[LargeFormat] Happy Holidays and Zeiss Convertibles!

[Clive Warren]

Dear All,

The list has been unusually quiet this weekend - guess you are all out 
there doing your seasonal shopping.

I have been hit by a flu bug that has really taken me out over the last 
couple of weeks. If I owe anyone EMail then please  be patient as there is 
rather a lot to catch up on.

As usual, I will be travelling around the country over the next few days 
and hope to be taking photos. There are a couple of shots that would be 
good to revisit..... In addition there are a few lenses that need to be 
tried out, including a Ross Convertible Anastigmat that surfaced here 
recently. This lens was manufactured in around 1896 by Ross in the UK under 
licence from Zeiss. At the time, Zeiss did not have the manufacturing 
capabilities to produce any quantities of lenses so simply licenced out 
their patents to lens producers in various countries. In the US it was 
Bausch and Lomb, in France it was Krauss. The lens was later renamed the 
"Double Protar" or Series VIIa Protar and it is as you may have guessed, a 
convertible. The Anastigmats are composed of two lens cells each containing 
a completely corrected  4 element symmetrical anastigmat lens.

Many convertible lenses suffer from poor performance from their single 
cells as they were designed to give optimal performance when combined. The 
Series VII Protars are a little different in this respect so I'm looking 
forward to using the lens. It's amazing that a lens over 100 years old will 
probably give even modern glass a good run for the money - it's not too 
fast though at f12.5

Anyway, hope you all have an enjoyable holiday and a happy New Year!

Cheers,
            Clive