T-thread spacers

[MG1]

Hi guys,

Can anyone point me to somewhere to get a t-thread spacer of approx () 12.95mm shoulder to shoulder?

It's needed to get the correct chip to flattener distance, although I'd me interested to know how much it matters if it's not spot on given that canon only state an accuracy of 0.03mm.

maybe it should be 12.5mm to allow for a bit of extra tolerance in making the joints.....am I worrying too much about this?

Alternatively it could be an sct M-sct F spacer of same dim to go in front of filter wheel....?

appreciate your input as ever!

Mike

[Cornelius Varley]

Astro Engineering do a set of three t thread spacers at 6mm 10mm and 15mm.

Check Ian king Imaging under accessories/adapters. Also a few other SCT F/M adapters.

Peter

[skye at night]

Adaptors - Baader T2 Extension Tube

[MG1]

Thanks guys. How critical is it to get the chip distance bang on with a field flattener? My calcs say I need a 12.95 but I could use the baader 7.5 and the AE 6 to get 13.5 which is only .55mm out. I wonder if I could use wet and dry to lap .55mm off, or even take 2.05 off the 15mm....?

Mike

[davew]

Hi Mike,

Here's how you find out

T2 Verlängerung variabel - 12-16mm stufenlos - Teleskop-Express: Astro-Shop + Fotografie + Naturbeobachtung

They may be available over here.

Should sort it.

Dave.

[MG1]

cheers Dave, i've not managed to find them over here yet, but will keep looking and post if i do.

Ta

[skye at night]

it shouldnt be that critical, depending on the system you are using...

focus distance is more important...

i think having the focal reducer nearer the rear cell/primary is better..

You should err on the short side and allow the focuser to 'take up the slack' so-to-speak...

I would buy a 12mm and test...

Steve

[MG1]

I've had a chat with Brian at Astroparts and he's going to knock me one up for around £25. Seems a good chap and hopefully it'll do the job!

Mike

[davew]

That's good news. I have a couple of bits that he's turned and they're very well made. Why didn't I think of him ??

If you can get under 12mm that will give you some room to experiment. I think one of the reasons some people can't get good results with flatenners when others can is mistakes on spacings.

Let us know how you get on.

Dave

[MG1]

will do

thanks guys