Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Astro-Tech AT72EDII Focuser Drawtube?

  • Please log in to reply
10 replies to this topic

#1 james7ca

james7ca

    Cosmos

  • *****
  • topic starter
  • Posts: 8,235
  • Joined: 21 May 2011
  • Loc: San Diego, CA

Posted 02 January 2019 - 12:59 AM

Anyone who has version two of the AT72ED (with the FPL-53), does the focuser drawtube have any kind of threaded connection? I notice in the pictures that there is a knurled ring (red in color) that sits close to the end of the drawtube that MIGHT be a threaded disconnect for the 2" eyepiece adapter/holder (near to the optical tube in the picture on Astronomics' website). If so, what size thread does that have?

 

I don't know, maybe it is just ornamental or perhaps something to do with the camera rotator?


Edited by james7ca, 02 January 2019 - 01:02 AM.

  • PirateMike likes this

#2 desertlens

desertlens

    Surveyor 1

  • *****
  • Posts: 1,641
  • Joined: 06 Dec 2010
  • Loc: 36°N 105°W

Posted 02 January 2019 - 01:47 AM

M63 female. I exchanged the 3-screw visual back for a WO roto-lock of this size (male). Show below:

 

AT72EDII.jpg


Edited by desertlens, 02 January 2019 - 01:50 AM.

  • Moondust, John O'Grady, james7ca and 1 other like this

#3 james7ca

james7ca

    Cosmos

  • *****
  • topic starter
  • Posts: 8,235
  • Joined: 21 May 2011
  • Loc: San Diego, CA

Posted 02 January 2019 - 02:19 AM

Craig, thanks. I'm surprised they don't mention this in the descriptions for the scope, since it is a very desirable feature.

 

Having said that, looking at your picture I don't see any obvious camera rotator, so is that M63 screw thread how they implemented the camera rotator? That would be a little odd, since a rotator is usually a rotating bearing with a locking screw (maybe the rotator is forward of the focuser, up toward your mounting rings).

 

So, to be clear you need a MALE M63 adapter to mate with the female locking ring on the end of the focuser drawtube? Do you have any idea on how deep or long the threads are on the M63 female coupling ring?


Edited by james7ca, 02 January 2019 - 02:45 AM.


#4 desertlens

desertlens

    Surveyor 1

  • *****
  • Posts: 1,641
  • Joined: 06 Dec 2010
  • Loc: 36°N 105°W

Posted 02 January 2019 - 02:31 AM

You might call Astronomics with your question. I suspect the rotator will mount with the M63 thread an have a separate rotation control. I do no imaging. I was a photographer for 50 years. I'm over it.


  • james7ca likes this

#5 desertlens

desertlens

    Surveyor 1

  • *****
  • Posts: 1,641
  • Joined: 06 Dec 2010
  • Loc: 36°N 105°W

Posted 02 January 2019 - 02:51 AM

James, I remembered seeing this. It should do the trick. You'll need a camera specific t-ring of course.

 

https://agenaastro.c...63-focuser.html


  • james7ca and PirateMike like this

#6 james7ca

james7ca

    Cosmos

  • *****
  • topic starter
  • Posts: 8,235
  • Joined: 21 May 2011
  • Loc: San Diego, CA

Posted 02 January 2019 - 03:32 AM

James, I remembered seeing this. It should do the trick. You'll need a camera specific t-ring of course.

 

https://agenaastro.c...63-focuser.html

Yes, I saw that and it looks really nice (as a camera rotator), but you'd still need something to adapt between the M63 male threads on that rotator to your camera (which for my small CMOS cameras is M42).

 

Without that rotator the following is what I think I would need (M63 male to M48 male):

 

  https://optcorp.com/...-female-adapter

 

With that I could add some M48 extensions and then terminate the adapters with a M48 to M42 adapter.

 

Then, there is also this from WO (M63 male to M48 male with extension, nice but I don't know what the backfocus allowance is on the AT72EDII and 80mm of extension may be too much):

 

  https://agenaastro.c...p-pam63-48.html

 

In all of this, I'm assuming that the focus drawtube on the AT72EDII ends with a FEMALE M63 connection.


Edited by james7ca, 02 January 2019 - 04:30 AM.


#7 desertlens

desertlens

    Surveyor 1

  • *****
  • Posts: 1,641
  • Joined: 06 Dec 2010
  • Loc: 36°N 105°W

Posted 02 January 2019 - 02:33 PM

The WO rotator terminates with a T2 (male), that's M42x.75. I suspect it should thread directly into your cameras as well as provide for T2 extension tubes if needed. I don't see that the M48 step is necessary. Yes, the AT72EDII drawtube ends with a female M63 thread. This thread seems to be common among some 2.5" focusers from AT, WO, SV and probably others. My earlier comments assumed you were using a DSLR of some sort. M42 connection to the camera should make life easier.

 

Edit: Just to be clear, the rotator is M63 on one side and M42 on the other, both male.

 

Edit 2: Oops! Nix this advice. The WO part is not configured the way I thought. My apologies. You might contact Agena for advice on how to proceed.


Edited by desertlens, 02 January 2019 - 04:09 PM.


#8 james7ca

james7ca

    Cosmos

  • *****
  • topic starter
  • Posts: 8,235
  • Joined: 21 May 2011
  • Loc: San Diego, CA

Posted 02 January 2019 - 07:26 PM

The WO rotator terminates with a T2 (male), that's M42x.75. I suspect it should thread directly into your cameras as well as provide for T2 extension tubes if needed. I don't see that the M48 step is necessary. Yes, the AT72EDII drawtube ends with a female M63 thread. This thread seems to be common among some 2.5" focusers from AT, WO, SV and probably others. My earlier comments assumed you were using a DSLR of some sort. M42 connection to the camera should make life easier.

 

Edit: Just to be clear, the rotator is M63 on one side and M42 on the other, both male.

 

Edit 2: Oops! Nix this advice. The WO part is not configured the way I thought. My apologies. You might contact Agena for advice on how to proceed.

Yes, the picture of the WO rotator seems to show the same size threading on both ends, that being M63 (male on the scope side, female on the camera side).

 

Thanks for the continued feedback.


Edited by james7ca, 02 January 2019 - 07:29 PM.


#9 bridgman

bridgman

    Apollo

  • -----
  • Posts: 1,090
  • Joined: 29 Jan 2019
  • Loc: Mosport, ON, Canada

Posted 11 March 2019 - 06:01 PM

Yes, the AT72EDII drawtube ends with a female M63 thread. This thread seems to be common among some 2.5" focusers from AT, WO, SV and probably others.

So here's a dumb question... the Astro-Tech web site says the AT72EDii has a 2" focuser, but if the thread at the end of the drawtube is M63 female that suggests a 2.5" focuser, doesn't it ?

 

My AT72EDii was just ordered so I can't just go measure it yet. It's always hard to tell from photos but at first glance the focuser on the AT72EDII appears to be the same size as the one on a Zenithstar 73 or a TS-optics 72 f/6. This is interesting because it means I might be able to thread a WO Flat73a into the drawtube and have a threaded-all-the-way imaging path rather than using a 2" eyepiece barrel flattener/reducer.

 

Of course *that* would mean that the 42mm EOS adapter I just ordered wouldn't fit any more (the Flat73a has M48 at the back), and the Flat73a is 1:1 rather than 0.8x reduction, but it wouldn't be fun if it was simple, right ?

 

EDIT - I think I'm going to stay with "simple" and find a regular old 2" barrel reducer/flattener.

 

BTW thanks for the tip about the 2" rotolock fitting... that's great to know.


Edited by bridgman, 12 March 2019 - 12:27 AM.


#10 bridgman

bridgman

    Apollo

  • -----
  • Posts: 1,090
  • Joined: 29 Jan 2019
  • Loc: Mosport, ON, Canada

Posted 14 March 2019 - 02:06 PM

My AT72EDII arrived today - looks like the eyepiece end of the rotator has an M54 female thread - so the rotator is M63 on telescope end and M54 on eyepiece holder end.


  • james7ca likes this

#11 bridgman

bridgman

    Apollo

  • -----
  • Posts: 1,090
  • Joined: 29 Jan 2019
  • Loc: Mosport, ON, Canada

Posted 08 April 2020 - 01:27 AM

One more update - the eyepiece end of the rotator is M54x0.75 (learned the hard way) and if you unscrew the small red ring from the larger red ring it exposes an M68x1 thread, which is also a nice bonus. The visual back screws into the M54 thread.

 

So you have at least 3 threads to play with - M63x1 before the rotator, and the above two threads after the rotator.

 

TS sells a rotator + visual back separately which seems very similar and has specs which for the moment appear to match what I have been measuring/testing on the AT72EDII and AT115EDT:

 

https://www.teleskop...M54-and-2-.html

 

I am experimenting with threading 2" reducers/flatteners into an AT72EDII and AT115EDT using the M48x0.75 threads on the front of the 2" nosepieces and (hopefully) using the M48x0.75 threads that some or all of the reducers/flatteners have after you unscrew the nosepiece. 

 

More details (including link to an AT92 sub-thread where a few different people threaded AT2FF's onto their scopes) at the following page.

 

https://www.cloudyni...ii-threads-etc/

 

At the time most of them were using an M63-M48 adapter going in in front of the rotator (which I didn't want to do) but I haven't finished the thread yet.


Edited by bridgman, 08 April 2020 - 01:35 AM.

  • james7ca likes this


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics