TLRs don't generally use helicoid focusing, instead mounting the lens pair firmly on a panel which is racked in and out in one linear action.
In this design, instead of the lenses being mounted on a single plate, pairs of elements are mounted on a single plate, thus a sandwich or laminate of plate/element sets is formed. The gap between each plate and its neighbours is actuated using an appropriate technology and controlled with the aid of feedback, via a lever/knob under the users control.
So, unlike most zoom lenses people are accustomed to currently, these zooms would not use a rotary gearing (or helicoid) to arrange the element positioning, nor to focus. The distance between elements and cells could be controlled electronically, to arrive at different focal length arrangements, and also to affect the overall focal distance.
A typical TLR has a rotary knob on one side (Rolleis seem to have alternated which side, on different models), which is the most common TLR pattern, although others exist: the Mamiya uses a pair of knobs at the bottom front edge, the Minolta Autocord uses a lever under the taking lens, the Ricoh Diacord does use a form of helical focusing with opposing levers poking out each side.
For this Zoom TLR, it might be nice to have a complex solid-feeling single control that you rotate in the normal manner for focus, but push forwards or pull back for zoom. This is interpreted by a cpu into appropriate spacings of the element and cell sandwiched layers.
I'm not sure what mechanisms should be chosen for the actuation, but they should maintain perfect parallel motion between cell plates.
In most other respects, this would remain similar to a contemporary TLR: it would use 120 film, it would feature TTL metering and flash control, it would be compact, ergonomic and robust.-- Ian Tindale, Jun 23 2007 My Mamiya http://www.flickr.c...-72157594207872508/ [Ian Tindale, Jun 23 2007] I bet I know who posted that one... <checks>.
Hi Ian! I understand very little about real cameras, but this sounds like a good thing. If we could use it on phone cameras as well it might help offset that annoying miniaturization thing that's going on with them.-- wagster, Jun 23 2007 In a perfect example of inefficient communication, the whole intelligent-sounding and doubtless well-thought-out and informative body of text to the left was met with "duuurgh, cameraaaaargh, hurgh hurgh hurgh" when it reached my brain.
That is to say, what [wags] said: I can appreciate a good photo, but I'm essentially clueless on real cameras.-- david_scothern, Jun 23 2007 <hums> My Mamiya! / Here I go agai-hain / My my / how can I resist you... </hums>-- jutta, Jun 25 2007 You can hum words?-- MaxwellBuchanan, Jun 25 2007 [Juta] - You should be in advertising - your talents are wasted here.-- hippo, Jun 26 2007 Hey, [Ian], I've got two of those. Both have lots of miles on them, and issues, of course.
I have a manual and tools, and when I get sufficiently bored I work on them.-- normzone, Sep 04 2007 halfbakery