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Alexa powered through Zephyr sled? Answered.


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#1 Dave Tree

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Posted 01 March 2012 - 08:57 AM

HI
I own an Alexa, and I bought a Zephyr. I tried to get a definitive answer wether or not the alexa could
1. Be flown on the Zephyr?
2. Be powered by the sled?

I didn't get a clear answer, there were some who said no way and others that said it could be possible and even Tiffen couldn't answer the question about powering. So I had a cable made up myself and I can now answer those two questions.

1 YES, the Alexa can be flown. It's very close to the limit on the zephyr but it doesn't bottom out and you should fly the Alexa as LW as possible. Remove what you can (this makes balancing much easier anyway) and use the 15mm inbuilt rods and Arri LW mattebox
2 YES. you can power the alexa through the sled provided that you get the 24v adaptor to rig 2x vlocks to the sled (good for counterbalacing the alexa too) and you make sure that in the menu you drop the Alexa power warning to around 12v. I think the batteries have a huge amount to do with it also! I'm using 2x Hawk wood VL-175's

I have the ARRI QR Baseplate for the Alexa which I'll use from now on as the pictured setup felt secure, but I'd rather have the additional support, even if heavier. The camera was solid tho. I believe this rig will take a RFF without any difficulties weight wise, I have to test the additional power drain.

I use a SmallHD monitor also, it's self powered and it has a better weight to it for counterbalancing.

hope this info is of any use to someone else.

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#2 RonBaldwin

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Posted 01 March 2012 - 09:21 AM

not trying to sound like a smart-ass, but isn't this question easily answered by the published zephyr specs (23 lb max weight and 12/24 volt capability)?
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#3 Alfeo Dixon SOC

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Posted 01 March 2012 - 10:22 AM

not trying to sound like a smart-ass, but isn't this question easily answered by the published zephyr specs (23 lb max weight and 12/24 volt capability)?

Only on paper Ron, not in the real world where we live and work in.... just wait until he throws on an MDR, motor, filters and then sound jumps on with a locket box and receiver with those hunky ass xlr connectors. OHHH! did we [production] mention you'll be flying a teleprompter today?!?! Good luck with all that.
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#4 RonBaldwin

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Posted 01 March 2012 - 11:39 AM

Yes Alfeo a fully loaded alexa is closer to 30 lbs (sometimes over) but I do not think anyone with a zephyr would be attempting to fly a fully loaded alexa with all the typical gak. This guy said he owns an alexa and is obviously talking about stripping it down to the bare minimum to work.

So yes, the 14lb body, a typical prime, clip-on mb , cables, camera dovetail, bfd and one motor seems to just fit in the afore mentioned 23 lb capacity and the sled is 24 volt capable. Using the published specs and knowing your limitations will help in all aspects of life, including the knowledge of what camera will work on what sled.
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#5 Robert Starling SOC

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Posted 01 March 2012 - 12:18 PM

I think the next concern would be rigidity / vibration with that much weight on top and bottom and such a tiny center post. I'm also concerned about rigidity and durability of the top stage / center post connection point; there's a lot of stress on that bit.

Maybe as the owner of the camera he'll be able to have more influence on all the AKS attached to it, but in the real world we don't have that choice always.

A lot will depend as well on how often you are flying your arm and rig at full weight capacity. My motorcycle will do probably upwards of 145 mph and my wife's car will probably get close to 175-180+ mph but neither will last long doing that everyday for extended periods. The same goes for your arm and sled.

Just because it can doesn't mean you should.

Robert
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#6 Mark Schlicher

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Posted 01 March 2012 - 12:48 PM

Yes, it can be flown in a reasonable lightweight configuration, with enough "headroom" to add a BFD, filters, etc. The body is only 14-15lbs without viewfinder. Add a 4lb Optimo lightweight zoom or a lighter prime with clip-on mattebox, 15mm rods, BFD and motor and you've still got a little wiggle room up top, but not much. A loaded configuration with cinetape, prompter, Preston and multiple motors, video TX, heavy lenses, baseplate, codex, lockit box, etc. definitely ain't happenin'.

The original weight specs published for the Zephyr were inaccurate. I tested my rig extensively and sent the results to Tiffen. Their revised, current specs exactly mirror my findings.

The 23lb camera payload is correct; you could probably squeeze up to 24lb. My tested arm lift is 36-37lbs. Bare sled with a monitor (no batteries) is roughly 7 lb, leaving a maximum of 7lb for a 12/24V plate, batteries, balancing weights, cables and other AKS mounted at the base.

Power is a challenge that is partly met with the 24V 2-battery plate. The power draw for camera alone is 80W or more. BFD and motor adds "up to 36W". Add another 12W or so if powering a monitor on the sled. That's around 130W, so you will be BLAZING through batteries, even with two mounted. No way can you fly with just one battery. You will need a bucket of batteries if it's a long day. A pair of 1 year old Dionic HC batteries (assume 75% of original capacity) will power for less than an hour.

Also, batteries will tend to "cook" and wear out much faster under high current draw, so running in 24V mode lowers the current, and is much easier on longterm battery health. A pair of (fresh) Powercubes or Dionic HC's are the minimum, with plenty of spares. Higher capacity batteries will probably work too, but be aware of the weight issue. Dionic 160's are 3.4 lb each, so a pair tips over the weight limit. Generic 160WH batteries tend to be lighter, about 2.5 to 3lbs.

Prospective Zephyr owners need to understand that the rig, though a great value, will not stack up to situations where production expects you to be able to handle any random monster Alexa/lens/baseplate configuration they throw at you. A good prep is mandatory, as is a willingness to say "no" to a gig that is beyond the rig's capacities.
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#7 Mark Schlicher

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Posted 01 March 2012 - 01:00 PM

Robert, your observation about camera stage attachment is well-taken. The post connects to the camera stage via a metal collar arrangement with five hex screws that go all the way through a metal inner-collar that, in turn, is pinned into the CF post. Seems structurally robust, but I definitely have to check the screws regularly....they tend to loosen up just enough to introduce vibration/play from time to time.
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#8 Mark Schlicher

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Posted 01 March 2012 - 01:03 PM

Oh, also...your sled-to-Alexa cable needs to be wired differently for 24V vs. 12V. Same connectors, different pinouts I believe... just throwing the 12v/24v switch won't work.
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#9 RonBaldwin

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Posted 01 March 2012 - 01:15 PM

That is a good point Rob...in all honesty, I would try to keep that rig at or below 20 lbs. The wonkiness of the vest may also be a concern.
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#10 Wolfgang Troescher

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Posted 01 March 2012 - 01:28 PM

In this video Peter Abraham demonstrates Arris Alexa on a Zephyr (at about 37:00). Sure, Alexa without any additional equipment. But in a pinch it seems to work.
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#11 Mark Schlicher

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Posted 01 March 2012 - 01:29 PM

Ron,

Curious what you consider to be wonky about the vest...?

The Zephyr vest appears to be essentially the old Provid vest with a Flyer-sized socket block and adjustable velcro-ed shoulder straps. Is it the velcro that concerns you?

That is a good point Rob...in all honesty, I would try to keep that rig at or below 20 lbs. The wonkiness of the vest may also be a concern.


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#12 RonBaldwin

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Posted 01 March 2012 - 02:20 PM

I meant any vest at the upper end of it's weight limit...general flex of the chest spar...etc
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#13 Mark Schlicher

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Posted 01 March 2012 - 03:05 PM

Gotcha. Thanks. It's a pretty solid vest, even up past 20lbs payload. Miles better than the old Flyer vest.
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#14 Dave Tree

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Posted 01 March 2012 - 05:58 PM

Thanks for some of the comments, others kinda prove my point on getting a definitive answer. At no point am I suggesting this is a solution for everything, it's horses for courses. For a simple shot and set-up, my tests so far have proved strong and sufficient.
I've shot a considerable amount of work for clients that don't require a telepromter or external sound, shots utilising high frame rates. I've factored the additional weight of a RFF, filters and a video sender. So as mentioned, I need to test the additional draw of those items.
I have the Zephyr for my C300 kits and others, but it's nice to know at a push, provided that its LW solution... my Alexa can be flown too, maybe not in your real world, but at least in mine.
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#15 Mark Schlicher

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Posted 01 March 2012 - 06:34 PM

I had lots of trouble finding good information on power. I did end up talking to some helpful folks from Anton Bauer, as well as the respected battery receller John Ritter, and digging up published specs where they were available.

There's actually good discussion in the archive but, as you say, not very definitive. The two issues are high current draw/battery wear, and high wattage/short runtimes.

Powering your monitor separately helps for sure. Plus I don't think the BFD is constantly drawing 36w, that's just the published spec that I believe applies when the motor is cranking.

The hardest thing for me to initially wrap my head around was the 12 vs 24v battery question. I've had some unpleasant surprises on Red Epic jobs with the age/performance of rental house batteries, but I don't want to tear my own batteries up unnecessarily by running at their current draw limits. 24V definitely solves this. You ended up going 24V for your Alexa power cable, correct?
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