epsilon owners ? question

graham.hobart (Graham stevens) · #1 26-08-2016, 08:50 AM

Hi
If you have a tak epsilon type astrograph with a corrector lens in the focuser, is the spacing from the lens to sensor critical?
the reason I ask is that on the e180 etc system chart they have a DSLR and CCD both connecting directly via a wide T mount (despite, I would imagine, different sensor back focus).

cheers

Graz

blink138 (Pat) · #2 26-08-2016, 12:58 PM

hi graz simmoW (simon) has an e-130 and has just posted on the astro equipment forum a pic with a new camera and the e130, he may not have seen your post
pat

graham.hobart (Graham stevens) · #3 26-08-2016, 02:30 PM

Hi Pat - thanks for the tip. I can't see it in the first few pages- how far back is it?

RickS (Rick) · #4 26-08-2016, 02:42 PM

Yes, the spacing is critical. The metal back distance for the e180 is 56mm. See the back focus measurement here: http://www.takahashi-europe.com/en/e...ifications.php

Cheers,
Rick.

graham.hobart (Graham stevens) · #5 26-08-2016, 02:57 PM

Cheers Rick.
Looking at the system chart, I can't work out if that implies you need the aux ring and the T mount for cameras or just the wide T mount?
What's a DLSR back focus? 44mm
so I assume the T mount adds another 12mm ?

RickS (Rick) · #6 26-08-2016, 03:34 PM

I expect you'd just want a wide T-mount adapter, Graz. That's what the system chart says (http://www.takahashi-europe.com/en/e...stemcharts.php). The standard T-mount flange focal distance is 55mm.

There's a Tak group on Yahoo if you want an expert opinion...

SimmoW (SIMON) · #7 27-08-2016, 07:44 AM

Hi Graz, sorry for my late reply, I often just rely on my daily notification emails.

As ever, Rick is right. There's a very specific canon bayonet adapter I got from Claude at AEC. Maybe call Claude and tell him I referred you :-)

But for CCD be very careful. I just did my head in with my new setup, the new ASI cam.

Backfocus is 56mm, yes. But with all my contraptions, filter wheel, OAG and custom designed precise parts adapter, I only had 15mm of back focus left. And that's with my cam only having a 6.5mm backfocus itself. I searched heaps but couldn't find any adapters for the cam, as the Tak focus size is unique. So it was rather easy to spec the adapter via precise parts.

Focus zone is even more critical with the f2.8 scope.

Best of luck!