Friday, July 8, 2011

Rangefinder calibrations on 110B- part6

Now there goes to final part of RF calibration.

We match the lens with rangefinder with a tailored cam, so camera can be range coupled with ONE specific lens, but that is all it can do, if you want to use other lenses, these lenses are range UN-coupled, that is, rangefinder as a pure rangefinder only, reading out the rangefinder indicates, then we adjust the lens position to match the focus.

What if we could change this ONE-LENS-ONLY range coupled camera into a multi-lenses RF camera? I thought about this for years, and many clients asked the same question also, everyone wants multi range coupled function.

Here I list some issues on this conversion as follow:

Multi cam
More than one lens range coupled needs more than one more cam, how many cam possibly be installed on a camera?
As we measured, each cam needs at least 40° of rotation, so as 360° divided by 40°, maximum we can make 8 cams simultaneously be installed on one camera, but that is too much and too complicated, I would say 3 cams is enough.
Each cam separated and distributed at every 120°, that leaves enough space and tolerance to mechanism.
Stacked cam and rotating pole shape
Each cam curve is dedicated to match a specific lens, there may be differences between lenses, although they are in the same focal length, or even the same type. So it is impossible to order a batch of 3-in-1 cams that restrict  clients to use only 3 pre-defined lenses, and since lens has its own character, to amend the outer curve in such a 3-in-1 is tiresome.
Best way is to separated each cam, stack 3 in a row according to each client's specific request.
But for keeping these cam staying at their rotating angle (120°), we should change the rotating pole from circular shape into a triangular shape.

Mirror arm and cams
As mentioned above, best way for multi-cam is to stack them to match the clients' request, but the original shape of the cam is un-stack-able,  it is too thick.

You can see that original cam is thick to mirror arm, so this installation is unfeasible to 3-in-1 stack cam design, what we should do, is to reverse the mirror arm- cam relation, that is , to make mirror arm a thick arm, and make the cam a thin metal sheet. Such arrangement makes mirror arm easily be triggered by stacked cams, and metal sheet cam makes stacked thickness in bearable range. And the greatest advantage is to make cam much easier to file, to tailor its outer curve to match the lens character.

Field operations
If we solve all the problem mentioned above, the final problem arise as how to operate this mechanism in field. We need a knob to rotate the cam pole, to match the lens we change, that involves changing the outlook of the RF housing, but pity there is no space for it in my opinion, best way is to re-design and re-mold the RF housing, but consider the quantity and mold making cost, I stop at this place and never go any further.
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