Dark Current Enable Tool

[Silentg]

First of all, I'd like to thank astronomer for all his hard work. A lot of people owe you a beer.

With that said, I've applied the Dark Current Enable Tool along with a bunch of other mods to my D800 and am a little confused as to how I'm supposed to process the images. From what you said, DSS is a poor choice to edit them because it doesn't understand that the black level has been messed with. What should I use instead? Also, it would be amazing if you could investigate performing this hack on the Nikon Coolpix A (it's a point and shoot with the D7000's sensor and no AA filter. 28mm equivalent and the same Expeed processor).

Thanks again.

[astronomer]

Hi,

It's my pleasure.

Regarding the calibration, I used the MaxIM DL and turned "Auto-Optimize" on since DSLR is mostly temperature unregulated. It's giving very good result based on some testing.
For me, I wrote a calibration pipeline in Rstudio to carefully cancel out dark current based on optical black pixels. And it's giving me extreme linearity for flat fielding. A typical 50mm lens wide field corrected with bias/dark/flat shows no vignetting in corner at all. That image is taken in the death valley so no light pollution and background gradient. Only level, curve and highlight is used in post processing.

I haven't compared mine with that from MaxIM. But I think MaxIM is sufficient if not the best at this moment. Due to hard to figure out the optical black pixels on other cameras, I have yet to publish that code.

Hope that helps,
astronomer

[astronomer]

Also, it would be amazing if you could investigate performing this hack on the Nikon Coolpix A (it's a point and shoot with the D7000's sensor and no AA filter. 28mm equivalent and the same Expeed processor).

Oh I left this one. Yes, the Coolpix A is the same processors/sensor/code base with D5100. I'll modify the tools and push for a new version.

[jpd321]

Astronomer - thanks much for the development of this tool - I'm using it with a D600 and looking forward to using it in the field. So far experimenting with measuring dark current etc.
One request though - I'm having some stability issues using it with an intervalometer - it seems to kick out of 'dark current' mode sometimes, even when remaining connected to a PC through USB, (and almost always when USB disconnected). Best long term answer would be a menu enable mode as you have done for D800 and others - any plans for this?
One fallback would be calling your command line tool via script before every shot - is there a 'quiet' flag that doesn't call the web page when calling the command line tool?

Thanks - Jeff

[astronomer]

Hi Jeff,

I just got a D610. The menu entry will be considered.

But recently I'm occupied with my own CMOS camera project so it won't be available soon.

Best,
astronomer

[Herra Kuulapaa]

Or even a permanent true dark current mode - It would be great for stand alone setups.
For the record I've got some nice results with D600 lately so it's a very capable camera

[drfalken]

Hello,
I just tested the "True dark current - Menu based" hack on a D7000, and it works, but it causes a couple of minor problems.
Problem 1:
The frame with the true dark problem is missing a few columns and a few rows:

Here is a 60s exposure, with the true dark current option turned ON:
https://www.dropbox.com/s/3w9cpgheiu5vg ... N.NEF?dl=0

Here is a 60s exposure with the true dark current option turned OFF:
https://www.dropbox.com/s/enet1upschbwl ... F.NEF?dl=0

The other problem is that with the option turned on, the USB transfer of data to a PC no longer works. I use Backyard Nikon v.1.0 to drive the D7000, and with the option dark current option (menu based) ON, I can no longer download the frames directly from the camera to the hard drive: the camera will just hang there.

Just wondering if anybody else has encountered these issues...
Personally, I could use (and would gladly pay for) a hack that permanently enables the true dark current, even after turning the camera OFF.
Thanks!

[astronomer]

Hello,
I just tested the "True dark current - Menu based" hack on a D7000, and it works, but it causes a couple of minor problems.
Problem 1:
The frame with the true dark problem is missing a few columns and a few rows:

Hi,

The "problem" you described is actually the feature intended for this hack. What you see is not missing column or rows but those are optical black and dummy pixels. Those are very important area used for bias and dark calibration. The dummy contains the ADC bias level, while optical black pixels contains bias+dark counts in long exposure. I personally uses both in an algorithm to achieve perfect calibration not possible by DSS.

The other problem is that with the option turned on, the USB transfer of data to a PC no longer works. I use Backyard Nikon v.1.0 to drive the D7000, and with the option dark current option (menu based) ON, I can no longer download the frames directly from the camera to the hard drive: the camera will just hang there.

Just wondering if anybody else has encountered these issues...
Personally, I could use (and would gladly pay for) a hack that permanently enables the true dark current, even after turning the camera OFF.
Thanks!

I can't do anything with that because Nikon SDK do not seem to support service features. It's up to the software dev to decide whether or not using PTP for maximum compatibility or nikon sdk for a limited feature. The digicamcontrol will handle the transfer even with this feature on. I suggests using that.

[abhoriel]

Given that 'Dark Current Enabled' disables all RAW processing, is there any point patching 'star eater disable' as well?
Or for astrophotography do you need both ideally?

It'd be a little inconvenient if you need both as it would make it more difficult to use the camera for normal photography and astrophotography without refreshing the camera in-between.

Also does dark current enabled disable NEF lossy compression?

thanks!

[astronomer]

Given that 'Dark Current Enabled' disables all RAW processing, is there any point patching 'star eater disable' as well?
Or for astrophotography do you need both ideally?

It'd be a little inconvenient if you need both as it would make it more difficult to use the camera for normal photography and astrophotography without refreshing the camera in-between.

Use the menu based one, it disable both and is switchable between daylight and night.

Also does dark current enabled disable NEF lossy compression?

Nope this is a separate hack.