[time-nuts] Subject: Re: I love the smell of tantalum in the morning

[Charles Steinmetz]

Jeremy wrote:

> Amazon indicates the different lenses simply snap in and out. Any idea how
> easy/practical this is? It it better to have two completely different
> visors each holding different magnification lenses?

Quite easy -- the lens plates are held onto the front of the visor by 
two plastic pins that just snap in and out.  You can see the heads from 
the outside (as opposed to the eye-side) at the far left and right of 
the lens plate.

That said, IMO it is always more convenient to have each lens plate 
mounted in its own visor.

I have to say that contrary to the original post, I find the 3.5x lenses 
WAY too strong for SMD work.  The working distance is only 3-4" -- not 
nearly enough to work safely with hot tools, or comfortably.  Even the 
2.5x lenses, with 6-8" of working distance, are too strong for me.  For 
anything that requires working on the object you're looking at (as 
opposed to just examining it), I recommend staying at 2x and below (2x, 
1.75x, 1.5x).

Finally, Donegan makes two series of lenses -- rectangular plastic 
frames with optical glass lenses, and rectangular plastic frames with 
molded-in plastic lenses.  The glass lenses are more expensive, but the 
large difference in optical quality makes them the only real choice, IMO.

At substantially greater cost, you can get "surgical loupes" (a/k/a 
"dental loupes").  These have compound optical systems, so you can get 
longer working distances at a particular magnification than you can with 
a single lens (like the OptiVisor has).

Best regards,

Charles