Adam1234

Brill thanks, I'll check the diameter and get one of those. Thinking of maybe getting this cc, and just hope I have enough manoeuvre for getting focus. https://www.firstlightoptics.com/coma-correctors/baader-mpcc.html

So here's photo of my focuser: Here's my camera attached, roughly at the focus position (have not moved focuser since last imaging session): And if helpful, I use this adapter for attaching T Ring to focus tube:

Sure, will do that when I get home from work

Hi alacant, yes I have a 2" focuser, but it's one with screw thread on the outside rather than one where you slot in and tighten. Would this still work with a cc?

I'll check for that circle with a line when I get home from work. I couldn't get prime focus with the nose piece either and had to find a very thin adapter to go from the 2 inch thread on the focuser to the T ring. I want to try and avoid having to get a low profile focuser at the moment, maybe when I get a new scope at some point in the future if I need one.

What do you mean by mechanical distance, is that something different from actual distance? I'm so confused. I've been looking on the internet at coma correctors but they look more than one or two mm in length, unless I am missing something and totally not understanding what you are saying.

So will the coma corrector change the position where focus is achieved with the camera? My concern is whether I'll still be able to achieve focus with the coma corrector attached? Currently to achieve focus I need to have my focuser racked almost all the way in with maybe about 7mm inward travel left. With the added length of the coma corrector, I don't want to risk not being able to get focus and wasting my money.

Could anyone help me understand whether I can use a coma corrector with my current scope or whether I need a different scope? I've got the Meade Lxd75 6-inch newtonian (D = 152mm, F = 762mm, f5) that I use for astrophotography with my DSLR. However in order to get focus I've got to have my focuser racked pretty much all the way in with perhaps only a few millimeters spare (couldn't tell you the exact amount but it's not much). Does this mean that I wouldn't be able to use a coma corrector with my current setup, as due to the extra distance this would create between the focuser and the camera, I would not then have enough inward focus to get the camera in focus? Also what exactly does it mean when a coma corrector requires say, 55mm backfocus? I did read a post from a few years ago on this but found it quite confusing.

As bottletopburly says, add the images from each night as a separate tab, the tabs are at the bottom of the table if you haven't seen them already. If you try and frame your new shot as close to your old one as best you can, maybe have one of your old shots handy, but DSS should compensate for a slight misalignment and rotate your images to match. Depending on the amount of misalignment, there will be some stacking artifacts around the edges which you can crop out.

That's brill, I try to keep my camera parallel to the OTA anyway.

Thanks guys! Hopefully I get some better flat frames next time. I've got the Optolong L-Pro Light Pollution broadband filter on it's way from FLO so hopefully that will help to reduce some of the gradients caused by light pollution. What's your opinions on reusing the same flat frames for multiple nights imaging? Obviously i take it the best option is to take new ones for each night.

Thanks Ton, next time I'll try dimming the screen more and aim for 2 - 3s and see what effect that has. I suppose I could on the same night, collect some flats at different exposures and see what affect this has on my images. In my case I was using no filters, just stick dslr and iso 800.

Hi all, I took advantage of a clear sky on Sunday and got just over 2 hours data on M81 & M82 at ISO 800. Lights 65 x 120s Darks 15 x 120s 50 x flats 50 x bias Here's my current version of the image, I may do some extra processing over time to see if I can improve the image further and will probably add extra subs from future imaging sessions. This was also the first time I've tried taking flat frames. Probably didn't do the flats correctly as I still had quite a gradient across the image but I think the vignetting on the original uncropped image was reduced. Perhaps most of the gradient was caused by the light pollution from the 3 street lamps outside my garden... I managed to remove the worst of the gradient using this photoshop method by Astrobackyard. For the flat frames I used the t shirt method, but instead of waiting until dawn as I've heard is recommended, I did this at the end of my session and positioned my scope upwards and balanced my laptop screen on top with a full white screen. Put camera in AV mode and ensures the histogram was between 1/3 and 1/2 from the left. Not sure what exposure times we're looking for here though? They seemed very short. I've heard to aim for 0.5s, so if that's correct maybe the brightness of my laptop screen could have done with being a bit dimmer. Any tips on taking flat frames will be much appreciated! Adam

I got fed up and frustrated using the polar alignment scope. I now polar align with the QHY Polemaster. Bit of an investment but I have found it worthwhile and it's so much easier than getting down on your knees and craning your neck. Much quicker as well.

I've done a bit of re-work on my image of M42 that I posted last week after learning about using layer masks from this YouTube video (https://www.youtube.com/watch?v=z5fZEF7pBvo&t=771s). Even though I still don't fully get layer masks and how to use them effectively, I followed the process in this video and found it very helpful and feel that it has improved my image dramatically. I do feel that each imaging session I do, I am improving bit by bit and am really pleased with the progress I am making, so thanks to all for the advice you have given me. I expect I can probably do more with this image? and I still have the .tiff file so I will probably keep working on it over time as I learn new tricks and tips. Here is the image as I posted it last week: Here is my current version of the same image after having a play around with layer masks: Comments welcome Best get back outside now, getting some subs of M81/M82 so watch this space. Clear skies! Adam

Great image

Incredible image

Lovely image

Thanks! Yes I am very pleased, a few months ago I never would have thought I could get images like these, especially with the 3 streetlamps facing into my garden. I can't wait to eventually get out into a dark sky site, or at least to somewhere not surrounded by streetlights on all sides!

So I finally had a clear night on Friday so I was given the opportunity to test out the QHY Polemaster I bought last week. After spending over an hour fighting with the Polemaster software, finding that it has massive lagging issues, I discovered that it works a lot better if you play a video in the background 🤔🤔 In the end I won and achieved far better polar alignment than I have previously been able to achieve with the polar scope. Despite the moon, and since I already had the scope out I decided to shoot M42 Orion Nebula and managed 27 x 60s subs at ISO800 before it went behind a tree. I stacked these with DSS, along with subs from 2 nights imaging earlier in the year, followed by a bit of processing in photoshop. The image is made up of a total of 66 x 30s subs, 49 x 45s subs and 27 x 60s subs with darks and bias frames taken on each night. I think ISO was 800 on each night. After Orion went behind the tree I turned my gaze to M81/M82 Bodes Nebulae and managed 89 x 60s subs. Processing in photoshop was proving a tad difficult due to some vignetting and weird colouration on stretching so I have cropped to show just M82. M42 Orion Nebula - 66 x 30s, 49 x 45s, 27 x 60s at ISO800 M82 Cigar Galaxy - 89 x 60s at ISO800 Hope you like. Clear skies to all. Adam

Welcome and good luck

Thanks, I'll have a look in the manual to see if there's anything about manual sensor clean, I think I did see something in there.

Thanks, I'll have a look for some compressed air and give that a try to remove the dust.

I decided to take a wide(-ish)field shot of the area around Orions Belt the other night using my Canon 2000D at f/5.6 and ISO-800 using the stock 18-55mm lens at 55mm. I took 35 subs at 60s each and stacked in DSS. I'm quite happy with the result, I can clearly see the Great Orion Nebula and if you zoom in a bit can also see NGCs 1973/1975/1977 just above Orion Nebula. If you look close, it looks like I've also captured a tiny bit of light from the Flame Nebula NGC 2024 by Alnitak. The only things I'm not happy about in this image: These black blobs that have been appearing in my images lately, I think these are probably bits of dust on my sensor. Any idea how to check if is indeed dust on the sensor and how I can clean it, or should I take the camera into the shop and get a professional to do it? In the meantime, is there any trick I can do in photoshop to hide/remove these from an otherwise nice image? Stars aren't perfect if you zoom in. Probably due to focusing (really difficult with getting good focus when using the camera lens pointed at a dark sky!) and less than optimal tracking/polar alignment. But not bad if you don't zoom in though, if you ignore the dark blobs caused by the dust! Thanks for looking.

Thanks! Happy birthday to you for Thursday. It looks like I may have a clear sky here tonight, so I may have a practice using the polemaster tonight. I'll check out that EQ6-R thread. Fortunately I have no stairs to go down so taking the mount outside shouldn't be much of a problem for me.