A glut of Mitutoyo 7.5x Plan Apo Objectives ?

[Greenfields]

Not long ago used Mitutoyo 7.5x 0.21 Objectives were reported to be rare.

In February 2017 Chris S. wrote: "these almost never come up for sale on the second-hand market. So far as I'm aware, only three specimens have come up on eBay in six years: these two, and the one I bought several years ago."

https://www.photomacrography.net/forum/ ... hp?t=33205


And Robert OToole, on a page last revised in June of this year: "The 7.5x M Plans are a bit more expensive at around $1300 retail new in- the-box and about $1100 sold as new on ebay, and about $600-750 used."

https://www.closeuphotography.com/mitut ... objective/

Now there are at least 16 ebay sellers, most offering several copies:

Listing Number, Price including shipping, Seller

https://www.ebay.com/itm/142906446145 5 copies# $615 sx-space (226 )
https://www.ebay.com/itm/142906451992 5 copies $618 sx-space (226 )
https://www.ebay.com/itm/163222945056 10+# $586 auto*fan (8309 )
https://www.ebay.com/itm/172825377516 1 copy $650 idea*for*life (20773 )
https://www.ebay.com/itm/173077487165 2 copies $1100 idea*for*life (20773 )
https://www.ebay.com/itm/173539814450 1 copy $580 idea*for*life (20773 )
https://www.ebay.com/itm/183413715689 1 copy $820 pickbestforyou (31993 )
https://www.ebay.com/itm/183568653029 6 copies# $425 idea*for*life (20772)
https://www.ebay.com/itm/202420083000 2 copies# $613 unique.buy* (25274 )
https://www.ebay.com/itm/223103846288 4 copies# $428 lehk013 (2787 )
https://www.ebay.com/itm/223103874258 5 copies $619 lehk013 (2787 )
https://www.ebay.com/itm/223104081961 4 copies# $433 songlcd (1447 )
https://www.ebay.com/itm/232971545853 2 copies# $426 shuaistar20150515 (1081 )
https://www.ebay.com/itm/253807440664 1 copy $425 jane-netwrok (4846 )
https://www.ebay.com/itm/253967849961 2 copies# $426 wudongpo2011 (3433 )
https://www.ebay.com/itm/283227278538 1 copy $511 unaliu*2010 (12239 )

# = Illustrated by an objective on what appears to be the same grey carpet tile.

Some of these listings are openly duplicates, and others are probably from a single seller using different names - but even so there does appear to have been an abrupt increase in supply and drop in price.

I wonder if a piece of equipment using this objective has been suddenly become obsolete and decommissioned: rather like the Illumina GAIIx gene sequencer.

When the GAIIx was quickly succeeded by much faster machines it appears to have released many objectives onto the market which are supposed to be OEM versions of the Nikon 20x 0.75 Plan Apo VC [though I have never seen a report that it actually works because it may have been re-engineered for a thicker cover glass, see:

http://www.microbehunter.com/microscopy ... php?t=6208

As for the Mitutoyo, and despite Robert OToole's warning about buying from China I took the risk of buying one from:

https://www.ebay.com/itm/183568653029 6 copies# $425 idea*for*life (20772)

It arrived in the UK in 10 days, had no cosmetic flaws and performs exactly as the reviews on this board led me to expect.

Henry

[Lou Jost]

That's very interesting, and congratulations. It's a great lens.

Unlike the OEM 20x VC you mention. I got one and it is terrible, probably for the reason you mention. Maybe through 2 cover slips it would work better? 0.17+0.17 is close to the recommended 0.3mm. Who would have guessed that this objective needs a thick coverslip?

[Greenfields]

Lou,

That seems credible.

The GAIIx genome analyzer cost $256,000 in 2014, and its successor, the HiSeq [which used an OEM Linos Objective] $654,000 so the cost of commissioning a bespoke objective design was probably not a major factor.

Now the GAIIx machines are being cannibalised for parts because they were largely built with open-source components which can be adapted for use in experiments.

https://www.nature.com/articles/d41586-018-05769-8

At least one patent for the technology included a bespoke objective design for an unconventionally thick [1.94mm] quartz window thickness [US Patent 7129505 column 9].

Definitely worth trying with two cover-slips. Would you need a film of oil between them or maybe a small air-gap will make no difference.

Henry

[Lou Jost]

I suppose oil between the cover slips will help, but that will also make it thicker and hence farther from the 0.3mm specs.

[ChrisR]

https://www.amazon.co.uk/iprotect-Premi ... B077MLGFL9

??

[Lou Jost]

How did you ever find/notice that???

I wonder if it is optical quality. Probably?

[ChrisR]

Motivation. I have one of those ***** objectives!

[abednego1995]

Those non-labeled PA20's are from the GAIIx's and the labelled PA20xs are for the MiSeq platform from illumina. (The internal code for the MiSeq is "BOLT" and you'll see that on some PA20's still in their shipping packages.)

As for the 300 micrometer coverslip correction for the non-labeled versions, go see their patent. It describes beautifully the need for coverslip correction, and how to balance it with multiplexing runs using both/many surfaces in a flow-cell.

https://patents.google.com/patent/US8143599

Cheers,
John

[Lou Jost]

That patent application is interesting. It sounds as though the objective might actually be designed for something closer to 350um (300um glass + 50um liquid) or even about 400um (300um glass + 100um liquid). They discuss a compensator in the "infinite space" between the objective and tube lens to permit low-aberration imaging from either 300um or about 400um. Does anyone know how that works?

[abednego1995]

Hi Lou,

My bad, I forgot that the GAIIx was a single surface TIRF microscope, (it only can excite the binded fluophores on the lower surface of the flow-cell.) so the correction must be for 300um(glass)+100um(liquid). I'm guessing later models including MiSeq which have multi-surface readout, incorporate a compensator behind the objective so they could use generic objectives than having custom optics made (hence the labelled PA's for the MiSeq)

There's a nice article about coverglass compensation by Shimizu and Takenaka. They're objective designers for Nikon.
Shimizu, Y., & Takenaka, H. (1994). Microscope Objective Design. Advances in Optical and Electron Microscopy, vol 14, p301-309.

Sorry for hijacking the thread. I have no information about the Mitutoyo, but the numbers and the countries they're coming from suggest that the semiconductor industry may be upgrading their inspection equipment.

John

[Macro_Cosmos]

The duplicate listings are from sellers that do this type of stuff. They would simply source stuff on Taobao and put it up on ebay with a higher pricetag, and if someone is unfortunate enough to buy it, they simply buy the item from the Taobao seller and flip for the difference. Many of these items can be found on Taobao offered for sale at much lower prices, by sellers that do accept returns and know what they are doing. Do be careful when buying surplus goods on ebay from China.

[Lou Jost]

Abednego, what kind of compensator can be used behind the objective? Can these be home-built?

I have just ran tests on the 20x with different numbers of cover slips and it looks very very good. Will post them on a new thread later today.

[RobertOToole]

Hi Henry

.....

Now there are at least 16 ebay sellers, most offering several copies

This is easy to explain. These are really the same stock of only 5 or 6 lenses. I believe these people don't even own the lenses and only order the product from the supplier after you send the funds. They make a quick 40-50% profit on top of the prices they pay.

At one point there were 5 or 6 Ebay re-sellers listing the same Printing Nikkor 105 all using the same images and the actual 105 PN was still available on Taobao by the actual owner.


If you can make a quick 50% on your money for a few minutes of work on your laptop, why not? That explains the 16 re-sellers.

As for the Mitutoyo, and despite Robert OToole's warning about buying from China I took the risk of buying one from:

https://www.ebay.com/itm/183568653029 6 copies# $425 idea*for*life (20772)

It arrived in the UK in 10 days, had no cosmetic flaws and performs exactly as the reviews on this board led me to expect.

Glad to hear you received a good lens. The Ebay re-sellers are a safer than straight from China since you are buying through Ebay but there is a 40-50% markup added to the prices you pay.

I am lucky with my last nightmare shipment from China with the bad/damaged lenses since I was able to re-sell the objectives that were okay and cover most of my losses. 2 of these were Mity 7,5x lenses, these were okay thankfully but 3 Nikon objectives were trashed. I won't do that again!

Thanks for the info on the Nikon 20x 0.75 Plan Apo VCs that is interesting.

Best,

Robert

[Greenfields]

Robert,

Thank you for the insight into the complexities of Chinese online trading.

Something I had never understood before.

The risks are real.

My worst experience [so far] is an objective in which the front element was severely chipped. It was certainly not the article illustrated, but was very well packed which means that it was conspicuously defective when shipped. I can't imagine that the seller expected it to be acceptable so from what you have said it may have been forwarded from someone else.

The seller refunded the payment within 4 hours of my complaint and did not want the objective returned ... so I took it apart:

http://www.photomacrography.net/forum/v ... hp?t=22651

Henry

[RobertOToole]

......
The seller refunded the payment within 4 hours of my complaint and did not want the objective returned ... so I took it apart:

http://www.photomacrography.net/forum/v ... hp?t=21250

Henry

That's a Labphot thread so I think its the wrong link, but I do think I remember a thread where you disassembled an objective. Thanks for the reminder on that thread. Would like to do the same thing with the LU Plan and a TU Plan I have here.

Best,

Robert