PETZVAL lens help~~~ to make a new lens barrel
Rencently I got a lens which I bought it as a big RR lens made by suter. When I received it I found it is a hermagis petzval mounted on a suter lens barrel...The suter lens barrel is shorter than original lens barrel, so I just want to make a new barrel for this hermagis petzval lens elements. And I know the focus of front lens is 500mm, rear lens is 700mm,combined focus is about 300-330mm, so does someone can tell me how to calculate the "RIGHT" distance between front and rear lens? Thanks!
Last edited by seanwang; 5-Nov-2017 at 08:09.
I suggest you measure the diameter of the front achromat and copy the data which is written in ink on the side of the two lenses which have space for them!
Hermagis did have a standard Petzval which they continued for decades, but also a faster one from later in the 19th century.
We could identify the series and the particular lens size and I'm sure someone (perhaps even me!) has this particular lens and can read off the barrel length.
I once had a set of Dallmeyer 3b lenses and found the correct barrel length through using the forum!
A guess would be that the lens diameter is 81mm?
Steven, thank you. The glass diameter is 81mm! And how to identify the series? I estimate the focus is 330mm F4.5Originally Posted by Steven Tribe
This can only be a series I. The other possibilities were:
no.4 Petzval "objectif a monture universelle" - this is the series with an extra flange thread on the brass hood! EFL is 24cm.
no.5 Petzval "ordinaire" from the early Wallet et Hermagis period late 1840's. EFL is also just 24cm, too.
Nos. 4, 5 and 6 series II Petzvals from ca. 187. These have EFLs of 22, 19 and 16cm, respectively.
So it must be the most common series I Petzval which is:
no.5 EFL 31cm so I think your measure is a little off!
There is a recent thread with the identification of exactly this lens, so the OP can measure his barrel length.
http://www.largeformatphotography.in...light=hermagis
This thread includes an extract from a late Hermagis catalogue on the series I. The number 5 size would have been a common choice for portrait studios.
Measuring the EFL is difficult when there is no Waterhouse, so comparison whith a lens of know focal length (compare length shown on the ground glass - or white wall) is best.
I may have the lens set too in the form of the "universelle" version, but I need to check the exact EFL! My barrel is 15.10cm
from end to end.
That's very helpful, THANK YOU!!
It is serie I no.5, I double check the focus, it's 310mm, I will build a new barrel for it.
I can't give you the position of the Waterhouse stop, as mine is from the period before French makers went over to the UK Waterhouse system. It has insert stops in the center of the barrel which screws apart. This may be the same place as the later WHS position - but can't be certain. Best to contact the OP of the other recent Hermagis thread and ask him to:
- check the barrel length (when the brass lens hood is unscrewed!).
- measure the position of the Waterhouse slot.
Of course, your new barrel will be plain, without the focussing brass sleeve. And get an extra external thread made on the outside at the front so that you can (eventually!) install a lens hood.
Brass threads for the early Petzvals were cut by hand, rather than on a lathe. So thre may be a little tightness or slack with modern precise cut metric threads on the barrel.
Have you checked the text on the side of the lenses?
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