30mm vs 30.5mm eyepiece mounts

[Mr Galasphere]

Why make two mount sizes 30mm vs 30.5mm so close in size?
Why didn't they standardize to one or the other?
Can 30mm be used in a 30.5mm mount or will it be too loose?

Thanks

[MichaelG.]

Why make two mount sizes 30mm vs 30.5mm so close in size?
Why didn't they standardize to one or the other?
Can 30mm be used in a 30.5mm mount or will it be too loose?

Thanks

.

(a) Presumably to differentiate between them [for technical and/or marketing]reasons
… it will ‘encourage’ use of the manufacturer’s own eyepieces

(b) … see (a)

(c) Yes it can be used … but may not perform optimally
… a layer of Kapton tape, or similar, would improve fit … but its only optical advantage would be improved centering.

Which microscope and eyepieces do you have in mind ?
… Someone here might have practical experience of their matching.

MichaelG.

[Scarodactyl]

30.5 is Meiji's standard for their EM line. They were an early player and likely adopted it before 30mm was completely standard--I don't know of there were other scopes using that standard at the time. Many companies have copied their design, first other Japanese companies and later Chinese factories which is likely how it spread. That said every Meiji clone I have handled has used standard 30mm eyepieces since that standard has clearly won--I have only seen it on genuine Meijis, and I assume the chances of finding a 30.5mm ocular in the wild are shrinking.

[Mr Galasphere]

30.5 is Meiji's standard for their EM line. They were an early player and likely adopted it before 30mm was completely standard--I don't know of there were other scopes using that standard at the time. Many companies have copied their design, first other Japanese companies and later Chinese factories which is likely how it spread. That said every Meiji clone I have handled has used standard 30mm eyepieces since that standard has clearly won--I have only seen it on genuine Meijis, and I assume the chances of finding a 30.5mm ocular in the wild are shrinking.

Thanks, that's interesting.
I have an Amscope SE306R-P-LED 20x-40x ordered off of ebay arriving in a few days. I know I'm getting ahead of myself, but I was looking around at accessories and checking out eyepieces looking at 5x and 15x if I wanted to go for 10x and 30x. Under the ebay listing of specifics it indicated that the mounting was 30.5mm.
Of course the specs on these listings are often out of date or inaccurate and you cant always be sure if the photos are of what you are actually buying. I suppose I'll have to wait till it arrives and get out the calipers just to make sure.

[Scarodactyl]

Don't bother with 30x eyepieces. Higher mag eyepieces can only stretch the light that's already there, and trying to stretch it out that much is just a losing battle on brightness and resolution.

[Mr Galasphere]

Don't bother with 30x eyepieces. Higher mag eyepieces can only stretch the light that's already there, and trying to stretch it out that much is just a losing battle on brightness and resolution.

I wasn't very clear on that. What I meant was 5x and 15x eyepieces to get 10x and 30 magnification. 15x eyepiece would also get me 60x mag which is probably as high as I would want to go.

[viktor j nilsson]

5x eyepieces are useless, as they only take the same image as that seen by your 10x eyepieces, and shrink it down to a smaller size on your retina. The effect is like looking through a pair of toilet paper rolls.

[apochronaut]

In fact in this case, 15X eyepieces will likely be useless for 30X as well, and certainly useless for 60X. In order for them to be usefull the N.A. of the 2 and 4X objectives would have to be .03 and 06 respectively. While this isn't impossible, I would need to know in advance and would Amscope even know?

[MichaelG.]

30.5 is Meiji's standard for their EM line.
[…]
--I have only seen it on genuine Meijis, and I assume the chances of finding a 30.5mm ocular in the wild are shrinking.

Just for info. …

https://amscope.com/products/ep10x305
https://www.bresser.de/en/Microscopes-M ... e-20x.html
https://www.gtvision.co.uk/Pair-of-25X- ... eld-Series
https://www.gtvision.co.uk/Pair-of-30X- ... eld-Series

.
I have no experience with any of these products.

MichaelG.

[Scarodactyl]

Oh yeah, it's very easy to find the eyepieces, so there must still be scopes that use them outside Meiji's (presumably including OP's scope). But maybe it is restricted to these fixed mag scopes and similar at this point.

[PeteM]

Zeiss OPMI stereo scopes were another oddball - recollection is they have/had a 25mm tube diameter.

I've seen some Meiji clones with 30.5mm eyepieces and as noted above, there are still generic 30.5mm eyepieces available -- and most cheap USB cameras come with bushings to go from the standard 23mm tube diameter to 30 and 30.5mm.

One "gotcha" with adapting 3rd party eyepieces can be where the image is picked up. Most standard 30mm eyepieces and some of the 30.5mm clones won't sit deeply enough to be quite right in a Meiji scope (wonderful stereo scopes, BTW).

There's a similar problem with using 30mm generics on some of the Wild Leica stereo scopes. One can still focus, but not maintain parfocality with a zoom. I've machined off a bit of some clone eyepieces, so they can sit deeper, and that is a fix for those eyepieces with enough "meat" to allow it to be turned down to fit a few mm deeper into the eyetube.

[Mr Galasphere]

In fact in this case, 15X eyepieces will likely be useless for 30X as well, and certainly useless for 60X. In order for them to be usefull the N.A. of the 2 and 4X objectives would have to be .03 and 06 respectively. While this isn't impossible, I would need to know in advance and would Amscope even know?

I was completely unaware of this. What is the relationship between eyepieces and N.A. of an objective?

Well if the 5X and 15X eyepieces are useless I can save a few bucks by not buying them.
Thanks for the warnings!

[apochronaut]

The total magnification should not exceed 1000X the N.A. of the objective otherwise any further magnification is empty.

The magnification increases but no further detail is provided. In fact , in many cases some of the details that are revealed and perceivable at lower magnifications become difficult for the eye and brain to assemble into a concrete whole at higher magnifications. Images also become dimly lit with poor contrast.