alan potts

19 minutes ago, Photosbykev said:

Very few camera lenses are coma free wide open, especially at the longer focal lengths and I'll take spikes over coma every day of the week. This was at f/8 on a Canon 70-200mm f/2.8L lens. Next purchase an astrograph lol

Really, I would have thought at the cost new now they would be decent from Canon of all people, this one though is about 12 years old and is sharp for normal work, I use to have the 200 F1.8, that stopped down 2 stops would still be F3.5. Now I have a duel mount bar on route I can play around with the telephotos I have, mind you the 500mm weighs as much as a telescope as I dare say the 600mm is more so.

Alan

Very nice shot Kev but I do wish camera lenses didn't leave the spikes, I need to try my 300mm F2.8 wide open see what come out. I tried it at F4 a while back on Orions belt but was far from happy, personal taste I guess.

Alan

Very nice image indeed there. I should do something like you are doing myself here as I have enough land to build a stadium or two on, but there is quite enough work to do without adding to it.

Alan

Met office so to speak rarely get it right here either, very nice shot of the bubble, well done!!

Alan

M22 is very easy to spot in that area but the moon will make it more difficult, there is no nebulosity around M22 though, As said M 8 and M 20 are nearby but whould not be over obvious with the Moon about.

Alan

8 hours ago, HunterHarling said:

I am going to experiment more with exposure length though...

I have an 071 Zwo on route to me at the moment so I will be doing the same. They say shorter exposure is what these cameras like, so it will be 2-3 mins for me. If it is as fast as people say I will try the LX 12 inch at 15-20 secs with the reducer to see if

 I can get some useable data on one or two other targets, like closer shots of say M13. 1980mm at F6.3 should be OK on the fork mount.

Alan

What ever Kev but I feel you would need a flattener with the WO offerings no matter which you go for. Same size chip but different scope My 1DS 2 was very poor at the edge of a similar 70mm ED.

Alan

58 minutes ago, HunterHarling said:

Thanks, Alan. Well, I started with 300 second for narrow band, but there wasn't enough signal. Then, I went to 600s and there was too much amp glow, so I settled on sort of a middle-ground at 400s which seem to give good results   

Judging by you fine results your not doing much wrong

Alan

I have often heard shooting stars make noise but I live in the middle of nowhere and it is very quiet apart from the odd dog, I guess space junk must come down all the time, maybe some others saw it too.

Alan

Halos or not it is a superb image, I keep looking at this and wondering about trying my Canon F2.8 300mm on it with a camera, should be about wide enough but I don't have any filters, only a visual Olll filter and H beta, both of which I imagine are not much good.

Alan

Another beautiful image from you, have to ask, any reason why 400secs, is it just easy to remember? I tend to work in minutes, but then what do I know.

Alan

That's another beautiful image there from the Spanish side of you scopes, must find some new words, but another I don't believe I have seen before, maybe worth a try with my M/N 190-mm one day.

Alan

I was in Bulgaria in an area where 99% of total occurred but sadly due to pressure of work I was unable to travel away to the east and see totality. It was a very odd sort of light with a purple hue.

Alan

Thanks John I will look this up, I like to look at a tutorial and write down step by step. Been using alot of select and mask of late which I picked up off Backyard Astro, it's a good way but not tried star removal yet, will look into it.

Alan

They must be very low in the UK as they are not too clever here and I am 11 degrees better off than even the south coast. all considered they are good shots.

Alan

8 hours ago, Starwiz said:

Have you tried star removal before stretching, then adding the stars back in afterward.  I did this for the first time with my last image.  It's a ton of work, but I was pleased with the results.

Nice image BTW.

John

I will have to look it up on how to do it as I tend to just stick to what I know in PS, I am sure it is not beyond me though. Some of the data in the stack was not the best of nights and there was some slight haze, that didn't help.

Alan

I posted this half way through data collection, bit of a mistake I guess. Thought some may like to see this 3 hours of data which is about as much as I can get at the moment without taking a 80yo walnut tree down. This is a collection of 3,4 and 5 minute subs at 1600 and 800iso, for no real reason other than I forgot what the night before was taken on.

Feel free to do what ever you wish and offer advice, wish I could have controlled that bright star better.

Alan

I can't get over how differnt the two image look, here is my not brilliant effort of a mere 3 hours

Difficult to believe it is the same area

Alan

Just now, MarsG76 said:

I wonder just how much quicker you'll be able to capture the equivalent with the 071... and whether 15sec subs will give you any of the deep nebulosity generally picked up by narrowband long exposure...

The 3m FL guiding will need to be guided via a OAG, for sure... but a good mount is essential, so if you are willing to spend the 3K on the CEM120, I'd say do it.. I feel like my CGEM is basically at its limit with 2m FL... than again who knows.. I'm constantly getting round stars even at the FL.

 

Oh on the SC I didn't mean narrowband work, just the odd globular cluster and the like, bright objects. As it is still on its fork I reckon 15-20 seconds is about the limit to keep it sharpish.

Alan

Cracking result I would say if lacking a bit of colour, it has a lovely something about it I just can't put into words, I like it.

Alan

With a Dob of any type the 100 degree type eyepieces will help a great deal keeping the subject in view longer. You don't have to buy TeleVue even though they are very good indeed, what you will find though is the wider the field of view of the eyepiece, and faster the scope, the greater the chance of coma being seen at the edges of field. I personally find this annoying and the faster the Dob the worse it will be, mine is F4.3 and I do use a Paracorr, this stops the problem. On the same Dob I don't see anywhere near as much with a 68 degree eyepiece . Fellow Mod John has a F5.3 scope and I don't believe he uses a a coma corrector or Paracorr, this is just TeleVues name for it.

Alan

Well hats off to the dedication you put into a fine image, I mean 27 hours, it's almost a day. I get a 071 next week so I imaging that could be used with filters too though as you said mono is the more accepted way here. I am actually thinking of banging the .63 reducer in the 12 inch SC and having a go at 15 sec subs just to see what I get. I was thinking long and hard about a CEM 120 for it and other scopes I have but sort of wonder if the 3 grand plus outlay was worth it with the difficulty of guiding 3M F/L.

Alan

Great image, I didn't know you could do this type of narrowband work with a DSLR, something to consider.

Alan

Superb image another I have never seen, thanks for posting.

Alan

8 hours ago, gorann said:

I bought an ASI071 about a year ago and I love it, so congratulations Alan! I cannot imagine you can get a better APS-C sized OSC camera.

I do use master darks with it, but so far my imaging train has been clean enough to avoid using flats, and bias is not necessary with these cameras. I read up on it initially and found that gain 200 was usually optimal, with offset 30 and I have mainly kept it at that (I am sure that there are some situations where this may not be optimal, depending on sky conditions and object). Then I made a series of master darks (25 or more frames) using that gain and offset and a few different exposure times (2, 3, 5 and 10 min). Regarding temperature I keep it at -15°C. Lower temperatures do not help much as can be seen from the T vs dark current curve. I attach a 7 hour example image with my Esprit 150 from spring this year (M100 & Co).

A lovely image there I must say. Can't say I understand a great deal of what is being said, maybe things will be a bit clearer when I get the camera and can see it working. At the moment Gorann I use dither, can that still be used with this type of camera, as I have to say I feel it works well with a DSLR.

Alan