Gina

No joy with that - the mist has come in so I've packed up for the night. Quite satisfied though - I've got the PA very much better Not sure how long I could expose for without getting oval stars - I only went up to 5m and the movement was a pixel or less. Looks like I won't need guiding with a lens of this FL or shorter. I plan to do some even wider field covering something like 15° x 20° later on with a 55mm f1.8 lens.

Found the galaxy BUT the sky isn't very clear and the moon is giving a strong gradient so RGB imaging is not on. I'll just have a little play with longer exposures and lower gain in Ha 3nm.

I now have the rig pointing towards M31 - except that there's no sign of the galaxy! Anyway, with zoom at 200 in SharpCap showing individual pixels I can see no star movement in five minutes which is an considerable improvement, so it seems the PA is definitely better Best cooling temperature I can get is around -20°C so long subs at high gain are not on but I could reduce the gain. Anyway, I'm doing what I said - M31. When I find it

Adjusted both axes and onto the fine adjustment. But I couldn't quite get the red and green circles exactly lined up. As I got nearer and nearer I got to a point where the green circle started dancing all over the place. I noticed that this corresponded to Polaris moving out of the green square. Both axes needed altering to perform this alignment, particularly the Azimuth. I just hope I've got the PA right and not totally undone the PA I got from AstroTortilla a couple of years ago!!. I guess an imaging run will tell me!

Clear enough for a run - this shows the misalignment.

Hmmm... waiting...

Clearing now

Cloud beginning to break up.

Sky around Polaris cleared for a few minutes and I was able to run PoleMaster for the first run. The PA looks well out! Now the clouds are back

After umpteen attempts to install the PoleMaster driver I finally have it working Now I just want the clouds to go away. I have the Allen screws loosened ready to adjust the mount PA - the elevation locking wheels are still tight but they are handwheels so I can easily undo or tighten these in the dark. I shall be interested to see how far my PA is out The other thing I want to do tonight is RGB on M31 when it's high enough. Really must try not to do too much or I'll only get confused It's very warm again so I won't be able to get the imaging camera cool enough for short, high gain subs.

Installed PoleMaster driver and software on my observatory laptop in the hope of some clear sky tonight to check and correct my PA.

I've ordered an OAG from ebay purporting to have an optical length of just 10mm. This may work with the EFW2 for use with the Esprit. I still prefer an OAG if possible. I've also been thinking about the ZWO filter wheel with the possibility of taking the Astrodon filters out of their carriers and mounting them with the M2 screws and washers provided, as unmounted filters. I think I will be returning the SX EFW+OAG as I don't think I can use it.

My last post leads on to another thought. I could use the triple scope rig mounting plate and put the WF rig where the second ST80 was then I could use the remaining ST80 for guiding. This idea is fine while I'm using the EQ8. That would give me medium FOV and wide FOV in one setup. For smaller DSOs I would remove that rig and replace it with the MN190 scope with OAG.

I've been looking further into using the Atik EFW2 plus OAG (FLO model) on the Esprit field flattener and I think I might be able to make it work. The EFW2 has a rotating camera adapter and I might be able to turn a replacement with a female thread to replace the Atik one with a male thread. That would enable me to use the 1600 camera straight on the FW saving 11mm. The OAG is 18mm long leaving me with 7mm to find. The adapter on the field flattener adds 10mm and I might be able to turn a shorter adapter for the FW. OTOH I'm not sure it's worth it - I could just use a guide scope on a dual mounting. I already have the triple scope rig and could simply use one of the ST80s as guide scope and remove the other. My lathe isn't really up to optical precision turning.

Thanks rich I did look at this idea a while back but not recently - sounds like quite a good idea for this new rig I'll look into it. This one looks a beauty but I'm rather reluctant to buy from the USA. Maybe I don't need that much quality I guess I don't really need a medium format lens, as you say I already have a lot of top quality glass.

I've put the rig back together and back on the EQ8, connected everything up and run all the software to check it all works still - which it does. So I'm all set up for next time we get a hour or so of clear night sky. Focussed on tree on distant hill which gives a good starting point for star focus. Weather forecast looks good for 2am tomorrow morning but I'm not staying up that late just in case they're right!

Thanks for your reply I'm going to have to give all this some more thought. I've put a question on FLO about using Astrodon 5.25" filters in the ZWO filter wheel (in the Q&A section of the ZWO FW page) as they apparently won't fit. Probably get a reply tomorrow. The ZWO filter wheel in small and light and designed specially for the ASI1600 camera - ideal for a lightweight WF imaging rig that could go on a lightweight mount.

Hmm... Things are not looking good. Checked the measurements again and yes, I do need 4mm more back focus from the camera. Also the adjustment for the guide camera is way less than the extra 11mm required. This filter wheel will simply not work with camera lenses, all of which have a back focus of about 45mm. I think there may be another problem too - the rear element of the lens is only 28mm and looks like it will only cover about half of the prism when this is far enough out to clear the camera sensor. So it's looking like an OAG isn't going to be possible with a camera lens after all Not sure yet about the Esprit scope. Drat!! Looks like I shall have to work out how to use another lens for the guide camera and mount it...

I'm doing more measuring... I'm not sure the guide camera can be brought into focus with the camera sensor being 11mm or so nearer with the adjustment available on the guide camera stalk.

I really don't want a separate guide scope! I wonder if the ZWO filter wheel could be modified to get that extra half millimetre room for the filters.

Ah yes - that's it! I guess I should have guessed the delight with the new camera and imaging rig couldn't last - I'm just not that lucky!!!!

The FW problem is my fault I guess - I forgot to check the optical length before I bought it Just checked now and the measurements are there on the web site

Maybe but "I'm depressed" is what I really meant. Or something like that - I forget now - long time ago...

I feel like the robot in HHGTTG now

That's good then You're having more luck than me! Been looking at other filter wheels on FLO's web site. The ZWO one looked just the job at first - very narrow and designed for their 1600 camera meaning that I would have room for the OAG I have. BUT the spec says " Important Note: 1.25" filters require threads shorter than 3mm and the height without threads must be less than 7mm. " The thread length is fine at about 2mm but the height without threads is 7.5mm for the Astrodon filters! So it seems the ZWO filter wheel cannot take Astrodon filters Bummer!! (excuse my "french"!) Really don't know what to do now! I guess email to FLO for suggestions.