Hi there!
A few weeks ago, I got myself a 10" Sky Watcher dobsonian flex goto scope with the view of trying my hand at lunar and planetary astrophotography. In a previous thread, I asked about entry-level ccd cameras (
http://www.iceinspace.com.au/forum/s...ad.php?t=86413) and took up Poita's generous offer to lend me his Imaging Source DMK21 to "try before I buy" (thanks Poita!).
Upon receiving the camera, I installed ICapture on my laptop (the software comes with the camera) and downloaded Registax 6. So far so good.
I was told by the astronomy dealer I had planned to buy the camera from that the problem with the Sky Watcher focuser I had on my scope was that it didn't have enough travel to reach focus with the Imagining Source cameras (not enough "rack in", to be precise). Luckily, my scope being collapsible, I could shorten the length of the scope by not extended it fully. I eagerly awaited for night fall with the intention of testing the DMK on Jupiter which was still visible in early evening.
The first night was a disaster. I hooked up the DMK in the focuser. I could find Jupiter in the viewfinder, but could see it on the computer screen (I was operating the scope manually). When I eventually caught it and kept it on screen for a few seconds, all I could see was a huge disc with swirls and the shadows of the secondary's arms... By the time I had my hand on the focuser, the disc was gone! I tried again and again only to managed to focus to a smaller white fuzzy disc. I was demoralised.
The next day (following Poita's advice), I tested the camera during the day. I shorten the scope by 15mm, pointed the scope to a far tree and managed to get the camera in focus. While I was at it, I took a few snapshots and a couple videos of gumtree leaves to practise on ICapure. Night time came, the scope was set up (extended minus 15mn). The viewfinder was perfectly aligned. This time, I had the tracking enabled. I aimed a Jupiter, locked it on the computer screen, focused... All I got was a nice white disc. I tried on stars and could only see the brightest ones on the screen and couldn't quite focus on them.
After a rainy interlude of a couple of days, I took the camera out one last time (I didn't want to abuse Poita's kindness by keeping the camera too long). The scope was set up at minus 25 mm. It was still daylight. The sky was overcast, it was windy but there was a 15 mn break during which I could catch the Moon, low in the western sky. As it was a much easier target than Jupiter, I caught it quickly on screen and managed to focus on it. The camera focus wasn't perfect, far from it, but the focuser could travel either way of the focus point. I knew then that the length of the scope was right for the camera. I recorded 3 AVI videos of about 10/15 seconds each with the Moon coming in and out of high clouds and the scope shaking in the win.
I have processed 2 of the AVis which show the moon drifting through the visual field. I ended up trimming each video to 3 seconds of the most stable images and stack about 300 frames on Registax. Here are the two resulting pictures. Bearing in mind the very bad seeing conditions, my total inexperience in imaging, the
ad hoc set up of the scope, I am rather pleased with the photos (see attached).
So what do I take out of all this?
Well, I can no longer take for granted that imaging is just a matter of popping a camera in the focuser and pressing on the Record button. I now foresee that it's much more than that. I am going to have to do my homework!
I also know that the scope as to be perfectly set up in order to locate and track the target object through ICapture.
I now sense that focusing the camera is a very big issue. I was only able to achieve rough focus. I need to get myself one of these focusing masks to improve focus.
I have worked out that my SW dobs scope isn't ideal to be used with an Imaging Source camera. But shortening the scope by 1 inch is a way to get around the issue (but with that configuration, I no longer get my EPs in focus, there is some fine tuning to be done to get both the camera and the EPs in focus at the same time).
It's also important to ask someone when you are stuck. I would have gone nowhere without Poita's help.
No matter how frustrating this challenge has been, I got a result, as imperfect it may be, and want to go further. Soon, I will get my own camera!
Any advice is welcomed.
Cheers,
Eric
PS Sorry for the long message.
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