July 23, 2025

Canon RF 70-200mm F2.8 L IS USM & Canon EOS RP


The Canon RF 70-200mm F2.8 zoom telephoto lens has a full-frame FOV range:
    (70mm)   28.8 ° x 19.5 °
    (200mm) 10.3 ° x 6.7 °
A Canon EOS RP in 27.1MP 6240x4160p full frame sensor mode was used in fully manual mode. The photos below were all shot at maximum zoom f=200mm and are single-frame short guided exposures with a minimal Skywatcher AZ-GTi tracker at Carleton Place ON Canada, a Bortle 4.5 location. This tracker with the default alt-az setup and payload capacity of 5kg is perfect for basic star-field exposures up to ~ 20 sec with minimal field-rotation effects, however for photos close to the E or W sky and not too high in altitude, alt-az guided exposure times considerably longer are possible with minimal star trailing at the edges of the FOV. The EOS RP camera weighs 0.48kg and the zoom lens with vixen mount adapter shown is 1.40kg for a total weight ~ 1.9kg. For astro photos, prime lenses are best in terms of image sharpness across the entire FOV but I wanted the zoom capability for several other uses (nearby nature photography) so this being my single Canon lens, the focal range, speed, size, weight and quality is perfect. The image quality is surprisingly good with some small star shape distortion and slight chromatic aberration at field edges, which I find quite acceptable. Click each image for the full-resolution image view (sized to the browser window) and zoomed in images. Some images are Stellarium Mobile Pro screen shots roughly matching the photo displayed just before.



(1) Ring Nebula M57 Lyra   f/3.5 15sec ISO-1600 July 1, 11:28pm
(2) Dumbbell Nebula M27 Vulpecula   f/3.5 20sec ISO-1600 July 1, 11:20pm
(3) Albireo Double Star Cygnus   f/3.5 15sec ISO-1600 July 1, 11:25pm
(4) Andromeda Galaxy M31   f/2.8 20sec ISO-1000 July 22, 3:35am
(5) Hercules Cluster M13   f/3.5 30sec ISO-1600 July 21, 11:41pm
(6) Ring Nebula M57 Lyra   f/3.5 30sec ISO-1000 July 22, 2:52am
(7) Whirlpool Galaxy M51   f/3.5 30sec ISO-12500 July 22, 12:01am
All times are EDT 2025 Carleton Place ON Canada