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BPM with a new ASI1600 MM Pro


(@detoxx)
White Dwarf Customer
Joined: 4 years ago
Posts: 22
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Hi all!

Im using BPMs with my DSLR Cameras. Now i have purchased a ASI1600 MM Pro and like to take a BPM as well.

In another topic, i read, that the guy dont use Flats, he uses Darkflats. Is there a difference between DSLR and a cooled Mono to use Bias or Darkflats, and no Flatframes?

The other Question is: I take 300 Second Subs, Multiplied by 50. But with what Temperatur? My DSLR are not cooled, so i leave them in the House and they become a Sensor Temp ~ 30C. Should i warm my ASI to the same Level or just Leave the cooling off?

 

Thanks!

Markus


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(@wvreeven)
Galaxy Admin
Joined: 4 years ago
Posts: 1651
 

Hi,

I use Flat, DarkFlat, Dark and Bias frames with my ASI1600MM-Pro Cool. And you should always cool the sensor because that reduces dark noise. I usually cool to -10º because in summer in Spain (where I until recently lived) the temperatures can be such that the camera can just cool to that temperature. I spent a full day shooting DarkFlat, Dark and Bias frames with Dark frames of different exposure times (30, 60, 90, 120, 300, 500 and 1200 sec) to create a master library that is prepared for various exposure times. All the frames were shot at the same temperature of -10º, the same gain of 75 and the same offset of 12. As long as I shoot Light frames with any of those exposure times and at that temperature, gain and offset I don't need to shoot any of the other frames except Flat frames which you ALWAYS should take.

HTH, Wouter


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(@mabula-admin)
Quasar Admin
Joined: 5 years ago
Posts: 3122
 

Hi Markus @detoxx & Wouter @wvreeven,

For a camera like the ASI1600mm-pro I would recommend to calibrate with darks, flats and flatdarks and skip bias. If you create bias, don't create them with the smallest exposure time. But create them with an exposure time of 1/10 second, not 1/1000 second. But then again, if you need to calibrate with darks for the lights and flatdarks for the flats, why use bias anyway? The bias signal is contained in the flatdarks and darks already 😉 . A CMOS sensor in such a camera will not produce reliable bias if you use exposure times of only 1/1000 second or shorter, that is why you don't want to use bias frames with such a sensor.

Then regarding the Bad Pixel Map, yes, to create a good BPM for the asi1600mm you can simply turn off cooling and make some darks of a couple of minutes. By not cooling, the non-linear and thus hot pixels will be very apparent in those darks and therefore they will be very suitable for creation of a Bad Pixel Map. On the other hand, I have an asi1600mm myself and I can confirm that the hot pixels are also nicely extracted from cooled darks fro creation of the Bad Pixel Map.

Let me know if this is clear 😉

Mabula


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(@wvreeven)
Galaxy Admin
Joined: 4 years ago
Posts: 1651
 

Thanks for the advice @mabula-admin regarding the bias frames!


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(@detoxx)
White Dwarf Customer
Joined: 4 years ago
Posts: 22
Topic starter  

Hi!

@wvreeven Thanks, i know that. I was only a little confused about the Bias or Flatframes with a Bad Pixel Map, because i also use an CMOS Sensor on my DSLR - but yeah i know, its a difference. But thank you for you explanation! 🙂

@Mabula

Thank you for that! So i dont take Bias, i take Flatdarks in the Same way i take Flats in the end of my Session. Because im drivin 30 Minutes to my Location here in Germany, i have to do flats and Flatdarks new, every damn night :P. But, it is, what it is.

With my DSLR, i take Bias and it works fine, i dont take darks, but a good BPM. Especially with my STC Duo Narrowband Filter for my APSC, that works very well! 

Here a Picture taken with my 700Da, STC Duo Narrowband Filter an a good BPM! 🙂

I hope to crack that with the Asi 😛

Thank you Guys!

Greetings from Germany, Markus

 

This post was modified 2 years ago 2 times by Detoxx

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