Night time exposure from Bryan Peterson

[mmcaleer]

If anyone has read Bryan Peterson's book "Understanding Exposure" I have a question about his night time/low light exposure method.

Bryan uses manual exposure and exposes off the dusky sky. First he sets his aperature to the widest possible setting (say f2.8) and adjusts the shutter speed to get the proper exposure from the sky. From there he resets his aperature to f16 for a wider depth of field and recomposes the shot. Then he does the math to determine how many stops he has adjusted his aperature from f2.8 to f16 and makes the adjustment to his shutter speed accordingly to get the proper exposure.

My question is this. Why set the aperature wide open? Why not just get the proper exposure using the f16 setting that you want to use for your shot? Is there a compelling reason to set the lens wide open to get your exposure in low light situations? This is the only time he uses this method.


Thanks all.

Mike

[JohnT]

I have the book. What page number is it?

[mmcaleer]

John,

Page 128. The chapter titled "Night and Low-Light Photography" All the examples use this method.

Thanks,

[JohnT]

Since I hadn't read the book in a long time, I'd forgotten about that. I do not understand the reason behind his methodology, but you can contact him at BryanFPeterson@mac.com. He does reply to email (I've emailed him in the past and got a response within a few days). Or hopefully someone here can shed some light on the subject, so to speak.

[mmcaleer]

Just sent him an email.

Thanks,

Mike

[Gordon]

I suspect its because most meters will fail to show a shutter speed at beyond 30 seconds. You'll usually get a blinking 30s.

However, if you meter wide open (and on a digital camera, I usually do this and jack up the ISO really high) you can get a useful shutter speed.

All you do then is double and half appropriately to get to the aperture and shutter speed you want - same thing to bring the ISO down to a more reasonable level

The other digital advantage is, if you shoot it wide open and the highest ISO, you can also get a reasonable test picture to check the composition, then use reciprocity to get to the correct exposure for your actual shot.

[jon_k]

Please update if the author replies. Although everyone elses response seems to be what the authors process is. I've got this book too.

[JohnT]

Originally Posted by Gordon

I suspect its because most meters will fail to show a shutter speed at beyond 30 seconds. You'll usually get a blinking 30s.

However, if you meter wide open (and on a digital camera, I usually do this and jack up the ISO really high) you can get a useful shutter speed.

All you do then is double and half appropriately to get to the aperture and shutter speed you want - same thing to bring the ISO down to a more reasonable level

The other digital advantage is, if you shoot it wide open and the highest ISO, you can also get a reasonable test picture to check the composition, then use reciprocity to get to the correct exposure for your actual shot.

Makes sense to me, and you're probably spot on. Thanks, Gordon.

[Gordon]

forgot to mention, you'll probably then need some sort of remote timer or cable release to run your camera in bulb mode for the right amount of time (minutes, hours, depending on the exposure you calculate) Least that's how I use the canon timer remote that I have.

[Comanche]

Originally Posted by jon_k

Please update if the author replies. Although everyone elses response seems to be what the authors process is. I've got this book too.

I have the book, and had the same question.

By the way - the book is superb! I highly recommend it.

[mmcaleer]

It is a fantastic book for understanding exposure. The best book I have read to get you off Program Mode to be more creative with the camera.

I will post the reply from Bryan when he sends it.

Mike

[mmcaleer]

All,

I just returned from Hawaii and Bryan responded with the following:

"Regarding your question it is one I get often and here is your answer: There is but one reason I speak of setting the aperture to wide open when metering scenes at dusk and its to answer those few shooters out there who still are using an older film camera whose shutter speeds dont go beyond 1 second. Sure they have 'B', (time exposure) and knowing that, this method of explaining helps them to get those longer 4, 8 or 15 second exposures. Most of us, yourself included, have a camera with a much higher EV range which is to say your light meter can easily 'see' the lower light it is presented and offer up exposures beyond 1 second even when stopped down to f/11, f/16 so YOU can easily set an exposure without having to set the lens to wide open first.
I hope you got yourself some more prize winners on your return trip to Hawaii.

All my best!
Bryan F Peterson"

[JohnT]

Thanks for the update, Mike. Hawaii, huh? I loved it when I went and would like to go back sometime.

[andyz]

So, if we have a follow up question, where will you go next?

[mmcaleer]

I will post some of the Maui trip this weekend. Not sure where I am going next.