[rollei_list] Re: Rolleiflex 35 SL lenses QBM IV (3-Pin)
- From: James Richard Tyrer <tyrerj@xxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Sun, 22 Aug 2010 10:37:38 -0700
On 08/21/10 03:29, John Wild wrote:
James,
I am sure you will experience 'the wrath of the gods' for posting images on the
list
Usually it is only a size limit on lists so I posted a small image.
But, if images are not allowed, I will avoid it in the future.
;-) but, yes the recessed ring with the two spanner key slots in it. The
depth of that ring determines the maximum aperture of the lens which the camera
picks up...
I am presuming here that there would be no reason to put a step in the
retaining ring if it weren't to provide the QBM IV aperture information.
I have measured my lenses, using the matt step of the mount - assuming this is
the reference register face - to the bottom of the groove using a digital
vernier caliper.
The reference surface would be the ring that has Pin-2 in it.
A dial gauge would be more accurate but there should be a reasonable tolerence
and I expect that the depth when plotted on a graph will be linear, so
discrepencies can be adjusted...
F1.4 - 1.15mm
F1.8 - 1.4mm
F2.8 - 1.9mm
F4.0 - 2.2mm
While I agree with 2.8, my f/1.4 lens is only 0.5mm so it would appear
that it is the lens that is the problem. This would mean that the
theory that all Planar 50mm f/1.4 2-Pins lenses will fully function on a
2000/3000 series camera is not correct.
Still not certain of this since measured on the camera, +/- 0.5mm should
work for f/1.4.
This would mean that I need a new retaining ring, if it is a retaining
ring since it does not have any notches or holes in it for a spanner
wrench like the Japanese or Singapore lenses have. Would this still be
a retaining ring but require a rubber device to remove like the front
retaining rings.
Nikkors are much easier to take apart. At least to the point of
removing the aperture ring (to replace it with an AI aperture ring); the
whole rear of the lens on most modern manual focus Nikkors is held on
with screws.
So, I now have a collectors item since most of these lenses were made by
Rollei Singapore, but I would like to use it. So, if conversion is
needed how would I go about this. With Nikkors to convert to AI, it was
necessary to purchase the correct new aperture ring, but I have seen no
indications that Rollei sold the retaining rings. Can you recommend a
repair shop that could take care of this?
--
James Tyrer
Linux (mostly) From Scratch
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