Ronchi tester

[libraryman]

Spured on by a mirror making thread by Glasspusher, i used the w/e to fill my stocking Santa does'nt know my address (all together aaah)

I made myself a Ronchi tester Dont know how to use it yet!!! Te Hee.

DTI i have had for over 20yr's never used it, elastic band from the wife! and an old kitchen shelf.

total cost £00.00

Light source to be fitted yet,but nearly there.

Ray

[Glasspusher]

Thanks for the mention Ray, nice to know folks are finding the thread useful.

John

[libraryman]

It was a really good thread John, i'm sure i am not the only member who found the tutorial uesful

Ray

[Hypernova]

Wow looks light years ahead of what I was working with at OO. Just out of interest where did you source the Ronchi grating eyepiece from?

[Peter Drew]

Someone once showed me a Ronchi grating made from a monochrome slide photo of a 625 line TV screen.

[Merlin66]

There are various sources...FLO and others....I use a 120 l/inch version.

Just google.

[libraryman]

The Ronchi screen was sourced from America, John alias Glasspusher dropped me a link ....http://www.ronchiscreens.com/screens.php

Great company, they even refunded some of the postage!!

Thanks for the comment Tom, OO must have been useing some weired kit if my humble diy tester looks better than theirs, i just cannot get my head around understanding what it's telling me yet.

Ray

[Hypernova]

The Ronchi screen was sourced from America, John alias Glasspusher dropped me a link ....http://www.ronchiscreens.com/screens.php

Great company, they even refunded some of the postage!!

Thanks for the comment Tom, OO must have been useing some weired kit if my humble diy tester looks better than theirs, i just cannot get my head around understanding what it's telling me yet.

Ray

It was pretty basic I can tell you that, as a mirror figurer there for a short while I eventually managed to kind of figure out by the end of my 7 weeks there what the lines meant and what I had to do to correct it on the machines or by hand figuring. The lines say a lot of things, it did throw me at first when I saw that the patterns were reversed either side of focus!

A thanks BTW for the link, I could knock up a small tester to go into the focuser, the 250 line screen would probably be my best bet.

I have always wanted to test the mirrors in my 8" dob but never got the time to take it to OO while I worked there. No intention of going back there so I'd rather do it myself.

[libraryman]

Well Tom if it took you a while to figure out what the lines meant with the skills available to you while you worked there, i wont be too hard on myself!

I spent a good few nights trying to work it out and managed to identify ROC but i was working with a f4.4 mirror and Glasspusher was very helpfull in guiding me along.

I did manage to assert that the lines fitted in quite well with the Ronchi calculator and having now had my mirror tested by OO it appears that it's quite a good mirror; notwithstanding the minor damage it has suffered, but i did not find the testing intuitive, i need to work a little harder at it.

Knife edge focault is another world and i'm not yet into that.

Any ideas where OO source the tubes from?

Ray

[Hypernova]

If you are asking about the OTA tubes then I know that CF tubes for AG and ODK models are sourced from a nearby company that specialises in the carbon fibre. The aluminium tubes for their other models are made on-site from sheet metal using a some kind of roller press.

[libraryman]

Cheers Tom, it was the aliminium tubes i was asking about, need a new one but OO's are quite expensive.

Ray

[Tim]

I have one of the Gerd Neumann Ronchi EP's from FLO, very nice it is too