Ontario Telescope Astronomy Journal

Guide scope or off-axis guider: a PHD2 guide graph reporting 0.41 arcsecond RMS beside elongated stars from the same night

Your Guide Graph Is Lying to You

astrophotography Stephen Mallia
Guide scope or off-axis guider: a PHD2 guide graph reporting 0.41 arcsecond RMS beside elongated stars from the same night

Your Guide Graph Is Lying to You

astrophotography Stephen Mallia
V-size Vixen and D-size Losmandy dovetail bar profiles compared to scale, about 44 mm against 75 to 84 mm

D-Size vs V-Size: A Complete Guide to Telescope Dovetail Systems

Stephen Mallia
A 55 mm back focus imaging train: spacer 16.5 mm, filter drawer 21 mm and camera sensor depth 17.5 mm, measured from the rear of the reducer

What Is Back Focus in Astrophotography? Telescope Reducers, Flatteners, and Spacing Explained

Stephen Mallia
Controlling a WandererCover flat panel from ASIAIR by switching the DC port: timing windows and preset brightness steps

Controlling Your WandererCover Flat Panel with ASIAIR

Stephen Mallia
ZWO Duo and Air cameras: the guide sensor sits outside the APS-C sensor, so the telescope needs a larger image circle

ZWO Duo camera's and compatible image circles

APS-C vs full-frame image circle -S. Mallia
Optolong L-eNhance, L-eXtreme, L-Ultimate and L-Quad Enhance filters plotted against the Bortle sky brightness scale

Navigating Optolong Filters: L-eNhance, L-eXtreme, and L-Ultimate for Astrophotography

Best filters for astrophotography -S. Mallia
May 2025 night sky calendar: Mars meets the Beehive, the Eta Aquariid peak, the four moon phases and the dark-sky window

May 2025 The night sky this month. Galaxy season wraps up.

astrophotography - S. Mallia
Ritchey-Chretien, Schmidt-Cassegrain, Newtonian and refractor telescope designs ranked from narrow field to wide field

Choosing the Right Telescope: Understanding RC, SCT, Newtonian, and Refractor Designs for Astrophotography

astrophotography - S. Mallia
Framing the California Nebula: its 2.5 degree long axis inside APS-C fields of view at 300mm and 400mm

Capturing the California Nebula: A Guide for Astrophotographers

asi2600 - S. Mallia
Fifteen autumn astrophotography targets grouped by what each one requires: wide field, long focal length, filters, long exposures, dark skies or tracking

Fall Astrophotography: Unveiling the Hidden Gems

Andromeda - S. Mallia
Pre-dawn summer sky: hopping from Saturn to the Great Square, Fomalhaut, Neptune, Mars, Hamal and Jupiter using fist widths at arm's length

Summer sky objects you don't want to miss!

- S. Mallia
Bahtinov mask focusing: the centre diffraction spike shown offset inside focus, centred at focus, and offset outside focus

The Power of Precision: Bahtinov Focus Masks in Astronomy

bhatinov mask - S. Mallia