4 replies to this topic

[Darth]

Hi folks, newbie here trying to theorize (and learn) a possible imaging setup, before I make purchases. Wondering if my calculations / options below seem sane to the experienced folks? Haven't yet completely decided on a main camera, but might just start off with one of the Sony IMX571 ones. I have never done back focus calculations before, and based on a few other threads I came up with the following.

 

This will be for a TEC 140FL on a AP Mach 2 mount.

 

• Controlling Hub
  • Pegasus Astro Ultimate Powerbox v2
• Focus motor
  • ThirdLynx QuickSync FTX40
  • Consumes 1 USB2 port and 1 DC port of UPBv2, attached to the TEC 3.5" focuser
• Guide Camera
  • QHY5III462C
  • Consumes 1 USB3 port of UPBv2, attached to Optec Sagitta OAG
• Image train
  • TEC 3.5" Focuser
  • AP S35RFAA Adapter
  • AP QuadTCC
    • Back-focus remaining 99.1mm
  • AP EXT327-18.3
    • Back-focus remaining 99.1 - 18.3 = 80.8
  • Optec Sagitta OAG
    • Back-focus remaining 80.8 - 31.7 = 49.1
    • Controlled by UPBv2 focus motor output via RJ45 and not by FocusLynx controller
  • QHY CFW3L
    • Back-focus remaining 49.1 - 21.5 = 27.6
    • RJ11 to the QHY camera
  • LRGBHaO3S2 Filters
    • Back-focus remaining 27.6 + 01.0 = 28.6 (adding 1/3 assuming 3mm thickness?)
    • 2" Filters threaded mount (or should I be looking at 50mm unmounted?)
  • QHY268PH
    • Back-focus remaining 28.6 - 12.5 = 16.1
    • Consumes 1 USB3 port and 1 DC port of UPBv2)

I haven't yet done a deep dive into the connecting thread patterns and assume adapters will be needed between some of those. So, if I didn't botch the calculations, I will need to add stuff to consume 16.1mm? Other than the adapters needed between them, should I be getting rid of the AP EXT327-18.3 and instead just getting one whole longer spacer, assuming adapters haven't already eaten up the space already? I think I also read in some thread that when getting stuff from precise parts, one should always get few mm short and then fill in with stuff like spacer rings?

 

Any alternative suggestions welcome for devices too.

 

Thanks much!

 

x-posted here on tec forums

[scadvice]

Thoughts:

 

The Optic Sagitta is a very nice OAG. However, unless your planning on remote imaging... IMO... the focus motor really is not needed.  Once you focus to match the image camera (which can be done by hand) your not going to hardly use it. Plus, if you find you do want it later it can be added on. 

 

I also suggest, if the budget can handle it, looking into Innovations Foresight's ONAG XM system.  It has auto guiding and continuous real time auto-focusing. 

 

Look at tilt adjusters like the Gerd he Neumann.

 

What software are you going to use?

[bobzeq25]

Get a mono camera for guiding, it's seriously better, particularly with an OAG.  The 290 and the 174 are excellent choices.

 

A 2" mounted filter is plenty large enough for a 571, and easier to handle with the frame.

 

Check with TEC for the recommendations for a reducer/flattener, you're generally best off with one matched to your specific scope.

 

The reason to go short with spacers and add rings is that reducer/flatteners often work best with a slight tweak to the spacing.

 

If when starting off you have a distinct sensation of having jumped into a very deep pool without knowing how to swim, consider getting a smaller scope (80 F4.8, reduced?) to learn the ropes with.  You will not believe how much easier it makes learning DSO AP.  The first night with my Stellarvue 70 I was practically giggling due to how easy it was.   When you're starting out, an easy setup is a very good thing.  Among many things the smaller scope makes issues far easier to diagnose.

 

There will be issues.  <smile>

 

Make it one of these, and it will be your "big target" scope, forever.  There are a lot of big targets.

 

https://www.skywatch...t-apo-refractor

 

https://www.stellarv...po-svx080t-3sv/

 

You didn't mention software.  It's half the game.  For starting out SharpCap Pro is good data acquisition software.  For data processing Astro Pixel Processor.  PixInsight is "the best" but learning PI increases your startup workload too much, it will be big enough already.  Time spent with APP is not wasted if you later move to PI, much learning will transfer.  Think of APP as PI Lite.

 

This will be the best $35 you ever spend in DSO AP.

 

https://www.amazon.c...d/dp/0999470949

Edited by bobzeq25, 03 July 2022 - 01:10 AM.

[Darth]

Software wise I have been looking at NINA lately, have it already setup with APCC Pro / AP Ascom V2 driver. Its running on a mini PC that I remote in. And then was thinking of using Stellarium for planetarium and PHD2 for auto-guiding. All based on videos / articles I have been seeing for NINA. 

[bobzeq25]

Software wise I have been looking at NINA lately, have it already setup with APCC Pro / AP Ascom V2 driver. Its running on a mini PC that I remote in. And then was thinking of using Stellarium for planetarium and PHD2 for auto-guiding. All based on videos / articles I have been seeing for NINA. 

NINA is a good choice, many people really like it.