# Crop Factor, Low Light and Aperture with m4/3 lenses? Part 2

Started Jun 16, 2014 | Discussions thread
Re: Crop Factor, Low Light and Aperture with m4/3 lenses? Part 2
1

bobn2 wrote:

Anders W wrote:

bobn2 wrote:

Anders W wrote:

bobn2 wrote:

Anders W wrote:

bobn2 wrote:

Anders W wrote:

If you can scale down manufacturing tolerances by a factor 2

Why wouldn't manufacturing tolerances scale?

That is such a ridiculous question, if just you stop to think about it. Every manufacturing process has an associated set of tolerances. So, if you use the same process to produce a smaller product, you are not scaling the tolerances. If on the other hand you develop the tolerances so as to be able to scale them for the smaller product, then that finer tolerance process is available also for the larger product. The exception is only if the smaller size itself allows some change in the process which provides for smaller tolerances.

See my reply to noirdesir here, penultimate section:

http://www.dpreview.com/forums/post/53893177

No connection with the question of scalability of tolerances at all. Linking irrelevant posts, implying that you had made some response to the point already is a most dishonest mode of argumentation.

http://www.dpreview.com/forums/post/53896543

OK, what you said was

The tolerances at issue in this case are those for producing and fitting glass elements. Suppose we were to fit a lens with a diameter of one centimeter and another with a diameter of one meter to the same precision in absolute terms, say one micrometer difference between the edges. Do you think that could be done with the same ease for the one meter lens as for the one centimeter lens?

That in no way answers the question. It is a 'thought experiment' situated in a fantasy. You have chosen an absurd example to 'prove' your case.

I just chose an example that makes the general point that the ability to reach a certain tolerance target as expressed in absolute terms (e.g., micrometers) rather than relative terms (proportions) depends on the size of the objects we are dealing with.

Shifting your ground again. 'Ability to reach a tolerance target' is a completely different thing that saying that tolerances scale.

If the ability to reach certain tolerance targets improve in inverse proportion to the scale, then tolerances scale, don't they?

Sometimes there might be an ability to reach a reduced target, others there might not and the costs might not be in proportion to the effect.

And in still other cases, the reduced dimensions facilitate things. As far as I know, it is a pretty well-established fact that certain lens elements can successfully be molded rather than ground into shape if they are sufficiently small.

Anders W's gear list:Anders W's gear list
Panasonic Lumix DMC-G1 Olympus OM-D E-M5 Olympus E-M1 Panasonic Lumix G Vario 14-45mm F3.5-5.6 ASPH OIS Panasonic Lumix G Vario 7-14mm F4 ASPH +28 more
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