From: Milton Aupperle <milton@outcastsoft.com>

Date: July 4, 2006 10:43:16 AM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] questions about sharpening before/ while stacking and IR pass filter


Hi Eric;


On 4-Jul-06, at 10:14 AM, Eric wrote:


Hi Folks,


Well, the holiday and some brief periods of fair seeing has given me a

chance to try out the DMK camera with IIDC.  I like the setup and it should

work well in the future :).


I wanted to ask about sharpening before or while stacking.  There are

various degrees of sharpening, including noise reduction, available in IIDC.

The manual shows the differences.  I was wondering if anyone else regularly

uses this presharpening and what benefits does it have?


Probably just me :)


Also, the IR-780 IR pass Schuler filter definitely didn't seem to be the

right choice.  It significantly dimmed targets over any of my other filters,

including blue.  Therefore, I'm going to exchange or return it if I can find

out the correct spectrum of the filter I need.  Anyone know which IR pass

range or filter offers the best transmission? (Alan, I must have been wrong

in assuming you had the Schuler IR-78)


It sounds like the filter has poor transmission accorss the board spectrum wise.


What does the spectral curve for the filter look like? Basically that shows the light transmission percentage on the vertical axis and the blue to red spectrum (low nm to high nm) on the horizontal. That should tell you how much light it filters out.


I replaced the original IR filter that shipped with my Flea Color Camera with one from Edmund Optics (this voids the warranty on the camera). The original Flea Filter was transmitting less than 40% of the light at 640 nm, 10% at 656 nm ( which important for  H-alpha emissions from Nebulas) was down to almost zero by 700 nm. The Edmunds filter transmits about 80% at 656 nm, 20% at 700 nm and is basically zero at 740 nm. So it's giving me a lot more light in the Astronomical spectral areas I'm interested in, especially for Nebula shooting. Some day I'll measure it.


HTH..


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@outcastsoft.com

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