Adreneline

I’m a fan of BYEoS and the focus aid is great. Others will advise APT which is much cheaper and more versatile and has a variety of focus aids. I seem to recall that if you go to the BYEoS site it gives you the optimum ISO to use for each Canon camera it supports. Excellent first image though - loads better than my first attempt. Well done! Adrian

Wow! Well that gives a completely different perspective on things. Which bit in particular are we looking at? Very nice stars - the RASA8 appears to be doing a great job for you. Thanks for sharing. Adrian

The situation with PS is now worse for Mac users. I purchased an education licence of PS CS6 Extended for Mac some eight years ago (~£180 instead ~£950); it has been used extensively for regular and astro photography over the years and I've certainly had my monies worth. However, with the introduction of Catalina things have gone pear-shaped. If you upgrade a Mac to Catalina in will advise you that certain pieces of software on your computer will no longer run and will be removed as part of the upgrade process. One of those piece of software is Adobe Photoshop CS6! I contacted Adobe and asked if I could exchange my Mac only licence for a Windows PC licence - response "No". When my 10 year old iMac and 7 year old MBP fail that will be the end of my Photoshop. I absolutely refuse to pay more to Adobe. Adrian

I am sure it is but when you buy a ZWO camera it comes with a whole bag of shim type spacers as well as various metallic spacers with various threads - unlike an Atik camera which in my experience comes with nothing! Adrian

Without my 0.75mm of spacers the 'infinity focus' position was before the 'L' mark and I had significant star shape problems in the extreme corners of the image with very noticeable 'coma' type star shapes in the top right and bottom left of the image. If I add another 0.25mm spacer the focus point moves beyond the 'L' mark. I cannot be certain my current spacing is 'perfect' but the star shapes are acceptable (to me). On modern lenses the lens can be set to focus beyond infinity - although I am not sure exactly what that means. As a final complication the focus point is different for all my filters. Using the ZWO EAF as a reference the focus position varies from 28302 to 28382. Now I've not done the maths to work out exactly how much that has moved the focus ring on the lens but I do know that even at the extremes it still stays within the 'L' so I am happy I've got it about as good as I am likely to get it without becoming obsessively compulsive about it. I hope this helps. Adrian P.S. As a footnote I spent two entire evenings stripping the camera and lens apart and messing around with an array of spacers before I got to where I am now. I'm in no rush to change anything! Good luck!

Hi Carole, I found it very difficult to get a combination of spacers that allowed me to get the 'infinity' focus position in the right place, i.e. within the bounds of the 'L' mark on the lens focus ring. In the end I had to take a 5mm spacer and grind it down using a belt sander (! - nearly ground my fingers away at the same time!) until it was just a shade over 4mm. I had a 3mm ring spacer but that wasn't enough - a 5mm spacer was too much. My experience is that the spacing is super critical. In my current setup I have 0.75mm of spacer between the EFW and the ZWO 16.5mm spacer; if I remove the 0.75mm the focus point is before the 'L' on the focus ring on the lens. I know the quoted spacing is 44mm but my experience with this lens, filter wheels with filters and astro cameras is that 44mm is a good starting point but it will not give an optimum focus position within the 'L' mark. I had exactly the same experience with the 85mm lens that I used to demostrate the effect of gravity!! I also understand there is a tolerance on the 13mm quoted on the camera but I am not confident to quote the figures I have seen. Theory is one thing but as with most things in this game it is careful experimentation that generally gives the best solution - and that coming from a theoretical physicist! I should go wash my mouth out. Adrian

The distance from my Samyang end plate to the camera sensor is 46.25mm and that takes account of the 1.25" Baader filters I use. I currently use the lens with a ASI1600 (6.5mm backfocus) but I have also used it with difficulty with an Atik428ex (13mm backfocus). This site gives some useful info: "So the first thing you need to do is check to see if your lens has an ∞ symbol printed on the barrel. Some lenses actually have an additional marking that tells you how far you need to go backwards after that hard stop in order to focus to infinity. This is typically shaped like a sideways “L.” If you line up the distance indicator (a vertical line) with the infinity sign, you won’t get the correct focus. If, however, you line it up with short vertical part of the “L,” you’ll be focused to infinity. Theoretically. Remember that if you’re off even a little it could mean the difference between tack-sharp stars and pancake shaped stars, so you’ll need to double check using the method below." My lens focusses here:

Looks great and excellent framing. If you're open to suggestions, if you lighten the background a little to R:G:B = 23:23:23 (advice I received on this forum), or thereabouts, even more of the hydrogen and outlaying nebulosity starts to appear and the background sky looks more natural and less clipped. As already suggested incorporating Ha into Red as a lighten layer can produce very pleasing results - worth a shot perhaps. Adrian

Very nice! Looks amazing to my eyes - love the colours - not too overstated. Adrian

Thursday night was quite fruitful in many respects. This is a two pane mosaic of the Rosette and Cone taken with the 135/1600 combo. Lens at f2.4 : camera at gain 139, offset 50, temp -20 degrees. Each pane is Ha, 10 x 180s unguided. Preprocessed and stitched together in APP; background extracted and histogram stretched in PI. Adrian

Exactly why I have gone for the iOptron CEM25-EC + ASIair to use with my Samyang/1600 combo. I can be setup and ready to image in less than 15 minutes and the ASIair plate solving is a godsend when it comes to repeatability to build up an image databases for these feint target. All I need now is the portable 12V supply and I am good to go. Question is which 12V power pack to go for?

That's a good start Sean - definitely something to build on. It is such a difficult target and I too only get a limited window of opportunity as it passes between the neighbours trees and the neighbours roof - my neighbour has got a lot to answer for when it comes to my astroimaging! Thanks for sharing Adrian

Prior to using an ASIair I used a NUC-i3 at an NEQ6 mount with ED80DS for three years running ASCOM, SGPro, CdC, etc and Atik cameras. I chose to hard-wire connect to the house network but wireless worked fine - most of the time! I operated the NUC from a laptop via Windows Remote Desktop without any problems at all. The only reason I stopped was because I moved to a light-weight setup using an iOptron mount, Samyang 135 and ZWO-ASI1600 - hence the move to an ASIair (which is Pi in disguise! - operated from my iPad - and I love it!!!!!). Good luck! The above clip-lid water/moisture resistant box is located next to the mount with usb connections to two cameras, the mount and the focussing unit. The filter wheel plugs into the usb hub on the back of the camera.

Thanks Alan, Aren't they just! I fear another day - 24 hours - might be what is needed! 😂 I first imaged this target in October last year at the end of a session, just to see what was there. I've been trying for months to get more data but the weather has conspired to stop me this year. As it was I had to temporarily relocate the scope to the very bottom of the garden to gain an extra hour before it went behind the house; imaging from the front of the house is a none-starter as we have a street light at the end of the drive! Adrian

Sounds like a plan! Just need another clear night and no moon - we get about one a year Thanks for the advice. Adrian

I started with a 600mm ED80 but rapidly got tired of taking images of tiny galaxies; there was never any prospect of buying a bigger or longer focal length telescope. I can be up and imaging in less than 15 minutes now and packed away in less than five and it's all down to a smaller mount, the 135mm/1600 combo and the wonderful ASIair. I also like to see these nebula in their context and am happy to trade a wider FoV for less detail. Good luck with the Samyang once you get it up and running and I look forward to seeing your images. Adrian

Well it is the top of Orion but I'm afraid I don't understand: Sorry. Adrian

I know I've broken all the rules but this is just a bit of fun lest we get too serious. In my defence I did use the Samyang 135mm. Sh2-264. In theory they are kissing angel fish but they could be kissing gourami fish! In some respects this image could be a metaphor for life. Adrian

I've found this image really difficult to process. This is 20x 180s of Ha and OIII using a Samyang 135mm at f2.4 + ASI1600MM-Pro; gain 139, offset 50 at -20 degrees - unguided. There was virtually no OIII that could reveal. With this target relatively low in the sky over my most light polluted horizon I had real problems removing the gradients. Pre and post processed in PI and finished in PS. There is minimal cropping, just enough to clear edge effects; Bellatrix is just off the bottom right corner of this image. As ever comments on how things could be improved are always welcome. Thanks for looking. Adrian

Hi Graham, I bought the rings from TS Optics in German - they are somewhat overkill but they also make it easy/easier to mount anciliary equipment. I use the ZWO EAF but the ASIair does not support autofocus. I have determined the focus positions for each filter using a Bahtinov mask and I manually change the focus between filter changes. (I have used the autofocus system in SGPro but never successfully - probably due to my ineptness! I have wasted so much time trying to get autofocus to work that in the end I just gave it up as a bad job.) Not that great so far. I initially found it very difficult to focus the mini guidescope/mini 120 combination. I have now achieved an acceptable focus and the guiding system works well in the ASIair. Having said that the iOptron CEM25-EC tracks so well that I don't really need to guide unless I want to dither. It does work well and it is excellent for a light-weight setup. The backfocus on the ASI1600 is 6.5mm. The ZWO EFW is 20mm and I have had to add the 16.5mm ZWO spacer and 0.75mm of spacer rings. I believe the Astojolo M42 replacement end plate adds 3mm. So that gives 40.25 + 6.5 end of lens to sensor. The 'infinity' focus position is as shown at f2.4 : HTH Adrian

Set up to do some imaging last night with varying degress of success. First up was Sh2-264 in Ha and OIII, 60 mins of each before it disappeared behind a neighbouring roof; it is proving really difficult to process. Next was an Ha mosaic from the Rosette to the Cone (10 s 180s on each) which worked surprisingly well but I've done it before. This was a single 60s test shot of the Seagull Nebula IC 2217 - no processing at all - it is a screen grab off my iPad using the ASIair interface. Using the lens at f2.4 with 1.25" Baader filters and ASI1600MM-Pro at gain 139, offset 50 and -20 degrees. What is interesting to me is the the star shapes are pretty good right into the corners (excluding where the neighbour's roof is!). I've rotated the image 90 degrees CCW so (going by my previous stacked images) I would expect to see some significant coma shaped stars in what is now the top left hand corner but in fact they are not too bad. If I have a small amount of corner coma in individual subs does/could stacking exacerbate the problem? The nebula was below 30 degrees and well in the light pollution zone so I am surprised it is visible at all. Thanks for looking. Adrian

You won't regret it Carole - money well spent! Whilst you are on a spending spree I would definitely recommend one of the M42 end plates that are on offer from FLO or Astrojolo - very easy to fit and makes using the lens with astro stuff a lot easier (IMHO). I have also purchased a Hoya Pro UV filter which has helped reduced blue/OIII bloating on stars. Enjoy! Adrian

We can't have this thread languishing on Page 3 so here's an image - not a great or even memorable image by any means but an image taken with a Samyang 135mm combined with a ZWO-ASI1600MM-Pro and ZWO-EFW. I decided that it was time to give my Canon 200mm a rest and reinstate the Samyang back on the mount, this time equipped with the Astrojolo M42 adapter to replace the EoS end plate. It took a bit of experimentation but then I finally found that the M42 adapter + ZWO 16.5mm spacer and 0.75mm of ZWO spacers plus the EFW gave me focus exactly in the middle of the infinity range marker on the lens. Decent targets are now pretty much out of sight from my location so I decided to go for a star test with M67. This is 600s of R, G and B pre-processed in APP and the post processed in PI with both Histogram and Arcsinh stretch. The two images were layer combined in PS followed by a little bit of noise reduction. Since fitting a Hoya UV filter on the lens (and on my Canon) my bloated blue and OIII stars are now largely tempered and the focus positions are very similar for all seven filters. APP reported very similar FWHM on all filters; if anything the red is now bloating. I've cropped off the very edges of the image so there is some coma type star distortion in the corners - best not to zoom in too much! Plate solved and annotated in PI: Thanks for looking. As ever any advice on how to improve are gratefully received. Adrian P.S. A few more images of my current setup showing the spacing and focus arrangements.

I bought one of these two years ago; it runs SGPro, APP, PI, and PS-CS6 faultlessly. It also controls my Intel NUC (running all the same software) via Remote Desktop. At £260 I can't really fault it! OK, the display isn't on a par with my MacBook Pro but everything else is great and you could buy a 4K external monitor and still be quids in. I replaced the DVD caddy with a second SSD caddy off eBay for £8.50 and fitted a 500GB SSD for image storage. Refurbished, recycled, upcycled!

This was taken paired with an ASI1600-Pro which is a fairly large sensor cooled camera. The Samyang 135mm is also an excellent lens but again very much better suited to larger targets, e.g. nebula.