Nikon, is that all?

Started Apr 14, 2009 | Discussions thread
bobn2
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Re: D700x and F4.0 Lenses
In reply to Ayoh, Apr 24, 2009

Ayoh wrote:

bobn2 wrote:

Ayoh wrote:

I would wager that the pressed metal parts and springs that make up a
body controlled aperture coupling mechanism are substantially cheaper
per part than the micro stepper motor and associated electronics
board used in fully electronic mounts.

I would wager that you are wrong. The micro stepper (probably
actually a simple DC servo, not a stepper) is needed anyway, it goes
in the camera, not the lens.

Canon lenses use a micro stepper motor

So they do. that doesn't affect the argument. A stepper is simpler than a DC motor.

And yes some actuator for stepping down the aperture is present in
bodies with lever control but like you said it goes in the body, not
in each lens. With an in body system you only pay for the actuator
cost once..

But it's bigger, more complex and more clunky, and the mechanical coupling probably costs just as much as the motor, especially since it imposes design constraints on the rest of the system. Advantage electronic, I'd think.

Th unit price for pressed metal parts can be in single digit cents,
but a micro stepper motor in the dollars.

The price of assembled pressed metal parts is considerably higher.
You are overestimating the cost of a motor, to the likes of Canon and
Nikon, that is also in the cents.

Here is an example form real life. I work with the manufacturing
industry and for one of our projects (mirror actuator) the unit
purchase price for a basic DC micro motor (not far removed from what
you find in a lens) for an annual volume of 3M is ~$3.00. We also
have some pressed metal flat spring parts (also purchased, would be
cheaper made in-house) at the same volume cost ~$0.02.

That's an expensive motor. I can buy them one-off for less than that. There's no way you could build two $3 motors in a $5 floppy disc drive or one in a $1 fan. I think you need to talk to you buyer about finding an alternative source. Then you have to factor in the cost of assembling your pressed metal parts into quite a complex mechanism. You'll end up with much more than the 2c.

Just think, you have several in a
floppy disc drive (remember them) which retails for a few dollars.
The point about the electronic system is that it requires no extra
parts.

Aside from the extra in-lens actuator in each lens.

That's not an extra part, it's the same part in a different location. It maybe adds to the lens cost, but reduces the camera cost (which was the topic). I would estimate, tough, that it reduces lens cost, because it simplifies design and manufacture considerably.

Would you estimate the pressed metal housing of the floppy drive or
the electronics and actuators to make up the bulk of its price?

I have no Idea, but I do know that they couldn't sell a floppy for $5 if each of the motors in it cost $3. My guess would be that the bulk of the cost is in the assembly.

the serial protocol to the lens is there anyway, the diaphragm
control motor moves to the lens, but it's not a saving overall, the
electronics are just control pins from the lens microprocessor.
Against that, every bit of a mechanical linkage (both drive and
aperture ring) is an added cost.

So to rephrase, It basically comes down to replacing the micro-motor
actuator with a pressed metal linkage. Again I guarantee you the
pressed metal parts are cheaper to manufacture and assemble. Think
about the number of processes, materials and precision that is
involved in the making of a micro-motor versus the shaping and
joining of flat strips of metal (at the same volume)

Where you argument falls is that the motor itself is a mechanism itself made from the same pressed metal, and considerably simpler than a diaphragm linkage. By your argument, nothing would cost more than the sum of it's piece parts. $10 Rolex, anyone. I've bought a $20 'Rolex'. It had just the same number of metal parts as a real one. For the four days it ran, it gained 20 minutes a day. Still, should have been just as good as a real one.

The reason they use in-lens actuators is not for lower manufacturing
cost. It is for possibly better position control, faster/quieter
response, simpler lens-body interface.

I think they designed an electronic diaphragm linkage (as has every mount design since) because it offered all those things and was cheaper too.

I think a simpler interface is
the main reason as at any point they can introduce a different
aperture control mechanism (say a stepless aperture for movies) and
not affect the interface. Each internal lens "system" can be
modularized and you won't end up with a cobbled together mount (like
nikon) as future functionality emerges.

That too is an advantage. The EF mount is a piece of design genius.

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Bob

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