 Tammy Scott |
Exposure I just finished Bryan Peterson's book "Understanding Exposure" and I have a question. On some lowlight and night shots he sets the aperture to what he wants to use (usually a small aperture like 22), points at the sky to determing the correct shutter speed then recomposes his shot and shoots. On others, he starts out with a large aperture such as f2.8 and points at the sky to get the proper shutter speed - however, then he changes his aperture to a large one to increase his DOF and changes the shutter speed in the equivalent number of stops that he adjusted his aperture. OK ---- my question is ---- why can't you start out with a smaller aperture before you meter off the sky to get the correct shutter speed for the proper exposure?
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- Gregory LaGrange Contact Gregory LaGrange Gregory LaGrange's Gallery |
If he didn't explain in the book, could depend on it being night or just lowlight. If night, metering off the sky beyond f/2.8, may be correctly exposed at a shutter speed longer than the cameras longest shutter speed. Such as if trying to meter off a night sky at 5.6 the exposure should say 40secs, but the camera is made to have a 30 second clik as it's longest shutter speed, you won't get a reading. You'll get a flashing 30. So use 2.8, then adjust. Or it could be something else. Reread and see, or send an email to him.
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Tammy Scott |
Well that makes perfect sense!! Thank you so much for clearing it up! I didn't even think about that one! I did wonder how he was metering of a night sky and that explains it! :)
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Justin S. |
I got a book you can read in your free time about night and low light photography by LEE FROST called "The Complete Guide to Night and Lowlight Photography" Which is a good book to explain metering at night,it has a couple of exposure charts which gives you some ideas on correct exposures for night time scenes also.
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Tammy Scott |
Thanks, Justin!! All the book stores (not to mention the libraries) around here are limited in the books they carry on photography!! I will look into this one!!!!!!!
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Andrew Laverghetta |
Just seeing if I can tag along really quickly. I had tried to take some night pictures but my 30" flashes as well when I change to something like f11 or f22. I would try to figure out exactly how long to time it with bulb and a stopwatch but I don't know exactly where each full stop is. My camera measures aperture and shutter speeds in stops and half stops so how can I sit down with a pencil and paper to figure out what is say 2.5 or 3 stops over 30"? Thanks!
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- Gregory LaGrange Contact Gregory LaGrange Gregory LaGrange's Gallery |
A stop is double the time. A half stop you take half and add it on to the time.
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Andrew Laverghetta |
so, if I have 30" on at a certain fstop and I was to change close the aperture 2 clicks (one stop) I will use an exposure time of 60"/1 minute? Thanks!
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