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

Innovations Foresight ONAG-SC - Calculator Spread Sheet

  • Please log in to reply
4 replies to this topic

#1 LaughingBeagles

LaughingBeagles

    Lift Off

  • -----
  • topic starter
  • Posts: 15
  • Joined: 26 Jan 2017
  • Loc: Ocean Reef, Western Australia, Australia.

Posted 15 March 2019 - 03:36 AM

Hi All,

 

I'm researching the idea of going for Innovation Frontier’s ONAG-SC (sensor size is right for my Atik383L+ Mono).  I emailed Gaston Baudat asking out of all the product options which would best suit my imaging train:

Atik 383L+ Mono > EFW2 (loaded with Astrodon 36mm 5nm Ha OIII and SII + LRGB) > Stellarvue 102 FF/FR > Moonlite focuser > Explore Scientific 102mm Carbon Fiber APO

 

My guide scope is the Orian MMAG.

 

Gaston responded by pointing me at his spreadsheet back focus calculator and suggesting I go with a guide scope with large sensor size.

I downloaded the spreadsheet and spent a fair bit of time reading Innovation Frontier’s website to understand what all the acronyms mean and how it all comes together and eventually worked out what figures to plug in where on the spreadsheet.

 

That said, according to my measurements I still don't have enough scope port back focus. 

 

I tried googling what the back focus for my scope is but most folks when asking in forums get "try spacers until it comes into focus," which didn't really help (I was looking for something like “the back focus for an ES102CF is xxx or calculated by xxx”)

 

I measured the distance I wind the Moonlite focuser out to achieve focus in my current config and get 65mm, that's apparently 58.5 or so mm short:

 

2019-03-15-16-16-18.jpg

 

Clearly, something is missing.  Any thoughts?

 

Pete

 

 


Edited by LaughingBeagles, 15 March 2019 - 10:35 PM.


#2 Corsica

Corsica

    Vendor (Innovationsforesight)

  • *****
  • Vendors
  • Posts: 556
  • Joined: 01 Mar 2010
  • Loc: PA - USA

Posted 17 March 2019 - 05:01 PM

Hi All,

 

I'm researching the idea of going for Innovation Frontier’s ONAG-SC (sensor size is right for my Atik383L+ Mono).  I emailed Gaston Baudat asking out of all the product options which would best suit my imaging train:

Atik 383L+ Mono > EFW2 (loaded with Astrodon 36mm 5nm Ha OIII and SII + LRGB) > Stellarvue 102 FF/FR > Moonlite focuser > Explore Scientific 102mm Carbon Fiber APO

 

My guide scope is the Orian MMAG.

 

Gaston responded by pointing me at his spreadsheet back focus calculator and suggesting I go with a guide scope with large sensor size.

I downloaded the spreadsheet and spent a fair bit of time reading Innovation Frontier’s website to understand what all the acronyms mean and how it all comes together and eventually worked out what figures to plug in where on the spreadsheet.

 

That said, according to my measurements I still don't have enough scope port back focus. 

 

I tried googling what the back focus for my scope is but most folks when asking in forums get "try spacers until it comes into focus," which didn't really help (I was looking for something like “the back focus for an ES102CF is xxx or calculated by xxx”)

 

I measured the distance I wind the Moonlite focuser out to achieve focus in my current config and get 65mm, that's apparently 58.5 or so mm short:

 

2019-03-15-16-16-18.jpg

 

Clearly, something is missing.  Any thoughts?

 

Pete

Dear Pete,

 

 

From ES website the ES102 (ED) scope back focus is 165mm at the end of the 2" barrel when the focuser is fully retracted:

 

https://www.explores...4241.1505224853

 

I am not sure whether there is any difference with the ES102CF on this matter.



#3 LaughingBeagles

LaughingBeagles

    Lift Off

  • -----
  • topic starter
  • Posts: 15
  • Joined: 26 Jan 2017
  • Loc: Ocean Reef, Western Australia, Australia.

Posted 18 March 2019 - 06:29 AM

Dear Gaston,

 

I think that should do the trick (and thank you for taking a look at the spreadsheet I emailed to you, very kind of you to assist).  

 

It appears to ensure parfocal between guider and imager, I require a 0.5mm spacer on the imager and I should be good to go.

 

I will email you offline to confirm.

 

Pete



#4 Corsica

Corsica

    Vendor (Innovationsforesight)

  • *****
  • Vendors
  • Posts: 556
  • Joined: 01 Mar 2010
  • Loc: PA - USA

Posted 18 March 2019 - 06:47 AM

Dear Gaston,

 

I think that should do the trick (and thank you for taking a look at the spreadsheet I emailed to you, very kind of you to assist).  

 

It appears to ensure parfocal between guider and imager, I require a 0.5mm spacer on the imager and I should be good to go.

 

I will email you offline to confirm.

 

Pete

Dear Pete,

 

I looked at your spreadsheet. You entered 565mm for the scope back focus I think it should be more like 165mm. Either ways it should work even with 165mm.
 

I would recommend to draw a sketch, at scale, of your new setup with the ONAG.
This is useful for checking all the mechanical clearances.

I do not foreseen any issue yet it is better to be safe than sorry.

 

The 0.5mm long spacer suggested for the ONAG imager port (IP) in front of your FW is for making both cameras (imager and guider) parfocal (coarse adjustment).
However the ONAG integrated helical focuser has a minimum travel of +/-4.5mm therefore there should be no need for any spacer there. This focuser takes care of the fine focus adjustment.


Edited by Corsica, 18 March 2019 - 06:48 AM.


#5 LaughingBeagles

LaughingBeagles

    Lift Off

  • -----
  • topic starter
  • Posts: 15
  • Joined: 26 Jan 2017
  • Loc: Ocean Reef, Western Australia, Australia.

Posted 19 March 2019 - 05:26 AM

Dear Gaston,

 

Your points are well noted.  The only remaining thing was taking the Stellavue 102 x0.8 flattener / reducer into account.  I think the resulting changed focal length will make a difference.  From what I can tell it would be:

 

                               Atik 383L+

                                    ^

                             Filter wheel

                                    ^

Scope > Flattener > ONAG > Oron Guide Camera.

 

I will measure as you suggest.

 

Pete




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