almcl

I had the same problem - washed out images because of light pollution - and opted for a City Lights Suppression (CLS) filter. The one one chosen was the Astronomik clip in variety. Eventually this was joined by 7 nm H alpha and Oiii filters. You may see quite a bit of advice against using narrow band filters with a DSLR, but I was happy with the results. While the CLS filter made imaging DSOs possible, it was quite hard/impossible to get an accurate colour representation. Fortunately we switched from Sodium street lights to LEDs a little while back and I switched from DSLR to dedicated Astro (OSC) camera. This set up doesn't seem half so badly affected by the LEDs as the DSLR was with the Sodium lights. Here's an example of DSLR narrow band (Ha + Oiii) image combined with an unfiltered star field:

I think it's in part down to the capture software: my version of APT writes the gain into the header, but not the offset, while ASI Image writes the header in a different order but does include both Gain and Offset. Afraid I don't know enough about Sequence Generator Pro (assuming that's what you use?) to say if this can be edited ?

From your description it sounds as though your mount isn't tracking. In your first screen shot above it appears tracking is 'off '. Also, when tracking a star the RA and Dec values should not be changing. Unfortunately, I am not familiar with your software or mount so can't tell you how to switch tracking on after your set up proceedures but at 300 mm focal length your target should stay in view for hours, not seconds,

No, no! It's your image just very lightly processed in StarTools - you've done much better than you thought!

Agree with Carole, 22 sec exposures with an unmodded camera on a target like the Rosette is going to be tricky. The good news is that you have got it, image below is just cropped and wiped and then given a gentle stretch:

Hi Martin, Thanks for the kind comments. Yes, this 190 MN came with a dual speed focuser. The only kind thing to say about it was that it had lots of travel. Unfortunately it had single point compression rings for securing eyepiece/T-adapter and extension draw tube and even when these were tightened with pliers, there was an enormous amount of slop in the system. Added to this the focus lock screw introduced even more tilt and the weight of an OAG plus ASI 2600 MC hanging off all of this did not make for happy imaging. The Moonlight has improved this by an order of magnitude.

Using the V2 Ha data and processed in StarTools 1.7.485, layering the Ha data into the LRGB image after separate processing.

Sorry, should have put some details in the original post. This was using the SW 190 MN with the ASI 2600MC , 42 x 180 sec lights offset 50, gain 100, -10°C 30 flats 30 dark flats 30 bias (don't understand why, but these are necessary to mitigate the over-correction of the flats) Approx 40% crop

Managed to grab a couple of hours with the newly fitted Moonlight focuser, which has made a huge difference to the stability of the imaging train and somewhat reduced the tilt. So here is M81. Still got problems with flats overcorrecting and not sure about the colours, but was quite surprised at the detail. Comments and suggestions most welcome.

A lens clamp might be the first step. Depending on the length of lens you are using, that may be all that's needed. For my 200 mm Canon lens I found I needed two clamps. The guidescope and guidecam were clamped next to it on an aluminium plate but you can buy dedicated platforms with all manner of holes for scope rings and such. Pictures and other suggestions in the thread here:

Try it during day time. Being careful to *only* have the guide camera connected, and no other image capture software running. You should only need a very short exposure to get a white screen but with a suitably short exposure it should be possible to get an out-of-focus image of a distant object if the ASI 120 is connected to the uncapped guide scope. Does this work? If not then what camera does Sharpcap report is connected? And have you got the latest ZWO drivers installed? (I use Sharpcap 2.9 as it was free and only needed for polar align so if you're using one of the later versions, I may not be much more help.)

To answer the first post point, if you are imaging with a reflector (of any sort) the guidescope mounting isn't the only source of flex. The mirror mounting can and does move as the mount and scope's orientation change and a heavy camera load hanging off of a Skywatcher focuser can also shift position. The shift to an OAG improved my imaging quite a bit. Stars were much rounder and I no longer got the image drifting steadily across the frame during the session. There's a thread here which describes a similar issue: and Oddsocks answer halfway down the page in this one was revealing:

Looks as if it could be differential flexure between guidescope and main scope? And, yes, until I switched to an OAG, I used to get something similar.

I think the answer to your question is 'yes'. If you place the flat frames in the tab (I assume you used the different tabs for the differing exposures?) with just the lights and darks for that exposure, they should only be applied to that set of lights. You don't say what camera you are using, but mixing different ISO and exposure lengths in the same stack can be problematic - no harm in experimenting though to see what works best, but you might want to try stacking the various different exposures separately to see the results?

I imaged for quite a while with my EQ5 and SW200p. I initially added the Skywatcher motors (the mount was purely manual to start with) but ditched those in favour of stepper motors and an AstroEQ. This gave horizon to horizon slewing in under a minute and guided at just over 1" oscillation. I still use the EQ5 when imaging with a 200 mm canon lens as its performance is more than adequate, it weighs a good deal less than my AZEQ6 and takes only a few moments to set up. I don't think Tom Carpenter (AstroEQ's inventor) is selling ready made units at the moment, but although my soldering skills are nothing special, I found building my own was not too great a challenge. Another advantage of the AstroEQ is that it runs at a nominal 12 volts which is easier to supply than the 6 volts that the Skywatcher kit motors required.

Can't give an identical comparison, but I recently acquired a ASI 2600 MC to replace my cooled Canon 700d. I wasn't brave enough to insert cold fingers into the camera, so its cooling merely reduced the EXIF reported temperature by about 10 or 12 º C. The few results the weather has allowed with the 2600 suggest that it's quite a marked improvement over the DSLR. Cooling set to -10ºC , no misting. No amp glow (my Canon suffered really badly from this), very low noise, lighter weight on the focuser. There were software problems initially; APT wouldn't download the image files, but a new driver from ZWO and updates from Ivo fixed that, I need a replacement focuser for the MN190, because although the 2600 is lighter than my Canon+cooler, the weight is further out and causes tilt. The weather has also been awful and getting 20 lights on a target has been all but impossible so I can't post any comparable before and after shots, but a couple of early attempts are here: My previous DSLR images with these targets were with a different scope, but were nothing like as good. But then the processing software has changed, too.

Yes, my thought being that it accounts for seeing differences in setting min move.

One recommendation (which may or may not help) is to nudge the mount north with the controller before running the calibration. But I find the GA a bit variable on backlash: some nights it's 'guide in one direction...', others it's backlash compensation of 2000ms +' and others it's 'Backlash is small...'. I've never figured out a reason and the mount usually hasn't changed apart from being dragged in and out of the shed, of course.

Hard to tell from a screen shot (at least that's what the developers over on the PHD2 group say) but did you do a guiding assistant run? It's always worth doing one at the start and accepting its recommendations. It appears that your oscillations are down around small fractions of a pixel, so assuming that all the figures were correct when you ran the 'New Profile wizard' that's probably close to the limit of what you can expect. I wouldn't sweat the PA too much, within 5 arc minutes is said to be fine and any Dec drift will be easily guided out. If you want an expert opinion, load up the log files to the PHD server as per the help instructions and post the log ref on the PHD2 board https://groups.google.com/g/open-phd-guiding One of the devs there will give chapter and verse.

Glad you got there! Afraid I only have an ASI120 mm so my settings probably aren't very relevant but I *think* the ASI driver when you first connect PHD2 (assuming that's what you're using) will offer a choice of highest dynamic range, lowest noise or unity gain and will select appropriate offset and gain for which ever of these is selected.

No, the camera sensor needs to be (approximately) where the first lens in the eyepiece was before it was removed. So loose the big extension as a first step, then screw the locking ring at the objective end further down the barrel and try screwing the objective further in. The moon is up now so you could try focussing on that?

Thank you, Olly. Here's a stack (from ASTAP which doesn't use Bias/Offset) where bias files were used instead of the Dark Flats (hopefully not quite so black clipped - min pixel value is ~4): Whatever the cause, it seems that both DSS and ASTAP need the Offset/Bias files on this occasion, which goes against much of what I have read for the ASI 2600 MC. Downloading files from the 2600 has proved 'interesting' and generated a fair amount of activity both on the ASI site and the APT forum.

Oh the frustration! Last night was the first clear night for 10 days, so I set out to do some simple imaging and to try out my new-to-me-home-made-cardboard+sealingwax EL flats panel. Weather was actually better than forecast so after taking nearly 90 minutes to get focussed and on target, I settled down to a run of 30 x 90 sec lights. For a change, the guiding on the AZEQ6 was reporting sub 0.5" oscillation (hooray!) We got to the end of the first run with no major drama so I set about a further 30. Halfway through this I discovered, while looking at the images in DSS, that somehow the focus had slipped and we had stars with holes in the middle. Stopped the run, slewed to a nearby bright star and reapplied the Bahtinov. Slewed back to target (no easy job as CduC and APT had suddenly decided that they wouldn't both use J2000, grrh!) and started the run again. At the end of what should have been the 90th light, the dew shield was removed and the flat panel was applied. 30 flats and 30 dark flats followed and then all was packed away. This morning armed with only the last 30 (in focus) lights, 30 flats and 30 dark flats, it was time to post process. Calamity, the first stretch of the stacked image revealed the most horrific vignetting: Tried stacking in ASTAP, results much the same - the flats are over correcting, but why? Delving into the forums here, I saw a recommendation to use bias frames if this happens. I had some and so tried a stack with flats, dark flats and bias and lo and behold the vignetting vanished! So I now have a 45 minute image (below) but it could have been so much better with 3 times the data. Holmberg IX would show up better and HIP48635 A + B might be resolvable (they are on the indidual subs), but when will the next opportunity be, I wonder? Rant over.

Processed in StarTools 1.7.455 with some messing about in Photopaint afterwards...

StarTools (you can download a fully functioning version that does everything but save here to see if you like it) doesn't work in quite the same way as other post processing software. I used four separate modules to emphasize the galaxy: Autodev, HDR, Life and Superstructure. ST replaces levels and curves with mathematical functions to avoid loosing data such as the faint outer edges of the galaxy while avoiding star bloat. Its creator, Ivo Jager, @jager945 posts here and may give a much better explanation of the philosophy and function.