A shutter for barrel lenses

[AZLF]

I read a post a few days ago which about what different people use as a shutter for barrel lenses. Someone suggested that it would be a good thing if someone came up with a shutter that could be used with these lenses and it got me thinking about the situation. I work for a company that does initial design of both mechanical and electro-mechanical devices. We have a full machine shop and people who spend their days thinking about similar projects. My current project is a medical device for testing the nervous system. All the basic design work has been done and I am working with the approved prototype to set up the initial production run. This device has three hand held sensors that feed data into a PDA which records the data on a smart card (SD) which is then inserted into the doctor's computer for analysis of the data based upon a program developed by one of our inhouse EEs.

I don't own any barrel lenses as none of my lf cameras(4x5") have a fp shutter and I did not see any need to purchase such a lens when I bought my gear. So I have a few questions for those who do own and use them.

1. My Schneider Super Angulon 90mm and my Zenar 210mm both protrude into the camera body at least an inch and in the case of the 90mm probably closer to 1.5". Do barrel lenses do the same? If so is there any standard length or does it vary with the focal length?

2. Is there a maximum intrusion length I could use in my intitial design stages?

3. Would it horrify the lf and ulf crowd were I to design a shutter using digital technology for the timing of a mechanical shutter? Personally I find the concept amusing in that the ultra modern digital technology would be serving the analog image maker.

I'm so far thinking along the lines of a "Galli" type shutter(see the above mentioned thread) with two thin metal plates held together on one side just in front of the rear element and opening by one plate being pulled up and the other pulled down to open an angled opening wider than the rear element of the lens. Digital circuitry would be used to set the varying times settings for the shutter to remain open. Possibly the shutter plates would be pulled open by solenoids but I have to come up with a way to buffer the attendant vibration.

The problems I envision so far are that the shutter must be very close to the rear element and there must be a cover of some sort over what ever depth the lens intrudes into the camera body to keep light from bouncing off the rear of the shutter and possibly making its way to the film. In that the length of that intrusion will vary then the shutter mechanism must be built on a length ajustable frame to account for the varying lens depths. And the entire shutter mechanism would have to be installed on the rear of a lens board.

So far I don't see a problem that is insurmountable but that might easily be because of my ignorance of barrel lenses.

A little help please.

The original post: (there was a url link here which no longer exists)

 

[bobfowler]

<snip>

I don't own any barrel lenses as none of my lf cameras(4x5") have a fp shutter and I did not see any need to purchase such a lens when I bought my gear. So I have a few questions for those who do own and use them.

1. My Schneider Super Angulon 90mm and my Zenar 210mm both protrude into the camera body at least an inch and in the case of the 90mm probably closer to 1.5". Do barrel lenses do the same? If so is there any standard length or does it vary with the focal length?

No, there is no standard. I have lenses that go back 4 inches, some that are flush with the mounting ring.

2. Is there a maximum intrusion length I could use in my intitial design stages?

It would make more sense (to me) if the shutter had a largish opening with an easy to fabricate front mount system That way, lenses that needed a lot of depth could be made on extended mounts.

3. Would it horrify the lf and ulf crowd were I to design a shutter using digital technology for the timing of a mechanical shutter? Personally I find the concept amusing in that the ultra modern digital technology would be serving the analog image maker.

Not at all. Melles Girot (sp?) still makes electonic shutters that are identical to the old Ilex electronic units. They are expen$ive, as are the controllers.

I'm so far thinking along the lines of a "Galli" type shutter(see the above mentioned thread) with two thin metal plates held together on one side just in front of the rear element and opening by one plate being pulled up and the other pulled down to open an angled opening wider than the rear element of the lens. Digital circuitry would be used to set the varying times settings for the shutter to remain open. Possibly the shutter plates would be pulled open by solenoids but I have to come up with a way to buffer the attendant vibration.

Along those lines, it would be simpler to just buy an electric Packard and make the electronic control circuits to get the desired shutter speeds. That way, you wouldn't be reinventing the wheel...

The problems I envision so far are that the shutter must be very close to the rear element and there must be a cover of some sort over what ever depth the lens intrudes into the camera body to keep light from bouncing off the rear of the shutter and possibly making its way to the film. In that the length of that intrusion will vary then the shutter mechanism must be built on a length ajustable frame to account for the varying lens depths. And the entire shutter mechanism would have to be installed on the rear of a lens board.

This is why I think it would be better to make a housing that had interchangable front plates which could be made in different sizes to work with different sized lenses.

So far I don't see a problem that is insurmountable but that might easily be because of my ignorance of barrel lenses.

A little help please.

No, not insurmountable, but it could be an interesting project. BTW - pardon my typing, this laptop's keyboard is a piece of crap...

 

[AZLF]

I'll have to think a bit about your suggestions. Off the top of my head what I don't want to do is base the design on using a dwindling supply of existing shutters. And I agree that much of what I would be doing has been done. However as I do a mental checklist of parts needed so far I don't see large amounts of money being needed for the raw materials including the speed control circuitry. 555 timer ic's are dirt cheap. Ditto fixed r/c timing designs.

This bone will take a good deal more mental chewing before tooling hits the metal.

 

[John Bartley]

Front mounted and electronically controlled ... a while ago, someone posted about a "falling leaf" shutter with different sizes of slots to adjust exposure as the rate of fall was constant (gravity)
So ...
Why not leave the shutter slot size constant and control the speed by moving the shutter leaf horizontally across the front of the lens with an electronically speed controlled motor??

just a thought

 

[Flauvius]

With the avaiablilty of Sinar auto shutters, the need for an universal barrel lens shutter is limited to lenses that are larger than 82,65mm.

As is the case with Sinar auto shutters, the logistics of sealing the rear element of a lens to the front stanrdard requires an integrated system. In particular, the front standard of a large format camera has to interface with the rear of a shutter. Given the multitue of front standard sizes, a threhsold concern is designing an interface that is not stanrdard dependent.

The upshot of all this is: a standarized > 82,65mm barrel shutter does not seem like something that is feasiable and the cost of custom fabricated shutters would seem to be prohibitive.

Flauvius

 

[David H. Bebbington]

As no one seems to have heard of it, I attach a picture of the Day shutter I mentioned earlier (the model I have is combined with the universal iris-type lens mount and will work with lens barrels up to 80 mm - I attach the shutter to the front of the lens, I could also have mounted the shutter on a panel and then attached lenses to this):

 

[AZLF]

As no one seems to have heard of it, I attach a picture of the Day shutter I mentioned earlier (the model I have is combined with the universal iris-type lens mount and will work with lens barrels up to 80 mm - I attach the shutter to the front of the lens, I could also have mounted the shutter on a pnael and then attached lenses to this):

It looks perfect. It also looks from the illustration that it hasn't been made for quite some time. Is it currently available other than as an singular oddity on ebay or some other online auction house?

 

[David H. Bebbington]

As you can see, Day was going great guns in 1958 but (I think) went out of business a short time later. There must be quite a few examples of this shutter still around, they do not have a maker's name on them and so will not be advertised as Day shutters - general second-hand dealers may not even recognise them as shutters at all. I got mine on e-bay 2 or 3 years ago in a job lot called "Antique camera parts" or something, it was together with a Newman guillotine shutter (check that one out for weirdness!) plus some wooden half-plate film/plate holders and the whole lot was £50 or so. The Day shutter was working but a bit dirty, I sent it to Newton Ellis in Liverpool for a service (they are very good with old/weird stuff) and it's been great ever since.

Regards,

David