September 11, 2006 at 7:08 pm #694Stu_PadassoParticipant
It’s been awhile since I’ve signed on, so I thought I’d drop in to say hello.
I have tried to do some more reading about the theory behind picture (aperature, exposure, ISO, etc.) Thanks to the help of some of the members on this site, I have been provided with some good advice (focus on one setting at a time, and taking pictures is the best way to learn), so I ventured out at lunchtime today to the park and snapped some pics on my PowerShot A95. I’d love a nice SLR like a Digital Rebel of some sort, but this will work for now.
Anyways, I decided to take some pictures of some wildflowers (they look great, and they don’t really move unless a breeze picks up).
Today, I wanted to play with aperature settings, to make the object in the foreground to appear sharp, while the background is faded. Pretty basic stuff, I know. Here’s my favorite one that I took:
I put my aperature the lowest setting possible (2.8 for that one).
During my shots, I ran into a couple of puzzling issues, and I was hoping someone could help me with them.
1. Why is it that when I use the optical zoom (I have digital zoom disabled) that I have less aperature settings to choose from? For example, if I zoom in slightly, the aperature number automatically increases, and it will not let me lower them past a given amount.
2. On another picture, I tried to mess with the ISO setting while changing the aperature. I had the fstop at 2.8 and turned the ISO up to 200 (I think I had it on auto or 100, can’t remember). When I did and took the picture, the auto-exposure on my camera showed “1/1000” in red. According to my camera manual, this means that the image is underexposed or overexposed. However, when I took the picture anyway, it appeared okay. Probably just my n00b inability to recognize over/underexposure.
So anyways, I guess that’s a long enough post. If anyone could give me some advice, I would greatly appreciate it.
Also, if there is a better photography forum out there for questions like this that you would recommend, please let me know (or PM me if talking about other photography forums is discouraged 😉 .
Stu_PadassoSeptember 11, 2006 at 7:38 pm #5899linguineParticipant
To your first question, I beleive you loose aperture size when you zoom in with an optical lense due to the changing of the focal length of the lense as you zoom in. I beleive larger, and more expensive, lenses will let you use a wider aperture when zoomed in because of the angles and physics required to zoom in.(If you want a more scientific explanation and noone else here can give one I can ask my brother for one thatll probably have all the science in it that you could possibly want)
As for the second question, the meter in your camera won’t always be right and sometimes you’ll get a better picture with an under or overexposure. I know my neighbor whos a better photographer than I am takes multiple shots of most things so that she can under and overexpose the shot to make sure she gets the best picture that she can.September 14, 2006 at 12:21 pm #5900Stu_PadassoParticipant
Thanks for the reply, linguine. I’ll pass on the scientific explanation, I believe you 😀 .
As for the under/overexposure warnings, I’ll have to test it some more to see what the camera claims is an under/overexposed picture. I’ll set it to make the warning come up again and then take a shot, then compare it with corrected values.October 14, 2006 at 3:33 pm #5901stupidoParticipant
The scientific answer ain’t too bad. The F-stop is the ratio of the focal to the diameter of the opening. If you double the focal length (zoom in) you double the F-stop. Wiki has an nice article:
But really, just remember, as zoom in, you cut the amount of light you are receiving and thus the F-stop number increases.
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