PD and T and Aleph2 lens equal?

[AilSnail]

I thought these are the same, but in the shoppe the PD and AlephII lenses are listed as different products. Don't they all use McR20?

And what are the lens diameters?

 

[McGizmo]

The PD window is sapphire with 1x AR coating and the Aleph 2 window is water clear soda lime with 2xAR coating. Better light transmission with the latter and better durability, IMHO, from the former. Both windows are approximately 23 mm diameter X 2 mm thick and interchangeable by design and hopefully in practice. :green:

 

[Fringe]

The Aleph window is more durable and transparent? I thought the saphire was as good as it gets.

 

[Kiessling]

Nah ... the Sapphire is tougher, more expensive, but lets a bit less light through ... IMHO.
bernie

 

[AilSnail]

Don, that is cool. I ordered a pd lens for a future project. hopefully I ca see which side is coated!

fringe, he said the sapphire is more durable. it is harder and so it doesn't become scratched so easily. in my experience ARef (not to be confused with abrasion resistant) coat on the outside wears badly. So with some use I believe the saphire comes out on top wrt light transmittance, that is the only reason I am getting it.

Kiess: I doubt it is correct to say saph is tougher, and i don't know whether it is stronger either - or more shock resistant. But these terms get a bit mixed up in my head.

 

[McGizmo]

AilSnail,
On the sapphire window, there is a vinyl disk stuck on the non-AR side. Once that is gone, good luck!

 

[Anglepoise]

Don.....Can you elaborate on your comment about the vinyl disk stuck on the
non Ar side?

My sapphire lens did not, to my knowledge, have any 'disk".

Too many Mai Tai's.......???

 

[Kiessling]

AilSnail ... so I am going to say Sapphire is more scratch resistant, but not necessarily tougher or more difficult to break. Would that be correct?
Thanx!
bernie

P.S.: david ... if yours hasn't a vinyl disk, I'd be extremely worried ... :nana: :wave:

 

[AilSnail]

kiessling; yea; so far so good; let's hope someone will come and fill in the blanks

 

[Kiessling]

Where's NewBie when you need him?

 

[McGizmo]

Anglepoise,

The sapphire windows come from the vendor in a small zip lock bag and there is a clear vinyl disk on the non A/R side. This allows you to know which side is which as well as install the window without leaving finger prints on it. The disk is larger in diameter than the window itself. I discard the disk obviously before installing the bezel ring.