Will this work as a shutter?

[eddie]

Holy crap - 3:30 A.M. ! I better get to sleep!!

har har har! it is 9:30 am here...sucker!

[Richard K.]

har har har! it is 9:30 am here...sucker!

Er, Eddie, I don't know how to quite tell you this...but...we live in the same time zone

[Richard K.]

Getting back to the original thread...

Would a falling slit not produce uneven exposure top to bottom due to the different slit velocity due to gravitational acceleration? This could be minimized I suppose the more one starts the slit above the lens but there will still be a difference. Is this not a visible (on the neg) problem?

[Len Middleton]

Richard,

There is the Jim Galli patented shutter, see: http://www.apug.org/forums/forum44/2...ll-please.html

I have no affilication with the gentlemen, nor know what his current royalty rates are for useage / reproduction of his device.

Regards from just down the road,

Len

[Paul Fitzgerald]

"Would a falling slit not produce uneven exposure top to bottom due to the different slit velocity due to gravitational acceleration?"

That's where the rubber bands come in, evens out the acceleration and allows for faster speeds with the larger sized slit.

[SAShruby]

Er, Eddie, I don't know how to quite tell you this...but...we live in the same time zone

He must be in Europe

[Don7x17]

Outstanding Don. The shots and the aparatus! So, how does one adjust for:

a.) barrel diameter (my lenses vary from about 2.5" to 5.5" (19" Sigmar)
b.) slit width (shutter speed)?

Then:
Where, how, does one get one (is this a Ron Tinchner (?) Shutter) or is this home-made?

Many thanks for the reply, Don. This may be exactly what I need and I love the fact that it's gravity powered!

Holy crap - 3:30 A.M. ! I better get to sleep!!

This was a prototype. Ron (Lee) is working on an improved version.
Barrel diameter could be easily solved by a softwood ring on the backside with three nylon screws (a technique for many filter holders).
Changing slit is done by changing the ratio of the two cards that form the shutter -- and this is done manually.

This topic was pontificated upon by many of the armchair "experts" in this forum, many of who said it could never work.... (like so many net forums, the "experts" far outnumber the experts....)

http://www.largeformatphotography.in...ad.php?t=51309

[jnantz]

is ron responding to emails ?
hugo z tried to reach him
with no response ...

[Richard K.]

This was a prototype. Ron (Lee) is working on an improved version.
Barrel diameter could be easily solved by a softwood ring on the backside with three nylon screws (a technique for many filter holders).
Changing slit is done by changing the ratio of the two cards that form the shutter -- and this is done manually.

This topic was pontificated upon by many of the armchair "experts" in this forum, many of who said it could never work.... (like so many net forums, the "experts" far outnumber the experts....)

http://www.largeformatphotography.in...ad.php?t=51309

I read through this carefully and I wonder if Ron has compensated for the fact that the sheet of film will be under-exposed at the bottom compared to the top due to the slit accelerarting as it falls? Also, if a slit could move at constant speed, then the size of the lens doesn't matter, the effective shutter speed would be the same (exactly true only for a true focal plane shutter but fairly close otherwise) regardless of lens diameter - certainly you don't need twice the travel speed for a lens with twice the diameter! The uneveness I would worry about but it seems to noy be a problem - is the neg compensated for in development?

[Richard K.]

The uneveness I would worry about but it seems to not be a problem .....

Possibly because the falling slit rapidly reaches terminal velocity due to friction?