Roy Foreman

Just reprocessed the M45 image using Affiniy Photo. Think its done a better job than Deep Sky Stacker and Photoshop, but you still can't make a silk purse out of a sows ear !

Very well done. This is something I've been wanting to do for a long time but never got round to trying. Separating Sirius B from it's parent is no easy task. Your results have given me the kick I need to give it a go. Once again, well done !

Finally, after over 4 months of waiting, a semi decent night where it was clear enough for long enough to do a test session with the RASA 11. Had to grab images between passing clouds, and the sky transparency was rubbish, but at least I managed to get something. Just didn't get enough data for high quality results, but it was good to practise in poor conditions so that when a really clear dark night arrives ( if ever ! ) it doesn't get wasted on learning the foibles of a new scope. And there were a few. The scope was fitted with Celestron's dedicated light pollution filter for the RASA. I'm really impressed with how well it performed - very neutral colour balance and what little light pollution I have was exterminated very effectively. Presumably this is why the filter costs £600 !!! All images - ZWO ASI 294 MC Pro M45 Pleiades - 21 x 30 sec M42 Orion - 10 x 30 sec Double Cluster - 42 x 30 sec Next time I will use my D810a to see how well the scope covers a full frame sensor Oh, yes, and I added star spikes to the Pleiades image to cover up the crappy spikes generated by the camera cables. Something to get sorted !

Just to add my two penny worth, I've owned an OO 8" reflector for about 10 years. Optics are first rate and still in pristine condition. Mechanics leave a lot to be desired though. The primary mirror adjustments are very primitive and awkward, and the tube diameter is a bit on the small side - there should be something like an inch between mirror and tube to allow air currents to spiral up clear of the light path - mine has less than half that. And OO tend to size their secondary mirrors on the small side. Ok for visual but for imaging you are going to want a couple of sizes larger - which they will do for you.

I recently used SharpCap to polar align my EQ6 and I have to say I was impressed by how quick and easy it was to do. As you probably know the software provides two methods of adjusting the PA. The first is by adjusting the mount until a highlighted star - later two parallel lines - coincide with each other. The second is by watching the RA and DEC offsets reduce in magnitude as you adjust the mount. If using the latter method it is important that SharpCap knows your latitude and longitude for accurate results. I managed to get my PA down to 25 arc sec, and the reason I could not get better than this is because the adjustments on the EQ6 were just not fine enough to achieve any better, so it is a very sensitive procedure. Just mounting a scope on the mount can shift the alignment by a small amount, particularly if it is a big heavy OTA. As for your star trails, if they are east-west then it is most likely down to periodic error, if at some other random direction then probably polar alignment. Since doing my PA I haven't had a clear night to try it out. When I do I will report back and let you know my findings Good luck and clear skies

Very nice and well done. Here in the UK we can only dream of such imaging targets !

I have been waiting over four months for a clear night with no clouds and no moon. According to my records 21st September 2020 was the last time I was able to do any deep sky work. I live in the southwest. Summer 2020 was, however, very productive, but it did mean waiting until 11.30 pm to start imaging !

Very nice shot. Clavius is my favourite crater. I always assumed a red filter was the one to use to minimise the effects of atmospheric turbulence, but your shot through a blue filter has worked really well.

Presumably a very tall one !!

It's one of the reasons I keep to short exposures, We actually had the first clear-ish night a couple of days ago, and it was a case of take a shot, wait for the cloud to pass, take another, wait for the next cloud etc. If you are doing 5-10 mins and that cloud comes when you're half way through ..... It;s good to know I'm not the only 'going slowly insane' astronomer around !!!

Yes I agree - using higher ISO is like turning up the brightness at time of capture rather than in processing. Never tried taking side by side images at ISO 200 and 6400 for the same duration and then processing each to see which reveals most detail / less noise. When I get a chance I'll try it. I've done it with 1600/6400 and the 6400 turned out less noisy. Can't show you the results of that because I since discarded the images as being below par.

To reply to the above few posts in one hit - firstly the D810a is not like a regular D810. The lowest ISO setting has been raised from 64 to 200, so the sweet spot is probably higher at something like 1600. I seem to remember reading that somewhere. A 60 sec exposure at 1600 could probably be pushed to look like a 60 sec exposure at 6400 but I've never tried it. I have taken images of star clusters at ISO 200 and they can be pushed quite dramatically, but nebulae are not quite so forgiving. Most modern cameras perform really well at high ISO's these days, and my personal preference is to keep exposures as short as possible to minimise tracking errors, atmospheric effects and the like. In terms of total imaging time, to a certain extent, yes, 15 minutes of imaging at 6400 gives similar results as 60 minutes at 1600 - for a single image. But, at 6400 you will need a minimum of 5 exposures to smooth out noise, whereas at 1600 you can get away with three. So it's 75 minutes versus 3 hours ! I must stress that the above applies to the D810a, but I can't see why the same logic cannot be applied to other cameras. Nice image of the heart nebula Joel, well done at ISO 200 !

My camera is a Nikon D810a and is designed for astrophotography, so I think nothing of using ISO 6400 on a regular basis. Other cameras may not work so efficiently at these high ISO's, but I would suggest most would give decent results at ISO 1600. The advantage of high ISO's is shorter exposure times, which is an advantage when making the most of short imaging windows in the weather, as I often have to. Here is an example of an ISO 6400 image :-

There is a trade off with ISO settings. Low settings like 200 will give higher quality and can be pushed further during post processing to bring out details, but will require longer exposure times. Higher settings like 6400 will reduce your exposure times quite dramatically but will produce a lot more digital noise. Generally you can offset this but taking several identical shots and stacking them together (I usually take 5 or 7) in photoshop. As a guide for the Pleiades, try 5 x 60 sec at ISO 6400 and see what you get. Let us know how it turns out

I too am driven to despair with the weather. I have a brand new and very expensive RASA 11 that has been waiting 4 months to see first light. And it's still waiting. Sometimes I think 'why am I bothering with all this', Then, when eventually the skies do clear, I know exactly why I bother - astronomy is in my blood and has been all my life. If it really is in your blood you will endure all the aggro alongside the pleasure you get from being under the stars. As others have said, clear skies will return soon !

Thanks for the welcome Jeff ! I have seen the sun on occasions recently, but not clearly enough to consider looking at it through a solar scope - yes I have one too. I keep a log of the night time weather - have done for several years - and here in West Somerset, the last time we had skies cloudless enough to consider deep sky imaging was 21st September 2020. That borders on unbelievable. The forecast for tomorrow night, Saturday is for clear skies from 11pm until 3am. I shall be staying up to witness this incredibly rare celestial even, but I expect it will be clouded out as usual ! Roy

Thank you Dave - the warm welcome is much appreciated !