View Full Version : What is this?

07-12-2011, 02:33 PM
Hi, this is a "thing" that I inherited from my dad. It is some kind of a magnifier, but I don't know what it is used for and how it ought to be used. It is made by a German company (not sure if it is still in business).





07-12-2011, 02:33 PM


07-12-2011, 02:40 PM
Looks like it is for measuring on some flat object,like a map?

Are the grads millimeters and half millimeters?

Could be for checking the thread count in fabrics,too. Or,whatever else is flat.

07-12-2011, 02:42 PM
I'll bet that's for the garment industry for visually examining thread count per inch.

07-12-2011, 02:54 PM
Dad got this from the metalworking company he worked for. The company was regularly auctioning off equipment that doesn't meet the calibration or accuracy standards and dad used to bid for some of the items.

So I think it's gotta be related to machining. Dad was a boring mill operator at that company.

07-12-2011, 02:55 PM
I speculated that it is used to examine grain structure of a flat section of steel, but I think a microscope would be needed to reveal grain structure. Hmm...

07-12-2011, 02:56 PM
Are the grads millimeters and half millimeters?

It seems to be millimeter graduations.

07-12-2011, 03:32 PM
Looks like it is for measuring on some flat object,like a map?

Or a single frame of 35mm film.


07-12-2011, 03:39 PM
Isn't that an optical flat for checking the flatness of parts?

07-12-2011, 03:57 PM
My guess would be an optical comparator to check spacing or accuracy of layout lines and center punch marks. It would be easy enough to count the lines once the size of the graduations is known.

07-12-2011, 04:42 PM
Here's the company that made it. You could always send them a picture and ask them what it is:


07-12-2011, 05:53 PM
As Madwilliam suggests, it appears to be what is called a "Linen Glass" for measuring the count of threads per centimetre in fine fabrics. It may also be known as a "printer's glass" as the two are interchangeable. In that case it is used for inspecting the registration of 4 colour (CMYK) halftone images.

A.K. Boomer
07-12-2011, 08:57 PM
It's for beer - its to check the head froth bubble count - very valuable tool to know if you need to add more yeast or more sugar, used to have them just like that back in the old country.

Mike Nash
07-12-2011, 10:12 PM
Here's the company that made it. You could always send them a picture and ask them what it is:

That looks more promising than what I found on Google images:


07-12-2011, 10:20 PM
I also thought it was for fabric. Could be for photo use,too. I am not familiar with processing halftone images.

Weston Bye
07-13-2011, 05:22 AM
A linen tester (Google it)

A linen tester is a strong magnifier with a measuring scale.

The linen tester was invented to check the quality of woven fabrics. It is used in the textile industry to measure the number of weft and warp threads within a certain area of fabric. Today, it is more commonly used to measure the line width and check the registration of color separations in the field of printing and publishing.

It consists of a strong magnifier and a glass disc which has a measuring scale engraved in it. Nowadays, the scale is usually divided into millimetres, older linen testers had an inch scale. Simpler models have a square opening in the foot, with a scale applied to one or more edges of the opening.

Linen testers are also used in other branches of industry. For example, they can be used to measure the line weight of barcodes. - Wiki

Yours is a little unique in construction compared to the typical linen tester.


07-13-2011, 05:55 AM
+1 for the thread count, we used one to check the warf and weft threadcount on molten metal protective clothing, the melton cloth was first xrayed aft fairly low Kv/Ma and then we counted the threads on the xray to see if it was to british standard, i'm fairly sure that you could have easily used it for other things, the xray kit came from germany and it came with it so i suppose these are common in that area, it also came with sets of din and iso wires to check defect size

A.K. Boomer
07-13-2011, 06:24 AM
the fine grid is used for pilsners and lagers which have a much finer bubble count and the courser grid is used for the more conventional brews and IPA's and such. boy - haven't seen one of those in awhile - really brings back some memories...

07-13-2011, 12:52 PM
Thanks guys for all the replies. It all makes sense. Most likely dad's company was using this type of magnifier to make sure the clothing worn in the metalworking section of the fab was conforming to the code, as boslab pointed out.

A.K. Boomer, when analyzing beer with this, do you let the bottom of the magnifier just touch the surface of the beer? I'm just curious how you examine the bubbles :?

07-13-2011, 12:59 PM
That looks more promising than what I found on Google images:


ROTFLMAO Thanks, I needed that *LOL* [:-D

A.K. Boomer
07-13-2011, 02:46 PM
A.K. Boomer, when analyzing beer with this, do you let the bottom of the magnifier just touch the surface of the beer? I'm just curious how you examine the bubbles :?

It's missing a critical piece - that's the one thing I noticed about the unit is it's missing a lower holding mechanism - its called a foam scoop - maybe Evan will be so kind as to google it up for you - wish I could but kinda busy right now - ok gotta go - tootles:)

Steve Steven
07-13-2011, 02:54 PM
This thread brings back a memory for me. I read a book on the air war in WWII and a part of it discussed the valuable contribution of the ladies who examined the photo intelligence taken by RAF recon planes. At the start of the war, they had no way to accuratly measure things in the photos, untill one of them who had worked in textile industry brought in a thread count glass and used it. Soon everyone was using them and it brought a measure of standardization to the process. Interesting part was all of the glasses were made in Germany!


07-13-2011, 09:33 PM
Looks like an early version of a magnifying loupe with reticle, sometimes called a POCKET optical comparator, measuring loupe, measuring magnifier, etc. with the unusual property that it is made out of a single piece of glass.

SPI, Fowler, Mitutoyo, AB, Flexbar, shars,edmund scientific, etc. make or sell similar measuring instruments, but with separate lenses and interchangeable reticles.
Typical magnifications are 7X, 10X, 15X. Actual accuracy of the reticles is often unspecified, even though some are NIST traceable. The quality of this device is probably closer to those than to the folding linen testers (most of which do not even have a glass reticle, just lines outside the aperture). But it does seem to have considerable pincushion distortion. The reticle was probably well made.

Usage instructions tend to be non-existent but you don't need to be a rocket scientist to figure it out.

It is used for contact measurement and inspection of small features, particularly flush features which you can't get a caliper or micrometer into. Photos/negatives, maps, cloth, printed circuit boards, gear teeth, coins, screw threads, hole sizes, engraved/printed text, angle measurements, cutting tools, tooling marks, casting voids and other flaws, spectrographs, astrophotographs, surveillance photos, biological specimens, forensic specimens, gemstones, watch parts, etc.

Use graph paper, calipers, micrometer, gage blocks, flatbed scanner, screw pitch gage, etc. to determine the line spacing (probably metric, like 5 lines/cm). Calibration instructions requiring use of an optical comparator (not to be confused with the pocket type):
(also won't work since reticle is not removable).

Note that measuring carbide, diamond, or abrasive cutting tools is a problem since they can scratch glass. You could use clear plastic to protect but this can introduce some parallax error.

Given that over the last 140 years the company (founded by a protege of carl zeiss) was involved in making watches, aviation instruments, movie cameras, cinetheodolites, astronomical instruments, general precision instruments, etc. a number of original applications are possible.

We see Edmund advertising pocket comparators to the machining trades since around 1953. Edmund may have started out as Edmund salvage co selling war surplus optics, including magnifiers and gunsight reticles. The folding linen testers without reticle have been around since at least 1895. Reticles in various forms have been around since at least 1820 (probably earlier as theodolites have been around a long time), though early versions were just crossed wires but glass reticles have been around since at least 1884. A watchmaker's loupe modified to accept interchangable screw on reticles may well have been developed or at least popularized in WWII for examining survalence and/or machine shop inspection and I can't find pre-WWII references to magnifiers with integrated reticles.

http://www.mitutoyo.com/pdf/Section-I-1001.pdf (pg 44)

The thread count glass had a translating magnifier:

There is also a variation in which two magnifying loupes travel along a long glass scale. A one dimensional coordinate measuring machine. Then there is the two dimensional variety. These would have been used for surveillance photos, parallax measurements of astrophotographs, etc. Reference to measuring machines for parallax measurements from 1915, 1897, 1928, 1907, and 1901:
Some used screws, some glass scales.

An incomplete snippet from 1845 mentions using a reticle to measure to 0.001" or less.

In the 1940s, they apparently had trouble etching reticles fine enough: