Surprise! Ross did adopt the Dallmeyer Patent Portrait Lens!

[Steven Tribe]

I was checking the equivalent focal length of a newly purchased Ross Cabinet no.1 with catalogues from the late 19th century and found that this is given as 6" - which didn't agree with what I had measured it to. Must be the "back focus", so I checked a much later catalogue from 1934 from Kodak (UK) which still had the big Ross Petzvals alongside the Dallmeyer and Cooke competitors. This gives the equivalent focal length for this cabinet as 8 1/4" - which corresponds with what I had found. So don't trust the catalogue data - it may be "back focal length", even it is doesn't say so.

The description of the Ross Cabinet series says ".. diffusion can easily be obtained by unscrewing slightly the outer cell of the the lens". Checking the rear cell, I find this is not true! The complete lens cell is loosened fron the barrel. This method of introducing diffusion was that which, amongst others, Darlot had employed - and used in public discussions against the Dallmeyer Patent in the 1860's.

However, looking at the rear cell, I quickly found out that the construction was of two separately mounted lens which could be unscrewed from each other. The lenses were also exactly the same as the Dallmeyer Petzval redesign. The internal rear lens screws in towards the front cell - in exactly the same way as the later "turn the barrel" version of the Dallmeyer Patents (but a more simple design!). There is even a pair of marks to indicate the "standard position"

It could be that Ross eventually (by 1934) used a rear cell which could be adjusted from the outside. My Ross Cabinet ( 67193) is from the start of the 20th century. I would suggest that all Ross Cabinet lenses after this serial number have the Dallmeyer softness adjustment.

[gtoffoli]

Very interesting, thank’s for sharing this.




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[RJ-]

Hi Steven,

Thank you for sharing your re-discovery of the Ross Cabinet lens adoption of the Dallmeyer patent.

I've always been fond of Ross lenses, probably because of their historical legacy and home in Clapham, London. The company also adopted the Dallmeyer patent for the rapid rectilinear design (after Dallmeyer) which were called 'Rapid Symmetrical' or 'Extra Rapid Symmetrical' lenses.

In the Ross Extra Rapid Symmetrical 12" f5.6 version (following the Dallmeyer patent for the rapid rectilinear), there are markings, worn on my version, making me wonder if I am hallucinating since this was a general and rectilinear all purpose lens. On a different Newcastle & Co produced rapid rectilinear lens, no rear element barrel marking exists.

I wonder if the markings on the Extra Rapid Symmetrical were done by a 19th century photographer trying to turn his Ross extra rapid rectilinear unsuccessfully into a Dallmeyer type petzval

Kind regards,
RJ

[Steven Tribe]

I have a couple of the Ross Symmetrical lenses, which I havn't actually used yet. I'm not quite sure who was first, Ross or Dallmeyer - there were a lot of makers (including Grubb of Dublin) who were marketing this kind of construction.

I know that most paired markings on cells and mounts relate to perfect matched threads as most larger threads were still cut by hand, rather than lathe, in the 1860's. The marks on my late Cabinet could be the same kind of matching thread marks as it would require a very skilled machinist to get the distance right everytime. But the marks would still be useful for graduating how much softness has been selected.

As I grew up in London S.W.17, I know Clapham Common very well! I remember the Common mostly from local newspaper reports about lewd "after dark" activities and parking areas with discarded "French letters"! A very English expression!

[RJ-]

Hi Stephen,

Andrew Ross founded the Ross Company in 1830; Dallmeyer, born in the same year, came to London much later - perhaps 1850s' from Westphalia and apprenticed under Andrew Ross. I think the Balham Optical Company no longer extant) also grew up near Clapham. M.P.P in Kingston Upon Thames was also south of the river, as was Wray, based in Bromley (now a south London borough).

Since you left for Denmark, Clapham's reputation has cleaned up due to real estate and its geographical confluence of trains, commuters and transport serving the south coast. You would still need an extra stop with a noctilux to photograph the common at night, an activity which the local police might help with push-pull processing.

I see some alignment markings for the Taylor Hobson Series III triplet lens too - with the potential for over-turning the alignment mark (by screwing the element in even tighter). I've never noticed these finer aspects of traditional lens design until your emphasis.

Hope to see some of your examples from your Ross Cabinet lens. I think I'm out of whole plate film until the next run unfortunately.

Kind regards

RJ