Packing the backfocus on a Tak FSQ

pmrid (Peter) · #1 09-02-2013, 06:35 PM

All Tak owners will identify with the maze of threads and adapters you need to attach anything to these scopes. I've just managed - after a couple of months of messing about and getting all the bits and pieces together - to get my BabyQ (FSQ85EDX) set up with the Tak .73 reducer and a FLI PDF focuser. It was a tight squeeze to get these items to fit in with the SX OAG/FW and ATIK CCD I have for it. In the end the only way I could get the lot to come to focus was by removing the camera rotator cuff thing (the adapter that replaced the old Capstain Wheel).

I have the PDF first followed by the reducer and then the OAG/FW/CCD. That allows me to maintain exact backfocus between the reducer and the sensor at 72.2mm. All this required a bucket of cash to have the right adapters tooled up by Ashley Stevens. By the time I actually got this scope fit for duty as a widefield imager, it has cost me an arm and a leg.

So what happens - cloud and rain - that's what. One more new moon of total overcast to add to an already very long list.

Still, it's done. And perhaps by winter - just maybe - we'll have enough sky to work with. Dream on!!

Peter

RickS (Rick) · #2 09-02-2013, 09:04 PM

It's fun isn't it, Peter! I'm glad to hear you got it all sorted out and look forward to some images from the combination. You must have a focal length not much over 300mm. Are you using a big sensor as well? Should be a nice big FOV...

I have a collection of adapters shipping from Precise Parts on Monday. Hopefully, everything I will need for a while.

Cheers,
Rick.

LewisM · #3 09-02-2013, 10:26 PM

This issue is the only negative thing I have to say about Takahashi. I thought Vixen was a pain until I got a Tak. What a royal PITA! The FS60 for example has a whopping 2 inches of drawtube travel. It's usually an IN-FOCUS distance issue, not usually back focus. GRRRRRRR.

Vixen, thankfully, is simpler, and cheaper. If I use the focal reducer, no need for any extensions. If I don't, yeah, I need a spacer.

I understand the Japanese modular idea, but their exclusivity of thread sizes etc is frustratingly annoying! Vixen is 60mm, Tak is 56mm which you step up to 57mm, then step down and....ARRRRRRRRRRRRGGGGGGGGGGGGHHH HHHH

RobF (Rob) · #4 09-02-2013, 11:39 PM

Shame there isn't some sort of software simulator for the adaptors. Nothing worse than waiting ages for an adaptor then finding you've "missed it by that much".....

pmrid (Peter) · #5 10-02-2013, 11:15 AM

Quote:

Originally Posted by RickS

Are you using a big sensor as well? Should be a nice big FOV...

Sadly, no. I have exhausted my astro budget until I sell something. So I'm using a 4MP 15x15mm sensor'd ATIK LE4000 (the same as the SXVR_H16). But the FOV is still pretty good at 158x158 arc minutes. That's about 7 square degrees. If I want to go wider, I'll have to learn to do mosaics.

Of course a nice big U16 or similar would be great. But alas, that is unlikely to happen.

Peter

RickS (Rick) · #6 10-02-2013, 03:13 PM

Quote:

Originally Posted by pmrid

Sadly, no. I have exhausted my astro budget until I sell something. So I'm using a 4MP 15x15mm sensor'd ATIK LE4000 (the same as the SXVR_H16). But the FOV is still pretty good at 158x158 arc minutes. That's about 7 square degrees. If I want to go wider, I'll have to learn to do mosaics.

Of course a nice big U16 or similar would be great. But alas, that is unlikely to happen.

Peter

Commiserations from a fellow gear addict

Still, I'm sure the ATIK will be capable of some fine images and 158x158 arc mins is not to be sneezed at!

Cheers,
Rick.

Logieberra (Logan) · #7 16-02-2013, 10:25 AM

Sorry to hear of the troubles Peter. The simplest connection for Taks, in my experience, is from Tak CA35 (camera adaptor) - unique for each scope, to Tak wide T-mount to SLR. Otherwise, metal back distance gets darn complicated! Rick, good call on Precise Parts, great for those fiddly in-between adapters. P. Tan is also real good and cheapish