23.2 vs 30mm

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david_b
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23.2 vs 30mm

#1 Post by david_b » Fri Feb 07, 2020 10:24 am

I am used to 23.2mm eyepiece tubes but recently acquired a compound microscope with 30mm eyepieces.
What a difference!
No more squinting or struggling to get my brain to see one image instead of two.
Now I have a clear, bright field of view that is much more relaxing to use for long periods.
I have yet to see the downside of using 30mm eyepieces.

Larry060
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Re: 23.2 vs 30mm

#2 Post by Larry060 » Fri Feb 07, 2020 12:12 pm

What make is your 30mm microscope?

david_b
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Re: 23.2 vs 30mm

#3 Post by david_b » Fri Feb 07, 2020 12:23 pm

Larry060 wrote:
Fri Feb 07, 2020 12:12 pm
What make is your 30mm microscope?
Motic BA310

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Dmi3n
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Re: 23.2 vs 30mm

#4 Post by Dmi3n » Fri Feb 07, 2020 12:56 pm

Probably the struggle with seeing one image instead of two doesn't have to do anything with field of view of eyepieces. It looks like binocular head fallen out of adjustment or eyepieces had bad centering. I had old Zeiss Lumipan microscope with only one pair of eyepieces which were "eye of the needle" K7x but it didn't cause any struggle to see one image using the binocular.
Scopes: CZJ NfPk w/ 45mm apo objectives, Phv phase contrast, Epi Pol illuminator, trinocular head, CZJ Epityp-2 Pol (currently dismantled for full restoration and recollimation) w/ D32 microhardness tester and photomicrography attachment.

PrecisionInstruments
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Re: 23.2 vs 30mm

#5 Post by PrecisionInstruments » Fri Feb 07, 2020 1:26 pm

Only downside to larger field of view is brightness. Not as bright, though may not be an issue in most circumstances.
Older fluorescence microscopes using only 50W mercury lamp had small f.o.v eyepiece to get good signal from specimen.
I have a headache, For which the future’s made

Scarodactyl
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Re: 23.2 vs 30mm

#6 Post by Scarodactyl » Fri Feb 07, 2020 2:28 pm

I understand how more magnification gives less light, but I don't understand why a wider fov would.

30mm is generally nicer but as said above it shouldn't make a difference on image convergence. What was your previous scope?

einman
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Re: 23.2 vs 30mm

#7 Post by einman » Fri Feb 07, 2020 3:32 pm

My personal experience is a microscope built to maximize 30mm eyeieces has no deficit in brightness. Quite the contrary the view is much brighter. This is especially true when used with wider field objectives.

Withn that said I was not aware the Motic BA310 had 30 mm view eyepieces. Their website indicates the BA310 comes with Widefield eyepieces N-WF10X/20mm with diopter adjustment on both eyepieces. That is significantly smaller than a 30 mm eyepiece. I am guessing if you measure the ocular tube you will find it is not a 30 mm eyepiece. When calling an eyepiece 30mm you measure where the eyepiece interfaces with the ocular tube not the glass nearest the eye.

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Re: 23.2 vs 30mm

#8 Post by Scarodactyl » Fri Feb 07, 2020 6:17 pm

10x/20 seems standard for a cheap 30mm diameter eyepiece, though the same can be accomplished in a 23mm pretty easily (though 18mm is probably more standard).

david_b
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Re: 23.2 vs 30mm

#9 Post by david_b » Fri Feb 07, 2020 6:31 pm

Scarodactyl wrote:
Fri Feb 07, 2020 2:28 pm
I understand how more magnification gives less light, but I don't understand why a wider fov would.

30mm is generally nicer but as said above it shouldn't make a difference on image convergence. What was your previous scope?
Brunel infinity scope. Actually produced a good quality image, but the Motic is so much more comfortable to view for long periods.

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Re: 23.2 vs 30mm

#10 Post by david_b » Fri Feb 07, 2020 6:33 pm

einman wrote:
Fri Feb 07, 2020 3:32 pm
My personal experience is a microscope built to maximize 30mm eyeieces has no deficit in brightness. Quite the contrary the view is much brighter. This is especially true when used with wider field objectives.

Withn that said I was not aware the Motic BA310 had 30 mm view eyepieces. Their website indicates the BA310 comes with Widefield eyepieces N-WF10X/20mm with diopter adjustment on both eyepieces. That is significantly smaller than a 30 mm eyepiece. I am guessing if you measure the ocular tube you will find it is not a 30 mm eyepiece. When calling an eyepiece 30mm you measure where the eyepiece interfaces with the ocular tube not the glass nearest the eye.
The Motic is exceptionally bright - no complaints there at all.

Image

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Re: 23.2 vs 30mm

#11 Post by apochronaut » Fri Feb 07, 2020 8:27 pm

A wider eyepiece diameter has the possibility of producing a wider field of view always but it is not necessarily wider or better than a superior design in a narrower format. That is strictly determined by the design of the eyepiece itself and there are dozens and dozens of designs.

Many eyepiece designs are more expensive to produce, so it is cheaper for a manufacturer to make a simpler design in a wider format , than a sophisticated design in a smaller format. Grinding and polishing 2 or 3 lenses ,irregardless of their diameter is a lot easier than grinding and polishing 5 to 9 elements and cementing a couple of doublets, or even a triplet.

Many older scopes had narrow fields of view but the resolution within those borders was stunning. Often, with a simple optical system, the field of view can be expanded and seem incredibly wide and expansive , yet with mediocre resolution .....especially true on cheap microscopes.

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Re: 23.2 vs 30mm

#12 Post by einman » Fri Feb 07, 2020 10:22 pm

I fully agree with Apochromat. What do the eyepieces look like from the bottom? Well that is less than 30 and I am guessing the eyepiece itself may have some restrictions.

Here are the measurements of the 30 mm eyepieces on my Leitz Diaplan.

Image

david_b
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Re: 23.2 vs 30mm

#13 Post by david_b » Fri Feb 07, 2020 10:34 pm

einman wrote:
Fri Feb 07, 2020 10:22 pm
I fully agree with Apochromat. What do the eyepieces look like from the bottom? Well that is less than 30 and I am guessing the eyepiece itself may have some restrictions.

Here are the measurements of the 30 mm eyepieces on my Leitz Diaplan.
It's a 30mm eyepiece/tube.
The inaccuracy was due to trying to take a photo on my phone with one hand while holding the gauge with the other.
Accurate measurements are:
Tube: 30.05 mm
Eyepiece at bottom: 29.90 mm
There may still be a margin of error - the eyepiece is a tight fit to the tube.
Last edited by david_b on Sat Feb 08, 2020 4:54 am, edited 1 time in total.

einman
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Re: 23.2 vs 30mm

#14 Post by einman » Sat Feb 08, 2020 1:03 am

hmm..well they seem to be 30mm eyepieces! Perhaps it is an optional head.

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Re: 23.2 vs 30mm

#15 Post by david_b » Sat Feb 08, 2020 5:04 am

einman wrote:
Sat Feb 08, 2020 1:03 am
hmm..well they seem to be 30mm eyepieces! Perhaps it is an optional head.
It's a standard head.
I'm not clear why you believe the eyepieces on the BA310 to be something other than 30mm.
If you're referring to the 20mm measurement in your post above, that relates to the (wide) field of view, not the diameter.

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Re: 23.2 vs 30mm

#16 Post by Scarodactyl » Sat Feb 08, 2020 5:39 am

20mm is achievable in a 23mm eyepiece (ie Olympus whk from the bh2 series). It's a bit narrow for 30mm but certainly wide and comfortable overall--zeiss has a lot of 10x/20s on compound scopes that certainly aren't cheap.

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Re: 23.2 vs 30mm

#17 Post by einman » Sat Feb 08, 2020 4:11 pm

Correct -I was not clear. It is the FOV i am thinking about as I never thought about a 30 mm eyepiece having such a small FOV. Generally speaking a 30 mm eyepiece was reserved for high end research scopes. Motic's description of the field of view as being 20 mm does not correspond with the higher end 30 mm eyepieces. For example the Leitz 30 mm eyepiece has a FOV of 26 mm as does the Nikon 30 MM eyepiece. Zeiss has a 30 mm eyepiece that has a FOV of 25mm. This information is displayed on the eyepiece as 10X/26 or 10x/25. It appears the Motic BA310 although having a 30 mm eyepiece ( as measured in diameter) perhaps only has a FOV of 20 mm per their technical data. I can find no data suggesting the FOV is higher than 20 mm. Quite interesting actually. B&L had a 15X widefield eyepiece, that although it fit in the same ocular tube, as their regular field eyepieces, the optics were such that you had a wider FOV. The lenses necessary to accomplish this feat resulted in a very heavy eyepiece.

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Re: 23.2 vs 30mm

#18 Post by Scarodactyl » Sat Feb 08, 2020 4:26 pm

Alas, the 30mm uwf eyepieces of the 23mm era largely set the high water mark. I think Nikon's current uwf offering is only a 25, not 26.5 like in the labophot/optiphot days, and standard 30mm eyepieces are like 21 or 23 or so.
Unless you get a mitutoyo uwf head with a 30mm fov, though that is with a larger diameter eyepiece yet.

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Re: 23.2 vs 30mm

#19 Post by einman » Sat Feb 08, 2020 4:31 pm

True. I made a false presumption that since it was only a FOV of 20 mm it most likely was not a 30 mm eyepiece. Oh and yes the Nikon was 26.5 rather than just 26 I just rounded it down for brevity. I own all three eyepieces the Nikon, Leitz and Zeiss. Although my Zeiss eyepieces are showing some signs of deterioration. Common with the Zeiss optics of the time apparently.

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Re: 23.2 vs 30mm

#20 Post by einman » Sat Feb 08, 2020 4:41 pm

Speaking of FOV I replaced my Leitz 1x objective turret with the 0.8x, combined with the Fluotar objectives and the 30MM 10x/26 eyepieces, the FOV is incredible. There is a point where it is probably overkill as I find my eyes wandering around-LOL.

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Re: 23.2 vs 30mm

#21 Post by PeteM » Sat Feb 08, 2020 6:03 pm

FWIW, I had a Motic 400 series trinocular head. 30mm eyepieces in it had a clear, flat 22mm FOV.

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Re: 23.2 vs 30mm

#22 Post by ImperatorRex » Sat Feb 08, 2020 6:20 pm

einman wrote:
Sat Feb 08, 2020 4:41 pm
Speaking of FOV I replaced my Leitz 1x objective turret with the 0.8x, combined with the Fluotar objectives and the 30MM 10x/26 eyepieces, the FOV is incredible. There is a point where it is probably overkill as I find my eyes wandering around-LOL.
Some may find this interesting in context of the FOV topic:
viewtopic.php?f=5&t=6121#p55179

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75RR
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Re: 23.2 vs 30mm

#23 Post by 75RR » Sat Feb 08, 2020 7:05 pm

Scarodactyl wrote:
Sat Feb 08, 2020 5:39 am
20mm is achievable in a 23mm eyepiece
So it is ...
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Re: 23.2 vs 30mm

#24 Post by MicroBob » Sat Feb 08, 2020 7:55 pm

What I find interesting: Leitz made a lot of advertising for their Orthoplan with it's very wide field of up to 28mm on 6,3x and 8x eyepieces. As far as I know todays microscopes in this price range don't offer this extremely wide field any more, just 26 or 24mm or so. Has practice shown that the advantages of 28mm eyepieces are not so great after all?

Bob

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Re: 23.2 vs 30mm

#25 Post by einman » Sat Feb 08, 2020 8:48 pm

I seem to recall reading an article that associated the larger FOV's with increasing the rate at which a researcher's eyes became tired. As I recall the larger FOV's resulted in more eye movement as opposed to slide movement. I can testify to that to some extent. There is no doubt an increased cost associated with the much larger FOV's while maintaining optical specifications. Perhaps those two issues alone were sufficient to stop producing the wider fields.

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Re: 23.2 vs 30mm

#26 Post by david_b » Sat Feb 08, 2020 9:10 pm

I confess to being a bit confused!
Field of view is Field number divided by (eyepiece magnification x objective magnification)
Tube diameter plays no part in the calculation?
I'm comparing comfort of long term viewing of 30mm eyepieces vs 23.2mm, not field of view, which is the same for both (assuming the same field number).

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Re: 23.2 vs 30mm

#27 Post by PeteM » Sat Feb 08, 2020 10:15 pm

MicroBob wrote:
Sat Feb 08, 2020 7:55 pm
. . . As far as I know todays microscopes in this price range don't offer this extremely wide field any more, just 26 or 24mm or so. Has practice shown that the advantages of 28mm eyepieces are not so great after all?

Bob
Bob, Not a complete answer but I have a Leitz ultra wide head from this era. There's not much eye relief and (eyeglass wearer that I am) it's not my a favorite head for long sessions.

My own experience has been that a flat 18mm FOV seemed just fine for any reasonable use, but sort of like big screen TV's you get used to larger and larger. 26mm (in a more modern Leica) does seem useful for scanning a slide and a "wow" view. That said, 22mm personally seems more comfortable and now pretty much the default for modern lab quality scopes. I'd guess enough users felt the same way that the big four stopped their pursuit of cinema-wide eyepieces at all costs??

I also wonder (and don't know) if "instrument myopia" and eye strain is more likely with the ultra wide eyepieces: https://en.wikipedia.org/wiki/Instrument_myopia

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Re: 23.2 vs 30mm

#28 Post by PeteM » Sat Feb 08, 2020 10:18 pm

David, At least in theory you should see the same field of view from a 10x/20 eyepiece fitted into either the standard or the wider 30mm tube. In practice, it may be easier to get a high eye relief in the larger tube. That might be part of the much improved view you're seeing?

Beyond about 20mm FOV, though, it's hard to get the glass wide enough in a standard tube size. Hence the trend to 30mm tubes for FOV's of 22mm and larger.

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Re: 23.2 vs 30mm

#29 Post by david_b » Sat Feb 08, 2020 10:26 pm

I'm not sure Pete, I also have a BH-2 with WHK (high eyepoint) 10x/20, 23.2mm eyepieces. Viewing is much more comfortable with the Motic (resolution is better with the Olympus but that is likely the SPlan glass).
10x/20 doesn't seem uncommon for modern 30mm eyepieces - eg. Olympus CX33, Zeiss Primo - though admittedly they are not high end research microscopes.

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Re: 23.2 vs 30mm

#30 Post by PeteM » Sat Feb 08, 2020 11:25 pm

Hi David, Not sure why the 10x/20 Motic beats (less eye strain?) the 10x/20 Olympus WHK for you. I've had good luck with the Olympus, but only had 10x/22 in a Motic (and also in an AccuScope, BX, and Eclipse) to compare. All were good, though 22mm field was a plus. Maybe your reaction has something to do with the "instrument myopia" link posted above, where you have the BH2 focused a bit off your natural relaxed view and a bit of accompanying muscle strain?? Having one eye off focus is another factor. It's said that the best way to get a natural focus is to focus very quickly, before your eye muscles have much chance to get into the act.

I'm old enough to have very little accommodation range. So, you'd think I'd get things spot on? That said, very late in the evening my eyes sometimes struggle to focus on either a computer screen or through a microscope. Next day, eyes rested, fine again.

The scopes you'd mentioned with 10x/20 and 30mm tubes are good ones -- but also the budget/teaching models in those respective lines. For example, move from an Olympus CX to a BX and the field goes from 20x to 22x. And the better Olympus UIS2 optics for the BX line will support optional 26mm fields (so, incidentally, will your SPlans with a UW Olympus finite head). So the 20m field is now sort of "teaching/economy," the 22mm a nominal "professional standard, and the 25mm+ field "pro plus" as far as I can tell -- and all now fitted to a 30mm tube. Newer scopes, sometimes even larger.

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