P3D Re: Hastings triplet for red button

["Dr. George A. Themelis" <DrT-3d@xxxxxxxxxxxxxxxxxxxxxxxxxxx>]

Dennis Selwa wrote:

>Does anyone know of a Hastings triplet that will fit into the lens 
>barrel of the red button viewer? It can be F.L. of between 40MM and 
>47 MM . I'm not sure of the diameter but I think it is 24 or 25 MM.

The red button lenses are 20 mm in diameter.  Trying to fit 24 or
25 mm lenses in a metal holder that accepts 20 mm lenses is certainly
a problem.

Grant Campos replied:

>I just tried putting Hastings Triplets in my Kodaslide I, and the 
>centers were very beautifully sharp, but the edges were greatly 
>distorted. 

I wonder if you installed them front to back correctly or if you
tried both ways... I am sure you did it right but if anyone else
in the list is thinking of installing achromats in a viewer, have
in mind that the lenses are not symmetric and if you put them
reversed front to back then you will get a very distorted image.

George Themelis


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