[biz-engineer]

Evaluating exposure settings for night photography or long exposures, i.e. stacking a series of 30 s. long exposures vs single long exposure in B (Bulb) mode, I was astonished by the result. In the B mode experiment, I let the lens cap on and covered the camera VF to avoid light leak, captured 30 minutes and 60 minutes exposures with and without LENR (subtract dark frame in raw data), at ISO 100.

I was expecting that all pixels would gradually turn "white" with longer exposure times due to creeping dark current at photo sites, with histogram shifting to the right when exposure gets longer and longer. Surprisingly, the image histogram from the 60 minute dark exposure turned out to be the about the same as the histogram from the 30 minutes exposure, close to black level. Only a few scattered pixels turned white (or red) with all other pixels remaining mostly black.

Wow, that is good news ! If we don't mind about some "rare" bad pixels here and there, the digital sensor is capable of hours of exposure without losing much of its dynamic range. What that means is the sensor isn't what limits night photography, the biggest limitation of image quality (image contrast) for long exposures is light pollution from artificial in urban areas, unfortunately .

---------- Post added 15-08-21 at 07:43 ----------

* 60 minutes exposure + LENR took two hours to complete, probably why we don't see that sort of tests in camera/sensor reviews.

[cmohr]

Agreed,

When I'm shooting Milkway images, I always use the dark frame subtraction, most of my shots are 44- 55 secs, so waiting that time again isn't really a issue, and the results speak for themselves.

Single Frame, 44sec exposure, F2.8, Jpeg direct from the camera.

Without LENR it will be snow in the shadows. This is 20 minutes and the shadows lifted to show the house.

Up to 5 minutes I use no LENR and get no penalty, but after 5 minutes I want to use LENR.

[pixie]

Biz-engineer, thank you for the test and write-up about it, confirming the K-1's sensor's great capabilities. My approach is to always use LENR when I am working in the dark. With the astrotracer shots it isn't too bad as one can't go for too long exposures anyways. With foregrounds at low ISO though, the extra double time is a pain, but as the above gentleman from Sweden proves it is worth the wait!
A two shot combo from two years ago:

[biz-engineer]

With foregrounds at low ISO though, the extra double time is a pain, but as the above gentleman from Sweden proves it is worth the wait!

When in the field if I use LENR on very long exposure, I try to do it to the last exposure because I go back in the car and drive. The camera does the dark frame exposure in the car while I'm driving to another location or back home/camp/hotel room.

---------- Post added 18-08-21 at 13:09 ----------

Too bad when they review or test cameras, there is nothing about long exposure noise performance. All tests are mostly about high ISO / fast shutter speeds.

[Nakedgun]

I don't find LENR in the menu, how does one accomplish this?

[Mikesul]

I don't find LENR in the menu, how does one accomplish this?

LENR= Long Exposure Noise Reduction. It is one of the noise reduction options.

[Nakedgun]

I see "slow shutter speed noise reduction" on my K-1ii, is that it?

[biz-engineer]

I see "slow shutter speed noise reduction" on my K-1ii, is that it?

Yes, correct.

[Craigbob]

It's much better to do the dark frame subtraction outside of the camera.

A: it maximizes your time shooting under dark skies (You can always take dark frames later) I tend to take them on the way home with the camera on the floor of the car in the camera bag.

B: Since Noise is random, yy averaging a set of dark frames to a master dark you get better noise reduction as that master dark frame is subtracted from each light frame equally. LENR is just a single frame each time and aside from hot pixels doesn't do as well.

That said, the K-1 is so good, I don't have to use darks as often as I used to.

[Ken Lee]

Those are some great photos!

[kiwi_jono]

Biz-engineer, thank you for the test and write-up about it, confirming the K-1's sensor's great capabilities. My approach is to always use LENR when I am working in the dark. With the astrotracer shots it isn't too bad as one can't go for too long exposures anyways. With foregrounds at low ISO though, the extra double time is a pain, but as the above gentleman from Sweden proves it is worth the wait!
A two shot combo from two years ago:

Stunning shot! I am also very please with how the K-1 performs with long exposures (much better than I thought it would be)

[pixie]

Stunning shot! I am also very please with how the K-1 performs with long exposures (much better than I thought it would be)

Thank you!

[PixL8]

I have not tried that function on the camera and have never tried this technique before... now may be a good time to start. Great pictures!

I had the idea that those noise reduction options only applied to JPEG's. No?