Questions about the A-Minima

[Aaron Tan]

My University finally bought the Media Production department a brand spanking new Aaton A-Minima. (But it could only afford a second hand lens and second hand video assist unit) It's a really sweet camera. I had my first play with it today and was impressed by its simple controls and handy size. Loading it was a bit tricky at first but wasn't to the point of frustration.

 

My question is this:

According to the Aaton A-Minima user manual, earlier models had a 180 degree shutter and later ones have a 172.8 degree one. What is the purpose of having a 172.8 degree shutter?

 

My only beef is with Kodak's pricing. :P The special 200ft. factory loads are classified as a premium stock and therefore a student discount isn't applicable. Whereas the 400ft. can be discounted.

 

For example, Vision 200T 200ft is approx $125 (Australian $$$). The same in 400ft. is approx $145 after the discount. I'm not really complaining. It just means I'll have to learn to reload onto the 200ft spools. But I would think a student discount applying to all stocks would help encourage more film use at the educational level.

[Adam Frisch FSF]

You can wind it up yourself. I've done that with Fuji film a couple of times at my local

lab. It's horrible to sit in a pitch dark room and hand wind film onto the plastic cores, but

it does save some money.

[John Pytlak RIP]

Do keep the winding orientation correct, especially with regard to the KeyKode numbers. Always wind in a clean darkroom, to avoid picking up any dirt that may result in "hairs in the gate", and keep yourself and any rewinds grounded to avoid static discharge.

[Aaron Tan]

Thanks for the advice, John.

[Sam Wells]

But I would think a student discount applying to all stocks would help encourage more film use at the educational level.

Agree, especially as this was one of the motivations for making the A-minima in the first place.

 

-Sam

[John Pytlak RIP]

I'll pass it along to the Kodak Student Filmmakers Program team for their consideration.

[DanStewart]

It's true that the stock price has made the a-minima a non-event in the London student scene. I know of a guy who was offered a minima kit practically free for a few days and ended up using an ST because of the stock issue (of course it was MOS). Such a shame they didn't just go for 400' or 100' rolls - halfway house loses the benefits of both.

[Aaron Tan]

I'll pass it along to the Kodak Student Filmmakers Program team for their consideration.

 

Thanks John, hope something can happen. Do the discounts apply in America like they do in Australia? Here it's around 40% off.

 

Back to my original question. Anyone know why or for any specific purpose the 172.8 Degree shutter has?

 

Thanks.

[John Pytlak RIP]

I'm a technical guy, and don't really follow the marketing aspects of the business.

[Aaron Tan]

172.8 Degree shutter... anyone??? :blink:

[David Mullen ASC]

When filming at 24 fps under 60hz AC lighting, your optimal exposure time to avoid flicker is 1/60th of a second. A 144 degree shutter angle at 24 fps = 1/60th of a second.

 

For 50hz lighting, the optimal exposure time is 1/50th of a second. A 172.8 degree shutter angle at 24 fps = 1/50th of a second.

[Aaron Tan]

Thanks for clearing that up David. In terms of 60Hz and 50Hz AC lighting, is the difference because of the two different voltage outputs of various countries?

[John Pytlak RIP]

It's not the voltage, it's the frequency of the alternating current (AC) standard for that country.

[Aaron Tan]

Thanks John, I looked up that Australia has a 50Hz frequency which makes sense for the different shutter angle.

 

Just another question, (I'm clueless about this) Is the flicker refering to one kind of lighting such as flourescent lights or does it refer to most lights?

[John Pytlak RIP]

The flicker usually affects any gas discharge lamp that operates on AC through a standard ballast: fluorescent, HMI, mercury vapor, sodium vapor, etc. There are "flicker free" ballasts and power supplies that change the frequency or waveform of the current.

 

The mass of a tungsten filament usually averages any flicker in the light output of a tungsten lamp. Carbon arc and xenon arc usually operate on DC (direct current).

 

One fun way to prove to yourself that a light source may be flickering is to "listen" to the light. Connect a silicon photocell to an audio amplifier and listen to the output with a speaker or headphones. You will hear a hum or buzz corresponding to the variations in light output with the AC current:

 

http://sofia.arc.nasa.gov/Edu/materials/ac...my/section5.pdf

 

You may not "see" the flicker, but your camera will unless you sync the shutter and framerate to the flicker.

[Tim Carroll]

John,

 

You are just full of fascinating information. I took a look at that pdf and had to laugh. Reminded me of stuff we did with photocells back in High School chemistry class back in 1974. The good old days of Radio Shack electronic kits and Heathkits, remember those? :D

 

-Tim

[John Pytlak RIP]

Yep. People who enjoy the technology of filmmaking often also have an interest in electronics. I'm an electronic engineer, and worked my way through college repairing televisions, and as a movie projectionist. Built a few Heathkits in my day too. B)

[Alejandro Wilkins]

I looked up that Australia has a 50Hz frequency which makes sense for the different shutter angle.

 

But America is 60hz so I don't understand why the A-Minima I used here had a 172.8 Shutter as well. :blink:

[randulff]

My University finally bought the Media Production department a brand spanking new Aaton A-Minima. (But it could only afford a second hand lens and second hand video assist unit)

A second-hand video assist?

I have been looking for those, do you know where to find one?

Also, curious if there are after-market video taps for this cam, maybe in color...

 

Bo

[Aaron Tan]

I believe they bought it from LEMAC in Australia. They've got a website at:

 

www.lemac.com.au