Focal reducer yay or nay

[stepping beyond]

I just received my Bday present and it's a dsi lll color, I've got an 8 in. newtonian f3.9 @ 800 fl would I need a fr and if so what size?

[Dave In Vermont]

At F/3.9, you should be fine. From what I have read and seen, the DSI iii, and the earlier versions, are quite forgiving. I have an older model I never got around to using. I'll be interested to see what you find out when you use yours. I did find a few useful, quick articles/threads around from Googling dsi III color (more are available by doing the same):

http://www.stark-labs.com/craig/resources/Articles-&-Reviews/DSI3Review_API.pdf

And this is from Dr. Clay Sherrod's website -

http://www.arksky.org/smf/index.php?topic=1823.0

And a Happy Birthday!

Dave

[ollypenrice]

You wouldn't use a reducer in a Newt like yours. Whether or not you'll need a coma corrector I don't know. The camera chip is very small (from memory, but check that) so you might get away without one, which would be nice. It would give you an all-reflecting system which has some advantages.

Olly

[Dave In Vermont]

I should think Meade, who made the DSI-series, would be selling coma-correctors if such were needed with a product of theirs. Just a hunch though. Coma-correctors are pretty expensive little beasts! So i'd recommend taking the camera out for a few test-spins to see what it does. If everything comes out looking like seagulls are attacking - then we can figure out who makes a decent c-c at a cost that won't kill you.

When I dug my DSI out of a case of astro-goodies I'd set aside, I couldn't figure out what the thing was! A waffle-iron from Pluto? A fly-swatter that gives the fly a sporting chance? Now all I need to do is figure out how to get my imaging-software to recognize it.

Have fun!

Dave

[michael8554]

You need to fire up your Planetarium and put some DSI III / 8"  f3.9 frames around some DSO's and planets.

Then you can decide whether you like the framing or not, and whether you need a Reducer, or maybe a Barlow.

Michael