Coverage of B&L Zeiss Protar Series VII?

I would appreciate if someone could tell me the image circle of one

of these. The sample I am considering is a 9 7/8" f: 7.7, a 14"

f:12.5 and a 19 3/4" f: 12.5. It is mounted in a #4 Acme Sychro. If

anybody knows first hand about image quality of the lens I'd

appreciate input on that too. Thanks!

Kevin

 

I don't know a darn thing about them, but I know that Ron Wisner uses those lenses and that he used to have quite a bit of information about them on the Wisner site. You might take a look there.

 

Kevin

Series VII convertible protars are very desirable lenses and perform well if stopped down. Most protars are uncoated and give less contrast than modern lenses but this can be compensated for to some extent by longer development times. Lens performance of the combined lens is roughly on par with that of a Dagor.

 

Protars cover from 70-80 degrees. An old chart that I have indicates that the 9 1/2" Series VII Protar is recommended for the 6 1/2 X 8 1/2 plate. I would guess that it has a useful image circle of around 300mm when stopped down to f/45 or f/64.

 

Sandy King

Kevin,

 

According to the B&L catalogue I have the 'set' (#12?) you're considering will

cover 8x10 'at small apertures'. At one time I had a very sharp 9 1/2" double

protar consisting of 2 - 16 1/4" cells - this lens would cut about an inch off the

corners on my 8x16 (IC ~445mm) but there was plenty of room for use on

8x10.

 

Cheers,

Roger...

As indicated, these are very good lenses. The Protar VII consists of two cemented quadruplets around a stop, and relies on symmetry to some of the aberrations. Each quadruplet is corrected for coma and can thus be used on its own. A Protar with both cells covers about 70 degrees, maybe 80 degrees at small stops. The single cells have considerable less coverage, maybe about 45 degrees or so (which is seldom an issue since the single cells are longer focal lengths). The 9 7/8" length should cover 8x10 and so will the individual cells. General rules when using convertibles - single elements are best used behind the stop (unless bellows limitations dictate otherwise). Some of the corrections (that rely on symmetry) are lost when using the single elements alone. To compensate, use a sharp cutting filter (a green is probably the best to use although any filter should improve results by cutting the spectrum) to reduce chromatic aberrations and stop down. These are good user lenses. Cheers, DJ

Thanks. It never ceases to amaze me how much I can find out just by asking here.