Lenses without indication of focal distance

[lungovw]

Hello,

Many lenses produced back in the XIX century have no indication of focal distance. However it is very common to find samples with "series" and N° 2, 4 ...

Was that a standard shared among lens makers? Can we say that more than often a lens marked as N°2 will work as a normal lens for a quarter plate, or any other statement alike? Any insight about that?


Cheers


Wagner Lungov

[Ernest Purdum]

"Series" designations indicate the design of the lens. Foir example, a Zeiss Series V is an extreme wide angle lens, while the Series VII and VIIa lenses general-purpose convertible types.

Within a particular lens line, "Number" designations indicate the focal length but there is no standardization, so you have to refer to a catalog to go from number to size. Fortunately, if you have in mind a particular lens you'd like to know more about, it's more than likely that somebody here on the Forum will have the necessary catalog.

[CP Goerz]

If you measure the focal length at infinity and then the aperture opening at wide open and divide one by the other you'll quite often have a good indicator of lens design. The next part is to gauge the thickness of the cells and check if there are any air spaces, after that its child's play.

[Ole Tjugen]

"Series" designations indicate the design of the lens. Foir example, a Zeiss Series V is an extreme wide angle lens, while the Series VII and VIIa lenses general-purpose convertible types...

As a case in point, a Zeiss "Serie VIIa" will be a pair of "Serie VII" cells.

Before the lensmakers started making fanciful names, they would often use a "serie" designation.

In many cases, smaller No. means a shorter lens - and a No.2 from a German maker is often either a 150mm lens or one fit for use on 9x12cm. But some makers numbered the lenses in the series in the opposite way, so that a No.6 would be for 9x12cm and a No.1 for 50x60cm!

Ask, and someone will find it in a catalogue.

[Jim Galli]

The answer to your question is generally no.

Series is more about purpose and formulae. For instance in Wollensak land, a series II is always a general purpose of the tessar type. III is a wide angle. IV is an entry level lens, a dialyt. etc. Then the consecutive numbers are the graduations upwards in size. But no make matched any other make. There's no reason to assume a Goerz series iii no. 4 is close to a Voigtlaender Series IV #4. In fact, one is a 9 1/2" lens and the other is about 13" if I recall correctly. Voigtlaender was particularly frustrating. A series II #4 can be miles away from a series IV #4 even with both sharing the same name, Euryscop. Very little rhyme or reason to try to get a handle on. The lens Vade Mecum is about all we've got and it's only helpful maybe 60% of the time.