RAC

Well that is very interesting, the color one is horrible to look at compared to the mono one. The color one looks brighter but there is a lot better data in the mono image and way less noise?

Wow looking really nice. I really like the carbon secondary holder, similar to my ones I make. Have you thought about motorizing the scope. I'm doing that atm with my 20" dob. I'm going down the Onstep road as any other option just costs way too much.

I only even removed the IR filter with my 60D and that worked fine but I ended up selling the camera before really using it. The only camera I ever made mono was the 1000d in the first post of this thread.

My 60d had springs.

That mirror looks really nice. Should be good.

Any updates on the mirror?

Good job. Now get out and use it! Good to see someone not killing their camera lol.

It was only the 25 that came with (some of) a curve already in it. Both my 20" and 18" were done by hand just like your one although I do have a powered spinning table and I wouldn't want to make a mirror without it. I really don't want to hog out the 30" by hand as it's going to need an 18mm sagitta! Anyway keep it up as it's awesome viewing with a large mirror you have made yourself !!!!!!!

Yep it's a lot of work. The 25" came to me as an unfinished f5 so I only needed to hog it out a few more mm's to get to f3.8. There is no where here in NZ that can pre generat a mirror sadly. For the 30" I'm going to make something using a grinder to get most of the glass out.

Big good flats are never going to make it into my budget sadly. I have no doubt it's a very good way of making a good mirror but it's not going to happen in my shed The 25" is not for me but the person I have been getting the glass from. He made a deal with me, I make him a fast 25" mirror and he'll give me a 30" blank with a secondary to suit and all the grit needed. The 25 has taken a good amount more time than the my 20" and has been more difficult with every step. I think your man John was interested in buying 2 of these 30" blanks I now have but the cost of getting them over there was too much. I do use the Ronchi test all the time. It's great and has it's uses but it's very easy to do the wrong things with it and it's hard to tell the exact shape of the surface. With a 20" f5 it would be about all you would need but not with these fast mirrors and even then I would use Figure XP. I wouldn't want to be figuring a mirror with the need to transport the mirror a long way just for testing as there is a need to test so often. Setting up a good foucault tester isn't hard when you use a spare focuser. I don't find it too subjective to use because I make a point of never remembering the required numbers for each mask zone, this means my brain will never try and target the right numbers even when they may be off. I must have a bad short term memory.

Please please tell me you are going to use Figure XP. I'm currently figuring a 25" f3.8 and I'm about a 1/4 the way in and with Ronchi only I'm lost so todays plan is to make a mask and start using Figure XP and when I do that I will be unlost and I will know what my next move will need to be.

For grinding and polishing the fixed post method would be the most common but I maybe wrong. It's easy and it works great. If I was to put Damian's mirror as it is on my fixed post machine with a 70ish % sized lap I would say you could have it back in good shape right to the edge in about 3-4ish hours so long as the lap was in good shape and playing the game. When using a fixed post setup the edge never really is a problem if your offset is right, In most cases it will leave a small hill in the middle but normal figuring strokes take care of that anyway. You can cut through a lot of glass with ceruim some weight a good lap and a fixed post grinding machine. Figuring is a little different and requires constant testing nearing the end so most would do this by hand.

I would like to here from anyone how has tried one of these with a fast scope(f3-f4) with a Paracorr.

Yep its a wire spider. I've never used one before so thought I'd better try one.

Yeah I just think the square trusses are more easy to mount and work with. No other reason.