Andy56

HI, I did the calculation on a spread sheet and did not copy them over correctly. Apologies. Should have been 67.7 - 44 - 9.77 - 0.3 = 13.63mm I've set the flattener to 13.63mm (or as near as I could get it using the marking on the flattener. So I checked the focus train and found the camera to t-ring was not good. I have wedged a single sheet of paper between the T-ring adapter and the camera at the bottom so it effectively lifting the back of the camera. I've also made sure the balance and focus were correct and I have achieved this : which to me is much better. (CR2 file below). The only elongation I'm getting now is along the RA travel b ecause my Star Adventurer has significant periodic error. I took someone suggestion and left the adventurer on to 48hrs at x12. The results are better but it could also be better balancing. So when the WO t-ring adapter arrives I'm hoping I won't need the paper. Also its good seeing tonight with the breeze. Kind regards Andy L_3545_ISO800_60s__17C.CR2

Andy: On finding my T-ring is loose I've ordered the WO version. Alan: Thanks for the info. I couldn't work out whether the diagram was correct because it didn't seem to be for the adjustable version. Also I wasn't sure if it was A or B. So with a 1mm filter (my T-ring adaptor is 9.77 Astro Essentials): 44 - 9.77 - 0.3 = 13.63mm I haven't started on the Star Adventurer yet. I rejected 50% of 60sec subs the other night. I made a video of all the subs and it has periodic error. Not sure how much the guider will compensate for, when I can mount it sensibly. But lets get the telescope fixed first. Regards and thanks Andy

Hi, I've just set the rig up and noticed that there is slack between the t-ring adaptor and the camera flange. All other joints/couplings seem OK. If it clears up soon I'll try a piece of paper in the bottom and to and see if the results change. If this fixes the problems I'll try the WO version it's £7 more. It's supposed to be clear from about 8 onwards but there will be a breeze. Regards Andy

HI, Another question. The WO AF61A is adjustable but on their web page they say adjust it to 12.9mm. This assumes a lot ie the T ring adapter will compensate for all flange distances/cameras. Also the diagrams are for the non-adjustable one. So how is the calculation done? I remember reading about it some time ago but I can't find it now. Kind regards Andy

Hi Alan, Many thanks for you great reply. Now that you've pointed it out, the stars in the bottom left are in focus and top left not so. Also it's more noticeable on the brighter stars at the top. I will take a photo of my set up each time now so I can relate focus to orientation. I've now check older images with camera lenses and they don't seen to show this as the mechanical coupling is much tighter. I'll set it up today and check for sloppiness. I took another look at the flattener and, oops, I forgot about the locking ring (newbie). It is set at approx. 13mm (I struggled to release the locking ring and the adjuster moved a little). I do note that the adjuster is quit sloppy before locking. I can't find any sloppiness in the rotator on it's own but I'll set it up and try it then. Now I have to wait for some clear skies to test it again. I guess pointing it vertical will remove focuser flop so that's worth a try. I'll check for sloppiness and post some more images when I get another chance i.e. a few minutes of clear skies. Now to sorting the periodic error. Many thanks Andy PS the Optolong CLS filter is 1mm so the 0.3mm of correction for me.

Hi All, I have a new WO ZS61 II with the WO Flattener ZS61A. This is mounted on a Star Adventurer. I'm using a un-modded Canon 600D at ISO800, 60secs, with an Optolong CLS filter. I look over the glorious lights of Newbury. I had about 50% rejects but I think this is periodic error. Also have the Skywatcher 9x50 with the ZWO 120MM for guiding but I did not know how to use it properly and the balance was poor so I took it off. I'm going to mount it on the counter weight bar when an adapter arrives. I took some images of M42 for test purposes and also it's quite beautiful and easy to find. Now the imaged seem to show some optical distortion (for the sake of a more precise word) which I thought I would not see with the WO telescope. The WO flattener is set to 5mm which I believe to be correct from other posts. In the image below the stars at the top middle seem to be elongated but at the bottom they are not. This concerns me because I would have expected the stars to be elongated in the corners if the flattener was not set correctly. Also I had some issues focussing using the Bahtinhov mask and ended up using the live view on the camera so it could be a focus issue as well Any thoughts or am I being to fussy. Regards Andy

Brilliant. I don't know if I would have the courage to mod my 600d yet. May be I could buy a faulty camera first. Do you have any before and after shot. I guess it may be too early to have any. I'm going to try the polyurethane box with Peltier first. I'll build this before the summer come around. Cheers Andy

Hi Spaced Out, I have no problems if you can improve my photos, it shows me what can be done. I can give you the subs if you like. It will show me what can be done with an expert on the job and give me hope. I know there's a lot te learn. Currently I use DSS, Sequator and Gimp. I have no access to Adobe products except Photoshop Elements 2020. I have taken some more shots over the last weekend at F8 with an Optolong CLS filter. I took the time to ensure the focus gave the least colour on the stars at F3.5 and then stopped down. The problem I have with these images is that the moon and the light pollution (LED lights) bleached out everything beyond my ability to recover the details. I have taken flats as well to remove some of the vignetting. The ZO 61 plus flattener arrives today. I'll be using this asap but of course there won't be any clear nights for ages now even as the moon wanes. Regards Andy

Hi, Peter Drew: Sorry I think you are correct. lukebl: Yes I understand. I'll still spend some time checking out the SES-4 thought. https://in-the-sky.org/ is a good site and I did not know of it's existence till today. Cheers Andy

Update: I've ordered a WO61 + fittings, OVL flattener and guide scope from FLO. 'Scope's in stock but there be a wait for the rest. Alicante: Tried the Zeiss at f8, much better on the colour but still more coma than I would like. Cheers Andy

Hi, Peter: If it were geostationary, would it not be stationary. Festoon: Thanks for the link. I've given my location in my profile, it's Newbury, Berks. Seems that SES-4 would have been to far east to have been it. I look in more detail later. Many thanks all, Andy

Hi All, I hope this is the right place to pose this question. I'm just starting in astrophotography and tonight I've captured a relatively slow moving object in Orion. It took approx 24 minutes to pass so I don't think it was an artificial satellite but possibly a minor planet or similar. How can I find this out ie where would I find tables etc. I'm not familiar enough in the world of astronomy to know where to start. These are a couple of the subs, the first taken at 20:44 and the second at 20:57 Any thoughts gratefully received. Best regards Andy

LeeHore7 and Callisto: Many thanks to your comments and complements. I do like the pics overall but the coma a CA put me off. Clarkey: Thanks for the heads up on the finder/guider bundle that should allow longer exposure if my skies allow it. Mind you lockdown eases I can get up to the hills where it's much darker. The Lazy Astronomer: I may get an L1 filter if I have issues. Looking at other's example I may not need it. Alicante: It may be a poor lens because as I remember the East German lenses could be a little unpredictable. I had a Zenith once which gave excellent pictures. In terms of focus the Pentax lenses are on a PK mount adaptor and at their focus limit. The Carl Zeiss can go just beyond infinity. I'll try it at F5, I had a CLS filter in at the time. I have other Pentax lenses eg 35mm, 50mm and these show coma on two cameras so at the moment I'm not to impressed with the old lenses I have. Your experience gives me hope. Stopping down the Pentax 210mm zoom from F4 to F8 made a considerable difference to the CA but still loads of coma. Regarding using old lenses I'd rather buy something with new technology now, while I have the cash, so I can get started without to much disappointment . This will also give me a longer focal length which I'm after. From this and further reading I think the WOZ61 is the best option being a doublet of FPL53 (at least one element) and lighter and possibly get the finder/guider bundle and while I'm waiting for these I'll try some more with the lenses I have, weather permitting. Kind regards Andy

Hi, I've just got back into astronomy in practical way. I was fortunate to get a Star Adventurer as a retirement present some 5 months ago. Up to now I've been using it with a Cannon 600D an some old Pentax zoom lenses (70's). I also bought a Carl Zeiss Jenna 135mm. Both of these give coma and the infamous purple star bloat. I don't have any modern lenses. I bought the 600D as body only. 15 darks, 42 subs, no light frames, ISO600 F3.5 Carl Zeiss Jenna 135. Bortle 6ish or higher. I've stretched and played with it in Gimp. It looks like it needs some light frames. So I want to upgrade to a small telescope so I don't have to fight lens quality as well as all the other new tasks laid before me when starting with astrophotograhy. My interest is mainly nebula and using Astronomytools around 400mm is what I will need. Looking through this forum I find two candidates William Optics Zenithstar 91 FPL53 and Skywatcher 72ED-pro. These are about the right focal length, f number and weight. The SW is significantly cheaper than the WO, probably a guide scopes worth. Looking through astrobin, both seems to give excellent results but there is no mention of how much processing was used. I realise that some star bloat can be removed by masking. I was leaning towards the Skywatcher but then I've just read this thread that seems to imply the Skywatcher has CA. So after nearly making up my mind all is in doubt. So do you good people have any suggestion as to which to go for and are there any other suggestions? Many thanks Andy.