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UltravioletPhotography

[Lens test] Olympus objectives (old and new)


aphalo

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I am testing some Olympus lenses (OM mount and MFT mount), and comparing them to two "Kyoei-like" lenses, a Soligor and a Hannimex. I have not included the old 20 mm Pen F lens, as nowadays it is being offered in eBay at 400 USD or more. You may ask why I would like to test these objectives? The main reason is that they focus much closer than other lenses from the 50-70's. A secondary reason is that I am used to focusing rings which turn in the direction Olympus uses. One of the lenses is a 50 mm f 3.5 macro lens earlier reported as good for UV (film) photography (Arribas, 20). Several weeks ago, when I read this in the methods of scientific paper, it woke up my interest. For me having a true macro objective usable in the UVA would be a dream come true. Before getting into the details, from the test done last evening and this morning, I can already say, that at 365 nm, it does indeed work quite nicely. Needed exposure at f5.6 is about 2 stops more than with the Kyoei, but this is not as much of a problem as one could think, at least with LED illumination, as image quality is already good at f5.6 even for UVA. I managed to get UV images at 1:2 magnification and with an OM extension tube at 1:1 magnification. As I am using a MFT camera, that is 1:1 magnification on a 4/3 sensor. With 365 nm LED radiation shining on a 18% reflectance Novoflex Zebra card, this macro lens requires the same exposure than the copy of the E.Zuiko 35 mm f 3.5 already included in the lens list at this site.

 

The original article shows that the lens is good for UV, my worries were mainly whether the copy I had bought was an early enough version, expected not to be multicoated. What was a real surprise was to find that the two new premium MFT prime lenses from Olympus that I tested, do transmit some UVA. Against all expectations objectives released during the last three years, with maximum aperture f 1.8, with 9 elements, 7 of which are multicoated may be usable for UVA imaging. This will require a lot of testing, but having a native MFT autofocus primes with focal lengths 25 mm and 17 mm usable in UVA would be nice. Deciding whether they are useful, needs more testing, as the required exposure was somehow longer than with the E.Zuiko 35 mm f 3.5.

 

Camera E-M1 (full-spectrum) + Baader U filter.

 

This is just to break the news, as I very happy to have stumbled on the paper mentioning this lens as good for UV! During the rest of the week I will continue editing this post and adding all the technical details and example images. I should be able later this month or next month to measure transmittance spectra, but probably I will not be able to do it with an integrating sphere.

 

 

References:

Arribas, O. J. (2012) The Ultraviolet Photography of Nature: Techniques, Material and (especially) Lacertini results. Butll. Soc. Cat. Herp., 20:72-114 + suppl.

https://soccatherp.f...bsch-20-101.pdf

https://soccatherp.f...10-apendix2.pdf

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Pedro, I'm so pleased to see this article, thank you!

I'll be back with more comments later when you have completed it.

Meanwhile, I'm going to read through the papers.

 

(Why are all those UV photos in the paper blue?? I guess they did not know about the white-balance trick back then??)

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  • 1 month later...

Hi,

I have had to take a break as the copy stand I have been using was borrowed for an experiment. Anyway the macro lens does not transmit very much UV, but on the other hand UV image quality is quite good even with the diaphragm wide open. The photographs in the paper are taken on film, and very likely not white-balanced in post-processing. The StraightEdge U filter has arrived and I will add a D.Zuiko 100mm f/2.8 to the next round of tests. We have quite a lot of snow already, so I will have to get some flowers from the shop.

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  • 2 months later...
  • 2 weeks later...

We finally have a sunny day, pointing at the Northern sky at noon with the StraightEddgeU filter exposure is almost the same with a Soligor 35mm f/3.5 and the Sigma 19 mm f/2.8 set to f/3.5. At ISO 200 1/20 s.This is with a full-spectrum converted Olympus E-M1 Mk1 camera. And as you mention above, auto focus works!

 

The surprise is that I get the same exposure with my own off-the-shelf E-M1 mk1! A piece of polycarbonate sheet leads to exposure increasing to between 1 to 1.5" in both cameras. I see same effect with a fluorescent tube or through window glass.

 

When comparing the two cameras with the Sigma 19 mm f/2.8 and a Baader U-filter, the higher sensitivity of the converted camera can be seen: f/3.5 1/4 s with the unconverted camera and f/3.5 1/10 s with the converted camera.

 

So, I guess for imaging in the long end of UV-A as transmitted by the StrightEdgeU filter and accidental objectives, the E-M1 mk 1 will work without conversion. Of course in the far red and NIR the conversion does a huge difference on the sensor sensitivity.

 

I will need to wait for the summer or do some tests in the Southern hemisphere in a couple of weeks, to be sure. However, the unconverted camera seems perfectly usable with this objective and filter combination.

 

So, my questions are: does the Olympus E-M1 have an unusual spectral response for a modern ML camera? Or is it what I observe just the result of using the new StraightedgeU filter?

 

Converted camera s/n BHP310990.

Off-the-shelf camera s/n BHP206577 (from the very first batch delivered in Finland).

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  • 2 weeks later...

I am now in Argentina. I could not bring a tripod, so I am doing some tests handheld. The Sigma 19 mm does work nicely with the StrightEdgeU filter an my off-the-shelf E-M1 (Mk I). The color balance in sunlight is so much shifted to the blue/violet that neither Lightroom 6.8 nor DXO Optics Pro 11 succeed at white balancing a grey target by lack of range into the green. BW images are good. Given the long exposure times I have been using, it looks like image stabilization may be effective even with the UV filter. Flowers in the Dahlia specimen I tried are very dark in the UV, with no false blue, at least in sunlight (cf. Andrea's images at http://www.ultraviol...__fromsearch__1).

 

https://flic.kr/p/R66MrH and https://flic.kr/p/RKnWuj

 

A Hibiscus rosa-sinensis red flower, seems to have in the UV-A, light-coloured nectar guides (or veins?) in the periphery and a dark region near the centre of the flower.

 

https://flic.kr/p/S94QwB and https://flic.kr/p/RKtGPw

 

I did test also the Olympus Four Thirds (FT, not mFT) 50 mm f/2 macro and it is usable, also even with auto-focus. Autofocus needs some help by manually roughly pre-focusing for close up distances.

 

https://flic.kr/p/R66XeD and https://flic.kr/p/R3rE3J

 

I am just giving links to Flickr, rather than uploading them to this site, as the photographs are currently useful as only test shots. The images linked to are part of a Flickr album at https://flic.kr/s/aHskPqSDtf

 

update: s/n's

Sigma 19mm 1:2.8 DN A s/n 51635210

Olympus ZUIKO DIGITAL 50mm 1:2 MACRO ED s/n 010210916

E-M1 (Mk I) s/n BHP206577 (off-the-shelf)

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  • 10 months later...

In the many months since I wrote the message at the top of this thread, I have learnt many tricks-of-the-trade from members of this forum. An update to my earlier post is needed. The 18% reflectance Novoflex Zebra card has quite different reflectance in the UV-region according to my spectral measurements. I have switched to using a PTFE slab. I have yet to build a "sparticle" filter array. Over the last week I have been using a PTFE slab illuminated by LEDs (345 nm, 367 nm, 389 nm and warm white, one LED type at a time) as my lens test-bed, and RawDigger to quantify the response of the camera (with StraightEdgeU filter, Baader U-Venus filter and no filter for UVA, and only no-filter for white light). The approach seems to work nicely, but consistently reproducing the position of the LEDs to achieve repeatable illumination of the slab is tricky. I have needed to use retesting of one or two objectives to transfer/combine/calibrate data from different measurement sessions. On the other hand I have managed to have very even and steady illumination of the slab. I have also been in touch with O. Arribas, the author of the paper that I cited, and he is not active in digital UV photography.

 

What is a "good-enough" objective for UV photography is not easy to quantify, as some objectives maybe usable at larger apertures than others, or transmit very well at the longer end of UVA but not at the shorter end. The UV transmission of the Olympus OM Zuiko 50 mm f:3.5 Macro I earlier mentioned, is quite low, so my earlier high expectations about this objective based on Arribas' paper need to be toned down by a fair bit.

 

A couple of weeks ago I bought a Sigma 30 mm f:2.8 DN Art MFT objective, second hand. It does transmit UVA better than my Sigma 19 mm f:2.8 DN Art MFT objective, bought new some months ago following Enrico's suggestion in this thread. Not that the 19 mm I am planning to buy the Sigma 60 mm f:2.8 DN Art MFT from the same series when I find one discounted (or when the Spring gets near and I get eager enough to be willing to pay full list price for it).

 

I need to repeat a couple of tests in which one sensor channel got saturated (= overexposed), and still test the Olympus ZUIKO DIGITAL 50mm 1:2 MACRO ED and my Olympus OM Zuiko G.Zuiko 35mm f2.8 (which is listed as UV-capable in the sticky post, and wrongly mentioned as 35 mm f:3.5 in my post above). I will write up the details in my blog (http://aphalo.wordpress.com) and summarise in a new topic here.

 

 

 

 

[Editor: corrected typo in url]

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Pedro, I have a question for you (which is off-topic from this thread). On your blog you have presented slide shows, and I am wondering what software was used to make them. Here is the link to an example: https://aphalo.wordpress.com/2017/10/21/fluorescence-of-glass-filters/

Can the slide shows in that article only be done in Wordpress?

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Andrea,

I have used Wordpress' gallery. In Wordpress it is very easy to display a gallery as slideshow with simple code: [gallery ids=1263,1262,1261" type="slideshow" link="none], or even generate this code through menus. I am not familiar with HTML 5, only with older HTML standards, but I think it should be possible to implement a gallery. Wipers are also possible, and they are really nice for pairs of VIS and UV/IR photos. I used a free plugin in Wordpress for this page: http://uv4plants.org/gallery/vis-and-uv-photograph-pairs-flowers/ (it loads rather slowly, be patient).

Pedro.

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A tangential comment to the "wiper" example: is the Baader 1 1/4" the older version of this filter? The dandelion in UV comparison indicates there is significant IR contamination present.
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I am not sure, I will try to find out. Those are not my photographs. When did the new Baader become available? At least some of those photos were shown to me for the first time about five or six years ago. The ones at http://uv4plants.org...utoflorescence/ I took myself, with a 2" Baader-U bought in October 2015. (I mean those where I did use a Baader...)
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Thanks Pedro for the pointers about slideshow and wipers. I used to have an old website called Uvirbloom (now gone) which enabled a click-through of a series of UV, visible and IR versions of a particular flower. I programmed it in php. I have long wanted to try Uvirbloom again but have no wish to write code anymore. So I need to find a nice app -- such as Wordpress?? -- that would permit slideshows.

 

**********

 

The improved BaaderU is about 10 years old I think. I got my first one in 2007 so I think it must have been first offered first in 06 or 07. But old BaaderUs could still have been in stock at various suppliers after 2007 or still in use by some photographers.

 

I think I also recall a change in the BaaderU after 2007, but it was more of a bandwidth tweak and/or coating change.

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  • 1 month later...

As the UV-photos in the UV4Plants-page came from me I can comment about the filter and possible IR contamination.

 

Yes, the Baader 1 1/4" is the older version of the filter.

 

For the possible IR contamination I think that there isn't significant IR contamination in the photos.

 

The UV images were taken with an unmodified Nikon D70s. It does have some sensitivity in IR but the sensivity is a lot less than the IR sensitivity of modified cameras.

 

I really started my IR photography with the modified Sony, but before the camera update I did take some IR photos also with the Nikon.

The camera settings of these can used to evaluate to amount of IR in the UV photos.

Same subjects were photographed, the camera was on a tripod and the f and ISO -settings were the same for IR and UV.

For the UV photos a Baader U 2” was used (current model bought in 2014, there isn’t significant difference in UV transmittance between the old and new one) and for IR Hoya R72.

 

Exposure times were similar for UV and IR, like 0,77s for UV and ½ s for IR.

Taken into account that the maximum IR transmittance of the older Baader is about 0.3% (

http://www.beyondvis...BV3-filter.html ) , the transmittance of Hoya R72 in IR is over 90% and that the exposure times were similar for UV and IR photos I think that there isn't signifiicant IR contamination.

 

With modified cameras the IR attenuation of the older Baader U might not be enough. It would interesting to test this, so I will most likely have a test shoot in spring.

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  • 3 months later...
Olympus 17/1.8 MFT have huge UV focus shift. Its visible on my spectrum test images. Awaiting for good weather to test other MFT lenses.
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Here in Finland the spring has already arrived more than 10 days ago... very unusual. Of all the FT and MFT objectives I have tested, there are only three I consider useful for UV photography: the three Sigma Art DN A f:2.8 series, 19 mm, 30 mm and 60 mm. Transmittance is best in the 30 mm, but in actual use in sunlight, there is little if any difference in performance between these three objectives with a full-spectrum converted E-M1. These objectives also seem to work fine in NIR, but this needs more testing. I haven't tested for focus shift as auto focus seems to work as expected in UV. My M.Zuiko 17 mm f:1.8 is on loan to my son, so I haven't tested it yet.
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Interesting about the Sigma lenses. The 19mm and 60mm are 8 elements in 6 groups. The 30mm is 7 elements in 5 groups. So that may explain why Pedro did see the 30mm as slightly better than the 19mm in the inital test I read. I am still hoping that the Olympus 30mm F3.5 macro will be useful. But I can't aford it yet. I am waiting for a used one to pop up on ebay for under $150. The advantage of the 30mm on the EM1, is focus stacking in camera is possible.

I have seen used 30mm Art lens pop up for $120. So I have also been tempted. But my old 43rds 35mm F3.5 macro works well for UV and has auto focus, which has held me off from buying the 30mm.

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An UV-capable MFT macro objective would be really useful! The Sigma objectives do support focus bracketing. What I haven't tried yet is to use them with macro extension tubes. I suspect they will not behave well as they have internal focusing as so many modern lenses. One more thing in my to do list.
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Interesting, I didn't know the sigma was supported for focus bracketing. Olympus limiting the 43rds lenses I think is silly. After all the E500 was first and only 43rds camera to do focus bracketing, and it worked well.

I have a 10mm and 16mm electronic m43rds extension tubes. These were cheap Chinese versions. I was going to rent the Sigma 30mm Art, but just bought a used one for under a hundered. So after it arrives I will let you know how mine compares.

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I checked again today. I have an E-M1 (mk 1). The Sigma MFT objectives support focus bracketing but not in-camera focus-stacking. I tried my Kenko extension tubes today, they do work with the Sigma objectives, even focus bracketing works with tubes. The only oddity is that I need to switch off and on the camera when swapping objectives on the extension tubes. As a test I simply took some handheld photographs of my monitor. The 60 mm and the 30 mm seem to work reasonably well with the extension tubes. The 19 mm shows strong barrel distortion when used with tubes, even with only the 10 mm tube. This was a very quick and dirty test, and useful to detect only major problems.
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Dimity, not true. Olympus has set limits in camera too what is allowed based on what lens. Too be fair so does Panasonic.

Using four thirds lenses on the first Olympus Em1, there are grey out sections not allowed.

Of course you can manually focus bracketing, or focus trap a manual lens. As you can for any camera. But the Auto functions are limited.

For the new Em1 mk2, pro capture mode is also limited based on lenses. But some functionality of it was added for four thirds lenses only in the latest firmware.

 

Updated: yes just reread the official Olympus statement and focus bracketing is only supported with micro four thirds lenses. What I didn't realize is that would include the Sigma. But Four thirds lenses are not supported.

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I see reason to limit it to CDAF lenses, they are designed to move focus point in small increments. All AF micro4/3 lenses are CDAF compatible, but only few FT lenses compatible too.
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