helicoid salvaging

[gunner]

I'm hoping to build a 6x17 panoramic camera using a 210mm Nikkor w lens which covers the format. I'm hoping to scavenge a focusing helicoid from a 35mm format lens as they are so cheap. Am I right in thinking that the longer the focal length of the donor lens the more travel the helicoid will have, plus longer lens tend to be of a greater diameter making it easier to fit the LF lens to it. If someone has tried this combination before is there a particular make/model of lens that was a suitable donor?

 

[Fixcinater]

Yes, a longer focal length lens will necessitate more extension & travel for focus.

Something like a off-brand/no-name 135/2.8 might be a good, cheap potential donor or 200/4 which are similarly cheap especially since you don't need the glass nor aperture.

 

[MattKing]

I would think you would need the helicoid from a larger lens - at east a medium format lens - in order to avoid vignetting.

 

[AgX]

A 210mm lens for LF will need the same extention as a 210mm lens for 35mm film, given that the same minimum focising distance is used. (And given that the 35mm lens is a standard built lens. A lens of tele-construction will need lesser extention.)

 

[Dan Fromm]

Hmm. OP, have you measured the diameter of your 210/5.6 Nikkor-W's rear cell? The brochure says that it is 60 mm. This seems a bit large to fit inside the typical 35 mm camera's focusing helicoid. Hanging the lens in front of one is feasible, but if my experience means anything mechanical vignetting will be a very real possibility.

If you're going to focus on the ground glass, concentric sliding tubes might work.

 

[pdeeh]

I have a fuji 210.
it's not a huge lens, but neither is it tiny. I'd have thought you'll struggle to find a 35mm heli of sufficient diameter?
just a guess really

 

[gunner]

The rear element of the lens measures 62mm, I'm hoping I can find a suitable fast prime lens as some that I've seen have up to 77mm filter threads so I'm hoping with a bit of machining (if necessary) the 210mm lens will fit

 

[Dan Fromm]

Not to be a complete idiot or anything, but why not just get a 5x7 camera and a 6x17 roll holder to fit it? Less work, less joy of making it yourself, more flexibility and possibly less expense than DIY.

 

[gunner]

Not to be a complete idiot or anything, but why not just get a 5x7 camera and a 6x17 roll holder to fit it? Less work, less joy of making it yourself, more flexibility and possibly less expense than DIY.

I sometimes wonder myself when I start these projects, but I have a 5x7 camera already and I have made my own back for it that lets me shoot 6x17, but its quite a lump to carry about and setting it up is not quick. The camera I'm looking to replicate is something like a fuji gx617 or linhof technorama: comparatively light, quick to set up just about handholdable at a pinch. Over the years whenever I've bought a lens for my 5x4 photography I've always made sure it covered 5x7 and 6x17 so I've got the lenses. If you look at the price of secondhand fujis or linhofs with a long lens prices seem to be anywhere from £2500-£5000. I'm hoping I can make something along those lines for £100, thats a big saving

 

[John Koehrer]

Also consider the depth of the rear group. You can buy from the bay individual helicals
that should be large enough diameter for you.

I modified one with the shutter mount section from an RB lens (00) but the rear diameter is ~2 3/8"
front is 2 11/16" travel is 5/8-7/8"

Long time ago I was doing something along the same line.......Lost interest, any need for a helical?