Help needed

[Petesandie]

Hi i'm new to astrophtograpy and your help is desperately needed here Trying my best to focus on Andromeda galaxy with no luck. I own a Celestron 8" HD telescope with Altair hypercam  178 colour ccd camera with Baader IR-Cut Neodymium filter Using Altair software to capture images Try'd every possible setting with it and this is the best i can get Your possible solution would be much appreciated many thanks

[Charic]

Welcome to the SGL.

At least you have an image!....Astrophotography is not my speciality, although I'm learning, but someone here will be better equipped to help you.

What your image does show (remind me) is what M31 looks like from my back garden through my 200P (8") scope? nothing more than a little patch, more grey in colour than your image depicts, but when away from the house at a darker site, wow! M31 fill's my field of view, with detail and shape!  Same scope, better conditions, the difference is remarkable . 

 

[ronin]

Will an image of Andromeda through a Celestron 8" HD telescope fit on the sensor of the Altair hypercam 178. M31 is big and I suspect the image could be too big. So what you capture is just a portion of M31.

How long is the exposure and how many exposures did you take?

I assume it is on an equitorial mount to track the target. With that scope I guess you will need a minimum of twenty exposures each of twenty seconds, then stacked before anything begins to appear. A lot will depend on the tracking accuracy of the mount and the twenty exposues will be need for the dim image caused by the long focal length and so the large image.

Reason I say 20 and 20 is that I played once with M31 and on a faster lens I needed 10 exposures at 25 seconds each stacked to get anything that even resembled a blob - no detail. So the above is very much a minimum for something fuzz like.

Are you using a focal reducer ? One would help.

How sure are you that M31 was central to the camera?

[DaveS]

First off, I put some details into FoV calculator in Astronomy Tools (See resources at the top of the page) assuming the sensor is the same as the ZWO 178, and this is what I got

https://goo.gl/LSTqFH

As you can see only the core is imaged, which is what I think I can see on your image.

Also you haven't said what exposure you're using, I suspect it's quite short.

What mount are you using? Are you guiding?

As ronin has posted (While I was typing) M31 is a big object, an 8" Edge HD has a long FL (2 metres or so) and the sensor is on the small size for DSO imaging.

 

[PeterCPC]

On the general issue of focusing - what I suggest is that you use a Bahtinov mask to get focus. It's fairly easy to do - you  will need one for the C8. First Light have them here

Peter

[ronin]

The scope appears to be the standard 2032mm focal length, M31 is about 3 degrees across so that produces an image of 106mm the Altar camera chip is 7.4x5.0mm in size.

That is a massive difference. If that is correct - seems a bit too much - then you will only get a very small bit of M31 on the camera as an image. I would say that event he central core would be bigger then the sensor.

[rotatux]

Another trick: first aim at a bright star, focus, lock it, then move to M31. Use your finder each time to check the target position in the finder w.r.t. position on the image.

[PeterCPC]

Yes sorry, I forgot to say that you focus on a bright star and then swing around to target.

Peter

[wimvb]

Buy a copy of 'Making Every Photon Count', written by Steve Richards (steppenwolf here). It's available from our our sponsor and from Steve. If you buy from FLO, add a Bahtinov mask to the shopping basket. Both items will be the best investments you can make (bang for buck).

The book has all the information you need to get started with this wonderful hobby.

[Petesandie]

Thanks guys firstly i focused on Dubhe a bright star using a Bahtinov mask then swung round to andromeda .In altair capture program i used Gain at about 4 Exposure Time was about 30 seconds and 10 frames

[wimvb]

What if you set gain to its maximum value?

You also need to stretch the image (= increase contrast).

[Petesandie]

Yes try'd Gain as high as 500 Just get very bright Image and a lot of Noise. Will try high Gain and short Exposure next clear night

[wimvb]

With these cmos sensors, you can use high gain/short exposure, but you need LOTS of frames (100+ is no exception). It's not just the seeing you want to beat, but also the noise.

Good luck

[Petesandie]

Thanks guys will be trying again next clear skys

[p14b]

Hi Mate

Only started AP end of last year myself.

The Andromeda will not fit inside your FOV , with a C8 and a 178 camera. accuual FOV below (used a ZWO camera but size is the same 7.5x5)

 Try the DUMBBELL or the RING both added below as these will fit in your FOV  actual FOV Below (first is Dumbbell second is RING) and both can be captured in frames under 30sec, i would try these targets as I myself being new found them easy to image and there both high in the sky at the moment up near the star VAGA .

 

[ollypenrice]

As Wim said, we stretch our DS images because, if we don't we only see stars and the brightest nebulosity. You could Google 'Levels and Curves routine' for advice.

Olly

[DaveS]

There's also the not-so-little image scale issue. You have 0.24" per pixel. Which might (Or might not) be OK for "lucky" planetary imaging with hundreds of frames  at very short exposure times, but for DSO is a world of pain, especially with a scope like a SCT with wobbly mirrors, and less-than-rigid mounts (Almost any mount is less-than-rigid at these scales).

With an 8" Edge HD, I'd be thinking.....0.7x Celestron reducer and OAG. This would at least get you 1400mm FL which is slightly less hard work. I might also be looking at a camera with larger pixels, probably a CCD, since DSLRs have caught the dreaded "More megapixels are better" bug leading to ever smaller pixels bringing you back where you started.

[Petesandie]

I managed to get something that resembles the Cigar Nebula Got some processing to do but its a first attempt things should get better Thanks for all your comments 

[Petesandie]

Hi all I've been practicing still a long way to go but now i'm at least getting an image resembling Andromeda

[M Astronomy]

Wow! What an improvement!  Just got into astrophotography myself and am excited to try imaging this object when I get some more equipment together. Keep up the astrophotography!

[Jannis]

That's really impressive!

What scope/camera did you use now? This last image have a much better FOV then your first image. Your first image of M31 did indeed include the core, but it was just way too small FOV to get much out of it. This is the FOV your first image had in comparison to your last one (i stretched it a bit to see better).

 

[tooth_dr]

Big improvement there!  Keep them coming.

[Petesandie]

Hi Jannis I'm still using Celestron 8" HD But now added a Hyperstar + Atik 414 colour camera. No filters. 100 subs 2secs. 30 flat 30 bias Processed in Nebulosity and photoshop Many thanks for all comments Pete