Flame and Horsehead.

[JohnH]

Lots of things still to learn but I feel I am making a little progress. From this image, and another image I am working on, I believe that I have been massively underexposing red and blue images. Also, I realise that I am going to have to refocus between filters.

I hope that when I next image, bearing in mind the above, I will have less noise and reduced Irritable Star Syndrome. I have made a small light box from an A5 tracing light pad which I can use to get flats before refocussing.



This was taken on 15th Jan with my lens set at 250 mm. 20 each of LRGB at 180 seconds. The stacked frames were horrible with blotches all over which I have managed to reduce a bit.

I am probably pushing my lens and mount too far but I hope to resist getting a guided mount for a bit - at least until I have a better idea of what I am doing.

JohnH

[Carole]

Hi John,

Are you the person I spoke to at the meeting and we had a chat about your kit.  If so I thought you said you had a non modified DSLR and an achromatic scope both of which you will struggle with.

So now I am confused.  It would be help if you could add your equipment, (Camera, Mount, and scope) and what length subs you are using.

Re the image, I can see the Horsehead and the flame, and the stars are reasonably round, so that's progress.  It's all a huge learning curve and the more you are out there trying and the more you post up results, whether good or bad, the more help you can be offered.

Carole

[JohnH]

Hi Carole,

I posted in a bit of a rush. I was using a ZWO ASI 1600 Pro with LRGB filters and a Canon 75 -300 mm zoom (very cheap and second hand) on a Mini Star Adventurer mount with a counterweight. The camera was cooled to -20C, the zoom was 234mm (according to plate solving).

I processed the frames in Astro Pixel Processor and then used Affinity Photo to stretch, filter and crop and to combine a luminance integrated stack with an RGB integrated stack to produce LRGB.

John

[Carole]

Thanks John.  Unfortunately I don't have any experience with CMOS cameras, Star adventurer, APP or Affinity Photo and am rubbish at camera lens imaging.  So I personally won't be much use to you regarding equipment or software, just general imaging advice.

I realise that I am going to have to refocus between filters.

That's correct.

Roger uses a mono CMOS camera, so hopefully he can advise on length of subs. 
Duncan uses a star adventurer and Mark is a good all rounder because he's very technical, so hopefully one of them will come along and offer any advice needed.

Carole

[RobertM]

John,

It looks very much to me like it's the lens at fault.  For a start there is what I'm sure is odd shaped caused by sagging of the front lens assembly.  Secondly it is either a tad out of focus or just a poor lens design which might also explain the CA.

The kit you have deserves a much better lens or a light short focus telescope (of known optical quality).  If you're doing Astrophotography then it's best to get something tried and tested.

As for length of subs; I suggest getting Sharpcap.  It can quantify your camera and conditions then recommend condition dependent exposure lengths.  It also has a fantastic polar alignment routine and costs peanuts (relatively speaking).

BTW I have a Star Adventurer and ASI1600MM.

I hope that helps
Best
Robert

[JohnH]

Thanks Robert,

I am planning on upgrading my lens to a telescope (and also my mount) when I feel that I have a little experience and when I can think of somewhere to store them. I really do want to improve my mount because, at the moment, I find myself spending half the evening getting the lens pointed in the right direction.

When I get a chance I am going to see if I can improve results by focussing between filters (I had hoped they were fairly par focal but they are clearly not). I knew that I should be doing this but the problem was taking flats during the imaging session.

I use a Mac and so SharpCap is not an option.

Regards,

John

[Carole]

If you have been a member for more than 6 months, you can borrow society equipment, and I see there is a Skywatcher HEQ5 Pro Goto Mount With Tripod in the equipment list.  This is the same mount that I have, so it might be a good idea to borrow this and see what you think.

If you haven't bought your scope yet, you need to get an Apo refractor or a Newtonian designed for astrophotography (i.e. the newtonian has been adapted to enable focus with a camera).

Carole

[RobertM]

No point in putting a cheap lens on an HEQ5 carole.  The star adventurer is good for at least 250-300mm F/L.

[Carole]

Hi Robert, no I was meaning when he starts using a telescope.
Sorry I wasn't clear.

Carole

[The Thing]

My experience with the Star Adventurer has taught me that really good polar alignment is critical. I use a guidecam with a 12mm cs lens with SharpCaps p.a. routine. To get it consistent you need a really good tripod that will not move a nanometer as the weight of the gear moves. I also  totally rebuilt the gear train on mine to remove backlash and make the rotation free and easy - any stiction means bloated stars.

When I've used lenses with my Canon 1100d I've settled on Pentax as a compromise between cost and quality, prime lenses are best but I have a 35-70 zoom which is excellent in the lower range. Focusing lenses is a bugger so I cut out a tiny bahtinov mask.

Hth

Duncan

[RobertM]

I completely agree with Duncan.  Elaborating slightly on the stability side... You will also need excellent balance and cable management (no dangly bits) - it's the same for any astro imaging but even more so with lightweight mounts like the SA where even a light breeze can cause havoc.

Robert

[JohnH]

Thanks everyone.

I'm shaking the piggy bank.

I am pondering whether to get an ioptron CEM25P, does anyone have any experience of it?

Regards,

John

[RobertM]

I'm not sure that you'll find much experience of using iOptrons in the society.  It's mostly Skywatcher.

Robert

[Carole]

I think Jim has an Ioptron but he has moved away and not sure if he goes onto the forum any more.

I just looked it up, it is GOTO and has a guide port and a Payload of 27 lbs (12.3 kg) with the mount-only weight of 10.4 lbs (4.7 kg), however I can't see a polarscope.
In this modern day and age I guess that's not so important if you can use Sharpcap or Polemaster, if you can find a place to mount the Polemaster camera, but it's possibly a bit too much for a learner to cope with.

It does however say it has a Polar alignment routine for those who can't see the Pole Star, so that might also overcome the lack of polar scope.

It's priced at Price: $948.00 which i assume is US dollars and that converts to £723.

Most of us use Skywatcher HEQ5 which is a similar price, or NEQ6 it's bit brother.
You would get better advice from us if you bought the Skywatcher.

You could come and see mine if you don't hang around too long as I am planning to send it for Belt Modification.  If you bought a new one I think it comes with that as standard.

Carole