ARRI 435 & Hytron 120

[Lars Erik]

Hey guys. I've been asked about doing a shoot with the 435.

 

I have a 12v systems Steadicam. And I also have a 14v-26v power converter from Marrell Electronics in the UK. I use AB Hytron 120's on my rig.

 

Will this be enough power to power up the 435? What about shooting at 72 or 150 frames?

 

 

Thanks for any info.

 

LE

[Alec Jarnagin SOC]

Lars,

 

The Hytron 120s handle a lot more amperage than their little brothers (Hytron 50s) and I use them all the time for 24Volts, BUT (and this IS a huge but) I jump up to 24 Volts by adding a Performer (NiCad) battery in series. How a Hytron 120 (or any battery) will perform with the 12V to 24V converter is the question. Anyone out there use this combo????

 

Search the archives too. They are vast.

[RobVanGelder]

Although in principle possible, you have a good chance of failure after a few takes.

In order to run 100fps and more a 435 needs certainly 28 volts or more.

Not only that, it cannot drop down during the ramp-up to speed, the camera will switch off.

 

It works fine for Arricams, Moviecams, Arri SR3 and (but i have no experience in them) likely the Panavisions.

 

The bottleneck is often the converter, it might be designed to handle high amp loads, like 10 amps or so continuously, but the startup is always the problem.

 

Also, as everything comes from the 12 volt battery, the amperage in that is doubled, so a 15 amp surge (which can happen with a 435ES to 150 FPS) is minimum 30 amps through the battery, in general, there are no cells in the kind we use (Nicad, NMHI, LI-Ion) that are indifferent to this.......

 

So I suggest, if your work is mainly on filmcameras, to convert your rig to 24/28 volts as most of the modern cameras are using that. Together with a low-cost but hi-amp DOWN-converter to 12 volts you can do the older camera's and video as well.

[Lars Erik]

Hey Alec and Rob,

 

thanks for the info.

 

I'm looking into making my rig 24v. I'm planning on using AB Hytron 50's in addition to the 120's. The 50's will be attatched at the rods and cable will go up and inside of the rig.

 

But I have just one more question regarding the 435. I spoke to the director and the highest he'll be shooting is at 50 fps. Will this be ok with the converter? Sorry for the questions. Only been operating since December, so there's lots of things to figure out.

 

Thank you.

 

 

LE

[RobVanGelder]

Providing your batteries, cables and connectors are in good shape, you should be fine on 50 fps.

But it can't hurt to check before, at the rental house.

This to avoid embarrasing situations on set.

[Brant S. Fagan SOC]

Gents--

 

For the record, according to sources at A/B, the NiMH battery chemistry can NOT deliver the level of current (amps) that are required to run an ARRI 435.

 

That camera requires, for some 14 milliseconds, 17 amps at 28 volts for startup. This is for 24 fps. High speed operations require even more for the speed ramp.

 

Most folks using two batteries to make a 24 volt supply combine chemistry types and sizes to meet that goal.

 

Using two Hytrons, which are both NiMH type, may not be to your satisfaction.

 

If you have specific technical concerns about your A/B products, contact Paul Dudeck, who posts here as well, and get your answers straight from the source.

 

Go get 'em.

 

Best,

 

Brant S. Fagan, SOC

Steadicam/Camera Operator

[Alec Jarnagin SOC]

Here is the official chart from AB's web site comparing batteries.

 

http://antonbauer.com/selecting_batteries.htm

 

Notice the maximum load column. Interesting to see they rate the Hytron 50 the same as a Trimpac and the Hytron 120 the same as a Propac. They are probably talking continual draw.

 

Another note: depending on the vintage of 435 one has, you can set it to ramp to speed slowly limiting the amperage spikes.

[Lars Erik]

Ok guys,

 

thank you very much for all the info. I'll look into different battery system than AB.

 

For the record, the DoP has decided to shoot on the Arricam Studio. And in worst case scenario, I'll use the 24v battery that comes with the camera and attach it with strong velcro to my dovetail which is straight under the post.

 

LE

[Mark Karavite]

Dear Lars,

 

When I bought my new rig, I did extensive battery testing with a 435 before I bought my battery package. Combining 2 Hytrons (or any NiMH) batteries is suspect for 435 use. The safest way, especially if you have a 12v rig modified to 24v, is to combine 2 NiCads.

 

I have a hybrid sled with a PRO DB3, XCS 2" post and gimbal, and the MK-V Nexus battery base. With my setup, combining a Hytron 120 with a Proformer gave me reliable 90fps with the 435. In order to run top speed, it required 2 Nicads. Other sleds may react differently. Wil's Ultimate sled would react differently to a battery combination than my sled would.

 

Although I tested my sled to 90fps with my normal batteries, I always bring NiCad's for 435 high speed work. Besides cold weather affecting both camera tension and battery performance, I'd never want to limit a DP to a certain frame rate, just because they said they wouldn't go higher than a certain fps in prep. We should show up ready to run the dedicated Steadicam body at all speeds.

 

You are smart to modify your rig to 24v. It is an issue you will run into on almost every job. What sled do you have now?

 

Mark Karavite

[Lars Erik]

Hey Mark,

 

yeah I've only been operating for a year almost. Bought my Archer in December of 2005. But I've been asked about 35mm jobs now, so I'll be upgrading my rig to 24v in November. I'm taking it to Michael Hofmann of Hofmann AB in Sweden. He'll help me with the upgrade.

 

The job eventually went all the way up to a 535. Which is too much for my rig. So I called a colleague of mine who has a MK-V rig. He did the job.

 

I agree with you about giving the DP all the possibilities he/she needs.

 

LE