From: "Tim" <tjp314@pacbell.net>

Date: July 4, 2008 10:36:48 AM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: IR/UV filter...


Mark:


I personally hate spending money on stuff without knowing what my

problem is first, so I try to rig up easy ways to find out.


if you get an out of focus image, at least, and the closest to focus

is with the draw tube all the way out, one thing you can try is

loosening the set screw holding the camera in place, and carefully

pulling the camera out while watching the image on the screen, to see

if it gets sharper.  If it does, you could use an extesion tube to

reach focus.  If you can't reach focus with the focuser racked all the

way in, then you either need a lower profile focuser than the one you

have,  or move the primary mirror forward up the tube (depending on

the way it's mounted, this might be easy or difficult).


-Tim.


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


Hi Milton, Here`s the scope;



I was wondering if something like this might work;

http://www.myastroshop.com.au/products/details.asp?id=MAS-347 

 I`m not getting any image of a star at all at present inside the  

FWHM/HFD rings? I`ve taken moon images with both scopes, the 4SE is in  

the background of the picture. Mark.

On 04/07/2008, at 11:47 PM, Milton Aupperle wrote:


Hi Mark;


On 3-Jul-08, at 8:24 PM, Mark Gaffney wrote:



Hi Milton, seems shifting the camera/nosepiece inside the eyepiece

holder won`t work for trees in the sunlight through the 10". Too much

light for the camera without a filter perhaps?


Most likely yes, especially since sunlight has a lot of infrared

light in it too.


I can bring the 20mm

eyepiece into focus on nearer objects this way though. Mark.


The puzzling thing to me is that you did shoot some lunar images

previously, which seemed to be pretty close to focus. Or was that

taken with a different Telescope than this one?


I believe your 10" is a newtonian, right?  If you put a bright star

in the field of view you twist the focus knob back and forth, you can

usually see the star go from larger diameter (out of focus larger

FWHM/HFD values) to smaller diameter (smaller FWHM/HFD values) and if

you continue twisting it then it once again becomes a large star  

again.


If your not seeing that sort of behavior, the 10" might not have

enough travel distance on the focuser then, either in or out to bring

it into focus.


HTH..


Milton Aupperle



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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