Leitz 12.5mm Photar brings $805. WOW!!

[g4lab]

I was watching this auction and I have to say I am amazed at the price this lens brought. Usually to go that high it has to be like unused with the plastic dome and the factory cartons and the papers. All I can say is wow!

[dmillard]

That's very amazing, especially since a similar lens
went for about half that amount two weeks ago: http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... :IT&ih=005

[Joseph S. Wisniewski]

I watched that one, too, and I was appalled.

Although I have a "soft spot" for Leitz Photars and Zeiss Luminars (note 1), I've also got a healthy respect for more "modern" optics (note 2). My own experiments (which have gotten me branded a "heratic" over at photo.net) lead me to the conclusion that my Nikon CF 20X M PLAN ELWD 210/0 (effectively, a 20mm f1.1) is a superior bellows lens to my 16mm Zeiss Luminar, shot side by side. Quality wise, I've always found the Zeiss and Leitz to be comparable, so I can't see what makes the 12.5mm Photar such a $$$ lens.

Notes:

1) My first "real" macro lens was a 25mm f2.5 Photar, and because it's a full stop faster than my 25mm f3.5 Zeiss Luminar, the Photar remains a useful tool.

2) Although older microscope objectives tended to require a great deal of correction by the microscope's eyepiece or photographic "projection" lens, the newer ones are much more heavily corrected at the objective. Nikon CF M PLAN objectives are as CA free and flat field as Photars and Luminars. And the Nikons are better coated and sharper.

[Joseph S. Wisniewski]

That's very amazing, especially since a similar lens
went for about half that amount two weeks ago

That's pretty normal for eBay. I was chasing a Nikon 5X M PLAN DIC the other day, and it went for twice what an identical objective did a week before. And the other seller was a more reputable one.

Although I suspect the seller from the recent auction. He had zero feedback, and the high bidder also had zero feedback. There's a word that springs to mind, rhymes with "chill"...

[rjlittlefield]

My own experiments (which have gotten me branded a "heratic" over at photo.net) lead me to the conclusion that my Nikon CF 20X M PLAN ELWD 210/0 (effectively, a 20mm f1.1) is a superior bellows lens to my 16mm Zeiss Luminar, shot side by side.
...
Nikon CF M PLAN objectives are as CA free and flat field as Photars and Luminars. And the Nikons are better coated and sharper.

Joseph, welcome aboard!

Results here are the same as yours -- the microscope objectives win hands-down. In my tests a couple of years ago, even a mediocre 10X objective handily outperformed a Luminar 16mm f/2.5 for central resolution. And as you say, the Nikon CF PLAN's extend that to the whole field.

One caveat is that the field of the objectives is a lot smaller -- just barely big enough to cover a 1.6X crop factor sensor. If one were to look at the total amount of information that could be captured by each lens in a single shot, I expect the Luminar would win that contest.

Nothing about this bothers me at all. The objectives are designed to work as well as possible at only one fixed, wide, aperture, over a small and strictly limited field size. Why would they not perform better -- under those specific conditions -- than lenses designed to cover a wider range of operating conditions?

BTW, I wonder if there's a typo someplace in your post. An objective that gives 20X on a 210mm tube would be more like 10mm, wouldn't it?

--Rik

[Joseph S. Wisniewski]

Joseph, welcome aboard!

Thanks. Glad to be aboard.

Results here are the same as yours -- the microscope objectives win hands-down. In my tests a couple of years ago, even a mediocre 10X objective handily outperformed a Luminar 16mm f/2.5 for central resolution.

The 16mm Luminar is just too slow. The objectives in it's "neighborhood" have a 1 to 2 stop advantage over the poor little thing.

10X 0.25 is a 19.1mm f1.91

20x 0.40 is a 10.0mm f1.15

And as you say, the Nikon CF PLAN's extend that to the whole field.

One caveat is that the field of the objectives is a lot smaller -- just barely big enough to cover a 1.6X crop factor sensor.

OK, I'm confused. How are you defining "the field of the objectives"? Where the coverage circle ends, or where we drop below a certain resolution?

Just to make sure I'm not going nuts, I mounted a Nikon CF 20X M PLAN ELWD on a Nikon PB4 bellows, shortened the bellows fully, and it covered the 1x D3 sensor quite nicely. Now, that's just a quick hand held test, I'd have to lock the thing down on the bench to see what it can do.

A quick test with the CF 20X M PLAN ELWD, the weird Nikon U10 and U20, and the Zeiss 8X POL (off it's INKO) showed that they all cover the 43mm image circle of the D3. They may have been designed to cover a 22mm field at 210mm (160mm for the U10 and U20), but they appear to have some ability to cover a 43mm field at 156mm. (again, I won't say how well they cover it, but they cover it).

If one were to look at the total amount of information that could be captured by each lens in a single shot, I expect the Luminar would win that contest.

Nothing about this bothers me at all. The objectives are designed to work as well as possible at only one fixed, wide, aperture, over a small and strictly limited field size. Why would they not perform better -- under those specific conditions -- than lenses designed to cover a wider range of operating conditions?

You've got a point there.

I've designed enough lenses to be familiar with setting up the cost functions in Zemax for optimization. Given the constraints that a Luminar has to have it's "goodness" spread over a 43mm field, while a more conventional objective is optimized for 22mm, and the Luminar has to be fully corrected while the conventional objective designer gets to put part of the correction off on the eyepieces (and the tube lens, for infinity optics) the Luminars should be easier.

But apertures? I shoot the Luminars wide open. Occasionally, I stop the 63mm down a stop, but the 40, 25, and 16 are always wide open.

And, in a bit of weirdness, my Nikon U10 and U20 microscope objectives have aperture controls.

BTW, I wonder if there's a typo someplace in your post. An objective that gives 20X on a 210mm tube would be more like 10mm, wouldn't it?

Technically, it's a "memo". I type what I wanted to type correctly, but I remembered what I needed to remember incorrectly. Or is it a "calco"?

[Charles Krebs]

FWIW.... the M Plan 20/0.40 ELWD has a focal length of 11.1mm.

[Joseph S. Wisniewski]

FWIW.... the M Plan 20/0.40 ELWD has a focal length of 11.1mm.

Charles, that just doesn't sound right.

Is it possible you subtracted the 1 in the fl=d/(m+1) formula?

Or am I having an off day?

[Charles Krebs]

Joseph,

Straight out of a Nikon Spec sheet/Pricelist for the CF M Plans. It provides a brief description, part number, focal length, and working distance.

a few other useful ones....

10/0.21 SLWD WD:20.4 FL:20.56
5/0.10 WD:20 FL:37.64
40/0.50 ELWD WD:10.1 FL:5.1
40/0.40 SLWD WD:14.9 FL:5.1

[Joseph S. Wisniewski]

Charles,

I'm apparently getting a bit foggy in my old age.

I've been working magnification equations as if the rear node of the lenses occurred at their mounting flanges, and just merrily using the tube lengths.

And in another thread, I was commenting on how far the rear elements of some objectives were recessed in the lens's mount.

Of course the M Plan 20/0.40 ELWD focal length of 11.1mm makes sense. We can even work things the other way...

11.1mm * (20+1) - 210mm = 23.1mm. So that's more or less how far the rear node is forward of the lens mount.

A little less, 15.8mm for the 5x, because it's so short.

And even less, 9.1mm for the ELWD and SLWD 40s, because you have to slide some elements back to make room for all that reverse Galilean stuff in front that gives them the long working distances.

It all makes perfect sense now.

It also means that I now have to measure the rear node locations for 13 objectives...