Konvas-1, Konvas-1M, Konvas-2M cameras have shutter disk with fixed angle of 150 degree.
The russian book show time of exposing of film for different shutter disk angle.
At 24 fps
the cine camera with shutter disk 150 degree will have time of expsing of film 1/58 sec
with 180 degree 1/48 c
The difference between 1/48c and 1/58c = 17%
1/48 s = 0.0208333 sec
1/58 s = 0.0172414 sec
1 stop - the difference at 100 % , 17% = near 2/10
The many digital light meters have scale 1/10 stop
But, need check of technical information of light meter.
The light meter Seconik L758 cine have Shutter-angle settings from 1 to 10o in 1o increments, from 15o to 270o in 5o increments plus 12o,17o,22o,144o and 172o individual settings.
Seconik L358 have cine mattering with shutter-angle 180 degree.
As of me, from practical experience, +/- 2/10 stops do not important at real shooting.
The more high error can have adjusting of aperture control of lens.
The matter is that, the every lens have adjustable interaction between real size of aperture hole and aperture scale.
The every LOMO lens have " T " stop scale. The "T" stop scale individual for every type of optical block.
If you set of aperture scale on 5.6 of OST-19 or OST-18 or Arri Pl lenses, the negative must have similar density ( If the lenses had correct adjusted T stop scale ).
WHY couldn't something similar be built to extent the focal length of the Lomo anamorphics, an OCT-19 mount tube extender with the OCT-19.
The technique of focusing of spherical and anamoprhic lens on short distance different.
The spherical lens can be adjust on short distance by moving of one part of optical block or full optical block.
The anamoprhic lens have complex design and consist from spherical lens and front anamoprhic component.
The spherical lens adjust on infity and total focusing of lens make by moving of optical component before anamoprhic component.
That's why, focusing of anamoprhic lens on short distance can be with special close up attachmnet only and do not work with tube mount extenders.
We build of front close up attachmnet on 150 mm BAS lens and had very good result.
The russian Square anamoprhic lenses had special clouse up glass attachment for shooting with short distance.
The minimum distance of focusing of 35BAS-4-15, 50 mm have 1.5 m, but, have two additional distance scales with minimum distabnce of focusing 1.0 m ( greq scale ) and 0.5 m ( red scale ).
This is two additional scales use with front glass close up atatchmnets.
The similar attachment have Foton-A, front anamoprhic adapter of Foton zoom lens.