Re: Oil vs water objectives

Posted by James Pawley on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Oil-vs-water-objectives-tp7579114p7579127.html

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Hi all,

Looks like you have received a lot of good
advice, but I would like to add one thing.

Yes, do a test BUT don't forget to be very
careful in adjusting the SA correction collar on
the water lens. )Find a point object: focus up
and down and adjust for symmetry (i.e., for the
same image a little above focus as a little below
focus. DON'T just try to "make it sharper!" The
collar changes the focus plane.)

The collars usually have markings in terms of the
coverslip thickness that they are designed to
correct for. One can easily see the difference
created by mis-adjusting a 1.2 NA objective by 2
µm-of-glass-replaced-by-water (my favorite unit
for "measuring" SA).

When modern water objectives first emerged in the
early 1990s, many folk bought them and then went
back to their oil objectives and I am convinced
that it was because they just didn't want to take
the time to adjust the collar properly.

Because, if you do adjust it properly, you will
get better (brighter? higher resolution?) images
of aqeous specimens beyond about 3 µm

Best,

Jim Pawley,

Near Harbin, China.



>Make sure the coverslip is orthogonal to the
>image axis with your water objective.
>
>A common aberration with water-immersion objective lenses.
>J Microsc. 2004 Oct;216(Pt 1):49-51.
>http://www.ncbi.nlm.nih.gov/pubmed/15369482
>
>Doug
>
>^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>Douglas W. Cromey, M.S. - Associate Scientific Investigator
>Dept. of Cellular & Molecular Medicine, University of Arizona
>1501 N. Campbell Ave, Tucson, AZ  85724-5044 USA
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>-----Original Message-----
>From: Confocal Microscopy List
>[mailto:[hidden email]] On
>Behalf Of Steffen Dietzel
>Sent: Thursday, October 04, 2012 7:30 AM
>To: [hidden email]
>Subject: Re: Oil vs water objectives
>
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>
>I second Michael's comment.
>
>Apart from that, when you have an aqueous(!)
>preparation, spherical aberration decreases
>image quality faster for the oil objective. So,
>directly behind the coverslip the oil objective
>(1.4) will give you the better image due to the
>higher NA, at some depth both objectives will
>give you similar quality and beyond that, the
>water immersion will be better.
>
>I seem to remember that for oil 1.4 and water 1.2 the crossing point is
>10-20 µm into the sample.
>
>If you have the Handbook laying around, check
>the chapter on Lens aberrations. Chapter 20 by
>Hell and Stelzer in the second edition, chapter
>20 by Egner and Hell in the 3rd edition.
>
>Needles to say that all above considerations
>assume that both objectives have the same
>transparency for excitation and emission
>wavelengths - which they probably don't. So we
>are back at Michael's comment: You've got to
>test it. Beads attached to the coverslip and the
>slide (various preparations with various
>distances between the two) give good test
>objects.
>
>Steffen
>
>On 04.10.2012 15:15, Gabriel Lapointe wrote:
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>>
>>  Hi,
>>
>>  I have a user who insist that using a 1,27NA water immersion objective
>>  is brighter and would give better images than using a 1,4NA oil
>>  immersion. I understand that deeper into the media that would be true.
>>  But, in that particular case, we are talking about imaging GFP at less
>>  than 100 micron away with a spinning disk.
>>
>>  So, I was wondering at which distance from the coverslips do we start
>>  seeing benefits of using a water immersion objective over an oil
>>  objective in aqueous media.
>>
>>  Thanks for your help.
>>
>>  Sincerely
>>  *Gabriel Lapointe, M.Sc.*
>  > Lab Manager / Microscopy Specialist
>>  Concordia University, Biology Department
>>  7141 Sherbrooke St. West SP 534
>>  Montréal QC H4B 1R6 Canada
>>  [hidden email]
>>  cmac.concordia.ca
>>  http://gabriellapointe.ca
>>
>
>
>--
>------------------------------------------------------------
>Steffen Dietzel, PD Dr. rer. nat
>Ludwig-Maximilians-Universität München
>Walter-Brendel-Zentrum für experimentelle
>Medizin (WBex) Head of light microscopy
>
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