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Thread: Photography/Lens thread

  1. #21
    Super Moderator Petr Schreiber's Avatar
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    Hehe,

    I recognize the shape of the "glass puppet", it looks very dreamy. The black and white checkerboard reminds me of Alice in wonderland

    Before your post, the most extreme story about cofee was my friend eating it in its raw form during exam time. But developing photo in coffee definitely beats it, this would never occur to me


    Petr
    Learn 3D graphics with ThinBASIC, learn TBGL!
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  2. #22
    Quote Originally Posted by RobbeK View Post
    The special about this is that the film is developed with coffee !
    A mix of Sodium carbonate (Household soda - to get the correct pH ) , Vitamin C (the anti-oxidant, converted into ascorbates by the Soda) and instant coffee (caffeic acid seems to be able to reduce silver salts - wasn't there a urban story that Coca Cola removes rust stains ?? ;-)
    ........
    We also were able to turn paracetamol into a developer...
    Unbelievable! Until now, I was perfectly sure experimentation of such sort was characteristic of the poorest societies only... I remember there were lots of popular magazines in the former Soviet Union that taught people how they could improvise with means at hand in order to get what they needed every day and what was not available in the stores. Not that Coke was popular or accessible at those times either though...

    Were you on the DDR side of the wall then, Rob?
    Mike
    (3.6GHz i5 Core Quad w/ 16GB RAM, nVidia GTX 1060Ti w/ 6GB VRAM, x64 Windows 7 Ultimate Sp1)

  3. #23
    Quote Originally Posted by Petr Schreiber View Post
    ... the most extreme story about cofee was my friend eating it in its raw form ...
    I confirm that chewing a handful of raw coffee beans was my primary trick with my Mom for fear lest she should smell tobacco when I used to come home after school.
    Mike
    (3.6GHz i5 Core Quad w/ 16GB RAM, nVidia GTX 1060Ti w/ 6GB VRAM, x64 Windows 7 Ultimate Sp1)

  4. #24
    Super Moderator Petr Schreiber's Avatar
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    I got an used Tokina 28-70mm f2.6-f2.8 ATX Pro, mostly for video: because of its stepless aperture and basically constant aperture across focal distance range.
    But it is nice for photography too. It has its issues, like:
    • not so good corner sharpness
    • tendency to produce images with "glow" when wide open
    • its heavyyy


    ... but still very enjoyable.


    Petr
    Attached Images Attached Images
    Last edited by Petr Schreiber; 28-02-2014 at 22:51.
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  5. #25
    Hi Petr,

    IMO an excellent picture -- everything leads to the central figure (which divides the fore- and background) , very well spotted !
    Tokina is an excellent lens maker, I think they also provided a lot of Cies (like Vivitar etc...) with lenses , for the moment there's a cooperation with Pentax IIRC.

    Often (almost the rule), optics for "moving" pictures are tweaked designs from "still" photographic optics -- somewhat faster (and less sharp - with the idea behind it that for moving objects ultimate sharpness is completely unnoticed. All world-Cies did this -- already in the 1930s Leitz made an Hektor Rapid doing f 1.4 (this was a prime lens - in those days a turret with a battery of lenses was common , i.o. zooming they rotated into the preferable lens ;-)

    However, I have a Schneider Variogon, designed for moving pictures that performs really well for photography !
    http://www.ipernity.com/doc/294723/25307055/sizes/1600

    (I wrote some programs for the dark room - all in ThinBasic , maybe I should publish them here - though no idea someone is interested in prehistoric skills ;-)

    best Rob

  6. #26
    Super Moderator Petr Schreiber's Avatar
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    Hi!,

    is the glow effect on your photo product of lens or post production? Tokina sometimes does produce this dreamy look at f2.6.

    I would be interested in your scripts, and I think it would not be bad idea to have special subforum for photography image processing scripts .

    I didn't know the Schneider Variogon brand, but I can see their did some really interesting designs, like Schneider-Kreuznach Macro-Variogon 7.5 - 45 f1.2, for example. But I can't find any photos made using this particular piece on the internet grrr.


    Petr
    Last edited by Petr Schreiber; 01-03-2014 at 07:54.
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  7. #27
    Hi Petr,

    Post processing - 3 image bracketing to get a wider dynamic range from a sensor. (The density range on film is higher than on sensor - it's physically thicker and can build its image also somewhat in depth (which may result in less sharpness )).

    Seems this one has a bokeh donut ;-) http://vimeo.com/74635789

    Dreamish wide open -- that's not bad to have that possibility , many lenses perform thise way imo - wide open some spherical aberrations may enter the system. In the past (during a certain era) such lenses were used for portraits - not every one has a soft and perfect skin and some details may be hidden somewhat .. but a lot changed over the years and the post 1950s images show most of the time (over)sharp portraits -- a question of taste, but a little but glow/glamour/soft focus may be very tasteful some time ...

    I attached one of these programs - I buy ciné film (300ft reels ;-) much cheaper - less than 1€/film ) cut it and spool it into cassettes - for my cameras only reading the DX code I need to fabricate these which is the reason for this code.

    best Rob
    Attached Files Attached Files
    Last edited by RobbeK; 01-03-2014 at 11:45.

  8. #28
    Super Moderator Petr Schreiber's Avatar
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    Hehe,

    one of the advantages of smaller chip on V1 is that it takes the best part of the lens (at cost of narrower view angle).
    In the video you linked, shot on GH3, it is evident the lens is designed for smaller surface. The donut bokeh is very unusual

    I attach few more pictures from tokina. One shows the overall sharpness is good at f4+, second a bit of abberation is present at the edges and the last one shows the mentioned glow at f2.6.
    EDIT: It seems the TB forum recompresses the JPEGs. Most evident on the middle image.

    I must say I was a bit down, when I got the glow for the first time, but as I know how to control it, I am no longer upset about it. These all are shot with Nikon D80 body, on V1 I get less corner abberation.

    Aaaand...I really, really like your script! This kind of utilities will be appreciated, I think.
    I will contact Eros asking about possibility of dedicated photo script subforum.


    Petr
    Attached Images Attached Images
    Last edited by Petr Schreiber; 01-03-2014 at 13:44.
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  9. #29
    Hi Petr,

    Don't worry about those slight remnants of aberrations (at the wider apertures) , take advantage of these when an occasion pops up.

    Rodenstock (Germany) made an expensive meniscus (!) (monocle in the slavic languages) lens with a heap of aberrations -- it uses a special sieve iris.diaphragma .... but , but look :
    http://radan.be/wp-content/uploads/2...-sepia-001.jpg ;-) this lens is called Imagon (but something similar can be made from the front lens of standard Helios lens on Zenit)

    Well I also made some theoretical related code for photography - a spring driven cloth shutter simulation.
    (I'll post it later, it needs some background information, and the history about constant speed curtains and accelerating ones ).
    Leitz made this big step (during WWII I think) on the Leica IIID (iirc))

    Ok - the question is , how uniform is the exposure made by exposing using the slit between those 2 curtains if both curtains accelerate.
    The amount of light is generated by the width of the slit , so at synchro time (as for a flash, when the 2nd curtain starts when the 1st reaches its end position ) the code calls this 1 frame (not included in the simulation) --
    Let's say the speed is so that it takes 1/30 sec - in case the 2nd start when the 1st is half-way we get 1/60 sec. etc... (see program).
    It can be proved (with functional equations) that with acc. curtains only one shuttertime can be completely exact.
    Calculating a complete model is something else, and reasonably difficult - I could find nothing about this so I wrote this simulator.
    In the program change values of the accelerations of the spring with moderate values , like 0.1 or something like.
    If both springs gets the same tension , you get the behaviour of pre Leica III shutter, as used in by Soviets in the Zenit, Zorki , FED and many many others . (it is much much more expensive to build a shutter à la Leitz LeicaIII and higher than those of Zenit (which uses a copy of the Leica II shutter).
    This simulation shows that if the tensions are reasonably the same the end result is acceptable.

    best Rob

    I very much like that first picture !
    Attached Files Attached Files
    Last edited by RobbeK; 01-03-2014 at 17:39.

  10. #30
    Super Moderator Petr Schreiber's Avatar
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    Hi Rob,

    script run well, disballancing the accelerations gives expected results
    But what is the purpose of 1/N Framespace checkboxes?

    And good news - Eros was very kind to add the sections in application forum.

    Do you think you could add your applications there?:
    http://www.thinbasic.com/community/f...play.php?f=390

    Recommended approach:
    • One application = one thread
    • First post always contains the latest version + screenshot


    I will move my video applications to dedicated section too, right now


    Petr

    P.S. I like the result from the monocle lens. What do you think about "reborn" petzval lenses:
    http://shop.lomography.com/us/lenses...al-nikon-mount

    My impression is that the bokeh is very "dramatic", it distracts the eyes a lot.
    Learn 3D graphics with ThinBASIC, learn TBGL!
    Windows 10 64bit - Intel Core i5-3350P @ 3.1GHz - 16 GB RAM - NVIDIA GeForce GTX 1050 Ti 4GB

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