39 replies to this topic

[VincenzoZito]

Smile, you didn't do your homework well.
Perfectly normal for 183.

[matt_astro_tx]

OK, so I'm taking my first set of darks this morning and WOW am I getting an "amp glow" phenomena.

 

Would anyone know if this typical for the ASI183MC pro ? I guess I now need "dark flats" !

Perfectly normal.  I also use the ASI183MC Pro and mine glows like a light bulb.  Darks take care of all of it.

 

Don't do dark flats.  Use bias frames with this camera.

[fewayne]

I mean, I don't know if dark flats are necessarily bad with the 183, but bias frames certainly work perfectly well instead. And for my money bias is just a lot simpler, so that's what I go with. Others' mileage may vary.

 

Just to be super duper extra triple clear, dark flats have nothing to do with eliminating amp glow. Amp glow comes from a thermal signal which is perceived by the sensor as infrared light. Short exposures, like the ones you take for flats, don't accumulate enough thermal signal to show up. What calibrates out your amp glow is dark frames.

 

 The 183's thermal signal is pretty sensitive to the exact gain, offset, temperature, and exposure time used, so if you're dark frames don't exactly match your lights, you're going to see residual glow. (Ask me how I know.)

 

(Noted in passing: That is quite the new profile picture, Matt!)

[matt_astro_tx]

(Noted in passing: That is quite the new profile picture, Matt!)

Well the winter beard is back so I figured I should show it off.  Lol. 

[jpoulette]

This may be old hat to some of you guys - but I found this document incredibly helpful understanding the functions of frames.

[jpoulette]

Forgot to mention - for folks new to PixInsight (like me) this link leads to all available reference tools & scripts documentation. Good luck !  

[bobzeq25]

Reinforcing the above.

 

The 183 (I own both) has bad amp glow.

 

To fix it you need bias, flats, darks.

 

Do those right, process them right, the amp glow goes away.  Make a mistake....

 

Dark flats can substitute for bias.  Like most cameras, the simpler bias works fine on a 183.

[bobzeq25]

This may be old hat to some of you guys - but I found this document incredibly helpful understanding the functions of frames.

 

 

Forgot to mention - for folks new to PixInsight (like me) this link leads to all available reference tools & scripts documentation. Good luck ! 

Good resources.  You might (I think will) also like these books.

 

Inside PixInsight.  Mastering PixInsight.

[jpoulette]

Reinforcing the above.

 

The 183 (I own both) has bad amp glow.

 

To fix it you need bias, flats, darks.

 

Do those right, process them right, the amp glow goes away.  Make a mistake....

 

Dark flats can substitute for bias.  Like most cameras, the simpler bias works fine on a 183.

I noticed the "glow" right off the bat with my first set of darks, but I knew it was probably a normal phenomenon with this camera. I've actually already gone through the process of integrated masters in PixInsight for dark, flats, and dark-flats at several different detector temperatures. I took a set of 30 each @ 120" (90 total) for each of the 3 temperature options (0, -10, & -20 C). It was essentially for practice - but hopefully I will be able to use them at some point.

 

There are a LOT of 'sea legs' to get in PixInsight !

 

I was a little surprised how long it took to calibrate, and then integrate, the dark-flats into a master. (only a few minutes, but by modern computer standards it seems like a long time) I think the take away here is that poor quality darks and dark-flats will clearly "lead to under correction of thermal noise". This means crappy images.......

 

Thanks for the comments - just about every word here is helpful !!

[jpoulette]

Newbie Progress report:

 

Since the weather has been so bad (another winter weather advisory tonight) - I switched over to getting a grip on the stacking / processing side last night.

 

Completed the first two freebie tutorial videos from Masters of PixInsight, and downloaded the free frame sets they offer. There are three free 45 minute videos that I would highly recommend to beginners who are learning PixInsight. With these I was able to Blink a set of light frames, use the Weighted Batch Pre-Program Script, do a Star Alignment, and Integrate the frames into an image. A good start on stacking (for me).

 

It's becoming clear that (like most things) the more you use PixInsight the less overwhelming it becomes - at least on the stacking, integrating, and calibrating side. I suspect a lot of the "magic" will come from the nuisances of post-processing which I suspect is a whole different learning path.

 

Onward and........upward !

[italic]

Nuance, nuisance, same thing! You'll figure out a workflow that works for you right away, then you'll start adding steps between that help out along the way. Good luck!

[jpoulette]

Newbie Progress Report:

 

Got out for a few hours 2/9 - perfectly clear skies. Everything seemed to work fine, especially polar align and auto-focus - surprising how fast it all was. Got a great focus position on both scopes.

 

What amazed me the most, is how many stars the camera can see with a 2 degree FOV. Extraordinary!

 

Then, (on cue) I think I made the classic newbie mistake and tried to guide with a star too close to Polaris. It would start off fine, then wander off and give error messages about increasing max RA.

 

At the time (outside and 21F) it was bewildering, but after reading quite a few posts later that night (inside and warm) - I got it now.

 

So now I wait until the skies are clear enough to try again. Doesn't look good for at least a week here - but we'll see.

[matt_astro_tx]

I've heard of people moving their guidescopes off axis when imaging near polaris.  Never imaged that region myself though.

[jpoulette]

I've heard of people moving their guidescopes off axis when imaging near polaris.  Never imaged that region myself though.

After thinking about it for a while - it makes perfect sense from a guiding perspective. The movements would be so small the closer you were to the pole that I can guess it could confuse the drive system.

 

I wasn't thinking "workflow" (like I should have been) but rather just getting stuff to work.

 

I'm really hoping to get some more time outside soon - although this time of year in New England is tough !
 

[jpoulette]

OK, my first image is here.

 

Very happy with the tracking of the AM5 - pretty much 1' total all night, even with a little wind.

 

Let the fireworks begin !