Help with a nice old Wray lens please ...

[pdeeh]

This has recently come into my possession. Pity it's not for 8x10, but for nothing one can't be picky.

I know there were zillions of lenses made early in the last century, but it would be nice to know any further details than the obvious ones.

Engraved "Wray London 5x4 No 3170" & aperture scale f/5.6 to 64

Two elements which both unscrew and appear interchangeable. 10 bladed iris. Homemade lensboard as you can see.

The focal length seems to be 5" (estimated by ruler and sharpness of image thrown on the wall )

If I remove one element, it still seems to throw a decent image and the focal length is doubled.

Am I correct in thinking this is a "rapid rectilinear" type?

Any ideas as to age?

Any further information?

 

[Dan Fromm]

It might be a Wray Portrait RR. Serial number, maximum aperture, and plate size are consistent with this. If it is a Portrait RR, each cell will be cemented doublet, concave to the diaphragm and convex to the end of the barre.

Pretty thing, innit?

 

[pdeeh]

Thanks Dan and yes, it is impossibly cute!

The cells are convex/concave exactly as you describe, but I simply don't know enough about lenses to establish their construction.

 

[Ian Grant]

I'm surprised you think it's 5", I have a Wray RR f8 - f64 marked 8x5 and it's a 300mm/12" lens. The quarter plate and 5x4 versions were f5.6. the Wray advert I have doesn't state the actual focal lengths.

Ian

 

[pdeeh]

With both cells tightly in place, and the aperture fully open, when it projects a sharp image of a distant object on a ground glass, the rear cell is approximately 5" from the image plane.

I have always assumed that this sort of procedure would more-or-less accurately assess the focal length of a converging lens so long as the object is sufficiently distant. Obviously it won't work if you choose an object a only a couple of feet away.

I'm happy to be corrected (though of course I'll be embarrassed to appear so dim if I'm wrong).

 

[Ian Grant]

With both cells tightly in place, and the aperture fully open, when it projects a sharp image of a distant object on a ground glass, the rear cell is approximately 5" from the image plane.

I have always assumed that this sort of procedure would more-or-less accurately assess the focal length of a converging lens so long as the object is sufficiently distant. Obviously it won't work if you choose an object a only a couple of feet away.

I'm happy to be corrected (though of course I'll be embarrassed to appear so dim if I'm wrong).

It's a symmetrical lens so add possible an inch maybe a bit more because it's the nodal point, the optical centre of the lens between the cells that you need to measure from.

RR lens for 5x4 were typically a bit longer than 6" and you'll have a difference when you focus at 20 -30 ft compared to a few hundred feet.

Ian

 

[pdeeh]

I'll check it again tomorrow Ian ... bit dark at the moment to focus on the local trig point

 

[pdeeh]

Well, this morning I've used a line of trees about 2 miles distant as my object, and the focal length seems to be 5½".

Even allowing for discrepancies in parallelism between lens board and ground glass, my eyesight and judgment about where the nodal point lies, the focal length must be no less than 5" and certainly not longer than 6"

 

[Ian Grant]

Wray made a 5½" f5.6 RR for Quarter plate cameras this may well cover 5x4 in terms of sharpness when stopped down to f16. it's possible it's marked 5x4 as that gives room for movements,. I just checked and my unnamed 5½" f8 RR does cover 5x4,

I can find adverts for SH cameras fitted with Wray 5½" RR's all are quarter plate cameras though as are similar Focal length RR lenses from their competitors.

5x4's of the era your lens was made were usually fitted with 6", 6½" or 7" lenses. My 8x5" Wray f8 RR is of the same series as yours SN. 2107 so I was quite surprised mine is 12" and only covers Half plate (according to the marked 8x5).

Dan's the has more knowledge in these matters but often stated/marked coverage is about sharpness and what was deemed acceptable at the time, criteria changed when enlarging became more common and plate/film emulsions improved.

Ian

 

[pdeeh]

5x4's of the era your lens was made were made ...

Which era is that Ian?

 

[Dan Fromm]

Which era is that Ian?

PMFJI. Per P-H Pont's Wray chronology, mid-1890s.

 

[pdeeh]

I had to google PMFJI

Thanks, that's a bit earlier than I had assumed. The glass is in pretty good shape, hardly marked at all.

I'll make some mods to my 5x4 sliding box and mount it and make pictures with it I think.

It came from the bottom of a cardboard box along with a multitude of other elderly photographica that I cleared from a friend's grandfathers' darkroom. He died about 40 years ago. I also have dozens of lantern plates, many stamped with dates in the 40s and 50s, boxes and boxes of what may be prewar paper, and a handful of Thornton-Pickard wooden plate holders. I couldn't fit all the beautiful Ensign-brand ceramic developing dishes into the boot, nor the enormous roll of Ferro-gallic paper or the huge magic lantern (or maybe it was an enlarger? I couldn't crawl under the bench to look properly) either ...

 

[Ian Grant]

Wray changed the way their diaphragms worked from a pin to a revolving ring at some point after 1897/8, actually it may have been slightly later as a 1900 Xmas magazine adverts show the pin instead of the ring.

The Vade Mecum is a bit woolly with regards to these lenses as, they state "One has been noted at No 210x with Waterhouse stops" note mine's SN. 2107 and Wray's own adverts 1897/8 show they were available with either Waterhouse stops or an Iris diaphragm.

Ian

 

[pdeeh]

Rather a late followup question in case either of you are still subscribed to this thread, but ... what sort of shutter would have been used with this lens? (Assuming one simply didn't use one's top hat)

I note that the rear cell has a thread rather like a filter thread - for what purpose?

 

[Ian Grant]

The rear thread isn't relevant it's how it's assembled.

Your lens was fitted to a Thornton Pickard roller blind shutter in fact it's still fitted to the front panel of a "Between the Lens" type. These allowed the shutter to be used with more than one lens, you just switched the panel. The shutter itself was screwed to the lens board.

This is my 8x5 Wray fitted to my Houghton Duchess.

Ian

 

[pdeeh]

thank you Ian, I wondered if the answer would be a a TP type

However I'm not sure what you mean by

The rear thread isn't relevant it's how it's assembled.

The rear cell has a male thread that screws into the mounting flange, but at the rearmost of the cell there is a female thread (see arrow in attachment); it's this I am referring to.

 

[Dan Fromm]

The rear cell has a male thread that screws into the mounting flange, but at the rearmost of the cell there is a female thread (see arrow in attachment); it's this I am referring to.

Female threads like the one you asked about are there for several reasons. The most likely is that the rear group/element's retaining ring screws into it. The next most likely is for a rear mounted filter. I have several TTH lenses that are threaded internally at the rear; with them the threading seems to be there to tame glancing reflections from the barrel.

I've had SKGrimes take advantage of some of my lenses' rear internal threads for mounting lenses on boards (retaining ring screws into, not onto, the rear of the lens) or in front of a shutter (adapter screws into ...)

 

[pdeeh]

Ok thanks

 

[pdeeh]

I finally got round to trying this in my 8x10 box camera with only the front cell in place. It seems to cover OK, perhaps a little falloff in the corners, and doesn't seem too soft or otherwise distorted at the edges either - perfectly adequate for the sort of photographs I take anyway.

Of course half way through the first exposure (I was using paper negs) I realised that by doubling the focal length, the f/stops indicated on the barrel are no longer accurate.

Using N=f/D, for the lens with both cells in place (i.e. at its "native" focal length of 5½"), I calculated that at the maximum stop of f/5.6, D should be ~1" - this agrees with my estimate with eye and ruler.
So by iterating that calculation, I can estimate diameter D for each marked stop (I think) and use those numbers to further calculate the new equivalent f/stop scale for the doubled focal length when I only use one cell - which seems to be 2 stops.

5.6 = 11
8 = 16
11 = 22
16 = 32
22 = 45
32 = 64
45 = 90
64 = 128

Am I on the right track, or am I driving off the end of the pier?