JUXT Astronomy Guild Evening
2022-11-04

rig

My Telescope

STellamira 90mm APO

Basics

• f-ratio = focal length / aperture

ME and mY f-ratio

• My telescope ( the SM90 ): 540mm / 90mm = f/6
   
• But, I use a Focal Reducer..
   
• Increases FoV (field of view), and brings the focal length down to 0.8x, which is f/4.8.

THE JUXT scope

• Celestron 8se
• Aperture 200mm (8 inches)
• Focal Length 2032mm
• Focal Ratio f/10

BIG lesson #1

• High f-ratios = very hard.
   

• Each step up, requires 2x the amount of time to gather photons.
   
• Images will take 2x the time to make for each step up!

F-ratio guide

• f/2 - insanely quick

• f/3 - quick

• f/4 - f/6 normal (ME NOW & SWEET SPOT FOR BEGINNERS)

• f/7 - getting serious

• f/8 - getting very serious

• f/9 - scary

• f/10 - JUXTScope & the limit of what I will eventually try

Short vs long focal lengths

Short focal lengths, let's call wide-field instead. Use for wider, bigger objects in the sky: Nebulae & near by galaxies

Longer focal lengths, use for smaller objects in the sky: Galaxies

Lets go to astronomy.tools.com

BIG LESSON #2

• Bigger isn't always better
• Start Astrophotography with a wide-field refractor
• Loads of beautiful targets = AWE
• Less imaging acquisition time needed = FUN
• Guiding - MUCH - easier at lower f-ratios = EASE
• Quality imaging scopes cheaper = EXPENSE

Telescope types

Reflectors

Sky-Watcher Explorer 130P-DS

Reflectors

Dobsonian

RASA

Trevor @ astrobackyard youtube

Big lesson #3:

prioritise the MOUNT

• Mine: CGEM2
• Equitorial vs AZ
• Mount is where the $$$ goes
• More $$$ = better guiding,
  more weight capacity

Hardware:

harmonic drive MOUNT

• Rainbow Astro rst-300
• ZWO AM5

Hardware:

premium mounts

• 1100GTO German Equatorial Mount
• Why?

Hardware:

mount showdown

Big lesson #4:

choose osc

• Mine: zwoAsi2600MC
• OSC = one shot colour
• NOT MONO!

OSC bayer matrix

Mono filter wheel

• Expensive (filters, EFW,
• More work! Calibration steps for each filter
• OSC produces amazing images, and processing capability to make better

big learning #5 - asiair is a gamechanger

Asiair awesomeness

• With a dash of evil

Big learning #6

• YouTube is addictive

youtubers:

lazy geek

youtubers:

Trevor - astro backyard

youtubers:

dylan o donnell - star stuff

Big learning #

• Keep a journal, for me Asciidoc

Over to Asciidoctor...

Resources

• Adam Block PixInsight Tutorial
• astrobin.com
• clearoutside.com
• astronomy.tools

Thank you and ask me anything