Re: Attachments for Microscope Photography
From: W. Watson (wolf_tracks_at_invalid.inv)
Date: 02/23/05
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Date: Wed, 23 Feb 2005 02:07:42 GMT
Kevin Cunningham wrote:
> "What Sun? Calif." <wolf_tracks@invalid.inv> wrote in message
> news:iiKSd.2988$MY6.1777@newsread1.news.pas.earthlink.net...
...
>>>Actually finding the distance between the objective and eyepiece ie.
>>>camera lens, is simple. On old objective they give you the distance on
>>>the objective, either 160mm or 170mm. On infinity corrected lenses look
>>>at the Nikon web site, they have a list of correction lengths.
>>>
>>>Kevin Cunningham
>>>SMS
>>
>>I'm pretty new to microscopes. Our museum has a Leica BF 200. It has three
>>objective lenses and they are marked: Achro 4/.10, 160/.17(32012); Achro
>>10/.25, 160/.17 (32013); Achro 40/.65, 160/.17 (32015). The eyepiece,
>>which is held in place by a small screw, is marked 10x18 (32002). The
>>eyepiece barrel is about 4 1/8". Achro is? Achromatic?
>>
>>It appears the distance is then 160mm (16 cm or 6.3"). What, for example,
>>does Achro 10/.25, 160/.17 (32013) mean? What is the magnifcation of this
>>combination? What is 10x8? 10 power and ...? How do I measure the 6.3"?
>>That is, from inside the turret of the microscope somewhere?
>>
>>I just realized that I might be able to mount the camera on my tripod and
>>figure on the two distances (with/without eyepiece). It'll be a little
>>tricky, but it's a lot steadier than me holding it my hand.
>>
>>The other microscope is a stereo Reichert-Jung, and is a bit less
>>expensive. I don't think it has any markings. In fact, the two eyepieces
>>are glued in.
...
> Wayne, Just to make it easier on me I'm going to use metric. Lets take a
> look at the 10X. The first number is the magnification, this is the least
> important number on the microscope. The next number is the numerical
> aperature, 0.25. This number lets you determine the resolution of the
> objective. Next is the tube length, in this case 160mm. The last of number
> of 0.17 is the cover glass thickness the objective was designed to use. The
> 5 numbers set at the end is the catalog number, maybe the most important
> number!
>
> Magnification of a microscope system is objective X tube factor X eyepiece.
> Your tube factor is probably 1, if you have an old fluorescence instrument
> it probably has a 1.25 tube factor. Usually eyepieces are rated by
> magnification and field of view. Magnification is usually 10X although in
> the past 12.5 was standard. Field of view tells you how big the image is.
> It ranges from 18 to 26. The tube length begins with the black ring at the
> rear of the objective and goes to the diaphragm in the middle of the
> eyepiece.
>
> Good luck!
>
> Kevin Cunningham
>
>
Good. Thanks. Is the 0.25 in cm or mm? I would think a 0.25mm aperature would be
very tiny. Similarly with thickness, 0.17 mm or cm? Yes, I agree that 5 digit #
is very important. :-)
Is the tube factor supplied by the mfger? So with the 10x eyepiece, I have 12.5
magnifcation. When you say field of view ranges from 18 to 26, that means in mm?
Well, I made some good progress by putting my camera on a tripod and the
microscope on a counter. I'm able to focus on a slide with the eyepiece in
place. The camera front is about 2" in front of the tube. Another thing that
helped is that in this arrangement, I could easily see the light from below the
slide area hitting the camera body. I can see working in a darkened area can be
helpful. Now to try it without the eyepiece.
Probably the tripod set up will be fine for awhile, but I'll eventually want to
construct a tube that holds the camera to the microscope's barrel. I have a
friend who's volunteered to do this, but we are going to need some tube stock to
do it.
--
Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA)
(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet
Web Page: <home.earthlink.net/~mtnviews>
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