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

Date: June 25, 2005 3:18:53 PM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: a couple of questions

Milton:

--- In Astro_IIDC@yahoogroups.com, Milton Aupperle <milton@o...> wrote:

Hi Tim;

Thanks for the info on APLux filter. Do you know if that is a glass  

or a plastic filter?

I was wrong!  The square glass filter I was looking at is the one that

I took out of the IBM PC Camera Pro that I tried to cannibalize for

the lens mount for the Aplux.  You are right:  The Aplux lens has a

pinkish reflection to the back element, which is FLAT, so it must be a

filter, not the lens itself.  

My apologies to all if I misinformed.

-Tim.

I know that the Unibrains, iRez Stealth, ADS Pyro and iBot have (or  

had things change over time) glass IR Filter (pink color) on the back  

of the lens. The Imaging Source Color cameras have a medium blue- 

green glass filter above the CCD. Both the The Point Grey Research  

cameras and pink Edmond Optics 15mm square optically perfect glass  

filter are pink too.

All the USB cameras (which aren't many) I've seen have thin plastic  

sheet IR filters above the CCD.

Also the further up the filter is from the CCD - the less affect dust  

has on the image (i.e. the donuts from hell syndrome). When I worked  

for a microscopy camera company this was a major problem. We  

eventually had to create clean rooms for final assembly of the  

cameras. Then as a final Q&A, we used each cameras on a 200x to 400x  

microscope to ensure there was no trapped particles on the CCD glass  

cover casting shadows onto the CCD.

TTYL..

Milton J. Aupperle

President

ASC - Aupperle Services and Contracting

Mac Software (Drivers, Components and Application) Specialist

#1005 - 815 14th Avenue. S.W.

Calgary Alberta Canada T2R0N5

1-(403)-229-9456

milton@o...

www.outcastsoft.com

On 25-Jun-05, at 2:25 PM, Tim wrote:

Milton:

--- In Astro_IIDC@yahoogroups.com, Milton Aupperle <milton@o...>  

wrote:

The IR filter on the UniBrain and every other FireWire Web camera

I've seen is on the back of the screw out lens. So once you remove

the lens, you have lots of IR hitting the CCD. I showed the

difference that this can make for color balance on page 37 of the

manual.

This is interesting!  I'll have to take a look at it again.  My  

3com (USB) camera has a small

square filter right in front of the CCD.  When I got the camera, it  

had been mishandled (the

case was cracked around the tripod screw, and I almost returned  

it), and the filter had

slipped such that I got a half filtered, half unfiltered view when  

I first tried it on Jupiter.

What was interesting was just how much light that filter blocked  

(it had a medium blue

color to it).  So, I took it out and used an astro IR cut filter  

instead, screwed into the

webcam adapter.

My ToUcam Pro also has an IR filter right ahead of the CCD.

And the Aplux.  It's a small square filter that fits right in front  

of the CCD in a recess in the

lens mount (the one that's 8mm)...  I'd forgotten this.  It's in a  

drawer with the lens mount,

which I'm not using at the moment.  And since I don't have it in  

place, no WONDER I'm

getting Purple Jupiters!  h'DOING!  I should put it back, since I  

can't use the webcam

adapter and its filter thread mount on the scope.

Again, I don't know whether this configuration is typical of the  

plastic case-mounted fire-

i's, or just the Aplux version.  So, your mileage may vary.

-Tim.

P.S.  Milton, I've been reading the help  file, and learning as I  

go!  Love it!!!