Imaging the Saturn/ Venus conjunction with a short refractor?

[GazOC]

Clouds permitting I'd like to try to image the Saturn/ Venus conjunction on the 30th June, the only scope I've got that will fit the two planets on a chip at the same time is my 80mm f6 refractor (the planets will be ~44' apart). I know for visual some type of minus violet filter would be in order to cut down the colour on the these two objects, is there anthing else out there that could fo the job better for imaging, maybe a coloured planetary filter?

[MartinB]

What's your camera again Gaz - is it colour or B+W?

[GazOC]

Its a colour Logictech Webcam, it has a B/W software setting though that seems to improve lunar shots with short refractors.

[Kaptain Klevtsov]

It looks to me like you need about 300mm of focal length, like an ED80 plus 0.5X reducer, or less. That's going by Starry Night Pro, not like I worked it out or anything.

Captain Chaos

[MartinB]

If it's colour then any colour filter is going to stuff up the image and you would be better off with putting up with the CA. At least with registax you can do an RGB shift during the processing. The only alternative is to use the B+W mode and RGB filters. That is a good way of controlling CA but obviously a lot more hassle

[GazOC]

It looks to me like you need about 300mm of focal length, like an ED80 plus 0.5X reducer, or less. That's going by Starry Night Pro, not like I worked it out or anything.

Captain Chaos

I DID work it out...and you are right!! A 480mm scope and 0.5 reducer should be plenty (~65')

Cheers Martin,

I'll try colour and try the RGB shift. I was hoping to get a trial on Venus tonight but the skies didn't clear up until too late.

[Kaptain Klevtsov]

I'd check the real actual FOV and see if the FR works on a trial run because the reduction ratio varies with chip to FR distance and can be adjusted slightly. Also you get distortion near the edge of the FOV just where the planets will be if you push the FR by trying to reduce too much or using a chip thats too big for the reduction and stuff.

Of course you knew that Gaz, I just added it for anybody else reading this who might fancy a go. Dry run time I suspect.

Perhaps a good test would be a full disc moon image as the scale would be about right and another with the disc off the end to check for distortion and wierdness. (I'm sure somebody has posted full disc webcam moons here recently as well.)

Captain Chaos

[GazOC]

The Moon idea is a cracker CC!!

Er, sorry I mean KK

[Kaptain Klevtsov]

Just found this

http://stargazerslounge.co.uk/index.php?topic=13039.0

Geoff_K did a full disc shot with his webcam. Maybe he'll pop his two penn'orth in soon?

Captain Chaos