Jump to content

Altair Hypercam 183c gain and offset


BigRobMartin
 Share

Recommended Posts

I'm new to dedicated astro cams, and the Altair was what I could get at my price point. I have used Altair Capture and not found a gain setting that gets me low noise either unfiltered or with a cls filter. I have found several people say I should star around a gain of 30 or so and adjust from there. I get decent stars, but the other data is noisy and grainy. I have tried several settings in both directions with little change in results.

 

I tried switching to APT, and the settings there are WAY different, and I just have no idea where to start. I can't even get a decent preview image to know if I'm in focus. 

 

Apertura 72edr, Apertura flattener and Altair Hypercam 183c cooled are what is in the image train. I am using quality usb3 cables and the laptop I am using is a 10thgen Core i7 with usb3 ports. I have zero issues with getting quality images with either a full spectrum Canon 1000d or an unmodified 80d using BackYard EOS.

 

I finally have a few clear nights (rare in the summer and early fall in Florida) and I'd really like to shake this out!

 

Thanks for any help!

Link to comment
Share on other sites

9 hours ago, BigRobMartin said:

I'm new to dedicated astro cams, and the Altair was what I could get at my price point. I have used Altair Capture and not found a gain setting that gets me low noise either unfiltered or with a cls filter. I have found several people say I should star around a gain of 30 or so and adjust from there. I get decent stars, but the other data is noisy and grainy. I have tried several settings in both directions with little change in results.

 

I tried switching to APT, and the settings there are WAY different, and I just have no idea where to start. I can't even get a decent preview image to know if I'm in focus. 

 

Apertura 72edr, Apertura flattener and Altair Hypercam 183c cooled are what is in the image train. I am using quality usb3 cables and the laptop I am using is a 10thgen Core i7 with usb3 ports. I have zero issues with getting quality images with either a full spectrum Canon 1000d or an unmodified 80d using BackYard EOS.

 

I finally have a few clear nights (rare in the summer and early fall in Florida) and I'd really like to shake this out!

 

Thanks for any help!

A gain of 30 in Altair capture equates to a gain of 3000 in APT. This is way too high. Try using a gain of 400, and an offset of 20 in APT. Dithering your frames will also reduce noise, assuming you are guiding with PHD2.

  • Like 1
Link to comment
Share on other sites

All I cant think of at this point is something wrong with the camera. I went with 400 gain and 20 offset in apt and had horrific noise throughout. No filter, no dust in the image train, good quality usb3 cables on a newer computer. The noise is three or four times worse than a dslr on a hot summer night. If I had a cooled dslr, I'd never look back at this point. My frustration level is nearing its max!

Link to comment
Share on other sites

7 hours ago, BigRobMartin said:

All I cant think of at this point is something wrong with the camera. I went with 400 gain and 20 offset in apt and had horrific noise throughout. No filter, no dust in the image train, good quality usb3 cables on a newer computer. The noise is three or four times worse than a dslr on a hot summer night. If I had a cooled dslr, I'd never look back at this point. My frustration level is nearing its max!

What calibration frames are you using? With modern Cmos cameras the consensus is to use darks, flats, and dark flats, no bias frames are needed. If the problem persists, contacting the supplier might be the best solution, they are usually very good when it comes to dealing with astro gear problems.

Edited by AstronomyUkraine
Link to comment
Share on other sites

On my ASI183 cameras, same sensor different electronics, I just take dark and flat calibration frames. The darks contain the bias and that works great when calibrating with PixInsight. For some unknown reason I also have to use bias frames with AstroPixelProcessor though otherwise I see odd artefacts. I haven’t used DeepSkyStacker for years and can’t remember what that needed but that was in my DSLR days.

 

I’m not sure what gain and offset you should use with the Altair camera for unity gain. With the ZWO ASI183 cameras unity is a gain of 111 and the offset is 8.

I found this out from using the Windows drivers that came with the camera and it has the default in built. ASCOM drivers are the same settings for the ZWO. I actually use Linux and INDI (the equivalent of ASCOM which is Windows only) and use the same gain/offset as I mentioned above.

 

Maybe Nick from Altair could chip in with the recommended settings, this forum is actually Altair’s, or drop them an enquiry email from the Altair website. If you are on Windows then it maybe a good idea to use ASCOM drivers.

Link to comment
Share on other sites

As for calibration, I use dss, so dark, flat and bias go into the mix. Flats are from the same light panel I've been using for a year, and I processed some dslr andromeda shots the same night from my other rig and had no goofyness.

 

I use ASCOM drivers...windows...as well as the Altair driver in the Altair capture software. I'm really missing backyard EOS right now...I only get heat noise from any of my canons. If I get a chance a bit later, I'll stretch one of them out and post a crop. Maybe it is something you guys have seen and its an easy fix.

 

Thanks for your responses.

Link to comment
Share on other sites

  • 2 weeks later...

In the interests of just getting this sorted out so that I can get useable data, I went out last night and set up on an easy target...Andromeda. Using APT with a gain of 400 and offset of 30. I did an hour of 1 minute exposures, then 20 darks. Not trying for anything special, just useable. I could see the core of Andromeda in the preview window, along with several clear stars as well as the companion galaxy. On the right track.

 

Randomly, I opened one sub in GIMP and stretched it quickly to see if there was noise I couldn't see...grainy, but to be expected with a single sub, uncalibrated. 

 

Finished the session and tended to my other rig for a bit, then came in for the night. This morning, I loaded 60 lights and 20 darks into DSS and nada. Zip. Zilch. DSS said 1 frame would be stacked and that I should raise the detection threshold. I raised it to 50% and ran it again, same result. Ran it again at 95%...no go.

 

I went back to the light file and pulled three out at random, opened them and stretched them, same result for all 3, looked like Andromeda.

 

The 2 pics are the preview pane of APT and a random sub stretched. I know there is data there, but DSS is having a hard time of it. I will try 111 gain and 8 offset tonight, but something has got to give soon.

 

And yes, I know DSS and GIMP are "sub-par" pieces of software. They are what I have right now and work just fine for my DSLR data. I can learn about 1 thing at a time right now, and I'm having enough issues with the hardware. I don't feel particularly inclined to add another steep learning cliff into the mix until I get this one figured out.

20211016_114556.jpg

20211015_231744.jpg

Link to comment
Share on other sites

35 minutes ago, BigRobMartin said:

In the interests of just getting this sorted out so that I can get useable data, I went out last night and set up on an easy target...Andromeda. Using APT with a gain of 400 and offset of 30. I did an hour of 1 minute exposures, then 20 darks. Not trying for anything special, just useable. I could see the core of Andromeda in the preview window, along with several clear stars as well as the companion galaxy. On the right track.

 

Randomly, I opened one sub in GIMP and stretched it quickly to see if there was noise I couldn't see...grainy, but to be expected with a single sub, uncalibrated. 

 

Finished the session and tended to my other rig for a bit, then came in for the night. This morning, I loaded 60 lights and 20 darks into DSS and nada. Zip. Zilch. DSS said 1 frame would be stacked and that I should raise the detection threshold. I raised it to 50% and ran it again, same result. Ran it again at 95%...no go.

 

I went back to the light file and pulled three out at random, opened them and stretched them, same result for all 3, looked like Andromeda.

 

The 2 pics are the preview pane of APT and a random sub stretched. I know there is data there, but DSS is having a hard time of it. I will try 111 gain and 8 offset tonight, but something has got to give soon.

 

And yes, I know DSS and GIMP are "sub-par" pieces of software. They are what I have right now and work just fine for my DSLR data. I can learn about 1 thing at a time right now, and I'm having enough issues with the hardware. I don't feel particularly inclined to add another steep learning cliff into the mix until I get this one figured out.

20211016_114556.jpg

20211015_231744.jpg

Now you are guiding OK, I would increase your exposure times to maybe 3 minutes. Andromeda is not as bright as it appears, and DSS might not be picking up enough signal.

  • Like 1
Link to comment
Share on other sites

7 minutes ago, AstronomyUkraine said:

Now you are guiding OK, I would increase your exposure times to maybe 3 minutes. Andromeda is not as bright as it appears, and DSS might not be picking up enough signal.

That's a good point! Thanks.

  • Like 1
Link to comment
Share on other sites

Update: Everything the same last light, just changed exposure length to 180 seconds. Exactly the same result. Going to try changing the gain and offset tonight. Stay tuned...someone might be picking up a 183c Pro cheap.

Link to comment
Share on other sites

It’s a long time since I used DSS. I seem to recall you had a slider like this

36D5377C-8517-4DF4-BDB1-857CF7252596.jpeg.4bc27998d47a19a1b6175d3830635018.jpeg

 

The default is 10% and if you reduce it then it will detect fainter stars. You might be going the wrong way with the slider.

Link to comment
Share on other sites

So I went back and re stacked with 5% and got on average 24 stars to stack...definite step in the right direction. Threshold percentage not exactly intuitive there for sure. So the resulting image was very dark...WAY darker than the preview image in APT and a stretch gives me smudges at best. I'm guessing my gain is still off at 400. If unity gain for the 183 sensor is 111, is that a lower gain setting than the 400? Is this one of those instances where the gain setting for a brighter image is non-intuitively numerically LOWER? This is confusing for me and I'm sorry for being so dense.

 

My biggest problem is that I have always been a visual learner...monkey see monkey do. If someone sits down and shows me how it's done and smacks me upside the head when I get it wrong, I never forget it. My job involves some of the most technical, advanced welding processes there are, and those processes are ingrained into me through repetition and master/apprentice learning. This is sooooo different for me. There is no book, set of instructions, beginner's guide, etc. There is nobody looking over my shoulder and there is no instantly seeing the results of my labor. I'm not used to learning like this and it can be very frustrating.

Link to comment
Share on other sites

On 10/17/2021 at 6:56 PM, BigRobMartin said:

So I went back and re stacked with 5% and got on average 24 stars to stack...definite step in the right direction. Threshold percentage not exactly intuitive there for sure. So the resulting image was very dark...WAY darker than the preview image in APT and a stretch gives me smudges at best. I'm guessing my gain is still off at 400. If unity gain for the 183 sensor is 111, is that a lower gain setting than the 400? Is this one of those instances where the gain setting for a brighter image is non-intuitively numerically LOWER? This is confusing for me and I'm sorry for being so dense.

 

My biggest problem is that I have always been a visual learner...monkey see monkey do. If someone sits down and shows me how it's done and smacks me upside the head when I get it wrong, I never forget it. My job involves some of the most technical, advanced welding processes there are, and those processes are ingrained into me through repetition and master/apprentice learning. This is sooooo different for me. There is no book, set of instructions, beginner's guide, etc. There is nobody looking over my shoulder and there is no instantly seeing the results of my labor. I'm not used to learning like this and it can be very frustrating.

Gain is equivalent to iso on a DSLR, the higher the number, the more signal the camera can receive. Offset is just as important, if this number is too low, the black can be clipped. Basically the offset, moves the histogram to the right, the more you increase the number.

 

Have you checked your back focus to make sure it is correct. According to the website, your setup needs 56.5mm of backfocus, any slight discrepancy can result in sub standard images.

Edited by AstronomyUkraine
Link to comment
Share on other sites

  • 1 month later...

So, still completely flustered. A few nights after the last post, I got set up and managed to get 4 subs before clouds rolled in (because, Florida). I was shooting the Western Veil, and ended up shooting darks and flats waiting out the clouds. 30x 3min darks and 30x 3min flats (correction...30x 1/15" flats!) but the clouds never let up. Just for fun, I stacked and stretched the 4 usable subs and all of the calibration frames in DSS and surprisingly got a useable image that led me to believe I was heading in the right direction.

Fast forward a few weeks, I set up again last night. Exact same settings in APT (I just ran the same program that I started previously. Exactly the same setup (my telescope does not get disassembled), everything exactly the same but the temperature outside (it was 20 degrees f cooler). 60 lights (watching in the preview page of APT, I could make out the nebulosity and see plenty of stars), 30 darks, 30 flats. Deep Sky Stacker could not see one single star. Not one.

I'm a really bad golfer and yet that is more enjoyable than this right now. I'm about to end up with a very expensive guide camera or a for sale 183c. Is there anyone from Altair that posts here that could give me a nudge in the right direction? I have emailed them and not gotten a response. I can't even get decent images in the Altair Capture software.

The pic is a total of 12 minutes of lights, 90 of darks and flats. I was happy that I finally had it all figured out. Literally nothing was different last night.

 

westveilshitty.jpg

Edited by BigRobMartin
idiocy on my part
Link to comment
Share on other sites

7 hours ago, BigRobMartin said:

30x 3min darks and 30x 3min flats but the clouds never let up

 

You may be taking your flats incorrectly Rob. Taking 30 x 3min flats is not correct.

You need to cover the scope with a light source. Some people use a tee shirt stretched over the end of the scope. Then illuminate it by placing an iPad or other tablet set to just display a white screen. The tee shirt diffuses the light. 

Then you set the exposure of the camera so that the histogram is about 30 to 50% of maximum. This is normally a short period of time around a second or so dependant upon what filters you are using. Then take about 30 flat exposures with this setting.

 

You can also buy dedicated flats panels or other generators like a tracing panel. Amy explains them below.

 

APT has a flats aid to help you determine the correct exposure duration but its ages since I used that software but Kirk explains how to do it here:

 

 

 

Amy explains how to make a flats panel

 

 

Link to comment
Share on other sites

That was a typo, sorry...flats are being taken at 1/15 with a very dim tablet and a diffuser. Sorry, just frustrated. If i go into an individual light frame and stretch it, it looks the same as the previous session's light frame with no stretching. Just not sure how the two sessions with exactly the same settings produce vastly different results.

Link to comment
Share on other sites

On 11/25/2021 at 3:49 AM, BigRobMartin said:

The darker one is a single sub from last night, the lighter is from previous.

To see if it is the camera at fault, or the software, enable colour fits preview in APT. You will find the settings dialogue box under the tools tab. Choose the correct Bayer Filter for your camera. The image will download and preview in the LiveView window, it will be stretched, so will give you an idea what the camera is capturing.

 

Untitled-1.thumb.jpg.3df2766bb745c8c0a81c8243a7d06a52.jpg

 

 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...