A. M. lens: Who made it? "W W" code = ???

[Andrew Plume]

as far as I'm concerned, 'WW' is Ross

and Ian, what you've shown earlier today are imo two lenses both made by Ross, they're completely different than those made by Dallmeyer and TTH, I haven't I admit waded back through this post

.....and Pete is of course, spot on

andrew

[Ian Greenhalgh]

Andrew, what makes you think it's made by Ross?

The two lenses are completely different, they both have heavy brass barrels but the design of the barrels has little in common.

I have no idea who made the f4.5/5", it doesn't fit into any of the product lines of any of the makers as far as I can tell. Dallmeyer's version of the 4/4 double gauss was an f6.5 and the closest they made to 5" was 5.25", TT&H's version was an f6.5 too. Wray made a double gauss for aerial use, an f5.6/6".

The closest I can find would be the unsymmetrial f4.5 version of the Ross Homocentric introduced in 1912, and this f4.5/5" is indeed unsymmetrical.

[Andrew Plume]

Ian, thanks

it's the 'sheer design' only, they're way way closer to Ross lenses than the other UK manufacturers. There are plenty of people in the UK who would straight away say that that's 'a Ross lens'

also I go straight to the shape of the barrel and cut out any reference to the likes of 'double gauss' - another indication, to me, for determining which manufacturer is the f stops

information regarding the AM badged lenses per se, is, I understand, not always available and some of it, as has been indicated is open to some doubt, certainly the AM lenses weren't as good quality. as say a 'pukka Dallmeyer lens' - from memory, Steven Tribe has said this on here too

regards

andrew

[Andrew Plume]

anyhow, does it really, really matter who manufactured your lenses?, enjoy them instead.........let us know how they stack up on image quality, post some images too, they always help

regards

andrew

[Ian Greenhalgh]

To be honest, the barrel has almost nothing to do with the origins, I have Dallmeyer lenses with very similar brass barrels.

I'm not going to fall into the trap of making a generalisation not based on facts such as 'AM lenses were of lesser quality', I'll judge each lens based on it's own abilities.

There is absolutely no difference in the quality of the barrels of these AM lenses and 'pukka' lenses of the 1930s, the material is heavy, quality brass, the machining is of the same standard, it's quite surprising considering the need for brass for munitions.

I have several other AM lenses, most notably a Pullin London Pulnar f2.8/4" which was used for a target recognition system that projected silhouettes. I use it as a taking lens on my Century Graphic 2x3 and it is fabulous, sharper than my Schneider Xenar 3.5/105, my Ross Xpres 3.8/105, my Voigtlander Skopar 3.5/105, my Kodak Anastigmat Special 4.5/105, so it is a very fine lens indeed.

So I'm not subscribing to the AM lenses are of lesser quality theory, like any theory it needs to be supported by strong evidence and I haven't found any so far apart from the pot metal my Pentac 2.9/8" is made out of having corroded, but that is hardly unusual for an aluminium alloy of pre-1950s construction and you will find many alloy lens barrels that were nothing to do with the AM with similar corrosion.

[Dan Fromm]

Pot metal is a zinc, not an aluminum (aluminium in Commonwealth countries), alloy.

Ian, the VM mentions an f/4.5 5" WA Xpres. f/4.5 is very fast for a 4/4 double Gauss type wide angle lens. I take it that you decided the lens is a 4/4 double Gauss after counting reflections. Do look again. I make this suggestion because the dim reflection from the glass-cement-glass interface can be very hard to see.

For evidence of this, look at an RF-2,-3,-4 or -5 process lens (FSU lenses). The 1963 GOI catalog says they're 6/4 double Gauss types. Until given this hint neither Arne Croell, who is very discerning, nor I, who isn't always, could see the dim reflection from the inner group. Up to then both of us thought these lenses were dialytes.

[Ian Greenhalgh]

I thought 'pot metal' just referred to alloy of uncertain composition that had been produced by melting down old cooking pots?

Yes, 4.5 is suspiciously fast for a double gauss. I'll see if i can open the rear cell and see if it's a cemented doublet or two airspaced elements. Given that this lens covers 6x17, that seems rather large coverage for a tessar type.

I have a few lenses that I can't figure out the design from the reflections, a S.O.L. 4.5/184mm for instance, it seems to be quite complex as there are a ton of reflections, not been ale to open it and find out for sure. Same with the Pullin London Pulnar 2.8/100, the VM suggests a tessar type, but the reflections don't appear to match other tessars, I'm probably just crap at counting reflectons.

[Andrew Plume]

To be honest, the barrel has almost nothing to do with the origins, I have Dallmeyer lenses with very similar brass barrels.

I'm not going to fall into the trap of making a generalisation not based on facts such as 'AM lenses were of lesser quality', I'll judge each lens based on it's own abilities.

There is absolutely no difference in the quality of the barrels of these AM lenses and 'pukka' lenses of the 1930s, the material is heavy, quality brass, the machining is of the same standard, it's quite surprising considering the need for brass for munitions.

I have several other AM lenses, most notably a Pullin London Pulnar f2.8/4" which was used for a target recognition system that projected silhouettes. I use it as a taking lens on my Century Graphic 2x3 and it is fabulous, sharper than my Schneider Xenar 3.5/105, my Ross Xpres 3.8/105, my Voigtlander Skopar 3.5/105, my Kodak Anastigmat Special 4.5/105, so it is a very fine lens indeed.

So I'm not subscribing to the AM lenses are of lesser quality theory, like any theory it needs to be supported by strong evidence and I haven't found any so far apart from the pot metal my Pentac 2.9/8" is made out of having corroded, but that is hardly unusual for an aluminium alloy of pre-1950s construction and you will find many alloy lens barrels that were nothing to do with the AM with similar corrosion.

thanks Ian

I'll take your word for it Guv, it means very little to me, you have your view, I have mine, it's part of what this Forum is all about

anyhow, what's all this stuff about "falling into a trap", I haven't set one

regards

andrew

[Dan Fromm]

Re pot metal, see http://en.wikipedia.org/wiki/Pot_metal

[Pete Watkins]

Just to lighten this whole subject up a bit. I recently tested a "UU" 14" lens on 4x5 and I can't see how we even won the bloody war. I'm keeping it for soft focus though, it'll never be sharp.
Pete.