Thread: Is there a way to calculate how much light I will need?

1. Re: Is there a way to calculate how much light I will need?

Originally Posted by AnselAvedon
I am shooting an Egg on an 8x10.
I am looking to rent a light but am not sure what light to use. I do know it will need to be powerful.

My film stock is iso 50.
I want to shoot at 125th of a second.
At aperture F 32

I also know I need a bellows draw compensation of 5 stops

Is there math to figure out how much light I will need?
Why 1/125 second? The egg isn't going anywhere.

2. Re: Is there a way to calculate how much light I will need?

1/125th of a second is a challenge.
I'm a flash bulb kinda guy.

I would need a couple Guinness then set up some super flashbulbs with a *flash meter, but man the bulbs are spendy and rare. If Randy Moe were nearby I bet we would have put on the welding gloves and masks and had a lighting scheme tested already. It would be fun cooking eggs under flash.

If we keep to #5 or #25 clear flashbulbs I'm pretty sure ten set off at once in a tight reflector would work even on M sync @ 1/125th second. OK, maybe fifty.

I have a case of bulbs with a duration of 1.7 seconds, and a few Mazda 75 but frankly I'm too scared to fire them off.

*Yes, you can use a flash meter with bulbs IF you use a cord connection.

3. Re: Is there a way to calculate how much light I will need?

Thanks for all the insight. The 125th shutter is because I will be breaking the egg

4. Re: Is there a way to calculate how much light I will need?

Originally Posted by AnselAvedon
Thanks for all the insight. The 125th shutter is because I will be breaking the egg
Just curious - how do you intend to synchronise the egg braking with your 125th shutter firing?

5. Re: Is there a way to calculate how much light I will need?

I think you need somewhere between 102,400 and 205,600 candles per square inch.

I just set my Weston Master III to ASA 50 and reduced 5 stops to EI 1.5 for bellows extension

Then set the dial at 1/125 and f/32

And looked where the arrow points into 1/3 stop below the 0.4 mark on the second pass of the dial, which works out to...

Highest candles per square inch on Weston dial: 1600

1 more stop 3200

2 more stops 6400

3 more stops 12800

4 more stops 25600

5 more stops 102400

5 2/3 more stops -> The amount of light you need.
6 more stops 205600

Perhaps use a magnifying glass to focus the light on a tiny spot and shoot just a tiny part of the egg.

Please use welder's glasses or other eye protection to protect your eyes as you compose the shot.

6. Re: Is there a way to calculate how much light I will need?

Originally Posted by Doremus Scudder
How much light depends upon exposure time.
And depending on whether you just want to photograph them or also cook them with hot lights! I think there are enough responses above to elaborate any more.

7. Re: Is there a way to calculate how much light I will need?

Edgerton would have used electronic flash to accomplish this with some kind of trap to trip the flash at the precise moment. My method would be simpler. Put the egg on a flatbed scanner in a dark room and when the traveling band of light gets to the egg, push down on the lid. A borrowed scanner of course. I'd do it at Dan Fromm's house with his scanner.

Anyways, sounds like you're having fun and that's the main thing. Good luck. Share some results.

8. Re: Is there a way to calculate how much light I will need?

Jimbo, how did you know that my scanner also cooks? Scanner, printer, copier, rice steamer and electric fry pan.

9. Re: Is there a way to calculate how much light I will need?

I agree this is hopefully fun.

Many years ago I found a lot of CRT TV's in an alley. I wanted to video a large rock coming out of the front of a TV.

A variety of schemes were tried, mirror, ladders, strong men. I videotaped all the failures, and it was fun just doing it.

Before the Internet, we had to do something...

10. Re: Is there a way to calculate how much light I will need?

Disregard the 8x10 format because it cannot be justified, a medium format and a .22 CB cap to impact the egg would suffice with a sound trigger. It is a shame that today's persons have no idea.

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