[MF3D.FORUM:1393] Re: Those Horizon loupes again

["Greg Erker" <greg.erker@xxxxxxxx>]

My Horizon 4x loupe (the non-6x6 one)
is a real achromat. I can tell by looking at the
reflections of a desk lamp.  I can see two coloured
reflections and one pale white one. By pivoting the
loupe around and seeing the reflections move I can
see that the white one is in between the two coloured
ones.

So I'm 99.9% certain that it's a cemented achromat
and the white reflection is the small reflection that
occurs at the interface of the two glasses with different
indices of refraction.

I'd also guess the 6x6 loupe is real too. Just not very
good from a distortion perspective. And too powerful
for viewing 6x6 slides ortho.

Greg E. (still alive :)

----- Original Message ----- 
From: "Paul Talbot" <ptww@xxxxxxxxx>
To: "Medium Format 3D Photography" <MF3D.Forum@xxxxxxxxxxxxx>
Sent: Thursday, January 04, 2001 9:10 PM
Subject: [MF3D.FORUM:1392] Those Horizon loupes again


> Several of us have commented in the past on the
> disappointing quality of the Horizon loupes, in
> particular regarding their suitability for use
> as MF 3D viewer lenses.  (I suppose it's fair to
> say our disappointment comes from the expectations
> set by the product description, as opposed to what
> we have a reasonable right to expect based on the
> price.)
> 
> I had an interesting conversation last night with
> a non-computerized customer who recently bought a
> roll-film back Heidoscop from me.  He owns an MF3D
> viewer that uses the Horizon loupes for lenses, and
> feels there is nothing in the performance of the
> lenses that would cause him to believe they are in
> fact achromats.  He said he took a closer look at
> the loupes, and became suspicious that they might be
> "faked" achromats: i.e., they are not cemented doublets,
> but singlets with a line scored around the outside edge
> to make it look like it is a two-element lens.  He said
> he did not make an attempt to actually disassemble the
> lens itself to confirm his suspicion.  Has anyone here
> studied the Horizons closely enough (in particular,
> actually disassembled one into two elements) to give
> a definitive determination?
> 
> Paul Talbot
>