The sky brightness has been poor the last couple nights, with a measured value of sqml=19.38 mpsas. There appears to be a very thin cloud or haze layer, but it is clear enough to experiment with some star-cluster photography.
Equipment used: Rokinon 135mm f/2 lens with an Olympus E-M5, and a SkyWatcher SkyMax 102 MCT with a Sony A7iii. Exposures were limited to between 20 and 30 sec because of the sky brightness.
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| M36 (LL) and M38 (UR) in Auriga. Rokinon 135mm + E-M5, 20 sec. |
The Olympus E-M5 is the original version, bought new in 2012, so this is a 14-year-old camera. At the time, this was a game-changer in the micro-four-thirds format. It is still a good camera, but no longer my first choice for astrophotography.
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| M35 in Gemini. Rokinon 135mm. 20 sec. |
The SkyMax 102 has a nominal focal length of 1300 mm, not quite ten times longer than the Rokinon. The fully illuminated image circle from this scope is about 22 mm, slightly smaller than the 24mm height of the Sony "full-frame" sensor. This corresponds to about a 1-deg FOV.
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| M35. SkyMax 102, 1300mm, 30 sec. |
There is a smaller and dimmer cluster to the lower right of M35. This is NGC 2158. It appears much smaller because it is almost six times farther away.
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| NGC 2158 at 135mm. 4x enlargement. |
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| NGC 2158 at 1300 mm. |
The limiting magnitude in both images is in the range of 14.5–15. The 1300-mm image obviously has higher resolution.
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| M37 in Auriga. SkyMax 102, 1300 mm, 20 sec. |
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