Re: Correction collar not working

Dear Satoru,

I thank you all for the very useful comments regarding my lens.
It is now on its way to the dealer and I will let you know about
further developments.

Now to Satoru's comments regarding undesirable changes of
PSF (Point Spread Function) with different settings of the cor-
rection collar.

If I interpret what he means correctly he is using deconvolution
and for this reason needs to rely upon a stationary point spread
function for his objective.

I am not sure that such considerations are valid for visual or
photomicrography work of a conventional nature. It is true
that every different setting of the correction collar effectively
creates a different objective lens, but the effect upon conventional
microscopy can only be beneficial, since it improves definition
and contrast in each case. In this case and particularly in cases
were the sample is of different thickness below the coverglass
a correction collar should be of value.

Best regards
G.R.

"Satoru" <satoru_uNospam@xxxxxxxxxxxxxxxxxxx> wrote in message
news:f32fmj$2rbj$1@xxxxxxxxxxxxxxxxxxxxx
Dear GR,

It is difficult to judge the correction collar effect at the focus,
but it has rather obvious effect on out-of-focus Airy rings. The Airy
rings will dissappear or get stronger as the collar rotates in certain
direction. Opposite thing will happen to the other side of focus.

But as the other answer stated, I am now convinced that you got a
lens with a broken pin... Luckily, it never happened to me.

Hope your lens will be fixed soon!

Regards,
Satoru

BTW, I have a personal preference to pick a lens without correction
collar, since it affetcs the PSF while it is almost impossible to set
the collar position reproducibly... I glued the correction collar on
our water-immersion lens with silicon rubber (so that I can remove it
if I need to) and we are matching the coverslip thickness to the collar
position by hand selecting them. Yes, you can call me a paranoid... :)

NoSpam <NoSpam@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_unospam@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 <NoSpam@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_unospam@xxxxxxxxxxxxxxxxxxx> wrote in message
news: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 <NoSpam@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.






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