jambouk

Thanks. Do any of these holes need to be tapped or can I just get them drilled and then have nuts underneath? I’ve seen new brake discs of 300mm in diameter online for £25 so may get these and then just paint them in hammerite once drilled. I still worry about the forces between the two discs by the M18 bolts applying too much lateral pressure on them and cracking the discs. James

Would it matter that the outer part of the puck was unsupported? The 8” Altair Astro puck would overhand the raised bit of the disk brake by about an inch all the way around... https://www.altairastro.com/skywatcher-eq8-pier-adapter-cnc-443-p.asp

Thanks. How do I then attach the puck to the top brake disc? [I have in my head how the bottom disc would attach to the pier, probably with M12 threaded bar up through the concrete, and got in my head how the top disc would levitate above the bottom one with five M18 bolts leaving about a 10cm gap between to get my hand in for the mount heads central bolt, but no idea how to attach the EQ8 puck to the top disc.]

They feel like they are cast iron; is that a suitable material? This is why I wish there was an off the shelf option.

My friendly garage had some old disc brakes but they have a gap between the two halves; photo of one disc below. It already has central holes which I could pass threaded bar through from the pier, but then I’d need to drill through the disc itself to pass M18 bolts through to the disc above. Are these suitable?

Following on from two other threads, I seem to have solved in my head my pier issue (pier to live outside so concrete construction). Now I need to solve the pier head issue. I want something like the metalwork shown in this image (taken from Google), not the same, but similar, and to eventually take an EQ8. Is this something I can buy off the shelf to bolt down into threaded bar coming up out of the concrete and then attach an EQ8 puck on the top? Nothing in stock at RVO or FLO, and AA haven't replied to my email, and emails from an astro engineer gone silent. Thanks for any help. James

Planetary is hard. The Canon isn't ideal as the pixels are on the larger side and the video mode compressed the data, and the “shutter speed” is too slow. You also need to ensure collimation and focus are optimal and kit is properly cooled down. Then pick a night when the planet is high and the seeing is good... lots of things against all of us, but on the whole I’d be very happy with this image.

For planetary and lunar you can use PIPP. Can you show two raw images to show how much the target moves?

These lined cardboard moulds seem like a good option for me: https://www.preconproducts.co.uk/products/monotub-dd/cardboard-column-formers James

OK, so I am thinking a 10" diameter pier to ensure there is sufficient concrete around the pole and to really bond it all together with some rebar I'll put down into the slab beneath and into the pole itself coming outwards. What qualities does the 10" diameter pipe need? I was just thinking of waste pipe like this stuff, and leaving it on after the concrete has set. Or are there advantages of taking the pipe off afterwards? Straight pipe of corrugated stuff? The fact I've not seen any corrugated piers would suggest straight pipe... Thanks James

Check to see what mirror lock setting you have. Are you setting the intervalometer to 60 second exposures, or 60 minute exposures? If the camera in in bulb mode, and mirror lock is disabled, the fault lies with the intervalometer / operator I think. James

You need to take flats and accept there will always be some vignetting.

Are you using a 2” or 1.25” nose piece? If the latter use the former; if the former a focal reducer may help, though may introduce other issues. It is a massive sensor so I think you are always going to get some vignetting. Flats will help.

Possibly. I think it would be OK weight wise, but I've no experience of the motors on this mount, and you have a very long focal length and likely a small sensor, and keeping a planet on that sensor is a challenge, even more so if adding in a Barlow or Powermate. So the better the mount and the better the polar alignment, and the better the tracking, the easier your life will be. James

Revised idea for my outdoors pier. There are two options. 1. This plan would be to shorten the existing steel pole which is hollow, and then place a 10-12" pipe around that with the existing pole in the centre, and then fill the hollow pole and the rest of the pipe with new concrete to the desired height, and then set threaded bar into the wet concrete to eventually take a universal pier adapter. But how to best bond the old and new concrete? 2. Find a steel pier which could tolerate living fully outdoors all year round and able to take say an EQ8 and C14. If there was room for the shortened pole to go inside the pier it could, else take the pole off to just below ground level (not easy but do-able). I presume the majority of piers available are meant to live inside observatories, not be fully exposed to the elements all year round. Grateful for any ideas. James

Skipper, thanks. Why do you say avoid expanding (anchor) bolts out of interest? James

Dave, No, I've not done any drawings yet, but I examined the proposed pier today which is made of concrete, and it is much less stable than I had anticipated, so ditching that idea. I think my new idea is to install a custom bought pier onto an existing submerged concrete block. The only issue will be attaching the pier down onto the block, as there are no bolts sticking up from below, so the only option would be to drill into the block and use some dedicated expanding bolts. James

Are there any reliable UK engineers who could make the bottom half of a pier adapter for me, as I can source the upper plate to adjoin the mount. Non-standard pier. Or has anyone ever used an online CNC company, and if so with what results? Thanks James

You need a tracking mount if you are using an 8” SCT for planetary imaging else you will spend 99.9% of your imaging time trying to get the planet on the sensor of the camera.

Do piers like this one on the Widescreen Centre website have a solid plate at the bottom or is there a hole? https://www.widescreen-centre.co.uk/AA-PIER-32.html There is an existing metal pole anchored into a submerged concrete block, and I wonder if a pier like this could be slotted over the pole and concrete poured inside the pier to bond it to metal pole. The pole is probably 6” in diameter and at least 1.5m high but could be shortened. What do you think?

500 rule is a starting point, but it is not an abolute guarentee. I would conduct your own experiements with the kit you have at difference places in the night sky (due eat, due west, due north, due south, near the NCP and at the zenith). James

Lots of potential causes. I wonder if the most likely cause is that the Moon wasn’t in the fielD of view of the eyepiece when focusing. Use the lowest power eyepiece first. Test it out in the day time on a distant terrestrial object to ensure you can actually achieve focus.

What do you want to put on the mount and what do you want to do with it? I would seriously consider buying second hand as you’ll get more for your buck.

Yes, very nice. Well done.

We are not saying you can’t use an Ha filter with a OSC camera, just making you aware of some of the limitations. Very few things are black and white in astronomy.