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Objectives Old and New

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#1 bumm

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Posted 16 July 2019 - 04:28 PM

Since nabbing my old brass Spencer just over a year ago, I've been  happily using it to harass the local pond life.  I've captured and  identified quite a few "animalcules," from bacteria on up through  protozoa, rotifers, hydra, etc.  However, while I thoroughly enjoy the  feel and beauty of antique equipment, I began to wonder if I was  handicapping myself in actually seeing the finer details of my little  jar dwellers. I've been using more modern wide field eyepieces since you  can just plunk them in, but I realized that aside from a few glances at  prepared slides in college, I'd never looked through an objective made  after 1930.  My father's scope I used as a kid in the late 1950's -  early 60's was patented in the 1890's.  My present Spencer ones had  passed the century mark.
     My most used objectives  were a 10x and a 20x, the 20x hitting a sweet spot, allowing me to chase  little creatures through a well slide without crunching the cover  slip.  It also allowed the use of a 20x eyepiece to give a magnification  of 400.  (Some would argue vehemently with this, but "empty  magnification" is a concept I'm intimately familiar with as a long time  amateur astronomer, and I wasn't seeing it here.)
     Not wanting to break the bank, I opted for some inexpensive Amscope  examples.  The 10x was $16.99, supposedly marked down from 33.99, and  the 20x was 22.99, supposedly marked down from 45.99.  These aren't top  of the line, most likely Chinese made, but I figured they'd do, and I  probably wouldn't notice the flatter field etc, of more expensive  objectives.  But I may be wrong.
     For the last few  days, I've been mounting the objectives next to each other so that I can  compare views as best as possible.  This takes a little fiddling, since  the old and new objectives obviously aren't parfocal with each other.   I've been comparing views of cilia, flagella, and any other details that  may give a hint at the limits of my powers of observation.  This  morning, I spent most of an hour flipping back and forth looking at the  straight tufts of cilia on a fascinating Floscularia from a local pond.   And so far, I've seen very little difference.  I'd been expecting to  see some advantage in the newer objectives.  Maybe in contrast, due to  modern coatings, versus no coatings at all. No, they aren't top of the  line, most likely Chinese made, but they aren't 100 years old either.  I  didn't have to disassemble them to dump the dirt out, and they've never  been wiped off by some Philistine that didn't appreciate the delicacy  of such matters.

     So there it stands.  Right now, I'm  leaning toward mounting the new objectives on my old Spencer just to  save the beautiful lacquered brass finish from constantly being nudged  around by my grubby fingers.  No, they don't look right, but nobody ever  goes down in my little room anyway.  But...  I don't know.
     Anyway, did I run a fair comparison?  Were my antique Spencers really  that good?  Should I opt for more expensive modern objectives?  Any  advise, insults, or name calling would be greatly appreciated.

                                                                             Marty

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#2 Richard O'Neill

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Posted 16 July 2019 - 04:44 PM

 Old optics have a charm of their own. One likes what one likes, no more need be said.

 

BTW, nice room. No doubt filled with many interesting things. waytogo.gif 


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#3 bumm

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Posted 16 July 2019 - 05:07 PM

 Old optics have a charm of their own. One likes what one likes, no more need be said.

 

BTW, nice room. No doubt filled with many interesting things. waytogo.gif

I'm doing my part to increase the entropy of the universe.

                                                                                    Marty

Post Script...  I recently built boxes for a couple of those microscopes that didn't have them so I could get them off my little table without having to put them on the ancient concrete floor.  I'm letting the finish outgas for a month or so before I use 'em.  One is set up for dark field, the other is 3D binocular.

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#4 Richard O'Neill

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Posted 16 July 2019 - 07:29 PM

 Uniquely you, very cool. Thanks for the peek. smile.gif  I'm sure there's a story behind each and every treasure in your special room.


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#5 Crusty99

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Posted 17 July 2019 - 10:30 AM

Do you give tours?

 

Seriously, I really do admire this tribute to what it means to be an amateur astronomer.

 

bow.gif


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#6 bumm

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Posted 17 July 2019 - 04:28 PM

Do you give tours?

 

Seriously, I really do admire this tribute to what it means to be an amateur astronomer.

 

bow.gif

Philosophically, Astronomy and Microscopy are very complimentary.  I go out and look at galaxies millions of light years away and a hundred thousand light years across, and my mind struggles to even comprehend the vastness of the universe.  The routine problems of the day begin to fade.  Then, I look at a drop of water under a microscope, and I realize that on the cosmic scale, I'm no more significant than the protozoa swimming under my cover slip.

                                                                              Marty

Oh, and it's taken 40 plus years for that mess in my basement room to organize and mature... :)


Edited by bumm, 17 July 2019 - 04:30 PM.

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#7 EJN

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Posted 17 July 2019 - 07:13 PM

For the last few  days, I've been mounting the objectives next to each other so that I can  compare views as best as possible.  This takes a little fiddling, since  the old and new objectives obviously aren't parfocal with each other.

 

No, they wouldn't be parfocal. Old objectives had a working distance, specimen to mounting flange,

of 36mm. Modern objectives are DIN standard with a working distance of 45mm. Both are designed

for a 160mm tube length.

 

I have some 1950's B&L objectives which I have compared against Amscope objectives. I found

it was six of one, half a dozen of the other. I could see no difference in contrast or resolution.

 

More expensive objectives (plan or fluorite) would be better, but most these days most are infinity

corrected (vs. the older 160mm tube length) and require an appropriate relay lens.


Edited by EJN, 17 July 2019 - 07:19 PM.

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#8 Microscopy

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Posted 21 September 2019 - 02:52 PM

No, they wouldn't be parfocal. Old objectives had a working distance, specimen to mounting flange,

of 36mm. Modern objectives are DIN standard with a working distance of 45mm. Both are designed

for a 160mm tube length.

 

[...]

"DIN standard" refers to standards set by the Deutsches Institut für Normung (German Institute for Standardization). In the case of microscopes the relevant standards are DIN 58887 and DIN 58888.

 

Older objectives were designed for a mechanical tube length of 160mm OR 170mm, while many manufacturers changed over time from 170 mm mechanical tube length to 160mm.

 

170 mm: older Leitz and many smaller and lesser known German manufacturers (Hertel & Reuss, Karl Kapps, Seibert Wetzlar, Beck Kassel, ...) as well as Meopta Praha and ROW-Rathenower Optische Werke.

160 mm: most of the well known brands: Zeiss west and Zeiss Jena, Reichert, Wild, Will, Olympus, Nikon, Baush & Lomb, American Optical, Nachet, CTS, Vickers, ...

 

Older objectives may have a working distance of 32.3 mm, 32.5 mm, 36 mm, 37mm.

Equaly important as the working distance of the objective is the exact location of the real intermediate image formed by the objective. According to DIN 58887 that image schould be exactly 10 mm below the upper edge of the eyepiece tube, but there are hughe variations, ranging between brands and sometimes even between models/generations.

 

Furthermore, many older objectives were corrected for a cover glass thicknes of 0.18 mm, instead of the more recent 0.17 mm.


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#9 vertex2100

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Posted 27 September 2019 - 08:43 AM

Cool looking workbench. I just bought my son a 1914 Spencer microscope that looks just like yours. We haven't looked through it yet since it is Christmas present. I hope the views will be comparable to what you are getting and no different than low end modern objectives. Good to know that modern 160 mm objectives will work with it if needed.
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