Calculad

Thanks for the useful replies. I'll answer the questions. There is no imaging involved. The photometer counts over 10 sec on the star then 10sec on the sky to subtract. Also on comparison and check stars to get a differential mag. Sounds complicated but it's much less so than CCD IMHO. I'm a bit too old to change to that now. I used to be able to get sufficiently high counts about 7th mag with my old 8" (20cm) Newtonian. The reason for the increased size is to maybe push this a bit fainter. I also wanted a visual instrument for a bit of interest for the grandchildren. So there's a compromise going on here too. I think I need to strap the photometer on one and try it. I have tried to contact amateurs in the Brighton area but had no replies sadly.

I am returning to photometry and my guide requirements are (compared to imaging) pretty low. I have to keep a stellar image inside a 2' graticle for 10 seconds. On my last telescope (8" Newt Refl) I did not need to guide my equatorial mount. Wind was generally my biggest problem. To the question. I am tempted by the Celestron AVX11 telescope and mount: https://www.365astronomy.com/celestron-advanced-vx-11-schmidt-cassegrain-computerised-telescope Most reviewers (astrophotographers) advise that this system is not up to astrophotography. As you can see I think my requirements are less stringent than imaging, but I await any advice offered on this mount. The increased light grasp would help my photon counts. The 11" f10 Celestron would reduce the graticle to just over 1' of arc. Thanks for reading.

Thanks for that. It is indeed the old C8. Unfortunately they had the dovetail clamp on the OTA. I think I'm correct in saying that all the modern stuff seems to have the opposite arrangement with female dovetail clamp on the munt and male dovetail on the OTA.

Identify Parts please. Can anyone identify the black fitting that came with my mount. I think the aluminium male dovetail part bolts onto my Super Polaris mount. I assume the black part connects to a telescope tube but it's not a smooth contour and has a step between the two curve sections.

Thanks for the replies. Useful food for thought.

I am a fairly experienced observer returning to photometry following a long break and house move, and wondered about the Celestron Advanced VX 11. There are previous posts about its unsuitability for astrophotography, but I haven't ever done astrophotography and my Optec SSP3 photometer just requires a light bucket and being able to keep target stars in a fairly large ring for 10 seconds only. I accept the comments about setting up and would aim to get an observatory with permanent set-up. I have a 20cm Newtonian on a non-portable equatorial mount, but quite like the idea of the larger optics and the option to be occasionally portable. Some stars I am interested in are not visible at certain times. Once centered I do have to rotate the flip mirror to allow light onto the detector. It is a very light touch action. I guess the vibration could be an issue. I can't deny the price is attractive but if it can't cope then.... Thanks