MicrobeHunter.com Microscopy Forum

Following the helpful responses to Mike Bradley's recent query, I am hoping that someone can answer this:

I have a couple of the 8x Kpl eyepieces, as illustrated on the left, here:
Source: http://www.science-info.net/docs/zeiss/ ... ystems.pdf


The scale is obviously for dioptric adjustment, but why are there two fiducial lines ?

MichaelG.

... Any ideas ?

Michael, a wild guess: If the scale position uses a fiducial line as marker, and you can use the eyepiece with OR WITHOUT reticle, won't the two modes require two separate lines, given the thickness of the disk ?

note, this is "hands waving", not a true explanation; and I had to look up the "fiducial" in a dictionary... this word is absent from English-learning texts...

Hobbyst46 wrote: ↑

Wed Sep 18, 2019 10:01 pm

Michael, a wild guess: If the scale position uses a fiducial line as marker, and you can use the eyepiece with OR WITHOUT reticle, won't the two modes require two separate lines, given the thickness of the disk ?

note, this is "hands waving", not a true explanation; and I had to look up the "fiducial" in a dictionary... this word is absent from English-learning texts...

Quite possibly, Doron ... Thanks
'though it does seem strange that I can find no reference to usage.

Apologies for using obscure [but rather pleasing] terminology.

MichaelG.
.
.
Edit: But if you are right ... why does the W version only have one line ?

MichaelG. wrote: ↑

Wed Sep 18, 2019 10:09 pm

Hobbyst46 wrote: ↑

Wed Sep 18, 2019 10:01 pm

Michael, a wild guess: If the scale position uses a fiducial line as marker, and you can use the eyepiece with OR WITHOUT reticle, won't the two modes require two separate lines, given the thickness of the disk ?

note, this is "hands waving", not a true explanation; and I had to look up the "fiducial" in a dictionary... this word is absent from English-learning texts...

Quite possibly, Doron ... Thanks
'though it does seem strange that I can find no reference to usage.

Apologies for using obscure [but rather pleasing] terminology.

MichaelG.
.
.
Edit: But if you are right ... why does the W version only have one line ?

May I answer the riddle with a riddle: The eyepiece on the right - KPL-W - is marked with eyeglasses, so it is supposed to be used by eyeglass wearers. Yet the two eyepieces in the photo have (perhaps! if they are 8X) the same eye relief distance (almost) - 8 and 9 mm, these are not really convenient! my ordinary 10X KPL-W Zeiss eyepieces (not for micrometers) have an eye relief distance of ~20mm. So ? is the table related to the photos ? where is the 12.5X ?

I cropped the page, to make the posted image clear at the forum's permitted dimensions

Yes, images and the full table for this group of eyepieces appear together, on p74 of the linked document.

MichaelG.

Thanks, that was really dumb of me! the Z.O.S. document has been on my PC for ages since 75RR first pointed it out to me.
So, sorry, no clue about the fiducials.

I think the mystery is solved ... and the answer is what was first suggested.

The current version of Zeiss document 'Microscopy from the very beginning' describes the modern 'infinity' microscopes [which have superseded the 'finite tube length' models] ... but it includes the following brief statement:

The eyepieces are labelled with a diopter scale ( + 0 - ) and “foc”. If an integrated reticle is used, the red dot represents the zero mark because of the image shift which then occurs.

One can only assume that the red line on the old eyepieces corresponds to the red dot on the new ones.


MichaelG.

.

Ref. http://www.its.caltech.edu/~bi177/priva ... inning.pdf

I have a similar eyepiece, the 12,5 with a 17mm micrometer disc (graticule), catalogue # 46 41 23 and can confirm that the scale on the micrometer disc is most sharply in focus when the red line is on 0

75RR wrote: ↑

Fri Sep 20, 2019 7:47 pm

I have a similar eyepiece, the 12,5 with a 17mm micrometer disc (graticule), catalogue # 46 41 23 and can confirm that the scale on the micrometer disc is most sharply in focus when the red line is on 0

Excellent, thank you

MichaelG.

Inspired by this beguiling discussion, and a previous remark by 75RR, I just purchased a 18$ unbranded Chinese 10X eyepiece (free shipping) with a reticle inside, for size measurements on demand; to keep my routine viewing eyepieces uncluttered by rulers and crossed lines. Hopefully it will be in focus with something...