Re: [APML]: varimagnifier/FOCUSING

[cvedeler@bio2.edu (Chris Vedeler)]

Yea, when it was all said and done, to connect my OM1 to my Lumicon GEG using the 
SureSharp and getting the right angle viewer it was about $200!   I'm going to use my 
1-12 screen to frame with my OM1, so didn't need the Duo View.  Granted, this is about 
the most expensive little gizmo I have ever seen for what you get.  However, if it does 
the job, then it is money well spent IMO.  I've seen the advertisments for the B&K 
Astrofocuser, but it doesn't look like it uses a Ronchi screen or knife edge as you are 
still focusing through the camera (I may be wrong on this, but it is not very clear on 
how it works).  I've learned after 2 years not to trust my eyes anymore when it comes to 
focusing at night on the scope.  

If you can consistantly get tack sharp focus with the B&K Astrofocuser, then that's all 
that matters regardless how it works.  I'm not trying to sell the SureSharp so much as 
the merits of knife edge focusing over focusing through the camera on a focus screen.  
Most of the finest astrophotographers in the world use some kind of knife edge system to 
focus.  It is tried and true. 

Clear skies!
Chris Vedeler 

>
>Well, as usual I am going to disagree on this subject. I am looking at
>the Pocono Mountain Optics advertisement in Sky & Tel magazine.
>The Spectra Astro Systems prices are as follows:
>
>Sure-Sharp................$135.00
>RT. Angle viewer..........$ 49.00
>Duo View..................$ 79.00
>Shipping minimum..........$  6.00
>               Total     $269.00
>
>In order to have the same capability as the B&K Astrofocuser you need
>all three of these pieces. And you still have to remove the camera each
>time to focus on a new object and install all of these pieces and then 
>re-install the camera. In an all out shootout with the Sure-Sharp and
>MFFT-55 at several star parties, newcomers and vetrans alike
>consistently
>achieved better focus in 1/5th the time with the Astrofocuser. I have
>heard all the arguments otherwise. The negatives and prints speak for
>themselves. 
>Regardsd,
>Maxx             
>----------------------------------------------------------------------
>Chris Vedeler wrote:
>> 
>> 
>> I've wrestled the focus monster for about 2 years now, and it usually wins.
>> I have used 4 different focus screens, used an 8x finder out the back of the
>> viewfinder, used the Olympus Varimagnifier, a home made Kwik focus gizmo and
>> just about everything else you could think of.  My focus has always been hit
>> and miss.  I got better over the 2 years, but it was almost random if I got
>> tack sharp focus vs. slightly out of focus.
>> 
>> I just spent the money on the SureSharp by Astrosystems.  It is a WAY over
>> priced gizmo (like $135), but from everyone I have talked to, it is the best
>> way to go to get consistently sharp focus.  Focusing at night in near total
>> darkness on nearly a point source is next to impossible for the human eye to
>> do.  Knife edge / Ronchi screens do not rely on our eyes any more than it
>> takes to see stripes of light and dark.
>> 
>> If you are OK with only moderately sharp focus, a good focus screen with a
>> loupe can get you that.  However, if you want tack sharp focus consistently,
>> knife edge or a Ronchi screen is the only way to go.
>> 
>> Chris Vedeler
>> http://www.isomedia.com/homes/cvedeler/space.htm
>> Tucson, AZ
>> 
>> At 03:52 PM 1/23/98 -0500, you wrote:
>> >
>> >Hi!  I was looking at George Greaney's homepage, and he says he uses a
>> >20x achromatic loupe from Edmund scientific for focusing.  Does anyone
>> >else use a similar method, and how effective is it?  I want a good method
>> >for focusing but I'm a bit apprehensive about spending $250 on a B@K
>> >astrofocuser unless I have too. Any help would be greatly appreciated.
>> >
>> >Clear Skies
>> >Spilios Asimakopoulos :-)
>> >Toronto, Canada.
>> >
>> >