microscope objective scarcity

[rs6000]

Hello I have noticed since I started looking for objective bargains from the likes of niken e-series to the basic Olympus A series And there is plenty to be had of the 4x,10x 40x likes for Low$
geeze my olympus A4x cost me 15 shipped but there is a gap!! what about the lonely 20x objectives I have scoured all the usual places on the web LAbX Ebay but nothing Notta boatloads of 4 -100x objectives but no 20x at least for under 3-500$ for some high end APO infinity$$$
why are they so rare even in matched Sets I have seen offered from manufactures like Nikon and Olympus that are Very common on Auction sites they always skip the 20x "4X,10,40,100"

[PeteM]

Most of the scopes destined for schools etc. didn't originally include a 20x. Often just the 10x, 40x, and 100x oil immersion. Sometimes adding a 4x. Less commonly including and filling a 5 lens turret with the addition of a 20x.

Agree that it's a shame -- 20x is often just right for many specimens.

[einman]

you can find 20X from Chinese manufacturers on E-bay. Some are in fact the EXACT same objective but without the Olympus/Nikon labeling. You just have to compare the design etc. to insure they are parfocal etc.

[rs6000]

Ill try maybe amscope is a ok choice but Id like a older olympus or Zeiss
I find it so frustrating to see so many of the 10 and 40x objectives SOOO easy to find any rainy day all over the used market but no 20s you would not even notice if you were building a complete set until afterwards and then! OoPS wheres my gap filler sorry no 20Xs to be found on ebay other then Nikon and zeiss Plan-Apo type and I have been looking for close to 1 year