GraemeH

Wow - that sings from my screen.

I use the Celestron OAG with my Edge 8 - it's a chunky piece of kit and does take up a lot of backfocus, but gives me the advantage of being able to attach a 1.25" 0.5 reducer to my guide camera (QHY5Lii) to widen the FOV for finding guide stars. The downside is that if you're using the reducer, this OAG takes up too much backfocus to attach a DSLR (OK for cameras with shorter backfocus distances though - I don't think you said what your imaging camera is).

I believe you can install 32 bit Windows in a Virtual Machine inside your 64 bit Windows computer. I can't give you any pointers on this as I don't fully understand how it works myself, but what I do know is that the Virtual Machine behaves like a completely separate computer so you would need to install all programs that you want to use with the camera again inside the Virtual Machine, even if you already have them installed in the main computer.

It's a while since I've used my 350d, but I think this sounds like the behaviour I remember when I tried to connect it to a 64 bit Windows system. Are you definitely using a 32 bit system?

One other thing to point out (assuming you're using it via a Windows computer) is that you must use a 32 bit Windows OS - there are no 64 bit drivers for the 350d, and it simply will not work with any application in a Windows 64 bit environment.

I followed a similar workflow to @tooth_dr but with only 2 different stretches layered. I'll try to summarise as best I can, but I can't actually remember every step. Convert to 16 bit using Exposure and Gamma Use levels on the individual colour channels to line up the histogram peaks (your blue channel seemed to be clipped at the bottom end) Stretch with curves as far as possible without losing the trapezium Make a copy, then stretch one of them further to bring out more of the nebula Put the less stretched version as a layer on top, and use the more stretched version (gaussian blurred by 5 pixels) as a mask Convert to Lab colour space and stretch the a and b channels to boost the colour Convert back to RGB and recheck the histogram, using levels again to line up the peaks Try to deal with the vignetting using Astro Flat Pro plugin Clean the dust spots using Content Aware Spot Healing Brush 2 cycles of star reduction using Noel's actions 2 cycles of space noise reduction using Noel's actions I'm sure I've missed some steps, but this is an idea of what I did. Graeme

Thank you for sharing your stacked data - when the weather doesn't allow for collecting new data, it's fun to do some processing. I've played around in Photoshop with your stacked image and come up with this - I hope you like it - I'm still very much a novice at this. Graeme

The reason it works is based on 3D geometry. If you platesolve images which are separated by a move of the mount's RA axis only (i.e. no move in Dec between images), you can work out exactly where on the celestial sphere your RA axis is pointing, because it is the centre of rotation between the platesolved images. It works best if you take 3 images because this gives three points to work with and any 3 non-colinear points in space define the circumference of a circle. The centre of that circle gives the pointing coordinates of the mount's RA axis. It can also work with 2 images, because it's a reasonable approximation to use the midpoint of the 2 images as the third point for calculating the circle. I have used this method myself using an Excel spreadsheet to calculate the PAE, and then using APT's GOTO++ function to point to a position offset from a suitable alignment star by the amount of Polar Alignment Error. It is then a matter of adjusting Alt-Az bolts to centre the alignment star. On my last test, this gave me a calculated PAE (using my spreadsheet) of <2 arcminutes. This was confirmed by running the Guiding Assistant in PHD2, which also reported <2 arcminutes error. My reason for developing the spreadsheet for this approach is that I use an OAG on my Edge HD8, and I image with a DSLR. Sharpcap's polar alignment tool needs a larger FOV than I get on my guide camera, and it doesn't work with DSLR live view. I'd be happy to share my spreadsheet if it's of interest to anyone. Graeme

Perhaps strangely, I do think it's a bit noisy but I've convinced myself (maybe incorrectly) that it's the type of noise that just needs more exposure time to control.

I've never tried using darks. I read a few articles when I first started that suggested that darks with DSLRs can do more harm than good and that dithering is better. I've also read than the 6d has very low dark current, so I've never felt motivated to try darks. I guess there's only one way to find out if they really help though... Thank you for the feedback

I have no idea why the spacing is weird, and I can't seem to edit it.

Hoping for some feedback and pointers on my latest capture. I know that more exposure time will help, but I'm interested in thoughts about what's achievable with the equipment I currently have. Happy to share my stacked subs if anyone would like to try processing. Thanks for looking. Graeme Scope: Skywatcher Evostar ED72 Camera: Canon 6d (unmodified) Filter: Baader UHC-S Mount: Celestron Nexstar Evolution (on wedge) Guider: QHY5Lii-c and Skywatcher 9 x 50 finder Frames: 25 x 300", 50 flats, 50 bias Software: APT, CPWI, PHD2, DSS, Photoshop CC

This link explains what to do with the M5 - https://www.dpreview.com/forums/thread/4221308 There might be a similar menu option in the 7Dii.

Might be more to consider than just the specifications. If the 550d has a much lower shutter count for example, that might make it a better choice. I wouldn't like to sway your decision one way or the other, because I have no experience of using the 550d (I do have the 1100d and think it performs quite well).

Can't compare directly, but looking at the details there are 2 main differences. The 550d has slightly smaller pixels (4.3 micron vs 5.2 in the 1100d). Not a huge difference but it might make one a better match for your scope than the other in terms of pixel scale. The 550d also has marginally higher QE (40% vs 36%), but I doubt this will be significant enough to sway the choice.

@rodrigol - apologies for missing your question about using the 0.5 FR with the guidecam and OAG. I have attached a picture of my current setup - it's obviously different from yours because I'm using my OAG with a DSLR and the C8 Edge (which has a shorter backfocus distance from the SCT thread). I have my 0.5 FR screwed to the 1.25" thread at the front of the guide camera, which is then inserted into the helical focuser of the OAG. By using the FR, I had to shorten the distance from the prism to the guide camera sensor (without moving the DSLR) to compensate for the reducer - I think it's probably moved in by around 15mm, but I'm not sure of the precise distance. Main point is, the guide camera will need to move closer to the prism to achieve focus with the reducer. Forgive me if this is teaching granny to suck eggs, but the precise amount of reduction depends on the distance between the reducer and the sensor - I took an image with the guide camera and platesolved it to check on the exact reduction. This told me that the effective FL to the guide camera is now 1141mm (my DSLR images report a FL of 2142mm with the C8 Edge - I know this is a bit more than the nominal FL, and I'm not sure why), so the reduction isn't exactly 0.5 but it's pretty close. Hope this helps. Graeme

Wasn't really happy with the first process of this with some obvious black clipping, so I've been trying again. I'd love to hear opinions of whether it's better than the first.

As the title says, this is a widefield image of the full Veil Nebula complex. Scope: Skywatcher Evostar 72ED Mount: Celestron Nexstar Evolution Camera: Canon 6D (unmodified) Filter: Baader UHC-S Guiding: QHY5Lii-C and Skywatcher 9 x 50 finder Frames: 43 x 300" ISO 1600, 50 Flats, 50 Bias Software: APT, CPWI, PHD2, DSS, Photoshop CC, StarNet_Win Feedback and CC is always welcome. Thanks for looking.

Ascompad is one of the optional components of EQMOD. You need to install EQASCOM_V200q_Setup.exe from https://sourceforge.net/projects/eq-mod/files/EQASCOM/

I have no personal experience with this, but reading a bit on the AstroEQ webpage seems to indicate that you need to install EQMOD as well, and link your AstroEQ controller to that. PHD2 will then connnect to EQMOD.

First outing with the scope since March for me on 12 September. Hadn't been expecting to set up, but an unexpected clear sky when darkness fell persuaded me to check that I could still remember how to set up all my gear. Scope: Skywatcher 72ED Mount: Celestron Nexstar Evolution on wedge Camera: Canon 6D Flattener: OVL non-reducing flattener Filter: Baader UHC-S Guiding: QHY5LiiC / Skywatcher 9 x 50 finder Software: CPWI, APT, PHD2, DSS, AstroFlat Pro, Photoshop CC Subs: 41 x 180" ISO1600, no darks flats or bias (will take flats later when I get a chance, and reprocess) It's now almost exactly 2 years since I made my first attempts at deep sky imaging, and although I can see a lot of improvement in my images I still consider myself a beginner so constructive criticism is most welcome, especially anything that helps to improve with the gear I have rather than equipment upgrades.

I'll try to take a more helpful image to show my setup when I'm home later this evening, but for now I can share an older picture that might help a little. Graeme

Don't give up on it - I have the same guide camera (QHY5Liim) working in the Celestron OAG with my Edge HD8. My setup had the camera screwed to a C-T adapter, then a 6mm T spacer (supplied with the OAG) and screwed to the guide turret (I've since modified it using a 1.25" 0.5x reducer screwed to the camera to increase the FOV for guiding, meaning that the camera now pushes further into the guide port to achieve focus). I found the best way to focus everything was to get my main camera (DSLR) focused on a distant roof top using the primary mirror focuser in the scope, then adjust the guide camera focus using the helical focuser on the OAG. Hope you get it working.

Sorry for not being clear - I meant error in star alignment arising from platesolving close to the pole, and nothing to do with polar alignment. If you solve/sync close to the pole, your next Goto could be quite far off.

In common with everyone else who has replied to this, I just do a solve and sync in lieu of star alignment after polar aligning, but I don't think anyone has mentioned that it's definitely a good idea to do this well away from the celestial pole. Plate solving near the pole is likely to give rise to some significant alignment errors, so I generally try to get somewhere with Dec < ~50° for my first solve/sync.