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 Post subject: 185 Objectives?
PostPosted: Wed Aug 08, 2018 2:19 pm 
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Joined: Tue Jul 17, 2018 7:34 pm
Posts: 67
So being new to this hobby I went on ebay to look at objectives for my Nikon Labophot.

Found these

https://www.ebay.ca/itm/4X-10X-20X-40X-60X-100X-185-Achromatic-Biological-Microscope-Objective-Lens-1PCS-/302485060008

and figured why not, cheap enough and I wasn't expecting much in terms of quality. They arrived and noticed they were short. When I put them in i couldn't focus because the stage wouldn't rise up enough. Went back to the ad and noticed the 185.

I'm assuming 160 is what I should get. My mistake.

Anyway I searched for a microscope that uses 185 standard out of curiosity. Can't find any.

What scope uses a 185?


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 Post subject: Re: 185 Objectives?
PostPosted: Wed Aug 08, 2018 3:22 pm 
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Posts: 2127
Some of the student microscopes used such a configuration, with shorter than normal objectives. Presumably, your 100x objective is 25mm or thereabouts long.


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 Post subject: Re: 185 Objectives?
PostPosted: Wed Aug 08, 2018 4:07 pm 
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Posts: 1277
Hi, fibreoptix, I find it odd that these new and unbranded chineese objectives do not list their: 'tube length' as a spec!? The sellers chart of specs seem quite complete otherwise...hmmm.

Your clinical workhorse stand ( many of these Nikon Labophots are still in active duty in clinical labs) is a DIN standard err 45mm length objectives..with a crucial spec of: 160mm tube length.

I have a collection of three LOMO apochromatic objectives that I bought due the great price on eBay ( thanks Vlad, Chicago,US seller)...I 'pounced' because my brain homed in on their spec of: 160 tube length...sigh, they are RMS standard: about???34mm?? length objectives...thus my Nikon Labophot can't 'focus down' to function with these objectives. Older really vintage microscope do 'focus down' enough for the LOMO 'shorty objectives'. Perhaps hang on to your set of new/unbranded objectives for when you aquire a vintage stand?

It's a great question...what do they mean by: "185" objectives?! Again I'l tell you, fibreoptix, I have a large collection of Nikon objectives and occulars I can sell low cost if you are interested. Just pm me.

I'm glad you are starting with a Labophot...get a trinoc head as soon as you can...and 'trick it out' with Nikon optics rather than 'mix and match' brand optics...but remember it's a 160 tube length spec, and Din: 45 mm objective spec. Charlie Guevara finger lakes/US


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 Post subject: Re: 185 Objectives?
PostPosted: Wed Aug 08, 2018 5:03 pm 
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Joined: Fri May 15, 2015 12:15 am
Posts: 2127
charlie g wrote:
Hi, fibreoptix, I find it odd that these new and unbranded chineese objectives do not list their: 'tube length' as a spec!? : 160 tube length...sigh, they are RMS standard: about???34mm?? length Charlie Guevara finger lakes/US


Charlie G. It is not unusual for student grade optics to be unmarked as to the total optical path length( specimen to top of the eyepiece tube). Your Nikon Labophot isn't marked , either. It is in fact 160 + 45= 205mm. 185mm was in some ways a student microscope standard, although many objectives designed for a 185mm system had threads, other than R.M.S. The notice by the seller of 185, was enough to warn a knowledgeable buyer that these objectives would be short: 25mm parfocal, by deduction.

There is NO R.M.S. standard for objective length, only for the standardized R.M.S. thread that is most commonly used on microscopes. The mechanical tube length standard is D.I.N. 58887, by which Deutsches Institut für Normung,, established that the distance from the objective shoulder to the intermediary image should be 150mm and that the intermediary image should be 10mm below the top of the eyepiece tube, totalling 160mm. The length of the objective is not included in this standard. Various systems have existed based in this standard, as well as deviations from this standard; most notably that of Leitz and their cooperative companies( Seibert, the main one), and the early Japanese both of which used a 170mm tube. If the mechanical tube length is 160mm, then the objective parfocal length needs to be added to that, in order to find the total length. Lomo would be 193mm, AO 194, Baker( early) 194, J.I.S. based on a 170mm tube length is 206, Leitz 170mm system was 207mm; the 160mm system was 205mm, Bausch & Lomb 196.7mm, Reichert 197mm, PZO 205mm, Vickers 205mm, most Chinese 205mm. Zeiss for many years was non-conformist as well, with a total length made up of 147mm( instead of 150), 13mm( instead of 10) and 33mm for a total of 193mm. The more modern Zeiss are 205mm.

There is another D.I.N. standard associated with the 45mm parfocal distance utilized concurrently by many manufacturers and the tube lengths associated with infinity microscopes are a whole other thing altogether.


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 Post subject: Re: 185 Objectives?
PostPosted: Thu Aug 09, 2018 1:18 pm 
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Joined: Mon Nov 10, 2014 10:01 pm
Posts: 2559
charlie g wrote:
Hi, fibreoptix, I find it odd that these new and unbranded chineese objectives do not list their: 'tube length' as a spec!? The sellers chart of specs seem quite complete otherwise...hmmm.

Your clinical workhorse stand ( many of these Nikon Labophots are still in active duty in clinical labs) is a DIN standard err 45mm length objectives..with a crucial spec of: 160mm tube length.

I have a collection of three LOMO apochromatic objectives that I bought due the great price on eBay ( thanks Vlad, Chicago,US seller)...I 'pounced' because my brain homed in on their spec of: 160 tube length...sigh, they are RMS standard: about???34mm?? length objectives...thus my Nikon Labophot can't 'focus down' to function with these objectives. Older really vintage microscope do 'focus down' enough for the LOMO 'shorty objectives'. Perhaps hang on to your set of new/unbranded objectives for when you aquire a vintage stand?

It's a great question...what do they mean by: "185" objectives?! Again I'l tell you, fibreoptix, I have a large collection of Nikon objectives and occulars I can sell low cost if you are interested. Just pm me.

I'm glad you are starting with a Labophot...get a trinoc head as soon as you can...and 'trick it out' with Nikon optics rather than 'mix and match' brand optics...but remember it's a 160 tube length spec, and Din: 45 mm objective spec. Charlie Guevara finger lakes/US


IF YOU LOOK AT THE OTHER PHOTOS YOU WILL SEE THEY ARE MARKED "160"......

BILLT


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 Post subject: Re: 185 Objectives?
PostPosted: Fri Aug 10, 2018 12:57 pm 
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Joined: Fri May 15, 2015 12:15 am
Posts: 2127
Here is another set that is a little different.
https://www.ebay.com/itm/All-Metal-195- ... 0290.m3507

In this case, the objectives are 35mm parfocal( the oil immersion objective would be around 34.5mm +- long from shoulder to tip), so the total length of the system is 195mm. These probably conform to some standard used in China, prior to their almost wholesale adoption of the 45mm D.I.N. standard. Oddly, they didn't just copy over a system from Japan (J.I.S.), originally, because both the objective length; 35mm instead of 36mm , and the tube length are different; 160mm instead of 170mm, yielding very different total lengths of 195mm ,compared to 206mm.
It is somewhat puzzling that the J.I.S. standard, used the same tube length as Leitz. One possibility is that in the early days of the development of the Japanese microscope industry, the key player, that eventually morphed into Olympus, Tiyoda and Shimadzu, probably used optics supplied by E. Leitz, subsequently, copying them almost to a T. I have read that the Japanese made ones, used Leitz lenses. The tube was 170mm for sure.
Why would they then adopt a 36mm parfocal length, rather than a 37mm parfocal length, for the J.I.S. standard? Well, maybe they measured wrong, or maybe they were influenced by the considerable presence of instruments with other parfocal lengths invading occupied Japan, after the war.

anyway, here is a little about M & Katera.viewtopic.php?f=11&t=1637&hilit=M+%26+Katera


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 Post subject: Re: 185 Objectives?
PostPosted: Mon Aug 13, 2018 12:25 pm 
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Joined: Tue Sep 05, 2017 10:33 am
Posts: 76
Objectives are a pain when mix n matching, B&L brass, very short, lomo 33, Jena 35, Beck and Wild.. 38? DIN 45. All 160 and all different. I had to mod my Zeiss to work with them all. Luckily the worst mismatch I made was a Leitz 170. Many Lomo's are 190.


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 Post subject: Re: 185 Objectives?
PostPosted: Mon Aug 13, 2018 2:26 pm 
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Joined: Thu Apr 05, 2018 1:06 am
Posts: 84
Location: Idaho
These might help get your scope to focus with those objectives. Image quality might suffer due to incompatibility between objectives and eyepieces, but no real way to know except to try it.

https://www.ebay.com/sch/i.html?_from=R ... e+extender

_________________
Rick

A/O 10 Series Microstar
A/O 4 Series Microstar
A/O 4 Series Phasestar
A/O 4 Series Apostar
A/O Cycloptic Stereo
Several old monocular scopes in more or less decrepit but usable condition


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 Post subject: Re: 185 Objectives?
PostPosted: Wed Aug 15, 2018 2:50 pm 
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Joined: Fri May 15, 2015 12:15 am
Posts: 2127
GaryB wrote:
Objectives are a pain when mix n matching, B&L brass, very short, lomo 33, Jena 35, Beck and Wild.. 38? DIN 45. All 160 and all different. I had to mod my Zeiss to work with them all. Luckily the worst mismatch I made was a Leitz 170. Many Lomo's are 190.


I'm pretty sure, objectives over 170mm tube length will be metallurgical objectives. There were a whole slew of different lengths, 190mm being one of them. There are some odd tube lengths, such as 135mm for some hobby biological scopes. For almost all diascopic microscopes of a fixed tube length, though, the tube length will be either 160mm or 170mm. This is not always marked on the objective and it sometimes requires a bit of historical info., to determine the tube length or direct measurement. Irregardless of other corrections, an objective's tube length can be determined by measuring the magnification using a reticle or stage micrometer, by screwing the objective into a stand that has a known tube length. Using an eyepiece originally corrected for the test objective gives best results but probably any eyepiece will cough up enough of a result. A 160 objective will give roughly 6% greater magnification in a 170mm tube and a 170mm objective roughly 6% less in a 160mm tube.

However, with the complicating factor of parfocal distance and the distance to the intermediate image in the mix, not only does the magnification go askew using the wrong tube but also parfocality when mixing objectives becomes a pain, spherical aberration can be enough to reduce resolution,and as well, poor colour correction can flood the periphery of the field with lateral ca.
If the measurements are pretty close, there shouldn't be much of a problem but closing the gap between a 160mm tube and a 170mm tube with an adapter, is unlikely to provide an image that does not suffer from some degradation.

It wasn't really until the D.I.N. 45mm parfocal objective system with a 160mm tube came along and became almost ubiquitous that systems became somewhat theoretically interchangeable. This was however thwarted, by the invasion and necessity of W.F. eyepieces. Previously, the common use of Huygens eyepieces meant that eyepiece correction was somewhat consistent across brands. With W.F., proprietary designs were everywhere, so objective/eyepiece compatibility became the rule of the day, rather than parfocal/tube length compatibility.

The idea that fixed tube microscopes had interchangeability across brands is a myth. Maybe PZO and Zeiss West?....but mixing objectives is generally difficult and for sure you can put any other objectives on a compatible tube length stand, as long as you change to the correct eyepieces as well, so there is limited mix and match.

Even the short objective Nikon and Olympus systems were at odds with each other and as well the J.I.S. J.I.S. was a 170mm tube with 36mm parfocal. Nikon was 160mm with 35mm or less parfocal( I don't know exactly what it was) and Olympus was 160mm with 36.65 mm parfocal. The 3 companies, Shimadzu Kalnew ( once a major player in Japanese microscopes), Tiyoda and Olympus were all spawned out of the Japanese commercial microscope progenitor, M & Katera. M & Katera used 37mm parfocal and a 170mm tube. Shimadzu Kalnew spun off, using J.I.S., Olympus developed their own 36.65 and 160mm system and I am not sure about Tiyoda but it was probably J.I.S. Other Japanese makers , Carton, Kyowa were most likely J.I.S.


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 Post subject: Re: 185 Objectives?
PostPosted: Wed Aug 15, 2018 4:33 pm 
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Joined: Mon Aug 21, 2017 9:02 pm
Posts: 965
apochronaut wrote:
The idea that fixed tube microscopes had interchangeability across brands is a myth.
Apochronaut, I remember this very statement in your post from several months ago, and the more I read posts of folks trying different-brand combinations of optics, the more it becomes evident - mostly, I think, for microphotography.

_________________
Zeiss Standard GFL+Canon EOS-M10


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 Post subject: Re: 185 Objectives?
PostPosted: Thu Aug 16, 2018 5:32 pm 
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Joined: Thu Apr 05, 2018 1:06 am
Posts: 84
Location: Idaho
I agree the correct matching of objectives, tubes and eyepieces is most important for photography. For routine observation of tiny pond critters the requirements of careful matching may be not so important. My understanding is the effects of mismatches are most noticeable near the edges of the field. If the viewer is content with a sharp image in the central two thirds of the field, mixing and matching might be an economical way to get an incomplete system working at low cost. That can be useful if ones resources are limited.

_________________
Rick

A/O 10 Series Microstar
A/O 4 Series Microstar
A/O 4 Series Phasestar
A/O 4 Series Apostar
A/O Cycloptic Stereo
Several old monocular scopes in more or less decrepit but usable condition


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 Post subject: Re: 185 Objectives?
PostPosted: Fri Aug 17, 2018 11:40 am 
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Joined: Fri May 15, 2015 12:15 am
Posts: 2127
We are well into the era, where almost everyone expects W.F. imaging. A few don't, and there are some wise ones who accept the narrow field of older apochromat/compens combinations, knowing that the likelihood of putting together a similar economical plan W.F. combination, is likely a long way off.
By and large, in the past, when almost all microscopes were fitted with Huygens eyepieces, there was an acceptability level for coma or lateral ca and huygens eyepieces with their somewhat restricted f.o.v., would mostly cut off the field where the objective needed the most help , so mis matches weren't as noticeable. With W.F., the proprietary nature of the eyepiece's corrections, needed most outside a 70% circle, will often be a detriment in poorly matched optics. Sometimes the level of aberration and optical distortion is severe, so saving money and using Huygens eyepieces would be a good idea, rather than put up with a W.F. full of rainbows.

Earlier fixed tube length W.F. stuff, where the objective corrections were incomplete and the eyepiece was required to effect a completion, are all over the place.


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