In The Beginning: Indoor Observation and Attempts at Imaging

With wind gusts in excess of 30 MPH and my having to get to bed, it was justifiable not to be outside with my telescope but the moon was in direct  line of sight through my window, so I had to try and capture it. Something new is learned every day; since I've started shopping for a telescope and after receiving one delivery of the "Clestron 8" OTA with stock fork mount. Ready for use in "table-top" configuration.

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General observations since starting;


Focus can be fairly sharp but it only gets so sharp "sharp" before it can't be made any sharper when used from my indoor sky spotting corner. First few times I used it inside my room I was worried but once I took it outside on a cool night it became evident that far sharper focus was achievable.

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One thing I didn't really expect to learn but am not surprised by is the effect of atmospheric  conditions. Of course I was aware of diffraction and how humidity, clouds and random particles in the air could collude to reduce the image quality, whether it be visual or an image sensor at prime focus.

Most interestingly, if the atmospheric conditions outside are radically different than inside, you will find it hard to get sharp focus from inside.

Specifically, if it's 30 degrees outside and 74 degrees inside - it will be difficult or impossible to achieve sharp focus. The focus will always be sharper when the OTA cools down outside, perhaps becoming a uniform temperature as well.

If it is warmer outside, the telescope will perform better inside.

For those who think the window is the culprit, I tried opening the window to compare but the results of those test show something else but not particularly surprising. The image gets blurrier and distorted. It seems that the cold air has an affect on the corrector plate and because of the incongruous temperature -- essentially the existence of a sharp thermal gradient. Now, I suspect if I could cool the primary mirror down that things might behave a bit better.. but what of the secondary? Will vents do the trick? I've seen this fan-vent mod which makes the consumer grade 8" SCTs gain vents which resemble those found on some of the higher priced astrographs. 

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Inversely, when it is warmer outside -- even in the mid 50s (Fahrenheit) the gap between the indoor and outdoor temperatures is sufficiently narrow to allow sharper focus. Opening the window still has the potential of causing distortion although this is less of a problem as the outdoor temperature increases. Thus when possible, it is preferable to have the window out of the way. Naturally, the best way to do that is to take the telescope outside. The only time I really ever want to view from inside is when it's just too cold for my sensibilities on a given day.

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For a few weeks, while waiting for a back ordered mount, I've been using the BBQ as a sort of table-top surface for my fork. Shook a lot but it was preferable to putting the fork on the ground. The simplest short-term solution is a plank of plywood. I don't even need to bolt the OTA to it, although I do have the appropriate bolts so I'm ready. I was thinking about doing this if I needed more stability than the what the combination plywood and patio chair can provide. Also got an idea or two in order to make a cheap EQ wedge although I wouldn't count on it. I think I would use it more for convenience, for when the camera is too big for a 90-degree declination. Pointing straight up would cause the SLR to bump into the bottom of the fork in some configurations. As there is no motor for the dec, it's not a big deal but I'd imagine there might be a night or an object on a given night that requires me to be able to point straight up.


In short, the attempts at photography still come out like crap, except for the moon and the un-detailed disc of the sun. There is an obvious need for a few accessories like a Barlow and eyepieces which can work for me in eyepiece projection or other afocal methods but I have not pulled the trigger on it all because I don't want to waste money on things I come to not need soon after buying.

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I keep saying I can do without thhe JMI Motofocus add-on but I'm starting to get the sense that it would go beyond just being convenient to have. We'll see, or perhaps not, since I do not yet have a motorized focuser.