Large Format Lens Thread Size

[larry_menzin]

I am new to LF and have a question about LF lenses. My application is

to screw a LF lens into an M39 (39mm) threaded tube. Do LF lenses

have screw threads that I can use? What is the thread size of a lens

like the 150mm Sironar or 180mm Sironar? Are there standard rings

available to adapt existing LF threads to M39?

[btmuir]

Most LF lens are mounted in Shutter so you have to figure what kind of shutter is fitted to a particular lens. Every shutter I've seen has threads on the rear flange that ussally takes a retaining ring or "jamb nut" for mounting to a lensboard. Are you trying to mount a longer lens for the amount of bellows extension or what?? cause I don't know why you'd mount a lens to a tube. Can you explain the application you are attempting??

[larry_menzin]

My application is mounting a LF lens to a Zork tilt tube to get movements on my Pentax 67. The Zork tube has M39 threads. I'm now using a 135mm Rodagon enlarging lens and want to try a 150mm or 180mm Sironar. Do the Copal 0 and Copal 1 shutters have standard thread sizes for mounting? If I remove the shutter (which for my application is not really necessary unless I'm using flash), what does the lens have for mounting threads?

 

I am an MF shooter with no knowledge of LF lens mechanics and this information does not appear readily available.

[michael_briggs2]

<p>You can find a table of threads for Copal shutters at <a href="http://www.skgrimes.com/products/">http://www.skgrimes.com/products/</a>. The mounting threads of a #1 shutter have a 39 mm diameter, but the thread pitch is different from enlarging lenses. Most shutter mounted LF lenses have two lens cells, one in front of the shutter, one behind. Frequently the rear cell has a cone shape and sometimes has a maximum diameter that is larger than the mounting threads of the shutter. This isn't a problem when mounting the lens to a lensboard because you unscrew the rear cell to pass the shutter through the thin lensboard, then screw the rear cell back on, but might be a problem for mounting the shutter to a tube.</p>

[thomas_vaehrmann]

as already said, the treads of shutters and enlarging lens- barrels are different, get a process-lens like Apo-Ronar or G-Claron. They are small and will fit. The barrel of the 210mm G-Claron has E39 thread and will fit but the rear lens might be to large. 300mm Apo-Ronar comes in shutter size 1 and can be screwed in barrel of an enlarging lens which will have E39 too. Perhaps it will fit in your Rodagon-barrel. Smaler ones like 150mm Apo-Ronar come in shutter-size 0 or barrel with app. 25mm and can be adapted since that is an enlarging-lnes thread. 300mm-process-lenses are still in shutter-size 1, everything longer needs 3, smaler ones are still size 0. Try and play around.

[s.k. grimes inc]

Good Day Larry,

 

The following link shows how to specify a thread diamter and pitch. http://www.skgrimes.com/adapter/measure.htm

 

M39 generally refers to a thread with a 39mm OD (outside diameter) and a 1.0mm pitch. The Copal 1 shutters features a 39mm OD with a .75 pitch.

 

If a stock extenstion tube cannot be located,

 

-threaded adapters can be made to utilize your existing tube. However, since the thread diameters are nearly the same, your tube may need to be bored out and rethreaded with a larger thread. A step down ring can then be machined to accomidate the desired 39x.75.

 

-you could have a custom extension tube with the correct thread machined.

 

-you can elimate the threads on the tube all together. The jam nut /retaing ring for a Copal 1 shutter requires a hole 41.8mm in diameter. Your tube could be bored to that diameter and then the lens mounted to the tube using a retaining ring.

 

 

In regard to " If I remove the shutter (which for my application is not really necessary unless I'm using flash), what does the lens have for mounting threads? "

 

See http://www.skgrimes.com/products/index.htm for Copal shutter mounting thread specs. If you do remove the shutter from the equation, you will need the lenses' original barrel or a spacer to locate the optics the correct distance from each other. Otherwise, all you have is two loose cells.

[larry_menzin]

Thanks to everyone for the info. This problem is turning out to be more complicated than I thought. A Ronar 150mm F9 process lens is an intriguing idea, except that I think its image circle is relatively small (~130mm), leaving limited movements for a 6x7 camera.

 

Another idea is to use a LF lens (150mm Sironar-N) and the following adapter:

 

Schneider 0 to Leica Mount Adapter for Enlarging Lenses (Adapts M32.5 to M39 Thread) Mfr # 92010711 ? B&H # SCLAM32.5

 

The question is if the M32.5 thread on a Copal 0 will fit this M32.5 ring (do they have same thread pitch?). Murphy's Law states that they don't since Copal 1 and Leica have the same diameter, but different pitch.

 

Is there anything else I am missing here?

[dan_fromm2]

Larry Menzin stated:

 

"<snip> A Ronar 150mm F9 process lens is an intriguing idea, except that I think its image circle is relatively small (~130mm), leaving limited movements for a 6x7 camera."

 

Larry, the 6x7 negative will be somewhere between 56 x 68 mm to 56 x 72. Diagonal around 90 mm. Sorry, I don't have the P67 gate specs ready to hand. A 130 mm circle will offer you considerable movement. I've seen a Zoerk tube, all it will give you is tilt. No shift or rise.

 

If you need more coverage, consider getting a wide angle plasmat type process lens. For example, 150/9 Staeble Ultragon (also badged Eskofot Ultragon,Helioprint, & Repromaster) or 150/9 Konica Hexanon GRII or a G-Claron. And there are others. These things work well at distance, cost little, and have considerable coverage. You'll need a threaded adapter for either to attach it to a Zoerk whatsit, skgrimes has made similar devices for me at reasonable prices. I have a 150 GRII, its rear is M46x0.75.

 

He also suggested:

 

"Another idea is to use a LF lens (150mm Sironar-N) and the following adapter: Schneider 0 to Leica Mount Adapter for Enlarging Lenses (Adapts M32.5 to M39 Thread) Mfr # 92010711 ? B&H # SCLAM32.5"

 

and asked "The question is if the M32.5 thread on a Copal 0 will fit this M32.5 ring (do they have same thread pitch?)."

 

If you want to try that, the first question to ask is whether y'r 150 Sironar N's rear cell will fit inside an M39 tube. I suspect the answer is NO. If so, end of that idea.

 

Adam suggested one way to use, e.g., a Sironar-N, on your Zoerk gadget. Remove its cells from its shutter, put them in a barrel the right length and with a diaphragm, and attach the rear cell to your M39 tube. This will let you use, e.g., a Sironar-N, but will probably cost more than using a wide angle process lens.

 

You might widen your horizons a little. Dagors and similar double anastigmats were offered in barrels. Cooke Aviars too, also many flavors of Tessar, and no doubt many others as well. Look for a taking lens in barrel, they exist. Starting with a lens in barrel will save the expense of having a barrel etc. made.

 

Good luck,

 

Dan

[larry_menzin]

I ended up finding a 150mm G-Claron and a 105mm Staeble-Magnogon in an EBay auction. These both appear to be process lenses. The 150mm G-Claron has an M32.5/0.5 thread that I can adapt using the Schneider 0 to Leica adapter. The 105mm appears to have an M33.5/0.5 thread that would appear to require a custom ring. The rear cells of both lenses easily fit into the M39 tube.

 

Another lens that might be of use to me is the old 150mm Symmar convertible, except that it seems to come only with a Copal 1 equivalent shutter. Is it possible to find these lenses in a Copal 0 configuration, or as a barrel lens? I am still looking for a 150mm and higher LF lens with a rear cell smaller than M39 and fitting into a Copal 0. Process lenses are great for macro but are not optimized for infinity.