[APML] OT: Binoculars

[mschex@verizon.net]

The best binoculars I have used / owned to date are Pentax PCF-V 20 x 60s.  These guys have a small 3mm exit pupil and are tack sharp to the edge of the field.  They also have an integrated field flattener in the eyepiece.  There might be a small amount of light falloff at the edge but I have not noticed a problem, especially at night.  The FOV is small however.

Oh -- and the best part.  You can get these binoculars for about $180.00 mail-order.  They are made in China but the quality is excellent.

http://www.pentax.com/products/binoculars/bino_overview.cfm?productID=65787

Mike
 
> 
> From: Chris1011@aol.com
> Date: 2002/09/18 Wed PM 01:05:30 EDT
> To: astro-photo@seds.org
> Subject: Re: [APML] Petzval hot spot?
> 
> Speaking of hot spots in scopes, I have seen a marked deterioration of 
> quality in binoculars of late.
> 
> Last weekend I was at Astrofest. Lots of vendors selling stuff. Since I was 
> in the market for a good pair of binocs, I checked out just about everything 
> that was available. Every one of them had the same problem - uneven 
> illumination of the exit pupil. Yes, most of them had Bak4 prisms. That in 
> itself does not produce even illumination. Some binocs had 60 and even 70mm 
> apertures, but with internal field stops that limited even the on-axis 
> apertures to between 40 to 50mm. Edge illumination on most of them was equal 
> to about 30mm aperture. The reason for this is that the prisms are too small 
> in virtually all binocs - even models costing $400 and up. The effect is the 
> same as undersize diagonals on a Newtonian. Why do they put big lenses in 
> front and small prisms inside? Because the general public is not aware of 
> simple optical principles and it saves money, size and weight. 
> 
> I guess I will have to spring for costly Zeiss or similar binocs to get full 
> illumination of the field (or maybe put up with some light falloff).
> 
> Roland Christen
> 
> --  APML Archives at <http://astro.umsystem.edu/apml/>  ---
>              Unsubscribe at <majordomo@seds.org>
> 


--  APML Archives at <http://astro.umsystem.edu/apml/>  ---
             Unsubscribe at <majordomo@seds.org>