Re: Plan sure, does apo or fl matter now?

On Apr 23, 2:56 pm, Victor <microscope...@xxxxxxxxx> wrote:
On Apr 23, 5:04 am, Kevin Cunningham <sms...@xxxxxxxxxxxxxx> wrote:



On Apr 22, 7:45 pm, Rich <rander3...@xxxxxxxxx> wrote:

On Apr 19, 9:05 am, Kevin Cunningham <sms...@xxxxxxxxxxxxxx> wrote:

On Apr 18, 10:12 pm, Rich <n...@xxxxxxxxxxx> wrote:

I understand the need for plan objectives, but given we can remove most
chromatic aberration from images today, are apo or fl objectives as
important today as before?

Geez, yes!  Chromatic aberration has nothing to do with plan
correction, plan is flat field.  Now just how flat field depends on
the maker.

Flourites and Apos have higher NA, and NA is the only number you
really need when examining a microscope since NA equals detail.  Plan
lenses can be made using Achromats, Flourites or Apochromats, these
are the crucial details, then plan correction is nice.  Achromats are
the most used objectives since they are cheap to make.

You might want to take a look at the Olympus or Nikon sites, they have
excellent stuff on microscopes.  My book is a nice read too.

Thanks,

Kevin Cunningham
SMS

What is the title of your book?
Thanks

Just Google SMS or books on microscopes.

Thanks,

Kevin Cunningham
SMS- Hide quoted text -

- Show quoted text -

Kevin is right, the N.A.'s on the Plan Fluorite or Plan Apo objectives
are almost always higher than the normal plan achromats.   There are
definitely reasons when you would choose to use either.

1. Resolution:  The higher the N.A. the better the resolving power of
the microscope and the better the image, period.    There is simply no
way around this, it's physics.

2. Flatness of Field:  Generally, the higher the quality of an
objective, the larger the "flatness of field" area covers, which gives
you an opportunity to use wider field of view eyepieces, or have
better image stitching if you're acquiring multi field images.

3. Color Correction:  This is what the difference is actually all
about.    Fluorites are generally considered "semi-apochromats", and
are corrected for 2 of 3 colors, and Apochromats are corrected for all
3 colors, as well as the largest flat area and the highest NA.

When NOT to use them:

1. "Too much glass".   Sometimes less is more, in the case of older
optics, sometimes it's actually better to use a cheap achromat for
fluorescence for instance, than the highest end, most expensive plan
apo.   This is in part due to the optical cements which were used, and
the coatings for the lenses which were used, which provided a very
bright but very noisy image (lot of autofluorescence).   Nowdays, this
isn't the case, and Plan Apos tend to also be the best fluorescence
objectives as well.

2. You don't need them:  While it's always good to have "the best",
it's not always necessary.  Think about what you're trying to
accomplish when considering a tool, not what you might not be able to
do somewhere down the road.

Great post!

I'd also throw in working distance and dept of field. Usually the
more NA the less working distance and less depth of field. You may
have to balance your needs. For instance if you are examining thick
brain specimens then using an Apo would be a mistake, no working
distance, little dept of field.

You have to think about the specimens you will be looking at and what
requirements you actually have.

Thanks,

Kevin Cunningham
SMS
.

Relevant Pages

  • Re: Plan sure, does apo or fl matter now?
    ... then plan correction is nice. ... the most used objectives since they are cheap to make. ... the N.A.'s on the Plan Fluorite or Plan Apo objectives ...
    (sci.techniques.microscopy)
  • Re: Plan sure, does apo or fl matter now?
    ... are apo or fl objectives as ... correction, plan is flat field. ... then plan correction is nice. ... the most used objectives since they are cheap to make. ...
    (sci.techniques.microscopy)
  • Re: Plan sure, does apo or fl matter now?
    ... correction, plan is flat field. ... then plan correction is nice. ... the most used objectives since they are cheap to make. ...
    (sci.techniques.microscopy)
  • Re: Plan sure, does apo or fl matter now?
    ... are apo or fl objectives as ... Chromatic aberration has nothing to do with plan ... then plan correction is nice. ... the most used objectives since they are cheap to make. ...
    (sci.techniques.microscopy)
  • Re: Reason Magazine had an article on this...
    ... personalities drive policy in proportion to objective analysis. ... You start out with a plan. ... At some point, goals and objectives are ... separates the practicalities of achieving the vision from the vision ...
    (rec.arts.anime.misc)