Adreneline

Stu raises an interesting question here which has played on my mind also over recent time. I operate two rigs, (a) a RedCat 51 mounted on a AZEQ6 which is pier mounted and aligned using a PoleMaster and (b) a Samyang 135 mounted on a CEM25-EC which is tripod mounted. I use a PoleMaster with associated QHY software to PA the CEM25 but on occasion I have used (a) SharpCap and (b) the ASIair PA routine. On more than one occasion I have PA'ed the mount using the Polemaster and then checked it out of curiosity with the ASIair. The ASIair reported the PA was well off and needed adjustment which I completed to the point where I got the huge smily face and firework display and was told I was in the top n% of PA results. I felt very chuffed! Re-checking with the PoleMaster it told me my PA was well off the mark. I re-aligned with the PoleMaster and then thought I will check it with SharpCap using the PoleMaster camera. Low and behold SharpCap reported the PA was well off and needed adjustment. I suppose I could spend the entire evening playing PA and chasing my tail. For the sake of getting some imaging done I used the PoleMaster PA camera and associated software. The SharpCap routine works with either the imaging OTA or the PoleMaster camera which is on the mount axis but gives different results to the QHY software and the ASIair. I do not guide the CEM25-EC - using the Samyang 135 there are no discernible star trails. I do guide the AZEQ6 and achieve guiding r.m.s. typically in the range 0.35 to 0.75 dependent on 'seeing'. Just to add I didn't bother getting down on my hands and knees, twisting my neck into an unnatural position, removing my spectacles and looking up the polar-scope with its associated parallax problems. So which to believe? To say "It works" is fine if it does! I don't know whether it does or it doesn't but one thing is clear - all three methods give different results.

Interesting comparison.

Thank you Olly. This was just using the 6D to see what it would give. I went on to combine it with L from a ASI1600MM to produce a finished image hence the finished image being cropped. To my eyes the combination of L from the ASI1600 and osc from the 6D worked okay together. I've since properly collimated the RC so I need to have another go. Thanks again. Adrian

Without - the full 1370 mm - although I think it is a bit less cos' the primary-secondary spacing is not bang on.

This is the full frame before processing (STF screenshot) Dismiss it - make of it what you will - but it never does any harm to stick it on the end of the scope and have a go - irrespective of what the numbers tell you. It's all part of the hobby!

Can't disagree with Vlad but I have "messed around" using my Canon 6D with a GSO 6" and it definitely produces an image even at 1370 mm (no reducer): I know it's a pretty c**p image by the standards of others on this forum but an image it is - of M13. Have a go! Who knows what you might produce?

I've never done an osc mosaic in APP but I have done lots of mono mosaics. I have found using the 'remove light pollution' tool on each pane to be very helpful and then cropping edge effects in PI before going back into APP to assemble the mosaic. I guess you could use ABE/DBE but I find LPC works really well providing you take care to position the five (or more) boxes carefully - pretty much the same with DBE sample points I suppose.

I use a TeleGizmo cover and it seems to work very well keeping the mount dry/cool. I gave up with the draw cord and just use an elasticated tie from Halfords - works a treat. Lurking under the cover is a SW AZ-EQ6 which takes a RedCat which is stored indoors. One day I might like something a little more all-enclosing but for the moment it works just fine. Adrian

I have no experience at all of using Duo Band filters so am far from qualified to help but in the absence of anyone else popping up I'll give you an opinion - for what it is worth - and hope it helps. I used to own an ED80DS and it suffered rather badly from 'blue bloat' - not uncommon with doublets I understand. The optics are not bringing the r, g and b components together to a common focal point which results in the blue filter stars being bloated - and sometimes the red filter star. Mixing red with blue gives magenta - to my eyes a bad thing! I am very anti-magenta in images but that really is just me - lots of folk like it. Anyway, I digress. I found the inclusion of a UV/IR cut filter on the end of the reducer/flattener helped quite a bit, especially at the red end of the spectrum. Quite how all this equate, if it even does, to the use of a Dual-Band filter I am not sure. In narrow band imaging you can get the same effect with the SHO palette where the S (very much in the red part of the spectrum) and the O (lurking between green and blue) get similarly bloated and produce magenta. The same happens with HOO in my experience. Make of all that what you may! It may be of help and it may be a complete red-herring. Hopefully someone who knows what they are talking about will now hopefully pop up and help you and correct me. Adrian P.S. Nice image, by the way, of a very challenging target.

Great work Lee. Love the Skull and the centre of the Little Rosette - that little burst of blue. Looks like you've got the spacing close to spot on judging by the star shapes; it is so worth the time spent, effort and perseverance to get it right. Adrian

I am pleased to have been able to help. I think it looks great - I love seeing these targets in context and the 'dusty stuff' looks really good - it enhances the Iris and doesn't detract from the star of the show. Adrian

I used SCNR to remove green. I then inverted the image and used SCNR again to remove magenta - which has the side effect of improving the blue. I then used HistogramStretch to align the red, green and blue histograms; because this was a .jpg and I guess resampled using HT introduced artefacts but gave a better overall colour balance - to my eyes. I also used HT to pull the black-point in a little but no where near the point where any clipping was starting to take place; if I'd gone any further dark stuff would have started to disappear. I then used the DarkStructureEnhance script in PI to lift the dark stuff - it had a very small effect as it turns out. I didn't do any additional stretching or any colour saturation or enhancement - no Curves of anything else - very little really. Hope this helps. Adrian

Nothing to criticise here - I think it's very good indeed - I love the framing, the dusty stuff and the understated colour. That said I think it has a little more to offer but this is a very personal thing so feel free to ignore Adrian

Wow! What a difference! Looks great - you are onto a winning formula and if it works for you stick with it. I also use MLT-NR on my images with an inverted L mask but dialled back a little to (3.0,0.5,3 : 2.0,0.5,2 : 1.0,0.5,2 : 0.5,1,0.5 ) on the first four of five layers. Look forward to seeing more images from your setup.

You should be delighted with that image. I love the subdued colours and the framing with the Little Rosette is perfect - you've managed to achieve some real depth in the centre of NGC7822. I took a look close up and be careful with the noise reduction - it is introducing some unwanted artefacts. What method did you use to reduce noise? This sort of thing call also arise with star removal. I know you/I shouldn't pixel peep so hope you don't mind the comment. Adrian

I was only looking at this the other day and thinking should I give it a go. Thank you Steve for an informative and open-minded appraisal/first impression; refreshing to read such a thing. Adrian

Thank you - I'm glad you like it. Adrian

Thank you Jody. I am going to have a go with creating the mosaic in PixInsight and see if that can deal with the curvature. Cepheus is such a rich region and not just with the popular targets. Adrian

Thank you Robin, and also for the tips re. PixInsight. I think I need to get the co-ordinates method tried out on my 40 panes; obtaining the centre coordinates for each pane is no big deal as I have them already from the Telescopious planner. Adrian

Thank you Lee - and thank you for your feedback and advice throughout the journey. I started this in August and didn't expect to get enough clear skies to complete the Ha this early. I am hopeful I will get the OIII but that said clear, moonless nights are rare in the UK. Glad you like the star filled version. It is frustrating that the star shape in each individual pane is near perfect but the mosaic has regions where things are clearly amiss. I've tried everything I can think of to overcome the problem but all it seems to do is move the problem somewhere else! Hence the feeling this has to do with curvature. "Well, it's been 5 years in the making but..." - what a difference a pier makes!!! Best £500 I ever spent - get one!!! 😉 🤣 Adrian

Compared with APP I am inclined to agree - "painful". Again I did look briefly at PI the other night but then my brain stalled and I thought I need to look when I am more awake! As mentioned above APP works perfectly on small mosaics but I am pushing the limits here - a 20 degree f.o.v. is a bit extreme. I mentioned 1.06 GBytes above and that is the file size with individual panes down-sized by a factor of two!. APP is doing an amazing job - no doubt in my mind. That said I will try PI when my brain is fully awake! Many thanks for your advice and suggestions. Adrian

Spooky. I was out on my daily walk today and thought - I wonder if ICE might sort this. Thanks Vlad. I was determined to use APP as it is such a great piece of software but I think I am pushing the limits of what it can handle. All of my 2x2 and 3x3 sub-panes are stitched perfectly but as soon as I compile the whole things it starts to struggle. If I assemble the bottom half it works fine but as soon as I join the top half it starts to show signs of 'distress'. I feel it pain! It's the same if I do left vs. right. I will experiment and see how I get on. Thanks for the help/advice/suggestions - much appreciated. Adrian

Hi Everyone, For better or worse I have achieved the nonsensical 40 pane target I set myself totalling 41 hours and 9 minutes of Ha. The object of the exercise was to understand the nebulosity in this region, initially in Ha and hopefully at some stage with OIII and SII, and here it is: I think I am pushing the limits of the software. Astro Pixel Processor has done a greta job, but not a perfect job; the extent of the curvature has presented a real challenge. StarXterminator has removed the stars fairly cleanly and with careful processing I have managed to put them back reasonably well. That said the stars shapes are all over the place. I have tried compiling the mosaic using the individual panes, groups of 2x2 and 3x3 and a mixture of all three. The result presented below is the best I can get in terms of star shape; there are clearly some distorted stars. The distortion across this f.o.v. produced all manner of problems when trying to plate solve and it is clear the solving is a bit off in parts of the image - again I suspect due to the curvature. To put this into context the f.o.v. is approximately 20 degrees by 16 degrees - or ~40 Moon diameters by ~32 Moon diameters. It is what it is! I am either pushing the limits of the software or I have exceeded my own limits in terms of processing, etc. I was hoping to get all of NGC 7822 and Sh2-129 but as it is the compiled mosaic is 1.06 GBytes in size and my MacBook Pro has to take a deep breath every time I as it do something with only 16 GBytes of memory. I hope this is of interest/use to someone who may be imaging this area as part of the current SGL Challenge. If anyone has any experience of processing very large mosaics like this and knows how to counter curvature, distortion, etc. I am open to all advice and suggestions. Thank you for looking. Adrian P.S. I am going to point the trusty RedCat at something else for a while before I consider going after the OIII and SII.

You must be delighted with this image Jody. Sh2-129 is a really tough target and you’ve done an excellent job of revealing the elusive Squid. Very impressive stars too. Don’t you just love a RedCat + ASI1600 combination. I wouldn’t swap mine for anything. Adrian.

I have a tripod mounted (portable) CEM25-EC which I have used unguided with Samyang 135 and RedCat 51 with exposure up to 300 s with no problems at all. I have also used it with an RC 6" unguided up to 180 s, no problems at all, although that is getting well on to the stated weight limit for the mount and needs careful balancing. I have a pier mounted AZEQ6 where guiding is necessary and I happily work with that, but I love the unguided simplicity of the CEM25-EC and have no regrets with my purchase. I have tried guiding the CEM25-EC using an ASIair but to no advantage - certainly not up to 300s. A good PA and you are good to go!