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

DSLR And OAG on SW Esprit 120ED

  • Please log in to reply
5 replies to this topic

#1 Elephant42

Elephant42

    Lift Off

  • -----
  • topic starter
  • Posts: 23
  • Joined: 30 Apr 2020
  • Loc: Brisbane, Australia

Posted 28 May 2020 - 02:03 AM

Has anyone managed to do it and keep the required 75mm back focus to the flatener? - If so I 'd love to hear how you did it.

 

TIA...

 



#2 YAOG

YAOG

    Vanguard

  • *****
  • Posts: 2,120
  • Joined: 12 Oct 2015
  • Loc: Southern California

Posted 28 May 2020 - 03:22 AM

Has anyone managed to do it and keep the required 75mm back focus to the flatener? - If so I 'd love to hear how you did it.

 

TIA...

Add 20mm between whatever normal setup you use between the flattener and OAG? This is not rocket science.



#3 Elephant42

Elephant42

    Lift Off

  • -----
  • topic starter
  • Posts: 23
  • Joined: 30 Apr 2020
  • Loc: Brisbane, Australia

Posted 28 May 2020 - 04:04 AM

Add 20mm between whatever normal setup you use between the flattener and OAG? This is not rocket science.

The problem is the other way - I need to _remove_ the width of the OAG from an already fairly small chain of connectors.  There is only 20mm from the flattener to the 48mm T-Ring made up of a spacer ring (~62mm) plus spacer ring to M48 adapter, the T-Ring attaches directly to this.



#4 YAOG

YAOG

    Vanguard

  • *****
  • Posts: 2,120
  • Joined: 12 Oct 2015
  • Loc: Southern California

Posted 28 May 2020 - 02:41 PM

The problem is the other way - I need to _remove_ the width of the OAG from an already fairly small chain of connectors.  There is only 20mm from the flattener to the 48mm T-Ring made up of a spacer ring (~62mm) plus spacer ring to M48 adapter, the T-Ring attaches directly to this.

I'm still not understanding what the issue is to get 75mm from the back of the flattener. With a think OAG all you need to do is add approx. 20mm spacing between the OAG body and flattener. Could you list what items are in the imaging chain? 

 

44mm = DSLR Back focus depth Canon 44mm or Nikon 46.5mm 

 

0.5mm - 10.5mm = T-2 adapter ? Super thin T-2 DSLR adapters allow the OAG to take the space of the common 10mm +/- T-2 adapters

 

9mm - 10.5mm = OAG ? Thickness depending on which thin OAG used - most thin OAG are setup to provide 55mm+/- total to allow use with 55mm backspace flatteners / reducer/flatteners

 

0 = OAG adapter ? 

 

0 = OAG spacers ? 

 

0 = Flattener



#5 Elephant42

Elephant42

    Lift Off

  • -----
  • topic starter
  • Posts: 23
  • Joined: 30 Apr 2020
  • Loc: Brisbane, Australia

Posted 28 May 2020 - 05:21 PM

I'm still not understanding what the issue is to get 75mm from the back of the flattener. With a think OAG all you need to do is add approx. 20mm spacing between the OAG body and flattener. Could you list what items are in the imaging chain? 

 

44mm = DSLR Back focus depth Canon 44mm or Nikon 46.5mm 

 

0.5mm - 10.5mm = T-2 adapter ? Super thin T-2 DSLR adapters allow the OAG to take the space of the common 10mm +/- T-2 adapters

 

9mm - 10.5mm = OAG ? Thickness depending on which thin OAG used - most thin OAG are setup to provide 55mm+/- total to allow use with 55mm backspace flatteners / reducer/flatteners

 

0 = OAG adapter ? 

 

0 = OAG spacers ? 

 

0 = Flattener

As I said in the previous post - using the parts supplied with the scope, there is exactly 20mm made up of two items, a spacer ring and an adapter (3a and 3b in the diag below) between the flattener and the camera T-ring - that's it, that's the only space I have to play with.  The OAG and any required adapters must fit into this 20mm space if I am not to exceed the specified 75mm.  The two attachments from the scope user guide below show the situation in detail.

 

To sum up, I need an OAG that can mate to the flattener (thread unknown but it's approx a 62mm diam male thread) and mate to a standard Nikon T-ring.  The whole thing up to the T-ring must not exceed 20mm.  Part of my problem is not knowing the exact thread spec on the flattener.  I was kinda hoping that someone here had already done it and could just "magic" me up a solution wink.gif

 

ED120_1.jpg

ED120_2.jpg


Edited by Elephant42, 28 May 2020 - 05:22 PM.


#6 YAOG

YAOG

    Vanguard

  • *****
  • Posts: 2,120
  • Joined: 12 Oct 2015
  • Loc: Southern California

Posted 28 May 2020 - 07:09 PM

Elephant42, 

 

So you have a whole 31mm to work with, this should not be an issue, any of the thin OAGs will work for you. Pick one and read the spacing chart and then add the necessary spacers to arrive at 75mm from the flattener to the sensor. 

 

SW Esprit 120 flattener is M62x1 female on the telescope side and M62x1 male thread on the camera side. So what you need is a female M62x1 step down to male M48 for the telescope side of the TSOAG9, there is a zero length M48 T-thread in the TSOAG9 kit for your included SW M48 Nikkor F mount.  

 

So working back from the camera mount to the telescope:

 

46.5mm = Nikon DSLR

10mm  = T-ring 

9mm = TSOGA9 OAG body 

9.5mm = M48 to M62 adapter When you order the TSOAG9 from TS ask them to make you an M62x1 to M48 x 8mm adapter and leave the M48 threads long and also order a M48 jam ring to allow some adjustment

---------------------------------------

75mm = SW120 flattener


  • rgsalinger 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