it is to find a very bright star and make it as small as possible in LiveView.

[jonathanastro]

How did you know it was infinity Jonathan?

The way I've done it is to find a very bright star and make it as small as possible in LiveView.

i did the same

[Adam]

Can you post the problematic image?

[jonathanastro]

Can you post the problematic image?

yes
it's raw file

Attached Images

View Picture EXIF

File Date

 

[Alex645]

I bought the pentax k-1, I take a lot of night shots, after I bought the camera I went to photograph the Milky Way I had parameters of iso 4500, 20 sec, f 2.8 and the picture came with a lot of noise, I would like to know if the problem is known or it is a configuration problem, the lens I took with it Pentax 15-30 f2.8 I also put the focus to infinity and there were places in the picture that were not in focus

Noise:
Although the K-1 is excellent in low light, to reduce noise, Iʻd suggest not exceeding ISO 3200 for astro photography. Depending on your focal length, the stars will begin to blur due to the Earthʻs rotation starting around 30 seconds. And because the camera has astrotracer, Iʻd highly recommend you learn to use it so you can increase your exposure time while both lowering the ISO while stopping down a bit more to perhaps f/4 or f/5.6 on the 15-30 f/2.8 zoom.

I almost always shoot RAW exclusively, but for astro photography, Iʻd recommend shooting RAW+ jpeg. The K-1 processor can reduce noise really well and unless youʻre experienced with post-processing, the jpeg can often reduce the noise more effectively than the average user with PS or LR.

Focus:
I agree with previous posts here and donʻt trust the infinity mark on the lens. Manually bracket focus at f/2.8 of either shots at great distance (on the horizon or stars). Alternatively if you want to just leave it on the infinity mark, then bracket your AF fine tune in the menu. Try 0, then adjust one for +5 and another at -5. If +5 looks the best, then try +7 and +3, etc, until you find the sweet spot. Leave the focal length set to what you normally shoot the stars with throughout the testing. If you invariably use everything from 15 thru 30mm, then do the tests in the middle around 23mm.

Eliminate the possibility that what is perceived as mediocre focus isnʻt motion blur/camera vibration. Solid tripod without the center column extended. Avoid setting up on pavement as it can transmit vibration from vehicles, etc. Try to set it on terra firma. SR off! Remote trigger/cable release or self timer. Mirror lock up. If there is a remote chance of light entering the viewfinder during exposure, block the viewfinder with anything if you lost your light blocker made for that.

[pschlute]

If there is a remote chance of light entering the viewfinder during exposure, block the viewfinder with anything if you lost your light blocker made for that.

Chewing gum can work well. This is the brand Pentax recommends

[Larrymc]

Hi all, I'm looking forward to your help, I bought the pentax k-1, I take a lot of night shots, after I bought the camera I went to photograph the Milky Way I had parameters of iso 4500, 20 sec, f 2.8 and the picture came with a lot of noise, I would like to know if the problem is known or it is a configuration problem, the lens I took with it Pentax 15-30 f2.8 I also put the focus to infinity and there were places in the picture that were not in focus
I would be happy for help, thank you

Just looking at your EXIF data you were using ISO 6400 instead of ISO 4500 and your exposure time was 30 sec instead of 20 sec. maybe the extra shot of sensitivity could account for your noise.

Also, unrelated, you might want to check your camera time and date settings

Larry

[TerryL]

yes
it's raw file

That's pretty to my untrained eye.

[Adam]

yes
it's raw file

It also looks like there's a little star trail action starting in the corner, likely due to the long shutter speed.

You should be fine underexposing by a few stops then lifting the sky in post. ISO 800 or 1600, 10s or so. Combine that with a properly-exposed foreground from a separate shot if needed.