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Konvas registration test - hit or miss at 50fps. Help.


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#1 Thomas Worth

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Posted 12 February 2008 - 06:39 PM

I did a reg test on my Konvas 2M recently, and am having trouble isolating the problem with bad registration at 50fps.

I included a link that shows the tests. There are three total:

1. 24fps
2. 50fps
3. another at 50fps

Here's the thing. In test 2, there is crappy registration on only ONE of the exposures. The other starts out crappy, but stabilizes pretty solid at 50fps. So, based on this, I am going to assume the camera is capable of good registration at 50fps, as long as I can work out this issue.

Please let me know if you have any ideas. My hypothesis is that the loops are getting too short, but it may be something else I'm not considering.

Here's the link:

http://rarevision.co...=konvas_reg.mp4
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#2 James Steven Beverly

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Posted 13 February 2008 - 02:24 AM

50 FPS is pretty fast for a Konvas. That's the extreme upper end of their performance capabilities, If your camera is a bit worn, it may NOT be capable of good registration at that speed without a complete rebuild.
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#3 Phil Rhodes

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Posted 13 February 2008 - 04:42 AM

I'm not sure that's the point. Yes, it'll probably never be A-grade, but of four passes there we have one which is kind of what you'd expect and three which are just absurdly bad, worse than the best pass to a degree that suggests special circumstances, such as bad loops, are to blame. I think Mr. Worth's thesis is that if we can discover what factor precipitated the absurdly-bad passes and eliminate it, it ought to be possible to reliably achieve at least the performance demonstrated in the best pass.

Phil
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#4 Freya Black

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Posted 13 February 2008 - 05:36 AM

I did a reg test on my Konvas 2M recently, and am having trouble isolating the problem with bad registration at 50fps.

I included a link that shows the tests. There are three total:

1. 24fps
2. 50fps
3. another at 50fps

Here's the thing. In test 2, there is crappy registration on only ONE of the exposures. The other starts out crappy, but stabilizes pretty solid at 50fps. So, based on this, I am going to assume the camera is capable of good registration at 50fps, as long as I can work out this issue.

Please let me know if you have any ideas. My hypothesis is that the loops are getting too short, but it may be something else I'm not considering.

Here's the link:

http://rarevision.co...=konvas_reg.mp4



I havn't seen the footage yet but I'm wondering if it isn't the motor (always the weakest link in the Konvas chain). I'm sure I remember Olex even saying that his modified motors struggled at 50fps and I seem to remember something about motors requiring more voltage at 50fps too! It could be the motor is really struggling at that speed and it gets a bit all wobbly in some way.

Would the next speed down not be close enough for your purposes?

My understanding is that 50fps has always been difficult to achieve reliably on the Konvas.
Also Olex has a motor circuit that is crystal locked at variable frequencies so you could find out how fast you can go before it becomes a problem.

Hopefully Olex or someone who has also experimented with this will chime in soon with less fuzzy information.

love

Freya
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#5 Freya Black

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Posted 13 February 2008 - 03:09 PM

er hang on, I was feeling sleepy this morning. I think that even my motor only goes up to 40fps, so 50 is something preety fast indeed. I'm guessing you must already have a modified motor.

I do seem to remember that modified motors need 16 or 18 volts or something in order to go full tilt, but maybe you were already running at this speed?

love

Freya
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#6 John Sprung

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Posted 13 February 2008 - 03:15 PM

My hypothesis is that the loops are getting too short, but it may be something else I'm not considering.

You can easily check your hypothesis. Just run an old lightstruck short end thru a few times, stopping and checking the loops just by opening the mag and looking at them. Since you're in the LA area, the go-to guy for Konvas is Anatoly at Slow Motion Inc.




-- J.S.
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#7 Olex Kalynychenko

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Posted 13 February 2008 - 03:22 PM

Hopefully Olex or someone who has also experimented with this will chime in soon with less fuzzy information.


I think, i will need show of my answer, what i sent to Thomas on private letter.

The Konvas registration test at 50 fps complex question, because, the stability of image depend from many factors.
The first factor -design of claw mechanism of camera.
Konvas claw mechanism create for normal speed of shooting 24 fps and have maximum speed of 32 fps.
The manufacturer of Konvas to show of value of picture instability 0.02 mm at 24 fps and told about worsening at more high speeds.
Konvas camera have claw mechanism with one registration pin and if we check of design of high speed cameras ( speeds up to 150 fps ), we can see, the fast speed cameras have 2.. 4 pin transport pins and 2..4 pin registration pins.
Yes, Konvas can be use for shooting at 50 fps, but, the camera will ask of additional request of quality, adjust and service.

The next factor - condition of mechanism of cameras.
If you think to use of Konvas at 50 fps, the mechanism of cameras must have excellent condition.
The gaps at parts of transport mechanism must have minimum value, the mechanism must have minimum noise.
The block of shutter disk need re-balance at speed 50 fps.
From practical side, the good balance of block of shutter disk on 24 fps can be insufficiently at 50 fps.
The mechanism must be service and re-lube.

The gears of mechanism must be clean, especially, gears between main axis and film magazine.
The any dirt between of cogs of gear can give you instability of speed.

I recommed to "heat up" of camera before of shooting at 50 fps and run of camera at 24..25 fps 20..30 sec without film magazine.

You must draw of additional attention on condition of two small springs under of pressure plate of film magazine.
Because, of effort of this spring to influence on stability of pictures on film.
But, the effort of the springs not must be too high.

The loops of film of film magazine must have correct size.
Need check of every film magazine, because, the film magazine can lost of size of loops.

The battery must be charged.
The modified motors of 17EP-1414 have a soft acceleration of speed and ask of 18 v battery at 50 fps.
But, A some cameras can ask of 24 v battery at 50 fps speed.
Need check a "No-sync alarm" signal at 50 fps.
The modified 17EP-1414 motor can work with 24 v battery too, because, to have a big power reserve.
The output stage have limit 55 v 75A, diodes have Umax 100 v, capacitors have Umax 35 v.
But, not need forget about main DC motor .
The main DC motor DPR-72 have big power reserve ( nominal power 50W, peak power 210W ), but, this is DC motor for 12 v voltage.

The main schemes and programms of new style crystal sync speed controllers ( series 1404, 1414, 1416, 1421) tested on a many type of cine cameras ( Konvas, Kinor-16, Kinor-35, Arri 2C, Arri 35-3, BL2, BL3,..) and have high value of stability of speed.

And, If you to meet a all this claims, the footages will have high quality.
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#8 Freya Black

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Posted 13 February 2008 - 03:22 PM

er hang on, I was feeling sleepy this morning. I think that even my motor only goes up to 40fps, so 50 is something preety fast indeed. I'm guessing you must already have a modified motor.

I do seem to remember that modified motors need 16 or 18 volts or something in order to go full tilt, but maybe you were already running at this speed?

love

Freya


Oh bother I meant "running at this voltage" not speed. I think I need to stay away from this thread, or at the very least go have a lie down till I remeber where my head is. Bleeeugggggh!
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#9 Freya Black

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Posted 13 February 2008 - 03:35 PM

Thanks Olex! :)

Your warm up theory is an intresting one because maybe the first test was shortly after running at 24fps, so it was a bit more ready to go or something! :)

Thanks for posting this here Olex, lots of things for people to look out for if they want to try this sort of thing!

(and obviously I meant remember in that last posting, and now I really am going to go away and have a lie down!)

love

Freya
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#10 Thomas Worth

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Posted 13 February 2008 - 05:30 PM

I just wanted to mention that I had an 18v battery connected at full charge. The sync light was off during the entire take at 50fps.

I'll try again at 50fps and check the loops after a few seconds.

Another interesting tip Olex sent me through email:

I set of size of loops by my fingers.

The old user manual of Konvas-1 wrote:

The upper loop ? size of thumb,

The lower loop ? size of forefinger.


I usually just use my index finger, but I do notice that the loops are not equal size after the camera has been running. This sounds like it may be the solution!
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#11 Richard Boddington

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Posted 13 February 2008 - 06:52 PM

Well I've owned several Konvas cameras and shot with all of them in a wide variety of scenarios. Olex knows me well via e-mail :D

I will say this, the only time I could get "good" registration with a Konvas was using the 200ft mags with the core adaptors at the top and bottom. Using the Kodak core you can load in 150ft of film. No idea who would use those Konvas steel cores, impossible!!

I never got any decent registration with a Konvas and a 400ft mag with a 400ft load, even at 24fps. I did get ok registration with a 400ft mag and a short end, but not as good as with a 200ft mag and 150 ft load.

I notice that you have to use the mags that come with the camera. These fit the tightest. If you mix and match mags with the cameras the registration falls to pieces.

I always found 50fps with the Konvas to be pretty bad, however, no where near as bad as your test footage. Your test footage is un-useable, and my footage at 50FPS could have been used in a pinch.

Of course it's tough to accept Konvas registration when you've seen what the 435 can do at 150fps, rock solid!!

How many feet of film are you using? What size mag? Did you try a short end at 50fps?

R,
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#12 James Steven Beverly

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Posted 13 February 2008 - 11:31 PM

Of course it's tough to accept Konvas registration when you've seen what the 435 can do at 150fps, rock solid!!


These are Volkswagen cameras, ya ain't gonna run 'em at Indy! :D
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#13 Richard Boddington

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Posted 14 February 2008 - 01:04 AM

I do love the Konvas, small & tough.

I think Olex should build a pin registered version in PL MNT. I'll be the first to buy one. Just keep the price under $2000.00.

R,
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#14 Olex Kalynychenko

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Posted 14 February 2008 - 04:13 AM

I just wanted to mention that I had an 18v battery connected at full charge. The sync light was off during the entire take at 50fps.

This show, the electronics of motor to take a speed 50 fps good.
And. The transport pin can have different a final spot of move.

I usually just use my index finger, but I do notice that the loops are not equal size after the camera has been running. This sounds like it may be the solution!


Frankly speaking, i use my index finger for stup of upper and lower loops too.
I think, the more inportant to make of procedure attaching of magazine.

1.You need check of size of lower loops. You not need open of lid of magazine.
You need push on fixative pin on film track ( the film film move easy ). You move of film to upper side of film gate by to push of film at open part of film at film channel up to follow out of moving.

The next, You to begin of move of film to reversal direction (lower side ) and to count of perforation. You must move of film on 4 perforation ( the other my colleagues told me about 5 perforation, i think, the 4 or 5 perforation not important too much ).

After, you release of fixative pin and you move film on very short distance and must to catch
a hit the pin on perforation of film.

After this procedure, the size of lower loop to check and setup.

But, i must underline, If the size of loops will setup wrongly at procedure of loading of film, and the upper loop will have too big size, the film can receive scratches from touch with parts of body of magazine.

The next procedure, to attach of film magazine correct.
Before to attach of film magazine with new film, you need set of transport pin on upper position.
The film gate of camera have mark of upper position of transport pin and you need set of transport pin near this mark.

This is very important, because, this is procedure synchronize of phase of start-stop moving of film at film gate and permanent moving of film on film magazine.

After you set of transport pin on upper position, you can attach of film magazine.
The magazine must load easy without jam and blow.

The next, you need turn of axis of camera on a few turns by manual rotation of axis of motor on run of " Inch" mode at modified motor.

This is procedure need for connect of transport pin with perforation of film, for connect of gear of body of camera with gear of film magazine.

And, the all this steps give you a correct size of loops after run of camera.
Because, if you not set of of transport pin on upper position before attaching of film magazine, the size of loops will change with a first turns of axis of mechanism of camera

Richard open of very important idea about condition of film magazines of Konvas camera.
Yes, The quality of footages depend from condition of film magazine too because of mechanism of film magazine connect with mechanism of camera.
Konvas film magazine have dry friction clutch at takeup reel ( 200 ft and 400 ft magazine ) and condition of friction clutch to influence on stability of speed too.

The friction clutch to equalization of permanent speed of mechanism and variable speed of takeup reel.
The effort of clutch depend from effort of spring and condition of surfaces of parts.
If the friction clutch will have dirt, oil, dust, the value of effort will have pulses style and total speed will pulses too.
200 ft magazine have low rate of transfer constant and condition of friction clutch have less value of influence.
400 ft magazine have more big diameters of roll of film ask of less rate of transfer constant ast of additional power from main motor and can have more influence.

But, not need worry too much.
Need service of film magazine and check and adjust of friction factor of friction clotch.
If you open of lid of film magazine, the film rollers will jam and you must turn of take up reel without too big effort resistance.
I wish underline, the resistance of rotation must be, but, not too much. And must be constant, without jerks.
I use of special devices for adjust of breaking effort, but, you can use more easy technology.

You can adjust of traction coefficient of take up reel by way of condition of roll of film after run through of camera.
The used rolls of film must have not high density of winding, but, not must break up.
Need choice of better ration between :
- high density of winding, and high influence of film magazine on final speed of camera
or
- not high density of winding of roll and not high influence of film magazine on final speed of camera.

I prefer of second choice.
And not high density of winding of roll of film good for storage of film too.

But, this is not full list of parts of camera, what influence of final quality of footages and need of check and service.

About upgrade Konvas mechanism on in registration version, sorry, i can't propose of this service now.
This is modification ask of special version of mechanism, I don't have special parts for modification.
I hear, the registration pin modifictaion can make on Moskov and St-Petersburg, and i can help to searh of persons, who can do of this modification.

From theoretical side, i wish underline.
The modified Konvas will have one registration pin from other side from transport pin.
The more high characteristics have mechanisms with two registration pins from two side and one or two transport pins.
Any case, the claw mechanism with registration pin will have more high value of steadiness of footages.
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#15 Christian Appelt

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Posted 20 February 2008 - 04:01 PM

Thomas,
please check your negative with the registration problem. How do the sprocket holes look, are they in any way deformed or damaged?

If you project the neg, is the first run exposure steady in relation to the perfs? is it the second run exposure that jiggles, or do they both move?

I suspect that there is either damage to the perfs during the first run or that the loop is lost because there is some slippage in the first mag sprocket, causing the top loop to get too small.

Did you start the camera at 50fps or did you bring it up to speed from a lower fps?

50 fps with a Konvas is only possible if your camera and all your mags are in top condition (serviced/lubricated), with perfect brake tension, non-worn sprockets with correct spring load and correct gate tension.

Edited by Christian Appelt, 20 February 2008 - 04:05 PM.

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#16 Olex Kalynychenko

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Posted 21 February 2008 - 09:18 AM

Did you start the camera at 50fps or did you bring it up to speed from a lower fps?


P.S
Thomas use of modified 17EP-16 APK motor ( 17EP-1414-10 ) with modern crystal sync speed controller based on microprocessor.
The acceleration of speed of camera fluently, without jerk.
And microprocessor to control of special algorithm of acceleration.
This is not variable speed adjust at 50 fps, but, the acceleration of camera at 50 fps for near 1..2 sec.
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