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truflip
10-22-2006, 04:22 PM
anyone ever looked at this site before? http://www.uscoles.com/fstop.htm
its an easy (but long) read about apertures (f/stop). :o
saw this a while ago, never got to reading it all but its very helpful... amateur or professional ;)

hope this is worth somethin... enjoy!

tim11
10-22-2006, 10:02 PM
Thanks truflip. I came acroos that one before a while back but it didn't make much senseo to me back then. Time for another visit.
It sure will be handy.

truflip
10-23-2006, 02:59 PM
no problem sir =)

do u happen to have a gallery of your pictures.. maybe ones taken with the Tcon 17?:o and the F30 as well? hehehe :D

tim11
10-23-2006, 08:37 PM
Truflip,
I got FZ20 for over a year and only recently got TCON17, so I haven't got much chance to use it - only 3 occasions in fact. I do have some photos, only the birds were shot with TCON, and a couple in Panasonic forum FZ20 and Olympus TCon17 (http://www.dcresource.com/forums/showthread.php?p=168245#post168245).

Only bird shots TCON was used.
http://s102.photobucket.com/albums/m116/tim11_2006/animals/

As for F30, it ends up being the one I use most of the time, since it is small enough to take anywhere and can be use as long as there is light. I have been posting some photos from my F30 in 2 threads.
Photos from F10, F11, F20, F30, F31fd (http://www.dcresource.com/forums/showthread.php?t=24706)

I believe you can recognise its ability in an dimly light aquarium tunnel, I posted some photos in My first underwater photography: Stingray. (http://www.dcresource.com/forums/showthread.php?t=24829).
Hope you like them.

krzkrzkrz
10-23-2006, 10:02 PM
anyone ever looked at this site before? http://www.uscoles.com/fstop.htm
its an easy (but long) read about apertures (f/stop). :o
saw this a while ago, never got to reading it all but its very helpful... amateur or professional ;)

hope this is worth somethin... enjoy!

Errrr, not VERY helpful for the beginner. The article is tedious indeed, and that is what it is meant for. Its a different writing style, and frankly dont like it. The information is too cluttered, not concise and too many freaking numbers / formulas around!

A better example for beginners would be this article: http://www.morguefile.com/archive/classroom.php?lesson=2

Good concise information with the aid of visual effects, i.e. photos

FLiPMaRC
10-26-2006, 12:32 PM
Hey truflip, a friend of mine posted this in another forum trying to help me with my S3 :D


Shutter speeds make sense. We can wrap our heads around them. F stops are just weird. It's a form of math we aren't used to. Rick explained a little about the focal length ratio in another thread, but I'll expand on it and perhaps it will make sense why 'fast' lenses cost so much more.

Every F stop is an abbreviated number. F4 really means 'focal length divided by 4'. If I am using a 100mm lens, or a zoom lens at 100mm, the opening in my aperture at f4 is 25mm across. That's a circle about an inch in diameter. The area of that circle is pi*r squared. Therefore, the open area of your aperture is .79 square inches.

Ok, so if I want to let in half the light, I just need to close the opening of my aperture by half, right? So, f/8? That would make my aperture diameter half of 25mm- 12.5mm or half an inch. It's also 1/8th my 100mm focal length. Simple. Now, the area of that circle of light at f/8 is 3.14*(.25*.25). So that comes out to... .20 square inches? What? That doesn't make sense. That's a quarter, not a half?? It should be .40 ish, right? NO! This is where those weird aperture numbers come into play. Circles don't play by halves. To halve the area of a circle, you need to reduce it in DIAMETER by .7 times. To double the area, you need to increase the diameter by 1.4 times. Therefore, starting with F/1, we get this order - F1, F1.4, F2.0, F2.8, F4.0, F5.6, F8, F11, F16, F22 and so on. Your camera probably has half stops in between as well.

The cool thing about all these numbers is that F4 on a 300mm lens lets in exactly the same amount of light as F4 on a 16mm lens with the same shutter speed. The actual aperture opening on the 16mm lens is MUCH smaller, but its looking at a much bigger cone of light. The 300mm lens aperture is much bigger, but the cone is a tiny slice of the size of the 16mm's.

Now, if you realize this is a ratio to focal length, you can think about how big a fast telephoto lens has to be. For a 400mm lens to have a 2.8 aperture, the aperture has to be 143mm across! That's 5.6 INCHES. Lens engineers can do a lot with geometry and optical design, but they can't overcome physics. This is why long, fast lenses are HUGE, and very expensive. Lots of glass, lots of engineering..

Now, a point and shoot camera like the S3 IS is always showing the 'equivalent' 35mm focal length- 35-432mm, even though it is actually 6mm-72mm. Much less glass, less resolving capability, and small abberations can be seen easier. However, it allows for quick lenses and obvious portability, since at 72mm, the f3.5 maximum aperture is only 21mm across, or less than one inch.

Hope this helps!!