Helical focussing mounts in lenses

I see lots of lenses fitted with helical focussing systems. Obviously these lenses are suited for non bellows type cameras. I am interested in knowing, who makes the helical focussing systems? I assume only the manufacturer of the lens... and also, can a helical focussing system be used with any fl lens, or only lenses up to a maximum focal length? I never see them on long fl lenses?

Bill,

I have a helical focusing mount for designed for (and made by)

schneider 150mm apo symmar which I will be using for rodenstock

sironar-N 150 mm with my cambo wide camera. Different lens

manufacturer have different flange focal distance so if your camera

has a fixed distance from your lens panel (ie non-bellows)then you'll

have to make some adjustments. Which I will be doing when I receive

my sironar-N 150mm lens soon.

 

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Renee

Rodenstock makes helical mounts ($380.00 list) for their lenses

in either 0 or 1 shutter.

Bob, is this the determining factor for helical mounts? Will

Rodenstock helical mounts work on Schneider, Nikor, Fuji Copal 0,1

shutters? Are the helical mounts designed specificaly for one

manufacturer? Since the Helical adds glass, any loss in image

quality vs. bellows foccussing with non helical lenses?

There is no glass in a helical focus mount. Both Rodenstock and

Schneider make helical focusing mounts for most of their wide angle

lenses and some lenses up to 150mm. There are many mounts available.

They are specific to focal length and come with the appropriate focus

distance scale.

Bill. A helical focussing mount is just a threaded tube inside a

double-threaded collar, inside another threaded tube. The threads are

opposite handed, and when the collar is turned, the two threads wind

the assmebly out or in to focus the lens, exactly the same as on a

35mm, or MF SLR camera. No optical components are involved.<br>These

mounts become impractical for very long focal length lenses, simply

because of the extension involved, and the leverage of a heavy lens on

the threads.

The old Mamiya Universl (1960's-'80's) system basically used small

view camera type lenses (Very excellent Tessars) in helical mount to

interchange on the same camera body. The Polaroid 600SE being the

final version. All of the shutters were Seikosha 0. The 90 and 100mm

3.5 that was the normal for the system are sometimes VERY cheap on

ebay and would provide a size 0 helical mount and a useable Seiko

shutter if you're in the mood to tinker. The 127 4.7 that the 600SE

used will cover 4X5 about the same as a Kodak Ektar of the same

length. Just throwing out ideas so I won't be the only guy straying

off into weird areas.

Jim, are you suggesting that any helical focussing mount can be used

in any lens that used the same shutter? If so, this opens up a lot

of possiblilities...

"are you suggesting that any helical focussing mount can be

used in any lens that used the same shutter? If so, this opens

up a lot of possiblilities... "

 

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Of course not there is a tremendous difference in flange focal

length between a 35mm Apo Grandagon and a 150mm Apo

Sironar S or N all of which are in 0 shutter.

 

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Then there is the matter of the DOF scale on these mounts.

Again the difference is dramatic.

 

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Then there is the difference in the distance scales. Infinity

comes much sooner for a 35mm focal length.

 

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Bill stop complicating things.

 

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Each focal length lens that fits a helical mount has it's own

helicoid.

 

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Each has a dedicated DOF scale and focus scale. Each is at

infinity when fully collapsed.

 

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The most common helicoids where a single focus mount fits a

wide range of focal lengths is the one for lenses in 39mm or

32mm enlarging lens mounts. These do not have scale, DOF

indicators, etc. They do have extension tubes to allow infinity

focus with longer length lenses or to extend maginfication.

 

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They can not be used with shutter mounted lenses.

 

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Every current Rodenstock brochure for large format lenses in 0

or 1 shutter includes a section on the helical focus mounts for

them.

Rodenstock also has a special brochure for enlarging lenses

used for macro or CCD work in the Macro Focusing Mount.

 

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Would you like these mailed to you?

Bill, No, I was suggesting that someone that wants to tinker on a

budget might start with one of those. I think you'd be married to the

Seiko shutter though, a copal probably wouldn't fit. You'd end up

with adapted old, not pretty new, but all a helical mount does is move

lens glass forward and backward the same as a bellows.

Bill,

 

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I'm not sure what your application is for a helical. Are you just looking for something that moves a lens backwards and forwards to focus it on a ground glass. If that's the case, things like depth of field and distance scales aren't required. Or, are you looking to make a point-n-shoot camera that you will focus based on guestimated distance (like the Linhof 6x17). In this case you will need a helical with the proper distance and depth of field scales to match your lens focal length, as well as the proper mechanical size to match the shutter. You will also need to calibrate the "zero" distance (infinity focus) from the film plane.

 

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On the other hand, if you will have a gound glass to check focus, any helical of the proper mechanical size will do. How close you can focus will depend on the fore/aft travel of the helical. By all means, if you can afford one of the nice helicals from Schneider or Rodenstock get one. They are well made and worth the price (check places like Robert White and Badger Graphics for the most reasonable prices - you should be able to get one in the $200 range). If this is a low budget "experiment", there are cheaper (although less elegant) solutions. In addition to the Mamiya helicals, you might want to watch eBay and the used dealers for a Pentax helical extension tube. This may require a little hacking and will only work with lenses with a small rear diameter, but you might be able to find one for less than $100. Also, the guy who makes the Granview makes helicals to adapt a variety of lenses to his cameras. I have no idea how much they cost, but you might check his web site (I think it's www.granview.com).

 

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Good luck,

Kerry

Kerry, you are on the right track. My goal was to use helical mounts

in 80mm lenses and focus on a gg, so DOF and scales are not the least

bit important to me. So I think you pretty much answered my

question... i.e. If I find a helical mount that will mechanicaly

fit into the lens, then as long as I gg focus, it should work

perfect. Unless I am missing something here?

 

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Bob, thanks for the input, and sorry I complicated things, this is

what happens when one is trying to learn something in an area they

have no experience in. Once I confirm the camera design, I will

take you up on your offer for brochures.

" Unless I am missing something here? "

 

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The most obvious thing.

 

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Infinity focus.

 

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If it is designed for a lens longer then 80mm it won't focus to

infinty.

 

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If it is designed for a lens shorter then 80mm extension must be

added to reach infinity.

 

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Unless you are not interested in infinity focus.

BTW,

 

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Wayne at Casey's Camera on Tropicana can easily help you as

he is a large format expert and uses large format all the all the

time and can also give you instructions on helicoid mounts as

well as retail pricing (I gave MSRP not retail).

 

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He is an excellent resource with large format in stock.

Bob, totally agreed, I should have wrote, any helical mount designed

for the same fl lens I plan to use, that would physicaly fit my

proposed lens, would work perfectly. I assume this is accurate now...

The Rodenstock Helical Focus Mounts are only available for 0

shutters. They are not available for 1 shutters.

So Bob (or anybody), how do you check for infinity focus? I will soon

receive a second hand sironar-N 150mm and I will use a schneider

focus mount for apo symmar 150mm I know it is to do with the flange

focal distance for starters......

Is it or isn't at focus ay infinity when fully compressed?

 

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Don't be sur[rised if it isn't. The Rodenstock lens may have a

different flange focal length and/or a different effective focal

length. If those don't match the mount won;t focus properly.

I'm almost certain that the flange focal length will be different.

The apo symmar is 144.2 the sironar-N is ? When checking focus at

infinity, How do you find whether it is in focus? Try focusing on the

moon at night? Or something really far?

142mm.

 

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You simplt focus on something a few hundred feet away to be

safe.

It sounds like you will need shims to make it work.

Bob, since we are into the 21st century now, how about getting your

company to put these brochures on-line as PDF files?

Posting literature is Rodenstock's business. As we represent 21

different suppliers it would be impractical for us to post all of the

literature from our suppliers.

 

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Some of these brochures total hundreds of pages for just

Kaiser.

 

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But we will mail them to anyone in the US at NC. All you need to

do is ask or call our 800 # 735 4373.

Thanks Bob, you are right, I have to shim because the apo symmar's

(150) flange focal distance is 2.2mm longer. I'll try to adjust the

focusing mount first if possible. There are a few screws around.....