BIG lenses . . . but what were they for?

[Nas]

The f-stop engravings have been added later. Note the similarity in the adjuster, so looks like the aperture diaphragm was retro fitted by the Dallmeyer factory.

That was my point above. The quality of the work done to blank off the original waterhouse slot is superb. You have to look very closely to even notice. That kind of quality work must have been done by the Dallmeyer factory. The aperture control tab has the Dallmeyer arrow too.

 

[Nas]

I think the flange is possibly the 3" RPS standard, I have an unknown make 20" f8 RR & a T.T.&H f8 RR marked 12"x10" and Eq Focus 18.44 in, both fit the same 3" flange, as does a 1950s coated 12" Wray Wide Angle lens.

Ian

My issue is that most of my lenses which have flanges are larger than the 3" RPS standard.

 

[Nas]

The scale is rather odd, starting at 7.5, the Dallmeyer 15x12 RR is a 19½" f8 lens.

The pencil markings seem to indicate someone calculating the correct f-stop positions. I guess the next question is whether the lens is still as original, optically.

Ian

I don't know whether my lens somehow became faster after the internal Waterhouse slot mask was removed, changing it from f8 to f7.5? That makes sense to me. What's very odd is someone indicating f25 is more like f16 (more than a whole stop difference) then it jumps from f25 to f50.

 

[Ian Grant]

I don't know whether my lens somehow became faster after the internal Waterhouse slot mask was removed, changing it from f8 to f7.5? That makes sense to me. What's very odd is someone indicating f25 is more like f16 (more than a whole stop difference) then it jumps from f25 to f50.

I compared the lens to my 20" f8 RR, I bought it from a Polish seller who had travelled to the UK to attend a Wolverhampton Camera Fair. It appears to be British made.

Looking and comparing the aperture scales the engraved ones are very odd.

Yes, the R.E. is Royal Engineers. Engraved to the underside is 'ICST (Imperial College of Science & Technology), R.C.S. (Royal College of Science) Ast. Phys. Lab. (Astro Physics Laboratory)'. My lens has had an interesting history and I can't wait to use it on my 12x10 camera after I have a flange made. It's the added aperture control that sold it to me. I can't find any information online of another one like it.

I think the secret is in that history, that in itself seems to indicate optical modification. You need to compare front & rear cells, stick it on a camera.

BTW, I have 2 or 3 spare flanges, that don't fit any of my lenses



That does not include 4 or 5 T.T.&H medium-sized flanges, they sell for premium prices..

I don't have a spare 3" RPS flange, knowing your lens diameter is 2½" it shouldn't be larger than a 3" flange. I have larger just ask .

Ian

 

[MartyNL]

I don't know whether my lens somehow became faster after the internal Waterhouse slot mask was removed, changing it from f8 to f7.5? That makes sense to me. What's very odd is someone indicating f25 is more like f16 (more than a whole stop difference) then it jumps from f25 to f50.

This looks interesting, here is the source;
https://camerosity.wordpress.com/contents/f8-and-be-there-fstop-numbering-systems/

 

[Nas]

I compared the lens to my 20" f8 RR, I bought it from a Polish seller who had travelled to the UK to attend a Wolverhampton Camera Fair. It appears to be British made.

Hmmm, I think I may have bought some Linhof dual format film/glass holders from the same seller if it was many years ago. I used one last weekend to test some Ilford Panchromatic glass plates which were sealed. At ISO 5 they look amazing, factory fresh

Looking and comparing the aperture scales the engraved ones are very odd.

I agree but I trust Dallmeyer to know what they were doing

I think the secret is in that history, that in itself seems to indicate optical modification. You need to compare front & rear cells, stick it on a camera.

I'll stick it on a camera when I have a flange for it which won't be for a little while. I don't mind about optical modification as long as I like the image I see on the ground glass screen

That does not include 4 or 5 T.T.&H medium-sized flanges, they sell for premium prices..

I found that out when I sold off all my T.T.&H flanges I got in the big mixed box. Those were the first ones I picked out including a set of reducing adapter rings. The buyer was very pleased

I don't have a spare 3" RPS flange, knowing your lens diameter is 2½" it shouldn't be larger than a 3" flange. I have larger just ask .

I've been told my 15x12 lens thread is 3 1/4". Funnily enough there's a T.T.&H engraved adapter ring firmly attached to it. Hopefully that will come off in one piece. We shall see.

 

[Nas]

This looks interesting, here is the source;
https://camerosity.wordpress.com/contents/f8-and-be-there-fstop-numbering-systems/

Excellent. This matches with the handwritten f-stops or near enough. Thanks.

 

[AnalogueWendy]

The 36" Wray lens you have there looks exactly like a scaled up version of my Ross London 24" again F/6.3, my guess is they use the same lens formula but just scale it up. Mine came in a wooden case. It must be massive as I thought mine was pretty heavy at 8Kg.

It's huge, yes. Not as heavy, although I don't entirely trust my scales!
Still have not made the drive down to Newbury to drop it off.
I found another one in the meantime . . .

 

[Marley's Ghost]

I have the self same 18 !/2 inch Aldis

 

[HowLarge]

Ok so is there any sense in creating a stereo view camera with the two Aldi?
Or would the lens board apprentice just faint…