From: Mark Gaffney <markgaffney@mac.com>

Date: July 3, 2008 5:51:43 PM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Re: IR/UV filter...

Hi Milton, I tried again on early morning Canopus with the 10" but had little success. I found Canopus which is magnitude 1 as you know in the telescope eyepiece & then centred it in the finder`s crosshairs. I used mostly the settings you described, 33ms base exposure time with high gains & various fps & brightnesses but was unable to achieve a focused image anywhere on the focusers draw tube. The difficulty of course is co-inciding exposure factors with focusing ones! The faintest object I`ve had in view so far would have been 2 of Jupiter`s moons but that was 2 months ago with the 4SE. I think I had to nudge the direction buttons a little to find Jupiter. I`m unsure how accurate the finder alignment was then or is now on the 4SE. (it`s a laser dot arrangement). I`m wondering do I need some other accessory like extension tubes for the C10-NGT? I`ve heard they might be necessary to achieve focus with the Orion Short Tube 80 guide scope I hope soon to buy. I was going to try sliding the nosepiece in & out of the eyepiece holder both with trees this morning & some bright stars tonight. Mark.

On 03/07/2008, at 10:47 PM, Milton Aupperle wrote:

Hi Mark;

No it wouldn't cause that. It primarily blocks off infra red light

which causes color balance issues (mainly lunar / solar, but Planetary

too like Jupiter) and also improves sharpness as IR light comes into

focus at a different point than visible light.

Usually when you can't find objects it's because the finder and the

camera / scope are not pointing at the same place. The small field of

view at prime focus with most scopes allows for very tight tolerance

in alignment. After I remove the coverings on my scope, I usually have

to re-adjust the Finder scope so that the finder and camera point to

the same object. I usually do this right before dusk and site them in

on a dsitant terrestrial object.

HTH..

Milton Aupperle

--- In Astro_IIDC@yahoogroups.com, "Mark Gaffney" <markgaffney@...> wrote:

Hi Milton & others,I`m wondering if the lack of the above filter on

my IS DBK 21A F04.AS

would be affecting my ability to acquire stars in the camera window

of Astro IIDC. I`ve tried a

couple of times with my NexStar 4SE (as it`s easier to set-up) but

haven`t had any success

with more difficult objects. I`ll have to have another go with

Jupiter as I acquired it 2-3

months ago although quite overexposed with little chance it seems of

adjustment. Now that

my Firewire port has luckily started working again I can devote some

funds to a Baader filter

by the end of the month! Mark.

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