AWOOGA 20x nikon planapo objectives are back AWOOGA

[Scarodactyl]

This is not a test, the guy who lists cheap 20x nikon planapo objectives has dropped another set
https://www.ebay.com/itm/Nikon-Plan-APO ... 3965589886
It'a gone up from 100usd to 150usd but it's still a world class deal. These aren't the OEM ones corrected for odd cover glass thickness, this is a normal objective. I use my copies, one on my biological and one one my gem inspection scooe, and I like them a ton.
I'm posting about it because there has been a long break, and last time he sold a bunch in a single listing. I suspect dealers like to scoop them up for later too. If you don't have one you should consider if you can fit it somewhere in your lineup.
Yes, the 60mm parfocal length and 25mm thread makes them a bit prioprietary, but they will work well with a Nikon or Olympus tube lens, or in goofier contexts like on a CMO stereo (centered over one light path, and no doubt only at highest mag settings).

[PeteM]

+1.

Scopes like the Leica DMLS also use a 25mm thread, have the same 200mm reference tube length as Nikon (Olympus is 180) and have enough room to fit the 60mm parfocal Nikon's. With a Leica head and tube lens the image is still outstanding. Someone who is a bit "handy" could also adapt a Nikon head - or just the tube lens and use a camera and live view for viewing, composing, focusing - for an ideal match of corrections.

It really is a spectacular objective, with lots of working distance, in a magnification range that's ideal for many subjects. With it's 0.75 numerical aperture, it also won't mind being pushed to 750x.

[apochronaut]

It also works o.k. in the Reichert system series 400 stands, mated with other objectives of the Reichert Austria family., where it is about 18X. Cumbersome but the 45mm objectives could be extended to get parfocality. There is a 25X .65 planapo in that series already, which is about as good as the Nikon and in a more atractive magnification and format for that microscope but also about 100 times harder to find. The Nikon objectives are actually better than Olympus 45mm infinity objectives in that application. Olympus produce a bit of funny business going on off axis despite the tube length being almost identical to that of a Reichert. The Nikon would be a good option in one of the Poly stands adapted into the 28mm nosepiece.

Another option would be to buy a blank Bestscope 2081 stand. The last price on the 2081 I was quoted was 750.00 for the bare stand, for either of the 100 watt halogen or 3 watt led versions. A stage, condenser, 6 place 25mm nosepiece, head and 25mm f.o.v. eyepieces are a little over that : so somewhere in the vicinity of 1750.00 for a brand new 100 watt 6 objective, 25mm f.o.v. stand. Put in whatever 25 mm Nikon or NIS60 objectives you like.

[Scarodactyl]

Aaaaand they're gone. Hope people got while the getting was good!

[apochronaut]

I considered but never pulled the trigger on one of those that require the .40 cover. That specification is not insurmountable, since there are .40 coverslips available quite commonly for haemocytometers but it would be a cumbersome physical barrier against using any other quality objectives above .40 N.A. with it.
However, the difference between the two ( .17 and .40) is within the latitude that a correction collar could theoretically accomodate, which makes me question whether internally, the difference is not just a matter of shimming? In other words, could a cheap .40 version of that objective just be reshimmed internally to meet a .17 specification?

So, if anyone wants to send me both of them; the .17 version and the .40 version, I will disassemble them both and report back with my findings. I won't unfortunately be able to send them back. Temporarily, my nearest post office is that of Moscow, Ontario, Canada. No doubt, mail originating from that post office will be subject to severe scrutiny and likely confiscation and I would not want to risk the donor losing such important and valuable objectives.

[Scarodactyl]

It certainly seems likely that it's a minor tweak, given the identical shell. I use all three, normal and both oem versions, for viewing inclusions within gemstones. Hinestly the difference is pretty subtle when they're all being pushed out of spec but it's nice to have.

[patta]

In other words, could a cheap .40 version of that objective just be reshimmed internally to meet a .17 specification?

The black top lens holder of the .17 protrudes about 1.5mm more than the .40; the chromed brass barrels look the same.
I didn't dare to open them up
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[patta]

for so long time I refrained from posting this masterpiece:
no thorough testing, but let's just assume that it is not good.
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Nikon_20X075_extra_coverslip.jpg (44.34 KiB) Viewed 3183 times

[apochronaut]

Ah yes. The glass patio table for Lilliputian's mod.

[PeteM]

I've mentioned the Leica DMLS as an option for hosting these amazing objectives - and took a snapshot yesterday when I had one I'd converted to do a sort of shootout between a BH2 and three Leica variants (all Leica stand and optics, this Leica/Nikon hybrid, and a Leica DMLB with DIC).

Spec-wise the Leica DMLS stand is pretty much a Nikon E400 mechanically and electrically. Same 25mm objective thread, same 200mm reference tube length, same silky smooth focus mechanisms, same bright-enough 30 watt halogen lamps, and both built to a better and more reliable standard than most Chinese scopes under $5K. The DMLS was one of the last great US-made scopes. It also looks better in my opinion - a graceful arc rather than the Nikon's semi-Art-Deco facade with a big flat steel plate in the back. More importantly, the DMLS is often available cheaper.

The Nikon optics, however, are worth keeping -- especially that marvelous $3000 20x PlanApo .75na .17 cover slip objective. Nikon's regular 60mm parfocal CFI plan achromats also have excellent contrast and longer working distances than most of the competition. Turns out the Leica stand has enough room to host those 60mm parfocal objectives and still maintain Kohler illumination.

What's wanted - and shown - is to fit a Nikon head to the Leica stand to get proper (e.g. no) tube lens corrections. Shown are both a Nikon binocular head mated to an intermediate piece that rotates and contains a polarizer -- and a Nikon binocular head converted to a T-mount for 100% direct projection to any APS-C camera.
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[apochronaut]

You need one of my 100x 1.10 NIS60 W.I. objectives for that, Pete.

[Scarodactyl]

I need one too--are those babies for sale??

[apochronaut]

I have 4 of them. NIS60 is Nikon Infinity System , 60mm parfocal. The guts seem to be the same as the same spec. R.M.S. NIS45 objective, just fitted into a larger housing. The BS- 2081 stand ( E200 clone ), which has an optional 25mm f.o.v. head can use the NIS60 version, so I assume that the plan image circle of the objective is at least 250 microns and it should work well in U.W.F. Nikon stands.
. I have used one of the NIS45 objectives on a Diastar with different eyepieces : the same ones that I use for the Austrian Reichert objectives in a Diastar, and the corrections are very close between the NIS objective and the Reichert, if not identical. I have not done an ultra critical investigation of the peripheral corrections. This implies that the Austrian Reichert objectives are corrected to the same level as the Nikon objectives.
My Diastar is populated by a combination of planfluor and planapo objectives of Austrian production, some as old as possibly 1972 and some as recent as about 2000. The circa 1975 25 X Reichert planapo with the aforementioned eyepieces fitted , compares favourably with the 20X Nikon planapo in the system ( with a crude adaption to parcenter and parfocalize the two ) . However , I have not tried the 100X 1.10 W.I. NIS60 objective with the same settup because the immersion requirement makes the settup too cumbersome. The NIS45 objective works great however and it has the same internals as the NIS60. They are planachros.
At 1.10 N.A. , I am hoping they can be used straightup with a higher N.A. DF condenser but I haven't had the time to sort that out yet. They are nicely made objectives.

[Scarodactyl]

Shoot me a PM if one of those is available. I'd love to put one on my E800 and play with it.

[PeteM]

Darkfield with water immersion could be super convenient if that works. Hope you'll let us know, Phil, if you try it.

[apochronaut]

I have about 10 odds and sods of DF condensers but only a couple of them will fit the Diastar yoke or 20 yoke well enough to be stably centerable and work comfortably enough for a reliable assessment. Many of them do not have N.A. data on them too.
However, AO has had a degree of modularity going way back and the 214F condenser dovetail is designed to be removed with one locking screw and thus can be fitted to other condensers.
1.1 N.A. seems doable, if I can find a condenser with a bottom N.A. of 1.3. I will get to it.