A complete rig based on Alpha 77

David Kilpatrick
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A complete rig based on Alpha 77

Unread postby David Kilpatrick » Wed Jan 11, 2012 11:08 pm

Thought you might all like to see today's DIY project, which I completed after my new budget priced Røde VideoMic arrived this morning.
videorig-sonyrodeetc-web.jpg
videorig-sonyrodeetc-web.jpg (288.16 KiB) Viewed 5926 times

The Alpha 77 shoots video with the 16-50mm SSM lens to a better standard than the NEX-5, the autofocus is smooth and silent and very accurate during filming with this lens.

On top of the camera I have an Amaran LED video light, which is incredibly powerful, dimmable, needs fitting with its diffuser for subject comfort, and one of the largest so far of all the small units like this. It takes A100 to A77 type batteries, or can be run from AAs. In the UK they can be bought from Chris Buck at Studio81, [email protected], for £75 - I'm not sure if that includes postage, he has a dozen of them he brought in from SE Asia recently.

To the side, attached using an old Minolta camcorder handgrip bracket, is the Røde (you can see I bought it a Dead Cat too for outdoor shooting, in the playback which appears on the monitor). Fantastic news - the terribly hissy, noisy auto gain noise level of the built in mics disappears like magic with the Røde. It has three Gain levels, normal and -10dB or -20dB which are accessed by really hard to see, hard to operate dipswitches inside the battery compartment. It does not use phantom power and requires a 9v battery, which of course give a much cleaner sound than 5v phantom power. It also has a low-cut/high-pass filter if needed (can help with wind noise). I have only walked round the house with it so far but everything points to really good quality sound and no problems with auto gain. The Røde was £69.

To the rear, mounted on a second flat camcorder accessory bar (another Minolta leftover) is a Lilliput 7 inch HD format monitor with a short HD cable which relays the rear screen display even when the rear screen is folded to face the camera. You do not need to switch, the camera can tell a monitor is attached. It has sound through the HDMI, even during filming, but no headphone socket which is a great pity as the camera does not either (Sony's smaller 5" monitor does). These monitors, with the lithion battery you can not see mounted between it and the camera, cost around £150.

David

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[SiC]
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Re: A complete rig based on Alpha 77

Unread postby [SiC] » Fri Jan 13, 2012 10:49 am

Wow, that rig looks awesome :-D
Sony A700, A580, Nex-5t, KM D7D & VC-7D, M Dynax 500si
KM 17-35 F2.8-4 D, M 50 F1.7 RS, M 135 F2.8, M 28-100 F3.5-5.6 D, M 100-200 F4.5, T 70-300 F4-5.6 Di USD, S 18-55 F3.5-5.6 SAM, S 18-70 F3.5-5.6
Sony hvl-f42s, Minolta 3600 HS D
Sony Z1C & Z2

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Birma
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Re: A complete rig based on Alpha 77

Unread postby Birma » Fri Jan 13, 2012 10:44 pm

Very nice setup DK :) . Great that the light takes the A700 etc battery. I assume that the external screen shows the same as the rear LCD. You could use MF assist with peaking etc.? I imagine that would be a useful way to compose pictures if you were on a tripod taking your time.
Nex 5, Nex 6 (IR), A7M2, A99 and a bunch of lenses.

David Kilpatrick
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Re: A complete rig based on Alpha 77

Unread postby David Kilpatrick » Sat Jan 14, 2012 1:44 pm

In MF mode in video, I do not detect focus peaking though I have it turned on - what does happen is that if you are in a multi-point AF mode (which seems to work much better than fixed central point for video) the active sensors matching focused areas blip on and off tracking the subject - sort of focus confirmation. The quality on the external screen is very good.

Sony's smaller external screen also takes the camera's batteries, so you could have this and an LED light and use nothing but one type of battery for all of them.

I just wish that Sony would have changed the design of their camera-top flash units, like the HVL-F58AM, to use the NP-500 battery instead of four AAs. The lithion cell would be 7.2v, where four rechargeables are only 4.8v - that can make a very big difference to the speed of recycling, or if they wanted, to the GN/Ws power output. It would make so much sense for flash units to use the same battery as the camera.

David

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Re: A complete rig based on Alpha 77

Unread postby jcoffin » Mon Jan 16, 2012 10:55 pm

The higher voltage might help the cycle time, but might just about as easily not. The cycle time is governed to a large extent by the effective internal impedance of the battery, which limits the current the battery can deliver. Doubling the voltage would roughly halve the required current, but I'm not sure about the internal impedance of the NP-FM500H compared to AAs. Its total energy storage capacity is very high, but that's not really all that relevant for the purpose.

Increasing the guide number would be much less likely. A flash works by the batteries charging up a big capacitor (the cycle time is the time it takes the batteries to charge the capacitor). Then, when you do the actual flash, the capacitor discharges through the flash tube. The point of that is that the power output (and guide number) is limited primarily by the size of the capacitor, not by the batteries. You could theoretically run a big flash off of something tiny like hearing aid batteries -- if you were willing to put up with extremely long cycle times and short battery life.

None of that changes the fact that being able to power everything from one kind of battery would be extremely convenient though.

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Re: A complete rig based on Alpha 77

Unread postby sury » Thu Jun 28, 2012 3:10 am

David,
Impressive rig. How far those Amaran LEDs throw light at maximum brightness. I am curious if I can use them instead of flash
in an indoor setting (a get together at home) rather than flash. I have seen a 168 LED on eBay for US$50 + free shipping and
a 2X 198 package (2 of everything and 4 of filters) for US$99 + US$20 shipping.

With best regards,
Sury
Minimize avoidable sufferings - Sir Karl Popper

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Re: A complete rig based on Alpha 77

Unread postby David Kilpatrick » Thu Jun 28, 2012 7:14 am

They are not very bright - f/8 or so at ISO 400 for a closeup a couple of feet away, at the best. You need to use ISO 1600 to use them for a group and also maybe even use f/4. The light seems very bright to the subject - the LEDs are individually very brilliant points. They are fine for video, where the lens is fixed at f/3.5 and the ISO ranges up to 1600 anyway without showing noise. But they are not a substitute for flash for stills - more an additional fill-in or accent light for available light.

David

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Re: A complete rig based on Alpha 77

Unread postby sury » Thu Jun 28, 2012 5:45 pm

David,
Thank you. Now I understand the limitations of these lights for stills.

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Sury
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Re: A complete rig based on Alpha 77

Unread postby Headcell » Sun Nov 04, 2012 8:23 pm

OK, I know this thread is old, but I have a question or two about AGC (audio), David.

Do you know if the AGC is the same on the A77 and A57?

How does the AGC work? I've read somewhere (perhaps here) that the AGC sets itself to whatever the noise level is when movie recording is started. So, if the sound is loud, AGC will attenuate the audio for the WHOLE recording (if the sound level then goes quiet, the recording will remain quiet). Likewise, if the sound level is quiet at the start of recording, AGC will amplify it for the WHOLE recording. However, elsewhere I read that the AGC works much like that on other DSLRs (before the Magic Lantern firmware overlay or Canon's generous FW updates); that is, it works dynamically to boost or attenuate sound levels, albeit in a more gentle fashion to avoid audio 'pumping'.

I tested my A57 with a Rode Video Mic this afternoon, but couldn't figure out which of these it was. The recorded sound was very good, however, though there was a little noise apparent, but it illustrated how good the circuitry in the A57 is.

David, where did you buy the Rode from? £69 is a very good price.

I'm going to try the 19kHz audio trick (feed a 19kHz tone to one channel) to see if that makes a difference to the audio. I'll also try boosting the mic volume using a Fiio headphone amp which should reduce the noise generated by the A57.

Thanks for any feedback you can give.

H

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Re: A complete rig based on Alpha 77

Unread postby David Kilpatrick » Sun Nov 04, 2012 11:38 pm

I use an iPad to generate the tone, and you can feed it to both channels and record in stereo. It can not be heard and you just put in a 16-20 kHz EQ filter on the final audio edit, which removes it entirely.

It is dynamic, but appears to set the initial gain according to noise when you start recording. Using the signal method can knock back the overall volume level surprisingly, not just prevent hissy gain.

The BJP has a video I made - not public but I am prepared to make the link public here only, it's normally on BJP's app:

http://www.youtube.com/watch?v=d4v6XOLLe-A

David

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Re: A complete rig based on Alpha 77

Unread postby Headcell » Mon Nov 05, 2012 5:49 pm

Thank you, David. It's a shame Sony can't do it the proper way by including manual audio control. Nevertheless, the sound is pretty good on the A57 via the Rode. I think I could live with the auto gain, but in an ideal world I would have more control.

Time to invest in a cheap MP3 layer to produce the tone...

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Re: A complete rig based on Alpha 77

Unread postby Headcell » Sat Nov 10, 2012 10:46 am

I have watched the video - it's clear how effective this trick it; I was amazed and set out to find an equivalent tool for Android.

For anyone who is interested, there is a free app available from Google Play named True Tone that will generate 4 different types of tone (sine, square, sawtooth and triangular) from 1Hz to 21kHz in steps of 1Hz. The developer listens to users, too, to help drive improvements.

I'll be testing it out on my A57 later today to see how effective it is. I'll report back ASAP. It may help someone...

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Re: A complete rig based on Alpha 77

Unread postby Iknowit » Sat Apr 12, 2014 4:15 pm

Hello,

I just came in to this site...

For faster flash recycle, you would need to use an external battery pack, like ATG/Quantum Battery Pack. But you have to be careful of overheat, shutdown and killing your flash.

For saving, you should get the ATG Atomos Shogun Kim or lower model Atomos Shogun.

For video lighting, try looking into Costco for their zoom high power LED flashlight or security LED lights.


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