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Thread: Infrared and UV Photography with MF Backs - Hcam-B1 and Zeiss IR lenses

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    Senior Member Stefan Steib's Avatar
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    Infrared and UV Photography with MF Backs - Hcam-B1 and Zeiss IR lenses

    This article that I am linking here, was originally written for the Zeiss CLN News. They did not publish it now for nearly 2 years, so I think before all this work is just left alone and be forgotten, I´ll post it here. The Back came from bearimages.com Jim Taskett, I got this through Walter Borchenko/B3K our Canadian Distribution/Dealer.
    There have been historic originals supplied by the BSB-Muenchen, who are one of the largest Libraries in Europe and where I happen to do the consulting for Colormanagement, Workflow, Digital Photography and Scanning. Many Thanks to Dr. Brantl and Mr. Podalsky for supporting this effort. I also got a special flash with 1500 ws from Hensel Germany with uncovered blank flash tube to make sure we got full spectrum light to be able to filter as needed.
    The 39mpix of the Achromatic plus BW are probably close to net 60 Mpix on a Bayer scheme, so the resolution is quite good, the Zeiss 1,4/85 IR Planar is also pinsharp (used at F11) and covering the large chip easily. I tried several filters for this test : a Heliopan UV pass, and 2x IR Pass filters, best solution was with 1000nm IR pass.
    What was absolutely thrilling was how few light was necessary to achive the results with the NIR (near infrared) shots, I used a fully filtered dark red setup of the used hensel flash at lowest setting of 150 ws, the Achromatic plus was set to 50 ASA !
    There is a german and an english version of the PDF available

    http://www.hcam.de/downloads/Hartble...V3_Deutsch.pdf

    http://www.hcam.de/downloads/Hartble...V3_English.pdf

    I have plenty more images, so if someone is interested in this, I can send him more links.

    Thanks for your interest

    Greetings from Munich
    Stefan
    because photography is more than technology - and " as we have done this all the time "
    facebook:hcam.de - www.hcam.de - www.hartblei.de

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    Re: Infrared and UV Photography with MF Backs - Hcam-B1 and Zeiss IR lenses

    Stefan,

    Would you care to elaborate on this (from the link):

    Whats spezial about this system ?
    The used Hartblei Cam ist the only MF camera worldwide which uses an electronically managed 35mm bajonett
    mount supporting all canon EF lenses. This takes nearly an unlimited number of spezial lenses starting at 35mm up
    to MF – like the here used Zeiss ZF-IR lenses with nikon mount. These Zeiss Industrial lenses have an image circle
    which supports a much larger format, is transmitting all spectral areas, starting at UV-A around 250nm up to near IR
    up to 1150nm.
    AFAIK, the Zeiss IR lenses have no useful UV transmission. You can find the transmission curves online or ask Lloyd who put up the first review (afaik) of them.

    This one was also very amusing (misleading information, nevertheless):

    Additionally many other
    lenses like the Zeiss MF Hasselblad optics eg. The Zeiss UV Sonnar, Zeiss Luminars, Biogons and more are fitting.


    In addition, you may want to think about the lack of UV sensitivity of a digital sensor (relative to visible) and the enormous IR sensitivity playing havoc when you use a filter like the Schott UG-1 (it leaks blue and has a significant IR transmission), resulting in blue and and near IR capture rather than the expected near UV capture.

    There was an earlier thread on this topic. I gleaned from there, expensive (but useless- ie., UV blind) equipment are being used. Yours appear to fall in line with that.

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    Senior Member Stefan Steib's Avatar
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    Re: Infrared and UV Photography with MF Backs - Hcam-B1 and Zeiss IR lenses

    Vivek

    the achromatic+ is actually a BW sensor with no UV/IR cut filter. About the sensitivity - see here on the achromatic + website-

    http://www.achromaticplus.com/Achrom...grammetry.html

    it´s a Kodak diagramm that shows clearly the significant gain compared to standard sensors.
    We also used full spectrum flash with a significant UV portion.
    As you can see from LLoyds spectral data under 370nm the normal and the IR versions are having identical transmission of UV

    http://diglloyd.com/articles/Infrare...alTransmission

    so the results did show a significant improvement in contrast against the UVcutfiltered and flash illuminated images we did as a comparison. The Heliopan UV filter may not be the optimum solution for the UV shot, but we had filtered the red part of the lights with dark blue gel.

    Greetings from Munich
    Stefan
    because photography is more than technology - and " as we have done this all the time "
    facebook:hcam.de - www.hcam.de - www.hartblei.de

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    Re: Infrared and UV Photography with MF Backs - Hcam-B1 and Zeiss IR lenses

    Stefan, Thanks for the achromatic + link. Interesting and it does seem useful for UV.

    On reading the transmission curves (the link you posted):

    Look at the 50% transmission mark. The plain vanilla ("referenz") Distagon might leak some near UV up to 390nm while IR branded version won't go below 400nm.
    The same trend is with the Planar as well. Actually you are better off using the cheaper Zeiss lenses for "UV".

    When I started in the UV area, it took me >2 years to get the techniques right for digital UV. At the moment, (ie., 10 years later) things have developed a lot.

    The principles are pretty simple. Find a lens that transmits UV- the UV-Sonnar is a splendid example for this. Find a filter that is suitable for digital UV (not the plain vanilla UG-1 or anything like that). The flash- if you don't have the "right" one to start with, no amount of filtration would help.

    What is puzzling is- why would you buy or borrow a $XX,YYY achromatic back and couple it with lenses that are blind to UV to do Uv photography?

    Let me add here that I have not commented on your approach on using 35mm lenses on expensive MF backs using Hcam. That really does not bother me at all. If I am using an Achromatic+ for UV, I would use my UV-Sonnar on it.

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    Re: Infrared and UV Photography with MF Backs - Hcam-B1 and Zeiss IR lenses

    Hi Vivek

    The UV part was just a try and it worked pretty well, the contrast was significantly better than with my standard 1,4/85 planar that I tested in comparison.

    The main interest was put on the near infrared and this was amazing, actually giving near full transparency on 3-4mm thick papers.

    Just for info: The Hcam can take the Hasselblad V lenses especially the UV and Achromat teles with adapters(e.g. Novoflex)

    Regards
    Stefan
    because photography is more than technology - and " as we have done this all the time "
    facebook:hcam.de - www.hcam.de - www.hartblei.de

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    Re: Infrared and UV Photography with MF Backs - Hcam-B1 and Zeiss IR lenses

    Stefan,

    Photography isn't new (that realization, a long time ago, was very humbling to me).

    If you talk to any grand old Leica man/woman they will tell you that using a strong yellow filter and certain monochrome film will give you images with superb contrast. They could also tell you that with a dark red filter (on plain B&W film) you can get contrasty images with different effects.

    What happens there is very narrow spectral capture.

    With your set-up you managed to get near IR images (Schott UG filter and the whole fancy setup). Due to the narrow spectral light involved, you saw higher contrast. That in itself is not diagnostic of UV but rather IR (yes, well set up IR captures are quite contrasty unlike the Kodak films with no halation showed).

    If the achromatic back had seen any UV through the ZF-IR lenses, it would have given you low contrast images because these lenses are dogs for UV and would have reflected UV with every surface from all the elements they have.


    If you plan to promote small format lenses on MF for UV, I would suggest you to look at the UV-Nikkor 105/4.5 (currently UV105) and the Coastal Optics 60/4 (both Nikon F mount lenses). Both offer ~60mm image circles for documentation stuff and actually transmit UV.

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    Re: Infrared and UV Photography with MF Backs - Hcam-B1 and Zeiss IR lenses

    Hi Vivek

    you are definitely right that the Coastal or the Nikkor UV lenses would be the better solution for UV, but this was only a side effect of what we wanted to test. Normally nobody would throw hard UV to these historic samples, this was a sole exception, just to see what happens. And whatever the reason was ( maybe you are right and this was an absolute narrowband repro from the UG filters transmission) it worked very well, showing exactly the effect that was looked for, and most astonishing with very few light used............;-)

    This system will save a lot of time and effort to reconstruction and restauration purposes. The HCam - body can also be used for Multishot highresolution, normal color systems like Hasselblad/Sinar or Imacon.

    In 2011 we have also tested Megavision Multispectral backs with 12 channel LED lighting with the Coastal 120mm and the 60mm which will work in the same direction and shoot 1x UV, 6x visible color and 5x IR with stepped wavelenghts achieving an average delta E of 0,5 (in the visible range). Megavisons system uses narrowband lighting instead of filtering which is even better, diminishes the amount of light put on the sample and can be used for multispectral work in e.g. ImageJ but also commercial systems like the Zeiss Microimaging solution.

    http://mega-vision.com/cultural_heritage.html

    But that is another (ongoing) story, work in Progress...........;-)

    greetings from Munich
    Stefan
    because photography is more than technology - and " as we have done this all the time "
    facebook:hcam.de - www.hcam.de - www.hartblei.de

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    Re: Infrared and UV Photography with MF Backs - Hcam-B1 and Zeiss IR lenses

    Stefan,

    Subtle wordings are lost in languages, I suppose.

    You did no UV imaging.

    When one needs UV imaging, the samples need to be exposed to UV.

    Claims such as narrow spectral band lighting (365nm LED output in case of the Megavision lights) is "less harmful" than broad band lighting is at best incorrect.

    If you use a setup without filtration for imaging in the UV then you not only capture reflected UV but also (mostly) visible fluorescence.

    What I wonder is, why would anyone spend so much money to do something incorrect?

    Having said that, this is going to be my last response to your thread here.

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    Re: Infrared and UV Photography with MF Backs - Hcam-B1 and Zeiss IR lenses

    Have a nice weekend Vivek !

    Greetings from Munich
    Stefan
    because photography is more than technology - and " as we have done this all the time "
    facebook:hcam.de - www.hcam.de - www.hartblei.de

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    Re: Infrared and UV Photography with MF Backs - Hcam-B1 and Zeiss IR lenses

    Just to complete the informations before- I looked it up at my docs:

    The blue gel used for the UV test on the flash was Roscolux #375 which we decided to use instead of trying to get Filterstacks as Baader U or Schuler UV (besides we needed 77mm diameter, this would have cost a fortune).
    There was a 15-25% transmission left on the Zeiss lenses up to 400nm and the special flash had enough UV, we used this at a distance of only 50cm to the subject (yes nobody would do this normally - the restaurators would kill you !).

    Greetings from Munich
    Stefan
    because photography is more than technology - and " as we have done this all the time "
    facebook:hcam.de - www.hcam.de - www.hartblei.de

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