Ags

Coincidentally I was looking at the same box, should be here in a few days. I am going for a base board with 32 mm holes rather than pluck foam though.

It's not a Cass but it is a Cat.

Nice wooden boxes here! But don't judge a box by its cover... Pretty, pretty... Ugly, ugly...

The C6 spec weight is 4.5 kilos but if you get one it is actually much less. Regarding the UNI extension tube, you won't find it on the web site. They made it just for me. Contact their support team and I am sure they will help you out.

Couple of points in response: I do plan to get a cheap 3-inch apo in the coming months to complete my dual scope rig. It will work as a finder for the C6 and also for admiring the brighter double stars - I agree the C6 does not give as pretty an image of these as a refractor would. Although a 4-inch refractor might do as well on the planets I consciously went for more aperture as I have loads of floaters in my eyes and need to keep the exit pupil well above 1 mm. With the four inch frac, my maximum comfortable magnification would only be 80x. I like playing with imaging and for planetary imaging the C6 definitely beats the 4 inch frac. Also I can do crazy stuff like lucky imaging of galaxies, globs and planetary nebulae with the C6. Lucky imaging likes aperture (more aperture than I have, I know).

I am using a Berlebach report 112 tripod (astro version). It is nice and light and deals with the weight well. It is short so I use a Berlebach Uni 25 cm extension tube. The AZ GTi copes OK with the weigth as it should as I am within the stated limits but I wouldn't like to put much more load on it, and I don't slew at maximum speed to avoid excess torque.

A low-power 32 mm plossl is cheap and worth buying to get the maximum field of view for a 1.25" diagonal. I would look at a 15 mm plossl for higher power. As an alternative to the plossls the next step up would be BST Starguider eyepieces - they show more sky for the same eyepiece focal length. Next one up from that would be the Nirvana 16 mm. https://www.firstlightoptics.com/ovl-eyepieces/ovl-nirvana-es-uwa-82-ultrawide-eyepieces.html That would give 125 magnification and show an area of sky slightly larger than the full moon.

This thread has veered far over to the refractor side of things, which I think is very unfair. My setup (C6, AZ-GTi, ash tripod) can be picked up and carried with with one hand into the garden. There is no way I could do that with a 5-inch apo! I can swap the AZ-GTi for a Castor head, add a refractor alongside and it is still an easy carry. And... with the difference in price between the 5-inch apo and the C6, I can buy a perfectly nice 4-inch apo!

I tested out the adjusted scope tonight. The night was very promising by my Bortle 8 standards - I could see all the stars in the question mark in Leo and I could see two stars in Canes Venatici. I started with Arcturus - I am stunned by how bright first magnitude stars are in the C6. I was pleased to see the star surrounded by several concentric and complete diffraction rings - to my eye collimation was perfect. I zipped over to Izar, and it was much better resolved at 150 magnification than before my collimation tweak. The stars were also nice and round, so overall a much more pleasing image. I also noticed I could use higher magnifications post-collimation without the target stars going dim and soft. I ran through a few globulars - M3, M53 and M13. I did not detect an improvement in M3 compared to my observations pre-collimation. I might have been able to pick out some more of the cluster's stars, but if so that was probably due to the particularly dark skies tonight. But it was my first look at M13 with the C6 and it was phenomenal! So many stars... 😀 I realized earlier tonight that M94 is really close to Cor Caroli so I decided to try and bag M94 (no, not a test of collimation...) It was very awkwardly positioned at the zenith, but I found it eventually (the ST80 and Berlebach Castor make a great combination for scanning a region of sky). I couldn't make out any structure in the C6, but could at least see the bright fuzzy core. I then moved down to the Double Double but my C6 still struggles with this one. In moments of good seeing the pairs are split but it is a struggle - more so than with my 4 inch Maksutov. Maybe I need to wait for this one to get higher and away from the rooftops. A pleasing evening all in all! Hopefully in a few days I can try image Gassendi and see if I can pick out the rilles more successfully with my adjusted telescope.

@vlaiv thanks for that - that was quick work! It makes my current collimation state look "not good". I think however I will leave the scope in this state for a couple of observing sessions to see if I have actually improved the views, and whether I need to go further. I knew my collimation was out because I could see it in the eyepiece - diffraction rings were arcs and seeing blur seemed to spray out to only one side of the star. So I would like to see if that has improved now. Also I would like to try some lunar imaging like the rilles around Gassendi - possibly I will be able to draw out more detail now. I think it might be easy to get caught up in the pursuit of perfect images of Fresnel rings without paying due attention to what the scope is doing in focus 😀... Also I need to wait for a really stable night - tonight's work was done in gusts of wind and drifting cloud, so it was hard to judge what effect I was having. For the finer adjustments I need to wait for much better conditions.

Red face. The central bit was misshapen due to processing error in Autostakkert (missing alignment point). Here is a correct stack.

Yes the central bit is not point-like. I had the scope cooling for three hours outside so no tube currents I expect. I am reprocessing the SER now - I just spotted there was no alignment point on the middle bit.

I dared to take a screwdriver to my SCT tonight. This is the result of my efforts... I think I could still go a bit further, but I think this is a definite improvement.

I can get 99% imaging time utilization efficiency doing lucky imaging, but in processing will discard 50% of the data... If you you have a dual scope rig, can you claim 200% efficiency?

Yes the star was dead center. I couldn't see the issue clearly at the scope, but now I processed the SER file it seems pretty obvious. For my reference, how bad is my collimation currently? @vlaiv's collimation seems perfect!

This is how my collimation of my C6 is right now - I haven't touched the three front screws since it came out of the box. Does it need tweaking?

Aside from collimation, you can try this hack I did with my C6 to get shake-free fine focus. It works really really well. By the way, I don't think Venus is a good test "star" as it is not a point - it is going to mask any asymmetry in the donut. Pick a bright star like Regulus, Arcturus or Polaris instead. I find it easier to examine the donut on my laptop screen using a camera and Sharpcap. Also Sharpcap gives you crosshairs so you can be sure the donut is in the center of the field.

That. Is. Stunning.

In terms of alternatives, I see this is available for 50 euros less than the Skywatcher 72ED currently: https://www.teleskop-express.de/shop/product_info.php/info/p1151_TS-Optics-70-mm-F6-ED-Travel-Refractor-with-modern-2--RAP-Focuser.html Seems to be more travel friendly (retractable dew shield) and offers 81mm of drawtube travel. Also looks nicer to my eyes.

That sounds very good indeed!

I normally run from 11pm to 1am - that's when my neighbour's lights are out.

The 16mm works very well indeed on my cats. It's a lovely eyepiece ergonomically - it shows a huge field but is still small and light. I mostly use it as a finder eyepiece with my ST80, but it offers wonderful lunar views in my C6.

I don't want to get sidetracked by a discussion on the AZ GTi (or indeed astrophotography), but there are plenty of resources online about using the mount for AP, and I have direct experience of doing so myself. Regarding focus travel I believe there was an update to to the 72ED whereby the tube was shortened in more recent models?

I am looking for a step up from my ST80, which serves many functions. With my Herschel wedge and solar continuum filter, it is a solar scope, but I have doubts it can really deliver at magnifications of 100-120x. It works as my EAA scope but stars are of course bloated. It works as a superfinder mounted alongside my C6 on a giro mount, but can't go much beyond that role. It would be nice for the superfinder to be a refractor that can also show doubles as pinpoints with correct colors for example. Not wanting to spend a lot of money, the Evostar 72 seems like the right option. It's about the same aperture as the ST80. It should also be good for DSO photography with my AZ-GTi... What are people's experiences with the scope? Are there any realistic alternatives?

Thanks, my back seems back to normal this morning. Mag 10 is well within my reach - with a smaller scope I've seen moons of Saturn of similar magnitude. 113 seconds of separation sounds about right.