Stub Mandrel

That's useful to know, doubling the thickness will make them four times stiffer and I'd like to go with curved ones.

This is a big project! I was generously given a 6" mirror and secondary of some age. I had the main mirror recoated but the secondary is fine. I'm making them into a newtonian, using as much 3D printing as possible, although I have a vintage r&p focuser I want to use. The tube is an 8" diameter PVC ventilation duct that I split and reduced to 7" diameter with a reinforcing strap along the joint. Prototype reinforcing rings on the ends added lots of rigidity, but I realised that I coudl incorporate these into the mirror cell and secondary support. Here are my designs for the mirror cell and secondary supports. Annoyingly my 3D rpinter hasn't got enough Y-travel to allow me to print the full diameter, although the bed is big enough. I've ordered the ground rod, allthread and timing belt to let me add an extra ~50mm of travel. This will give me a bed large enough that I can print tube rings which will complete the stiffening of the tube. My one concern is that the 1.2mm thick spider may not be wide enough, although I printed a 0.8mm thick lens hood for a webcam which suggsts it will be strong enough, the question is will it be stiff enough? I can always make it thicker or straight. Note nut pocket for M5 collimation screw. The cover for the end tube includes a light tight baffled vent, ideal for 3D printing! The mirror cell clips into the mirror without obscuring any of the silvered surface, however I will be using adhesive as well, just in case. My printer has enough area to make the cell, a lovely job in Monoprice PLA Plus, totally unretouched straight off the printer 🙂

I got Juno last night, confusing at first as it wasn't exactly where Stellarium said it should be... You can see the prominent asterism like an 'L' on its back, with Juno to the right - with a 1/4 magnitude of the corner star. It took me far to long to figure out the missing asteroid was the extra star between the two in the horizontal arm of the L in my pic: I've done a few asteroids now, I should do more, they are fun to track down. (I have a strange idea of fun...)

Astra image would work wonders on that nice image.

Perhaps we don't smell as good 😞

I've been filling in the gaps in my photos of Messier Objects, mostly galaxies. Many of them are delightful objects, especially compared to those dull-as-dishwater (in isolation) elliptical galaxies in Markarian's Chain whose delight solely comes from how they are arranged. All of these are LRGB images, about half an hour of luminance and 6-15 minutes for each of RGB, aside from M40 which is only about 10 minutes of L and a few minutes for each of RGB. First M40, which is just two stars that happen to be lined up, but nearby two pretty little galaxies you can't help wishing Messier spotted. Next M94, the Croc's Eye, a galaxy so outrageously dressed up in concentric rings it's like a cake. This one would benefit from much more exposure time. M99 is far less neat and tidy, flinging arms in all directions like a miniature M101 justifying the name of 'Coma Pinwheel'. M102 is so small that you wonder how Messier spotted it, it doesn't even appear on Wikipedia's map of Messier Objects! One name is 'cat scratch galaxy' look closely and you'll see why. M104 is a more popular target, the Sombrero Galaxy, but a challenge for me as it floats through light pollution. M109 is really pretty, but for some reason it doesn't get a popular name.

You could try the banding reduction action here (comes with many other useful routines). https://www.prodigitalsoftware.com/AstronomyToolsActions.html I had a go on a screen grab, made it better but didn't completely remove it. Best other options are temperature matched darks (warm, cool, cold night darks should be OK) or a cooled camera. Plus flats and darkening the background will help a lot by making them less prominent.

Incoming googly... @Whistlin Bob gets really great results with a 200P-DS on a HEQ5, although he does benefit from the shelter of a shed with fold back roof and has the belt drive conversion. I've been using my 150PL (1200mm f/l) on my HEQ5 for the last few weeks, no belt drive, just well set up gears - judge results for yourself:

Take a look here: New Style Reticle for PolarFinder ... Might help.

No... read my post very slowly and carefully! 🙂

Sorry the sentence got changed a few times and drifted in its content... What I really want to know is - who is it who needs a case for their wooden eyepieces?

I see LOTS of home made tooling. In the UK people love iron castings, and if not fabricate from steel. Americans use aluminium alloys for almost everything. We tend to look for function before form and see ornate decoration of practical objects as pretentious which is not to criticise. As an example I've seen excellent tooling where every surface is hand scraped, a great demonstration of skill but many would consider it a waste of time. Yet as FLO say, there are plenty of UK people who will pay several times over the odds to buy something functionally identical but in red with a made in Italy sticker...

Can you post some example images?

I put a layer of ceramic thermal wadding under my bed and it heats up nearly twice as fast. Just lying a sheet of A4 on top speeds it up even more, but make sure you don't leave it in place... in the long term I might make a full enclosure. I'm printing the first prototype mirror holder for a mirror cell, using Monoprice PLA+ which is printing beautifully, no change to settings. To print the other parts of the cell I need to extend my Y travel 35mm to use the whole of my bed, so I've ordered a couple of 8mm rods and some M10 studding. Just realised I need a longer toothed belt 😞

Wow, that truly proves aperture is king!

Forgot to post the final version of this one. Please with the detail.

If I owned that table, I'd have to paint the underside greeny-grey-blue and mount a waterline model of a ship on top!

Last night I was imaging with a 150PL (which is similar weight to the C8 because of the long tube), ASI1600, filter wheel plus a DSLR on a ball mount with a double battery pack on the counterweight bar. Focal length is 'only' 1200mm but my imaging scale is 0.64" so I think yours might be a bit smaller than 0.56"? Anyroad up... that's on an HEQ5 and my guiding tops out at 0.59" when the seeing is good and the wind isn't gusty, but to be honest I get tight, round stars and lots of detail. The EQ6 achieves similar accuracy, but it can take a greater payload so my thought is either HEQ5 or EQ6R will handle the C8. The EQ6 has teh potential to take much bigger scopes but will be better in a wind as well I suspect. I think you would have to go to an EQ8 or similar to do better.

I see stop signs, not pictures...

Who needs the postman when you can collect everything you need yourself?

I threatened to go back and get more data. This is about 1 3/4 hours of L and almost as much one each of RG & B. Was a pig to get the colour balance right as there was a lot of blue in the background sky and od pattern noise in the L background that only appeared when I stacked both night's data .

Gradient Exterminator is well worth getting, but if you have Pixinsight, I'm pretty sure 'dynamic background extraction' does the same thing.

A possibility, but there may be too much variation in the bore of the weights as tehy are uaually pretty crude castings, plus I'm wary of relying on the bush alone to secure larger weights.

New flats 🙂

I could post the right-way-up version but I don't want to waste storage SGL space!