Coastal Optics (Jenoptik) 60mm lens mysterium

[Dr Klaus Schmitt]

Well, there is a some mysterium going on, on their site about the presented data...

Their new presented data show much less transmission... (magenta is new)



But their lens is much better than that...



I wonder what happened when JENOPTIK bought them, and I did ask their president Jay Kumler about that...

[longzoom]

I see only one explanation for this innovation: they used a new kind of glass for some optical elements. The new MC cannot deliver so radical changes to the charts you show. LZ

[BruceSD]

Maybe some more magical "pixie dust" conjured up the the maestro himself - Dr Thomas Caldwell ?

[Birna Rørslett]

The designer of the original 60mm, Brian Caldwell, likely has the explanation?

[Dr Klaus Schmitt]

The designer of the original 60mm, Brian Caldwell, likely has the explanation?

That old graph was from him, along with the CA diagram showing "Apo" correction -
the new however seems from Jenoptik and the CA diagram only shows Achromatic
correction...??

We chatted ever so often, so I could ask him, but my feeling is that he cannot talk
about it (NDA) most likely...

[Dr Klaus Schmitt]

I see only one explanation for this innovation: they used a new kind of glass for some optical elements. The new MC cannot deliver so radical changes to the charts you show. LZ

It is not that simple to measure lens transmissions correctly, I fear they made it simply not correctly ... ;-)
Their older graph and my recent measurements correlate well.

[Michael Erlewine]

my understanding from speaking with them not very long ago is that they don't have any copies of this lens built and on the shelf. However, they have all the parts to build them and will do so, on a one-by-one basis. So, perhaps they have different ways of assembling the lens from what they did before. I had the original but sold it, but recently had an opportunity to pick up another copy, which they told me was put together from parts. Maybe that says something. I have no idea. I don't see any difference between the two copies I have worked with.

[Dr Klaus Schmitt]

my understanding from speaking with them not very long ago is that they don't have any copies of this lens built and on the shelf. However, they have all the parts to build them and will do so, on a one-by-one basis. So, perhaps they have different ways of assembling the lens from what they did before. I had the original but sold it, but recently had an opportunity to pick up another copy, which they told me was put together from parts. Maybe that says something. I have no idea. I don't see any difference between the two copies I have worked with.

Michael, this lens has been designed by Dr Brian Caldwell and he has exactly computed of which quartz/fluorite/glass type each element has to be made, grinded and polished to which radii of each lens side and which coating applied then - there is no deviations from that, EXCEPT they (jenoptik) have re-designed it, which would be rater uncommon, as there is no reason for it (except some glass would no longer be made)...Al they do is take those the parts and assemble the lens mechanically.

My lens is an older one, never been used, sat in a "lens fault" for years. I'm pretty sure it is simply wrongly measured...