Re: Correction collar not working

GR, I once had a Nikon objective with a faulty correction collar, The
outer barrel had some set screws that allowed it to be removed for
access to the next layer (the tiny screws did not have to be taken out
completely). The pin was broken, which could happen by too-rough use,
I expect. I popped out the broken stub, clipped off a short piece of a
sewing needle of the right diameter, and with a tiny drop of epoxy,
cemented it into the collar hole where the pin goes. The pin has to be
to right diameter to avoid a sloppy fit, and just long enough to
engage a slot in the next layer of the objective barrel. After curing
and reassembly, it worked perfectly again. If the inside is clean it
will move easily with little resistance, so the pin has little stress
on it unless you apply too much muscle at the end of its movement.

Good luck, Greg

On May 23, 2:53 pm, "NoSpam" <NoS...@xxxxxxxxxxx> wrote:
Dear Satoru,

The correction collar is for correcting the coverslip thickness.

Putting a slide onto the stage and adjusting the correction collar for
the measured thickness of the coverslip and focussing for best detail
NO change is observed when rotating the correction collar.

Best focus by fine adjustment is independent of chosen collar position.
In other words there is no perceptible response to collar rotation.

Mounting a non-collar objective of the same magnification, but slightly
smaller aperture next to the objective in question and comparing images
looking at the same detail, an image of somewhat better contrast and re-
solution is obtained viewing through the objective without collar.

Thanks for your thoughts.

G.R.



----- Original Message -----
From: "Satoru Uzawa" <satoru_unos...@xxxxxxxxxxxxxxxxxxx>

Newsgroups: sci.techniques.microscopy
Sent: Wednesday, May 23, 2007 11:27 AM
Subject: Re: Correction collar not working

Is the correction collar for compemsating for difference in coverslip
thickness?
Or somthing else, like different mounting media? One easy way to see the
effect
of correction collar is to measure the PSF. I would say it's a lens with
good
design since the correction collar is not shifting the focus.

What are you expecting the correction collar to do??
How are you evaluating the image "quality"?

My suggestion is the measure coverslip thickness and use that value to
set the
correction collar, then measure the PSF (assuming that the correction
collar is
for the compensating the coverslip thickness variation).

Good luck!

Satoru

NoSpam <NoS...@xxxxxxxxxxx> wrote:
Dear Group,

Today I have a question regarding a mechanical-optical malfunction of
a microscope objective made by a major manufacturer.

The objective is a 40x, Plan Apo with correction collar.

Focussing on a slide one obtains a relatively good image, not as good
as one would expect, but acceptably good. What is curious is that ro-
tating the correction collar throughout its range produces no change in
focus.

An explanation on what might be going on?

Thank you
G.R.

"Satoru Uzawa" <satoru_unos...@xxxxxxxxxxxxxxxxxxx> wrote in messagenews:f3212o$2n5m$1@xxxxxxxxxxxxxxxxxxxxx
Is the correction collar for compemsating for difference in coverslip
thickness?
Or somthing else, like different mounting media? One easy way to see the
effect
of correction collar is to measure the PSF. I would say it's a lens with
good
design since the correction collar is not shifting the focus.

What are you expecting the correction collar to do??
How are you evaluating the image "quality"?

My suggestion is the measure coverslip thickness and use that value to
set the
correction collar, then measure the PSF (assuming that the correction
collar is
for the compensating the coverslip thickness variation).

Good luck!

Satoru

NoSpam <NoS...@xxxxxxxxxxx> wrote:
Dear Group,

Today I have a question regarding a mechanical-optical malfunction of
a microscope objective made by a major manufacturer.

The objective is a 40x, Plan Apo with correction collar.

Focussing on a slide one obtains a relatively good image, not as good
as one would expect, but acceptably good. What is curious is that ro-
tating the correction collar throughout its range produces no change in
focus.

An explanation on what might be going on?

Thank you
G.R.- Hide quoted text -

- Show quoted text -


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