Crystal sync - what's the big deal?

[Jared Rowell]

Hi,

 

I'm from the digital era and have recently been researching into 35mm cameras. I've been able to understand most things except what is the benefit of a crystal sync motor. I've seen the Arriflex IIC and Konvas 2m with and without them. The price difference is about $1000. Can someone tell me why it is worth that much? Thanks.

 

Jared

[David Mullen ASC]

Crystal sync ensures that the camera motor is running exactly at the speed selected, and not drifting. This is important when shooting scenes where the sound is being recorded, or else your sync will drift -- but it also matters when shooting under 60 Hz lighting with older magnetic ballasts, where you can get flicker if not shooting crystal-sync at a "safe" speed.

[David Sweetman]

well here's the thing - do you NEED one? it depends. Even if the audio does drift around, it's possible to patch it up in post, cut up and move the audio around till it fits. Of course, it's a heck of a lot easier and smoother with a crystal sync.

 

With the test I shot on my arri 16bl, using the standard motor (i have since gotten a tobin crystal control for it - but haven't installed & tested it yet) I got a fair amount of audio drifting (perhaps a side effect of my self-recelled battery.) however, I was able to work the audio (recorded on minidv) until it acceptably fit the image. If you need the extra grand, you can swing it without a sync. The sync I got was a heck of a lot less than $1000, so it was worth it to me. I'm not sure I would have gotten one if it was that expensive. I'd say it's much better to put that money into your lenses.

[Olex Kalynychenko]

Hi,

 

I'm from the digital era and have recently been researching into 35mm cameras. I've been able to understand most things except what is the benefit of a crystal sync motor. I've seen the Arriflex IIC and Konvas 2m with and without them. The price difference is about $1000. Can someone tell me why it is worth that much? Thanks.

 

Jared

 

A few technical notes.

Konvas-2M russian 35 mm cine camera can have a few type of motors.

This can be 15EPSS motor with analog system of speed stabilization and precision of speed control 2.5% ( on 24 fps ) and motors with crystal sync speed control : 17EP-16 APK, 18EP-16 APK, 19EP-16 APK, 5 BD-16 APK and other.

This motors can have a few crystal sync speeds or all crystal sync speeds with precision 0.01%.

All Konvas crystal sync motors can be modify on modern microprocessor control multi speeds system with speeds sync with 50 Hz and 60 Hz.

 

The few difference between Konvas-2M and Arriflex IIC :

- Konvas-2M mono lens mount design have reliable lens mount style of Arri PL or BNCR,

- Konvas -2M have fast system of change of film magazine with film. You will need 2-3 sec for replace magazine with film.

- Konvas-2M have fast removable motor and you can set any motor, at any time.

[Freya Black]

Hi,

 

I'm from the digital era and have recently been researching into 35mm cameras. I've been able to understand most things except what is the benefit of a crystal sync motor. I've seen the Arriflex IIC and Konvas 2m with and without them. The price difference is about $1000. Can someone tell me why it is worth that much? Thanks.

 

Jared

 

The other thing to watch out for with the 2M is that the crystal motors are generally 12volt and a lower ampage, whereas the 15epss is 8 volt and requires a lot of amps. It also seems anecdotally as if the 15epss is less reliable, although the electronics is the weak spot of the soviet cameras generally (not the lenses which people never seem to trust for some bizzare reason). This is why Olex offers replacement electronics.

 

For me that 12 volt versus 8 volts can be bigger than the crystal issue because it makes it a lot easier to power the camera if it is 12v.

 

love

 

Freya

[Olex Kalynychenko]

The other thing to watch out for with the 2M is that the crystal motors are generally 12volt and a lower ampage, whereas the 15epss is 8 volt and requires a lot of amps. It also seems anecdotally as if the 15epss is less reliable, although the electronics is the weak spot of the soviet cameras generally (not the lenses which people never seem to trust for some bizzare reason). This is why Olex offers replacement electronics.

 

For me that 12 volt versus 8 volts can be bigger than the crystal issue because it makes it a lot easier to power the camera if it is 12v.

 

love

 

Freya

 

I not agree of idea " the electronics is the weak spot of the soviet cameras" too much, because, need divide electronic of 70 and 2000.

 

About 15EPSS motor. This is motor design for military style motor with 27V DC.

From other side, the battery with 27 v not possible and have big size.

That's why, designer of 15EPSS motor to choose voltage changer from 8 v up to 52 v ( 27v+27v ).

From other side, 15EPSS motor design for 5 pcs of 15 ah silver-zinc cells.

If you take 8v and will need 50 W power and add efficiency of voltage changer you received big current.

But, 15EPSS motor can work with low temperature -30C up to +40C.

The power unit have special position of speed 24 fps for low temperature shooting.

Yes, 15EPSS motor have power unit with big weigt, have analog system of speed stabilization.

But, this motor can run camera on -30C.

 

15EPSS motor can be modify for use of 12 V battery.

 

The original electronic of 17EP-16 APK, crystal sync motor, reliable, but, this is design of 80 and have 6 fixed speeds only.

The near 90% of all faultiness of original electronic of 17EP-16 APK motor - connect battery with reversal polarity.

near 5-10% - jammed of mechanism of camera or magazine.

 

The modern film makers wish have more speeds, more technical possibilities and wish shoot with telecine post production for music video.

They need speed for 50 Hz ( PAL ) and 60 Hz ( NTSC ) sync, need have slowing down and acceleration

( speeds : 16.6, 25, 33,3 fps for 50 hz sync and 20, 30, 40, fps for 60 hz sync)

 

The new electronic of 17EP-16APK have more crystal sync speeds, especially for 60 Hz sync, have soft start of motor, manual adjust of phase of speed, low speed test run.

That's why, the use of modern chips with more wide possinbilities good choose for film makers

 

You can see more information about Konvas motors on page:

http://www.geocities.com/kinor35/repair/electronic.htm

[Freya Black]

I not agree of idea " the electronics is the weak spot of the soviet cameras" too much, because, need divide electronic of 70 and 2000.

 

I'm not sure what you are saying here, but maybe you are reffereing to the years 70' and this decade???

It doesn't really seem to apply to what I'm saying.

 

About 15EPSS motor. This is motor design for military style motor with 27V DC.

From other side, the battery with 27 v not possible and have big size.

That's why, designer of 15EPSS motor to choose voltage changer from 8 v up to 52 v ( 27v+27v ).

From other side, 15EPSS motor design for 5 pcs of 15 ah silver-zinc cells.

 

I'm sure it made a lot of sense to the people making it at the time in the soviet union but it's not really that convienient now, which is what I mean.

 

If you take 8v and will need 50 W power and add efficiency of voltage changer you received big current.

But, 15EPSS motor can work with low temperature -30C up to +40C.

The power unit have special position of speed 24 fps for low temperature shooting.

Yes, 15EPSS motor have power unit with big weigt, have analog system of speed stabilization.

But, this motor can run camera on -30C.

 

I'm sure that's great but mostly people won't be shooting in -30c. That's even colder than England! ;)

I'm sure it has been useful to the people shooting in siberia or somewhere however.

 

15EPSS motor can be modify for use of 12 V battery.

 

I guess you could step the voltage down from 12 to 8 volts but it would still have a high ampage requirement. It might be a worthwhile idea tho, to be able to run something a little more easier to power.

 

Of course these 15epps motors are getting quite old now and it seems like they are starting to fail.

 

The original electronic of 17EP-16 APK, crystal sync motor, reliable, but, this is design of 80 and have 6 fixed speeds only.

The near 90% of all faultiness of original electronic of 17EP-16 APK motor - connect battery with reversal polarity

 

I know reversal connection is quite a common problem. It seems like a diode or two might have aleviated this problem.

 

The 17EP-16 APK motors do seem to be a lot more reliable, however, they have now become very rare.

 

The modern film makers wish have more speeds, more technical possibilities and wish shoot with telecine post production for music video.

They need speed for 50 Hz ( PAL ) and 60 Hz ( NTSC ) sync, need have slowing down and acceleration

( speeds : 16.6, 25, 33,3 fps for 50 hz sync and 20, 30, 40, fps for 60 hz sync)

 

The new electronic of 17EP-16APK have more crystal sync speeds, especially for 60 Hz sync, have soft start of motor, manual adjust of phase of speed, low speed test run.

That's why, the use of modern chips with more wide possinbilities good choose for film makers

 

You don't think that replacing the motor electronics will improve reliability??

I assume your electronics are not succeptible to the reverse polarity fry?

 

My experience with Konvas cameras is always that it is the motor side of things that is the big problem and not the camera or the lenses. People always seem to assume that the lenses will be some kind of problem, perhaps because here in the west we associate cheap cameras with soft lenses or something, but for me all my problems have been, and still are, motor based. It is the weak spot, the achilees heel.

 

Probably this would not be the case if I had a 17ep-16apk but these motors are now very rare.

 

However that was the original point I was trying to make, it's not just a choice between a crystal motor and a non crystal motor, but between a motor that has lower power requirements and runs off 12volts instead of 8 volts, and a motor that will probably be a lot more reliable than say the 15epss period. So there are good reasons for the fact that crystal motor might be a lot more money because you are paying for something that is more standard and reliable and will cause you less pain. The fact it is crystal locked and presumably has HMI safe speeds etc etc can almost turn out to be an aside. Personally I'm not needing sync for my current projects, but I do need a motor that works and I can power.

 

The other big problem with the Konvas here in the west, is that the collective knowledge about these cameras here, is very incomplete compared to say Arri or Aanton or Eclair cameras and this can lead to some really nasty suprises. I think the motor thing is a bigger problem however.

 

So I agree that the people who made the Konvas motors may have had all kinds of good reasons why they did these things at the time, but I'm really talking about trying to use these cameras in the here and now and motors can be a problem.

 

love

 

Freya

Edited May 22, 2006 by Freya

[Hal Smith]

Much of the successful use of any technology is understanding the basics. Much of the mystery of motors and batteries would be cleared up with an introductory electricity course. One of the best was written for use in the U.S. Navy "A" Schools. The Navy school materials are often some of the best around because they're written for students who have aptitude for the subject matter but not much education in it.

 

The technicians on ships have to know what they're doing. When you're 1200 miles out to sea and something breaks, there is no option to take it to the repairman - you're the repairman.

 

http://www.amazon.com/gp/product/079061041...glance&n=283155

 

http://www.amazon.com/gp/product/048620973...glance&n=283155

 

The original BuShips Basic Electricity was written by Van Valkenburg, I'm not certain what the relationship between these two books is - the BuShips is a bunch cheaper probably because the USN picked up all the original costs of publication

[Olex Kalynychenko]

Yes of course, I agree of all your idea about reliability of camera, motor, battery.

I film maker too , I rate highly of reliable of equipments.

 

15EPSS motor not he height pink of perfection. This motor have merits and demerits, and the modification on 12 v battery can give you possibility use this motor now, but, not will improve of characteristics.

I use 15EPSS motor long time, and my motor work fine with 6 v battery.

I see The modern modification of 15EPSS motor on of design new power unit ans speed control module.

 

About 17EP-16 APK motor.

===You don't think that replacing the motor electronics will improve reliability??

I think, to replace of the motor electronics on new style microprocessor control will improve reliability of 17EP-16APK motor and will add more modern possibilities.

 

About protective diode.

Yes, the protective diode will protect of electronics from connect of battery with reversal polarity.

But, the protective diode cut a some voltage from battery ( 0.7 v ), thats' why, need use of fast diode.

 

Yes, Konvas camera have very good mechanic, high quality lenses and modern electronics will give you

reliability and modern possibilities. And many filmmakers use Konvas for shooting.

But, any cine camera - complex system of precision optics and mechanics and need current maintenance and service.

 

The russian cine cameras and lenses not sold on West too much at time of former USSR, because, big country -USSR need many cine cameras.

That's why, not many west filmmakers know about russian equipments too much.

But, now, i hope, we will change this situations and many west filmmakers can to estimate at one's true worth russian equipments and price.

[Hal Smith]

About protective diode.

Yes, the protective diode will protect of electronics from connect of battery with reversal polarity.

But, the protective diode cut a some voltage from battery ( 0.7 v ), thats' why, need use of fast diode.

Dear Oleg,

 

Another diode protection method is to put a diode >across< the camera input terminals, Cathode to plus (+), Anode to minus (-). Use a heavy duty diode, maybe 5 amperes or more. Place a fuse large enough to handle the maximum motor current in series with the battery or mains power supply. If the battery or mains supply is hooked up backwards, the protection diode will commit suicide, shorting out, and blowing the fuse. This method has the advantage that it does not lose any motor voltage, and the disadvantage that the fuse and diode have to be replaced before the camera will work again. My experience is that if the electronics powered this way have any filtering of the power supply to slow down power surges (a large capacitor, etc.), the diode will short before the motor and/or electronics are harmed.

[Guest Jim Murdoch]

Schottky Diodes have a much lower voltage drop (typically around 0.2V). They are widely used in computer power supplies and are quite cheap.

Instead of a fuse, consider a self-resetting Polyswitch

[Hal Smith]

Schottky Diodes have a much lower voltage drop (typically around 0.2V). They are widely used in computer power supplies and are quite cheap.

Instead of a fuse, consider a self-resetting Polyswitch

Not a bad approach either, I do prefer the quicker response of a fuse, particularly one of the ones specifically rated for electronics protection. Do Schottky's come rated for currents over 5 amps? I run across them from time to time in signal circuits but don't think I've ever knowingly run across one in a power circuit.

[Guest Jim Murdoch]

Do Schottky's come rated for currents over 5 amps? I run across them from time to time in signal circuits but don't think I've ever knowingly run across one in a power circuit.

 

I have some rated at 200Amps! 30 Amp units are routinely found in computer power supplies; you could probably scrounge one from a discarded computer. Most modern digital multimeters have a "diode check"range; that should show a forward voltage of less than 0.1 Volt with a good Schottky diode, and open-circuit the other way round.

[Lav Bodnaruk]

Hi,

 

I'm from the digital era and have recently been researching into 35mm cameras. I've been able to understand most things except what is the benefit of a crystal sync motor. I've seen the Arriflex IIC and Konvas 2m with and without them. The price difference is about $1000. Can someone tell me why it is worth that much? Thanks.

 

Jared

 

Hi Jared,

 

as some folks already mentioned in the early replies, the crystal sync becomes vital when using lights say in Australia for instance, on 50Hz... I too own a 16mm BL and have used it without the crystal sync (till i got one) and have gotten a hell of a lot of flicker throughout my footage... The lights I got onto were rather cheap and without flicker free balast.

 

It also just happens to have been freezing cold on the day and my battery failed to power up the camera well too - 12V Panavision battery, mounted in the metal box...

 

You do not need to be in siberia to experience that kind of cold, just have a go at shooting at night in the desert... that's right, it is freezing cold... and we all know that even rocks break on such a difference of temparature. DP from Brisbane gave me a word of advice in regards to shooting in desert, he said he always but always, straps his batteries on his torso and wears a jacket over it...

[Olex Kalynychenko]

=Another diode protection method is to put a diode >across< the camera input terminals, Cathode to plus =(+), Anode to minus (-). Use a heavy duty diode, maybe 5 amperes or more.

The paralleling of diode with DC input.

I not support of this idea.

This style of protect have not 100% of protect.

If you connect battery with reversal polarity and diode open, the battery will short-circuit, will go big current

and fuse will burn. But, the fuse will burn on a few millisecond.

This time reversal polarity will go to electronics and can burn electronics too.

The other situation, the diode can burn instantly ( to be reduced to ashes) and don't short-circuit of input.

From other side, the every diode have " reverse current", this is very small volume.

 

That's why, i choose set protective diode in series, i lost a some voltage ( Schottky Diodes, fast diode 0.2..0.3v, like SR5100-5a, MBR10100-10A, MBR20100- 20a ) but, i will have more high protection and not will have smoke, if i connect battery with reversal polarity.

 

About extinguishing of self-inductive pulses of DC motor, the modern FET have protective diode.

 

About "flicker free" shooting with HMI lighters.

If you use HMI lighters with magnetic ballast, need choose sync speed of frequency AC main power.

If this 50 HZ, the sync speed will :

100, 50, 33.333, 25, 20, 16.666, 14,285, 12. 5, 11.111, 10.....

If this 60 Hz, the sync speeds will :

120, 60, 40, 30, 24, 20, 17.143, 15, 13.333, 12, 10.909 10.

 

The analog speed control system can have precision 2.5 % and you can have " flisker " effect.

The crystal sync speeed motors have precision 0.01%.

 

About checking of power of battery.

A some time ago, i begin to set of digital voltmeter in my motors.

This is very good device show me condition of battery at any time.

The digital voltmeter show me voltage with precision of 0.1 v

 

 

That's why, i recommend to set some device of other filmmakers too.

This is very easy.

 

for 12 V, 7 ah battery.

The voltage more 12.65 v ? 100% power of battery

12.4 v = 75% of power

12.2 v = 40% of power

12.0 v = 25% power

11.8 or less = discharger.

 

The 18 v , 6+6+6v 4 ah battery:

 

The voltage more 18.9 v ? 100% power of battery

18.7 v = 75% of power

18.4 v = 40% of power

18.1 v = 25% power

17.8 or less = discharger.