A few quartz flourite UV lenses on the bench for lens transmission measurements II

A few years ago I was taking transmission measurements of some special quartz-fluorite lenses for reflected UV photography. This included the then Coastal Optics UV-VIS-NIR Apo 60mm lens, after the merger now called Jenoptik CoastalOpt® UV-VIS-IR 60 mm 1:4 APO Macro. 

So since I just recently bought that CoastalOpt® lens, I measured it (amongst others) with my newer spectrometric setup and compared my results with their published data. Surprisingly enough, my older and newer measurements of that CoastalOpt® 60mm Apo lens correlate very well - but not with their now officially published data on their site which shows much lower transmission values. Their formerly published data however showed much better spectral transmission, which correlated well with my own measurements.

[click on image to see a larger one]

Here in comparison the former (white) and now published data (magenta) superimposed:

My own measurements back then were these (amongst some other lenses):


[validity: approx 310 - 750nm]

and my newer current measurements (reaching deeper into UV) are these:

[validity: approx 300 - 750nm]

The differences in transmission of both my measurements are rather small. It is beyond my understanding how these new and quite different measurements (about 20% less) happened; I am just wondering why such an excellent lens is not represented well enough....

I have written about this lens before HERE.

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

A new apochromatic 60mm UV lens

Just today Coastal Optics has officially announced that they will release soon a new "UV-VIS-IR 60mm 1:4 Apo Macro high performance UV-VIS-IR lens for forensics, science, and fine art" in Nikon F mount (w. built in chip) for UV-VIS-IR covering a wavelength range of 315-1100nm.
It also sports an advanced floating element design for excellent close-up reproduction up to 1:1.5 magnification and consists of 10 lens elements in 9 groups. The chromatic error in the 315-1100nm range is said to be virtually zero. The design covers the full 24x26mm format which would make it suitable for all available UV capable cameras like the Nikon D200, D40, D70(s), the Fuji S3UVIR and S5UVIR. [Lens Image (C) Coastal Optics]


Informed sources mentioned, that the lens will be available in production quantities first quarter 2008.

Here is the link to download the published document on that new lens:
http://www.coastalopt.com/index.php?option=com_docman&task=doc_download&gid=29&Itemid=68


****** NEWS as of June 2009 ******
It has turned out a few days ago, that this high rated lens has a  serious hotspotting issue (UV+IR) from 1:1.5 to about 1:3 magnification especially at small apertures. It hasn't been noticed before by Pro's and ambitioned amateurs, so that comes as a big suprise. Coastal Optics made this issue public and is working hard to get that issue fixed which hopefully turns out not to be a design issue.
It will be reported here as soon as a solution has been found, so stay tuned!
****** NEWS as of January 2010 ******
Informed sources have stated that a solution has been found, yet officially Jenoptik (Coastal Optics new owner) was not willing to make a statement (yet),  if and when a lens without that hotspot will be available.
*********************************
In case you wonder about that hotspot and how that might look like, here an image shot at mag 1:1.5 and f11  (that hostspot is most prominent between 1:1.5 - 1:3, stopping down makes it more prominent)
Read more about it here.

(c) Andrea G Blum

 ****** NEWS as of  July 2013 ******

It has been found out that a very narrow sunshade is able to solve the hotspot issue satisfactory. The lens has not been modified in any way by the manufacturer so far.


Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos>