617 Panoramic camera concept. Gethering opinions.

[Lachlan 717]

Getting back to the design, why do you have both rail focus AND helical focus?

[SuperK]

Thanks, Joseph! Making the camera for film back which can be bought is a nice idea, I like it. I do understand that would make the designing and production much more easy.
In my concept each lens has it's own scale-focusing devise, mounted on lens board. The scale on those Chinese helicoids is different, depending on the lens. When you buy this helical on ebay, you must define the focal length. This focusing devices costs about 100$.
Concerning the camera - don't expect it soon (if I decide to make it), I'll be busy for a long time.
That's a good time for making your own camera now, due to CNC and 3d-printers. I'm a 3D CG-artist, that can help me somewhat.

[jb7]

My point was that you don't need a helicoid focusing device at all, given that you can position the lens along the rail, you can scale directly on the rail. I've used a helicoil on a 4x5 p&s, it really is less than satisfactory, if you need quick focus, there is a better way...

[SuperK]

Getting back to the design, why do you have both rail focus AND helical focus?

Oh, you misunderstood the main idea. The rail serves as main constructive element, holding Standarts. Standarts are moved by the rail quickly (rapidly!) for corresponding lens position, set by stoppers.
Focusing devices on lens board are used when you need to focus closer then infinity. Just as if it was Fuji GX617, Linhof 617, Fotoman, Horseman camera.
I replaced the rigid cameras cones (and their dissadvantages) with rail+belows.

[SuperK]

My point was that you don't need a helicoid focusing device at all, given that you can position the lens along the rail, you can scale directly on the rail. I've used a helicoil on a 4x5 p&s, it really is less than satisfactory, if you need quick focus, there is a better way...

I used stoppers for quick positioning the Standarts. But stoppers won't allow me to focus closer then infinity (lens must go forward for this) when I need this. You say me to use marks on the rail, or I misunderstood? Stoppers on the rail are faster and more precise, and secure.
About the helical. I use scale focusing on my Chinese DaYi/Gaoersi and I should say that I'm absolutely happy with this type of focusing and I never miss.

[Jac@stafford.net]

I used stoppers for quick positioning the Standarts. But stoppers won't allow me to focus closer then infinity (lens must go forward for this) when I need this. You say me to use marks on the rail, or I misunderstood? Stoppers on the rail are faster and more precise, and secure.

Two alternatives: 1. if you use round rails, you can precisely and cleanly mark infinity positions by using a small pipe cutter to make shallow surround marks on the rail or 2. make click stops using #1 with a small spring and steel ball in the standard.

[SuperK]

I have shot my 58mm XL on 6x17 (Shen-Hao 617PTB). It covers, barely, and only if perfectly centered. With the CF the very edge of the sides get a bit cut off. Maybe 2-3mm each side.

The 47mm XL has the same coverage, from the specifications anyway. I put it on the camera and it seems to be the same as the 58XL in terms of coverage. Haven't actually tried it.

I like the concept, but, I wouldn't buy one unless it was cheap. I did setup my Shen-Hao for "handheld shooting" once, but screwed up the focusing (bumped it or something). I need to make proper infinity/20ft/10ft markings or something as mentioned and try again.

That said, I had more fun / better success using 35mm film in a 6x12 back (uh, 35x112?) with super-wide lenses. I used a 38mm XL* to much success. Of course you get sprocket holes - unless you buy unperforated bulk film! Much smaller, lighter, and easier to handle too, using that back on my Chamonix 4x5 or Linhof MT and a flash bracket as a handle for the Cham.

*In this configuration, it is equivalent to a 58mm on 6x17 (same angle of view). So it seems quite well suited to your usage.

Whah, Corran! Thanks for your comment.
I was (and still) afraid that the markings on the Shen Hao railings can be not that accurate and can have some shift. But you use PTB version, so you need to Zero out your camera each time.
I also try to make the concept very simple, so it can be cheap. If I'll make it for removable film back, it would be Shen Hao film back.
Maybe it also can be used hand-held. Why not make a removable butt on the end of the rail .

[Corran]

Certainly there are issues with the idea of marking the "stops" - not least of which is the variable standard placements, both front and back.

Usually when I've done handheld panoramic stuff, I don't ever change lenses - I just setup the camera at infinity and focus a little closer for roughly ~10-15ft, stop down to f/22, and hope for the best. The time with the 6x17, I was focused more like at 3ft, which didn't work out too well with subjects 50ft away!

Also, regarding the PTB, I've been having a ton of trouble with my 72XL and side-to-side parallelism. It's hard to focus at the extremes of the image circle, and so several times I've had images where the plane of focus was way out of whack due to the front / rear standards being not parallel, despite trying my best to align them. Probably the back is my thinking, due to their design. I have some ideas about how to "anchor" the standards on the Shen-Hao and Chamonix, and sometime next year I'm planning on commissioning a custom camera from Chamonix with some of these design ideas...

If you are interested, here are some of my recent blog posts with panoramic images and thoughts, especially regarding my experiments with 35mm film in a 6x12 back:
http://valdostafilm.blogspot.com/search/label/Panoramic

[Jac@stafford.net]

Also, regarding the PTB, I've been having a ton of trouble with my 72XL and side-to-side parallelism.

As long as we are blue-skying ideas, if parallelism is an issue why not replace the bellows with three pieces of tubing that slide inside each other to telescope, guided along a single rail? Eliminate movements altogether.

Sorry for the poor quality pictures taken before good digital cameras were made. (Apple QuickTake 100). Photos show all steel and alloy 4x5 Printex cameras. It was fantastic when Kodak HSIE was still available.

http://www.digoliardi.net/printex-2.jpg
and another modified for 3" Biofon
http://www.digoliardi.net/printex-mod.jpg

This one uses one tube inside of the body extension. Your camera would use three tubes to allow different lenses. The lens 'board' is an aluminum disc exactly the size of a CDROM, attached by three screws which could be wing-nuts instead.

[Lachlan 717]

You can use a small block of wood to align the standards. As long as it's square (not difficult with a table saw) and thin/wide enough to fit under the bellows, you can wind the standards together. As long as one standard is not tight, it will swing into parallel as the standards wedge the timber together (hope that this makes sense!)

I do this following a similar issue with my 72mm as Bryan describes.