First Venus (C8 XLT + ADC) - 15 Oct 2023

[Maurizio83]

My last capture of Venus was done over 15 years ago with a 114/900 telescope, in afocal mode, using a 3MP digital camera. It's been ages since that... 🙂

This morning, I tried to capture the planet for the first time with my current equipment. The session was unplanned, but when noticed the planet in the sky, I decided to give it a try. The seeing was moderate, and there were some intermittent haziness, at times quite intense (some videos were discarded due to sudden changes in brightness). Due to the suboptimal seeing conditions, I had difficulty focusing directly on Venus, so I opted for a nearby star. I captured in visible light, using the classic UV/IR block filter.

The sun was about to rise, so I quickly experimented with various recording parameters: from nearly 400 fps with an exposure time of 1 ms (limited by the USB connection) and standard gain, to 125 fps with an exposure time of 8 ms and gain set to zero... In the end, after analyzing the results of the various videos, I found that the best outcome was achieved at 250 fps with a 4 ms exposure time, while keeping the gain very low.

I avoided multipoint alignment as it created artifacts (perhaps due to the lack of obvious surface details for tracking). I used global alignment, averaging the frames ("average" gave better results compared to the "median" option).

Subsequently, I carried out a fairly standard post-processing, as with the other planets. I noticed that by increasing saturation, you can faintly discern some subtle variations in the clouds. I haven't investigated whether this might be possible, maybe they are just artifacts...

I have two IR pass filters (one at 685 nm and one at 850 nm) that I could try. I'm not sure if filters specific for Venus (350 nm) are suitable for my color camera. I need to investigate this aspect as well.

If you have any comments or suggestions to improve on this subject, they are welcome! 👍

The full-resolution image and detailed shooting/processing information are available here: https://flic.kr/p/2p9p5db

Edited October 15, 2023 by Maurizio83

[Kon]

51 minutes ago, Maurizio83 said:

you can faintly discern some subtle variations in the clouds. I haven't investigated whether this might be possible, maybe they are just artifacts...

Nice image. Yes you can get some clouds in colour, very very subtle. In IR too, but not very often.

The 462 is awful in UV, hardly any response even with the AR window removed. I know because I tried and the reason I bought the 462 mono.