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Coastal Optics (Jenoptik) 60mm lens mysterium
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PostPosted: Sat Feb 20, 2021 8:18 pm    Post subject: Coastal Optics (Jenoptik) 60mm lens mysterium Reply with quote
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 strange graph (and their MTF graphs they mixed up, too) ...


PostPosted: Mon Feb 22, 2021 3:32 am    Post subject: Reply with quote
Light source variation? Different lens version?


PostPosted: Mon Feb 22, 2021 8:13 am    Post subject: Reply with quote
visualopsins wrote:
Light source variation? Different lens version?


1) No idea what they have done, but since at transmission spectra measurement it is first calibrated at 100% flat, all light variations are evened out...
2) Doubt it, they would have changed the design, the lens materials + coating: way too expensive for an existing design and rather low sales numbers for such an "exotic lens"


PostPosted: Mon Feb 22, 2021 11:39 am    Post subject: Reply with quote
Very strange. At first glance it looks like they've plotted similar graphs but using different x-axes. It almost looks as if the peaks in the magenta graph would line up with the original ones, if the magenta graph were 'stretched'. That doesn't account for the difference in absolute transmission though, and that is quite a difference. One of these days I'll get hold of one of these to test.


PostPosted: Mon Feb 22, 2021 12:14 pm    Post subject: Reply with quote
JMC wrote:
Very strange. At first glance it looks like they've plotted similar graphs but using different x-axes. It almost looks as if the peaks in the magenta graph would line up with the original ones, if the magenta graph were 'stretched'. That doesn't account for the difference in absolute transmission though, and that is quite a difference. One of these days I'll get hold of one of these to test.




Indeed, that was my first thought too Jonathan! Then I looked again and saw different "wobble peaks", but it really looked shifted in x- and y-direction!


PostPosted: Mon Feb 22, 2021 2:13 pm    Post subject: Reply with quote
Klaus, did you check the X axes when combining these graphs?



This one has a non linear X axis, logarithmic I presume.

Anyway, rectifying the axes will line them up more closely, but still nowhere near identically. So if their numbers are to be believed they either changed the transmission measurement protocol or the lens design, or both.


PostPosted: Mon Feb 22, 2021 3:03 pm    Post subject: Reply with quote
dickb wrote:
Klaus, did you check the X axes when combining these graphs?

This one has a non linear X axis, logarithmic I presume.

Anyway, rectifying the axes will line them up more closely, but still nowhere near identically. So if their numbers are to be believed they either changed the transmission measurement protocol or the lens design, or both.


Tried to do as best as possible...

Last edited by kds315* on Mon Feb 22, 2021 4:13 pm; edited 1 time in total


PostPosted: Mon Feb 22, 2021 3:39 pm    Post subject: Reply with quote
kds315* wrote:
dickb wrote:
Klaus, did you check the X axes when combining these graphs?


Tried to do as best as possible...


I have confidence in your mathematical skills that you can do better than this though Wink

When you check the nonlinear graph, the first peak is at roughly 420nm, and from say 870nm the slope goes down. For the linear graph I would estimate those points to be at around 450nm and 920nm respectively. So quite a bit closer than shown in your combined graph.

Anyway, this doesn't alter the fact that Jenoptik curiously now claims a considerably lower transmission for their current lens.


PostPosted: Mon Feb 22, 2021 3:55 pm    Post subject: Reply with quote
Here, did it segmentwise to fit it better...now the peaks at least correlate Wink



Still about 20% less transmission in the interesting UV band!


PostPosted: Mon Feb 22, 2021 5:04 pm    Post subject: Reply with quote
kds315* wrote:
visualopsins wrote:
Light source variation? Different lens version?


1) No idea what they have done, but since at transmission spectra measurement it is first calibrated at 100% flat, all light variations are evened out...
2) Doubt it, they would have changed the design, the lens materials + coating: way too expensive for an existing design and rather low sales numbers for such an "exotic lens"


1) drift? or mis-calibration not of light source but of measuring sensor?
2) Oh, I must have confused this lens with another you'd hesitated to buy because the new version had a different transmission?

I too noticed the different x-axis but determined the translation still resulted in big difference...

Maybe you can remeasure your lens using different (borrowed) equipment?


PostPosted: Mon Feb 22, 2021 8:16 pm    Post subject: Reply with quote
visualopsins wrote:
kds315* wrote:
visualopsins wrote:
Light source variation? Different lens version?


1) No idea what they have done, but since at transmission spectra measurement it is first calibrated at 100% flat, all light variations are evened out...
2) Doubt it, they would have changed the design, the lens materials + coating: way too expensive for an existing design and rather low sales numbers for such an "exotic lens"


1) drift? or mis-calibration not of light source but of measuring sensor?
2) Oh, I must have confused this lens with another you'd hesitated to buy because the new version had a different transmission?

I too noticed the different x-axis but determined the translation still resulted in big difference...

Maybe you can remeasure your lens using different (borrowed) equipment?


I'm pretty sure my measurements of that lens are accurate (as is my setup), as I have checked that very same setup with the UV-Nikkor 105mm and my measurements correlate very well with the data Nikon provided me.


PostPosted: Mon Feb 22, 2021 8:52 pm    Post subject: Reply with quote
kds315* wrote:
visualopsins wrote:
kds315* wrote:
visualopsins wrote:
Light source variation? Different lens version?


1) No idea what they have done, but since at transmission spectra measurement it is first calibrated at 100% flat, all light variations are evened out...
2) Doubt it, they would have changed the design, the lens materials + coating: way too expensive for an existing design and rather low sales numbers for such an "exotic lens"


1) drift? or mis-calibration not of light source but of measuring sensor?
2) Oh, I must have confused this lens with another you'd hesitated to buy because the new version had a different transmission?

I too noticed the different x-axis but determined the translation still resulted in big difference...

Maybe you can remeasure your lens using different (borrowed) equipment?


I'm pretty sure my measurements of that lens are accurate (as is my setup), as I have checked that very same setup with the UV-Nikkor 105mm and my measurements correlate very well with the data Nikon provided me.


Then Occam's Razor says Coastal Optics results are suspect. Need them to redo or a 3rd party test.

The mysterium continues! Smile


PostPosted: Tue Feb 23, 2021 9:14 am    Post subject: Reply with quote
visualopsins wrote:


Then Occam's Razor says Coastal Optics results are suspect. Need them to redo or a 3rd party test.

The mysterium continues! Smile


Yep, EXACTLY so!!

Wonder what / IF their president comes back with an answer...doubt it though.
They never reacted to the inherent hotspot issue this lens has either. Twisted Evil
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