Thread: Tokina AT-X 235 AF PRO 20-35mm f/2.8 BMMCC tests

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  1. #1 Tokina AT-X 235 AF PRO 20-35mm f/2.8 BMMCC tests 
    Senior Member shijan's Avatar
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    Followed by Poor man's Angenieux - Tokina AT-X-Pro 28-70mm F2.6-2.8 thread i was exited about vintage Tokina Zoom lenses. Looking at https://tokinalens.com/about/history/ i found one very interesting Tokina AT-X 235 AF PRO 20-35mm f/2.8 lens made during 1994-2007 and was able to get it at rather low price locally. Those old autofocus Nikon mount lenses don't have internal motor and electronics because they use screwdriver-like autofocus connector from motor inside camera. So they are simpler, more reliable and use real smooth damped manual focusing rings. Combined with 0.58x speedbooster this lens will produce normal zoom range 11.6-20.3 f/1.2 perfect for S16 BMMCC/BMPCC sensor. So currently i have the lens and waiting when Nikon G Speedbooster arrives to make some own tests and compare with other lenses.

    Here are some very subjective thoughts about this lens:

    Pros:
    - Constant F2.8 (F1.2 with 0.58x speedbooster)
    - 20-35 zoom range (12-20 with 0.58x speedbooster)
    - 0.5m close focus. (way better than older vintage zooms, but worse than modern zoom lenses)
    - Parfocal zoom? (Need to test)
    - Near zero barrel distortion at all focal lengths.
    - Nice smooth damped manual focus and zoom rings.
    - 90 degree focus throw (way better than modern AF zooms with 35-50 degree focus throw)
    - Non rotating front filter thread mount, perfect for variable ND filter or mattebox.
    - Front filter thread connected directly to the solid body frame separated from lenses and other moving parts.
    - Fixed external size during all zooming/focusing range.
    - Sharp documentary style look, but same time slightly not so clinically perfect and dead crisp as modern lenses. (Need to test)
    - Less contrast than modern lenses. (Need to test)
    - Smaller than any other similar manual zoom lenses. Don't feels bulky.
    - Way lighter than real cinema zooms.
    - Solid metal body. Build like a tank.
    - 77mm filter thread (no need step up rings for me)

    Cons:
    - Sharpness loss and dreamy halos at 20mm @ F/2.8 (varies from model to model, need to test my sample)
    - Typical aspherical zoom type harsh/jarring/busy bokeh look at wide angles. Probably can't match to older classic lenses smooth/creamy bokeh look. (Need to test)
    - May produce too pronounced long star rays from light sources. (Need to test)
    - Short focusing ring throw compare to fixed lenses. (Actually not a big problem in real life due very large focus ring diameter, well damped movement and 90 degree throw)
    - Wish focal length range could be slightly wider. (There is newer Tokina AT-X 165 PRO 16-50mm f/2.8 but it is made of plastic and have very short 35 degree focus ring throw, not too usable as manual lens)
    - Too thin diaphragm ring, but not a big problem because it is always possible to use clickless diaphragm ring on speedbooster.

    Some reviews of this lens:
    https://kenrockwell.com/tokina/20-35mm-f28.htm
    https://www.pentaxforums.com/userrev...-pro-f2-8.html
    http://lensbeam.com/obektivy/obektiv...5mm-128-235-af
    http://radojuva.com/2012/10/obzor-to...-pro-20-35-mm/

    Last edited by shijan; 07-13-2019 at 01:03 AM.
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  2. #2  
    Thanks for the info. Will be following this with interest.
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  3. #3  
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    The .58x of metabones boosters is applied to the crop factor of the sensor, not the equivalent focal length of the lens. So instead of 3.02x itís 1.75x. That would make a 20-35 behave like a 35-61mm, instead of a 60-105.
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  4. #4  
    Senior Member shijan's Avatar
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    BMMCC/BMPCC crop factor is 2.88.
    10mm lens at S16 equal to 28mm at full frame.
    12mm lens at S16 equal to 35mm at full frame.

    If be too precise:
    20mm x 0.58 = 11.6 x2.88 = 33.4mm
    35mm x 0.58 = 20.3 x2.88 = 58.5mm
    It is not ultra wide lens but wide enough for most situations. Also lens focal length and real life field of view always slightly different at different lenses. So with real life tests we'll see how it compare to other lenses. I don't have too many lenses to compare, but i'll use 12mm SLRmagic, 28mm Yashica, 50mm Yashica, and 35-105 Yashica zoom. Maybe i'll borrow some other lenses for tests from other people. Anyway Speedbooster will arrive at least in 3 weeks, so there is a lot of time to prepare things.
    Last edited by shijan; 07-12-2019 at 10:38 PM.
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  5. #5  
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    Depends on which dimensions you are comparing, diagonal or horizontal. Diagonal crop factor is 3.02 compared to full frame.
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  6. #6  
    Senior Member shijan's Avatar
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    Can't see any mistake in my calculations.

    From Metabones website Description:

    Increase maximum aperture by 1 2/3stop
    Makes lens 0.58x wider

    The new 0.58x Speed Booster reduces the crop factor of the BMPCC from 2.88x to 1.75x, and produces the largest aperture optics currently available, with a maximum output aperture of f/0.74. For example, a 50mm f/1.2 now becomes a 29mm f/0.74 (i.e, by using 50mm lens, the actual focal length in BMPCC is 29mm x 3.02 = 87.58mm), and the Sigma 18-35mm f/1.8 becomes the world’s fastest zoom lens at 10.5-20.3mm f/1.0 with stunningly sharp performance. (i.e, by using 18-35mm lens, the actual focal length in BMPCC is from (10.5mm x 3.02 = 31.71mm) to (20.3mm x 3.02 = 61.31mm).
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  7. #7  
    Senior Member shijan's Avatar
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    Lenses size compare (shoot on BMMCC):

    Last edited by shijan; 07-12-2019 at 10:39 PM.
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  8. #8  
    Senior Member shijan's Avatar
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    Still have no time to do a proper test and share samples, but i have some quick info:
    - The lens appears parfocal , but first Metabones Speedbooster required some back focus adjust.
    - The Focusing ring is very smooth and don't produce any shakes during focusing.
    - The zoom ring is so so. It have some play in the start and end, and lens block produce small shakes during zooming. So real time zooming effect may be slightly wobble and not 100% smooth. The effect is similar to when lens wobble in the lens mount.
    - Zoom scale mark ring seems like glued with self adhesive glue and may slightly move due very hot weather and extra applied force.
    - From some quick tests compared to SLR Magic and Yashica it feels like very low contrast lens when light source precent in the field of view. Maybe this is due Speedbooster?
    - Flares are very unusual and very saturated.
    - Hard star shaped ray effects from point light sources became visible only starting from F5.6. F2.8-F4 produces very natural less symmetrical ray effects.
    - No any color casts. Colors are very neutral compared to SLR Magic and Yashica.
    - Wide open with Speedbooster it feels almost like SLR Magic T1.6
    - Wide open it is way sharper than SLR Magic
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