From: Mark Gaffney <markgaffney@me.com>

Date: May 19, 2010 2:52:33 PM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Tarantula nebula..NGC 6744.. Jupiter


Milton, 

Got you..! 

That document is either lost way back in the sands of time in my messages or preserved somewhere equally difficult to find on one of my Macs or external HD`s! 

Apple Search or Spotlight is often difficult to get along with too. ( I often have difficulty with it because I can`t remember what the thing I`m looking for is called)..


Mark. 

On 20/05/2010, at 6:40 AM, Milton Aupperle wrote:

Mark;


On 19-May-10, at 2:03 PM, Mark Gaffney wrote:

Hi Milton, 

I may be a bit stupid  but I can`t get my head around how exactly to do this measurement? 


Why don't READ that "Using the CROAG"  document I sent you several months which has pictures in it that shows how to do this on the first page?


All I can think is to measure how far apart the two cameras are on my shipping container.


You don't do that.


You measure the distance from the telescope end of the OAG (that's the part attaches to the back of the Telescope / or Focal reducer) to the front of the CCD in each camera.


If the CCD's in both cameras are exactly the same distance to the front of the OAG, they are parfocal, which means both will be in focus at the same time. That's unlikely and you may need to add or remove extenders and then slide the Guide camera in or out of the holder to get them both in focus.


Once you have the distances so they are close, you'll need to fine tune it a little bit to get sharp focus with both cameras and that's where your 80 meter sign comes in.


Milton Aupperle