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Lens home columnation for Konvas and other


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#1 James Steven Beverly

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Posted 14 March 2009 - 05:25 AM

I read this on a Konvas.org email discussion and thought I'd share it. I tried to correct some spelling errors so hopefully I got it right. I'm curious if these methods are solid.

Hi rita .... I use the KONVAS like if it was a SLR ... to test my KONVAS or any other film camera ...
when i say a 36 exp roll , i charge one or 2 meter of film regular slide or negative i take it from my tanks .... BUT still photo films ....
like i DON'T HAVE FILM LABS in this country , and like i don t want crash the one hour labs chemicals .... i use regular cheap film ... results are excellent for the tests i need do !!!

I quittake off the KONVAS motor ....and if you tun the knob with hand , you can make a little mark when shutter is OPEN and when shutter is CLOSED ....and smoothly expose one frame by one frame ....

It is really really the best and cheaper way to do :
YOU can make almost MANY MANY TESTS !!!!!

A) COLLIMATION TEST of each lens ! you can exactly COLlIMATE "at HOME" any lens ----
the system is a bit longer to explain but work very good ....

Take a 50mm lens , place it on the one meter mark , Place exactly at one meter a Bif def chart ....
Place on the Mark barrel a millimeter paper , with marks each Millimeter .... 0 is the ref mark of the lens .... +1,+2,+3,+4,+5 is MORE distance from lens to film gate ... (more flange , closer focus) ....-1,-2,-3,-4 is less distance (so far away focusing ....)

Like i use the KONVAS like a SLR , i only make ONE frame for each setting .... of course you mark on the chart which setting is (+1,+2,+3 etc .... )

CONCLUSION , after 11 shots (11 frames , you have ZERO focusing at one meter ....and you can see and make a chart of which value have the correct focus sharp razor .... ) for this you can use a microscope or project the frames in a slide projector ....

If the best result is ZERO : BINGO , your lens is collimated for your camera !!! so if one meter is one meter focus, you get INFINITY !

SOME TIME lenses need adjusts ...

IF your better setting and better focus result is is +2 ....it want to say than you have to reduce the flange of the lens (this is possible taking off small rings in the mount ....)
OCT18 use other system to add or reduce flange of lens .... it is not too difficult .

if result is -2 you have to add flange .... go smoothly and test again until have perfect collimation ....

IF all of your lenses are wrong , maybe it is your MOUNT the problem ... but it is very rare to have to recolimate the mount ....


GG tests : see if the GG is collimated (to be sure than if i have focus on GG , i HAVE focus ON FILM ....) for this : use the 50mm at full open diaphragm ....
Place a def chart to fill the frame .... shot the chart focusing with GG only .... and repeat the system +1,+2,+3,+4,+5 and -1,-2,-3 etc ...
analyze the results .... same process ..

TEST OF APERTURES :

with same system (USING SLIDE FILM ) you can make a comparison chart of all diaph of your lens .... see if the stops are correct in each lens
and if all lenses have same stops .... (if f4 is the same f4 in all lenses )
for this i use a 21 zone gray card .... so i can see 1/3 of stops differences )

TEST of colorimetric of lenses ....

With same process you can compare the colorimetry of each lens ...
For this , place a white huge paper and light it to obtain a middle gray .(use spotmeter !!!) ... (remember we are making all in OPEN FLASH process)
around f 5,6 (middle of the stops for each lenses ...)

Expose ONE frame with each lens at same framing ratio (of course wide angle will be closer than teles ...) but if the surface is big (like a wall ) you will be OK ...
after this , you can compare the "color" of each lens .... generally I don t filter never my lenses to "correct the color ...." the difference is so small than all can be done in the lab timing .... But nice to know ...

TEST OF FRAMING gate :

Be sure than the frame you see in viewfinder is frame on the film ....

PLACE in 8 near corners a X mark with the middle of the X in the middle of the border of the frame .... expose one or 2 frames ONLY ....
after process you can know if all is OK or if something is discalibrated .... good to test masked GG (1.85) or 2 perfs !!!

It have a lot of tests you can done simply , and have results for 1 dollar process !!! in one hour ! using regular negative film you can buy at the corner ....

BUT remember , have all prepared , close the viewfinder to not have ghost light coming inside ....
work with OPEN flash system .... (have an assistant is good idea )
Place a paper with all settings in the frame you shot ....

Other easy tests ....


SYNCRO TEST : just shoot an electronic watch with 1/100 of seconds during 10 seconds ... and see results , depending of your frame rating (24 or 25 fps) you can count the frames exactly 10 sec is 240 frames ..or 250 frames . that's it ....

I have a HUGE manual written by a old friend who was First assistant during + than 40 years ..... it is a manual of First Emergency solutions for assistant camera ,
you can do them in the desert !!!! it is in french .... he was my "camera autopsy" teacher in filmschool 20 years ago ....

Good luck , Olivier .

Edited by James Steven Beverly, 14 March 2009 - 05:26 AM.

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#2 Olex Kalynychenko

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Posted 14 March 2009 - 04:37 PM

HI.
All this tests, good ideas and can be use, but, this is test for checking of parameters of camera, but, this test do not help you, if you will need adjust of camera.

Hi rita .... I use the KONVAS like if it was a SLR ... to test my KONVAS or any other film camera ...
when i say a 36 exp roll , i charge one or 2 meter of film regular slide or negative i take it from my tanks .... BUT still photo films ....
like i DON'T HAVE FILM LABS in this country , and like i don t want crash the one hour labs chemicals .... i use regular cheap film ... results are excellent for the tests i need do !!!


Very good idea, I use of this idea at my personal tests of cameras with film.
You can process of photo film at any photo lab and to order of prints of photos.
But, you must glue a some length of exposed film at beginning of photo film because, you will need have some length of film for load of film into film magazine.


I quittake off the KONVAS motor ....and if you tun the knob with hand , you can make a little mark when shutter is OPEN and when shutter is CLOSED ....and smoothly expose one frame by one frame ....


Good idea. If we told about 15EPSS motor, you can replace of disk for manual rotate of axis of motor on crank ( similar of crank of Konvas-1 camera ).
And, you can use of Photo flash with manual mode ( like Canon EZ-540) for exposing of every frame with fixed value of light.


A) COLLIMATION TEST of each lens ! you can exactly COLlIMATE "at HOME" any lens ----
the system is a bit longer to explain but work very good ....

Take a 50mm lens , place it on the one meter mark , Place exactly at one meter a Bif def chart ....
Place on the Mark barrel a millimeter paper , with marks each Millimeter .... 0 is the ref mark of the lens .... +1,+2,+3,+4,+5 is MORE distance from lens to film gate ... (more flange , closer focus) ....-1,-2,-3,-4 is less distance (so far away focusing ....)


As for me, this test do not have real result.
The any reflex cine camera must have correct adjusting of position of mirror disk and sharpness image on ground glass must give a sharpness image on film too.
The similar test use for rangefinder photo cameras.
As for cine cameras, you can use of similar test for checking of distance scale on lens, re-marking of distance scale on lens.

SYNCRO TEST : just shoot an electronic watch with 1/100 of seconds during 10 seconds ... and see results , depending of your frame rating (24 or 25 fps) you can count the frames exactly 10 sec is 240 frames ..or 250 frames . that's it ....


The result will incorrect, because, the any camera have time for acceleration ( can be 0.25...0.5 sec ) and time for deceleration.
As for me, i propose of change of test and set marks with crosses of zero frame, start an stop frames on the film.
The distance between zero and start frames must be 100..200 frames.
The distance between start and stop crosses must be 240 frames for 24 fps, 250 frames for 25 fps or any other quantity, multiply of speed of camera.
You load film on film magazine, rewind film up to zero cross will set at centre of film track. After, you connect of film magazine on Konvas without lens and zero cross must be at film gate of camera.

You start up of camera and look on film through lens mount of camera.
Only you see of start cross, you start up of electronic watch, only you see of stop cross, you stop
of electronic watch.
The time of between start and stop crosses and numbers of frames between crosses will show you real speed of camera.

The other simply test of speed of camera can have better result, if you will use screen of computer monitor and setup of difference frequency of frame scan.
If the computer monitor have 75 Hz or 100 HZ frame scan, you runing of camera, and can adjust of speed of camera 25 fps by stoping frame line at screen of monitor.
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