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

Guide scope for imaging with a TEC 250 - Focal length 2200mm?

  • Please log in to reply
11 replies to this topic

#1 Trackerthedog

Trackerthedog

    Lift Off

  • -----
  • topic starter
  • Posts: 19
  • Joined: 08 Aug 2019

Posted 21 August 2019 - 08:25 PM

Hi, I will be taking possession of a TEC triplet Apo 250 mm refractor in a year or a year and half's time.

I know that there is a wide range of opinions and solutions regarding guide scope size and f/l but I am looking for

some recommendations. Can anyone recommend: 1. An aperture and focal length for a guide scope, and

2. A good guide camera, that would work with such a long focal length (2200 mm) and with its 250mm aperture?

 

Thank you for any feedback you can give me on this. I asked Yuri Petronin, but he just said that any guide scope

would be good - up to 4". I'm hoping not to have to put a 4" scope on the 10" scope to guide with!! So your

recommendations would be very valuable to me. Thank you for your time and your wisdom.



#2 premk19

premk19

    Viking 1

  • *****
  • Posts: 680
  • Joined: 19 Apr 2015

Posted 21 August 2019 - 08:40 PM

What a scope! Congratulations. Have you considered an off-axis guider? That'd be the best option in my opinion.
  • psandelle likes this

#3 17.5Dob

17.5Dob

    Fly Me to the Moon

  • ****-
  • Posts: 5159
  • Joined: 21 Mar 2013
  • Loc: Colorado,USA

Posted 21 August 2019 - 08:43 PM

OAG


  • psandelle likes this

#4 SXBB

SXBB

    Vostok 1

  • -----
  • Posts: 110
  • Joined: 05 Jul 2015

Posted 21 August 2019 - 08:44 PM

An ONAG is a great option too.


  • psandelle and premk19 like this

#5 bobzeq25

bobzeq25

    Hubble

  • *****
  • Posts: 16784
  • Joined: 27 Oct 2014

Posted 21 August 2019 - 10:18 PM

Depends on the image scale of both systems.  IS is the parameter you want to use.  Pixel size counts here.  If you want to do this, I'd want something like a 290 with 2.9 pixels.

 

Most everyone is OK with a 3X difference in image scale.  Many with 5X.  A few, more.

 

With my 910mm refractor I saw a small increase in guiding quality putting on an OAG, and changing the ratio from 5 to 1.4.


Edited by bobzeq25, 21 August 2019 - 10:20 PM.


#6 Astrola72

Astrola72

    Viking 1

  • *****
  • Posts: 527
  • Joined: 16 Feb 2014
  • Loc: Maryland, USA

Posted 21 August 2019 - 10:28 PM

To guide you must first track. What are you going to mount that beast on?


  • calypsob likes this

#7 Traveler

Traveler

    Gemini

  • *****
  • Posts: 3121
  • Joined: 19 Aug 2007
  • Loc: The Netherlands

Posted 21 August 2019 - 10:34 PM

We are of course always willing to view a picture of your TEC...(hint)



#8 Trackerthedog

Trackerthedog

    Lift Off

  • -----
  • topic starter
  • Posts: 19
  • Joined: 08 Aug 2019

Posted 21 August 2019 - 10:58 PM

HI Astrola 72, the current choices are either a Software Bisque ME ll, an AP 3600 or a 10 Micron GM 300 HPS. 

Yuri - at TEC - says that they returned their ME mount because it didn't handle the TEC, but Wayne Parker at 

SkyShed PodMax (who is supplying the observatory) wants to speak with the guys at Bisque to double check

about the ME ll (as that is the mount that SkyShed usually work with).



#9 Trackerthedog

Trackerthedog

    Lift Off

  • -----
  • topic starter
  • Posts: 19
  • Joined: 08 Aug 2019

Posted 21 August 2019 - 11:09 PM

Hi Bobzeq25, I was looking at a Starlight Express Costar with 5.2 pixels.

But I will take a look at the 290 with its 2.9 pixels.

 

Thank you for your input.



#10 Stelios

Stelios

    Cosmos

  • *****
  • Moderators
  • Posts: 7525
  • Joined: 04 Oct 2003
  • Loc: West Hills, CA

Posted 22 August 2019 - 12:29 AM

Seriously, I can’t imagine why you would *not* use an OAG. You would skip the guidescope choice and the mounting hardware. OAG is a standout, unless you hate round, small stars.


  • Astrola72 likes this

#11 Trackerthedog

Trackerthedog

    Lift Off

  • -----
  • topic starter
  • Posts: 19
  • Joined: 08 Aug 2019

Posted 22 August 2019 - 02:10 AM

Thank you everyone for your input and advice. I will investigate some high quality OAGs and ONAGs.

 

Cheers.


  • psandelle and bobzeq25 like this

#12 Astrola72

Astrola72

    Viking 1

  • *****
  • Posts: 527
  • Joined: 16 Feb 2014
  • Loc: Maryland, USA

Posted 22 August 2019 - 09:24 PM

We are of course always willing to view a picture of your TEC...(hint)

TEC250.jpg

 

(from Baader-Planetarium ad)


Edited by Astrola72, 22 August 2019 - 09:26 PM.

  • psandelle 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