 BetterPhoto Member |
Tele-extenders and Polarizers I am working with a Canon AE1, 200mm F4 and 2xb tele-extender. I understand that the tele-ex doubles the focal length but also doubles the min. aperture of the lens, so my 200mm F/4 is now a 400mm F/8. In addition, I've noticed there is up to a 3 stop difference with my 200mm lens coupled with the tele-ex and polarizer. Barring the above 3 stop difference, Does this mean that if shooting on the beach on a bright sunny day that I can shoot (using iso 200)at the following settings; F8 @ 1/500th sec Back to the 3 stop difference, does this now mean to compensate, iso 400 must be used and the following settings are acceptable; F16 @1/500th sec I'm just now learning about setting the exposures myself using the sunny F16 rule and I'm wondering if my logic is sound or faulty. One last question... how can I tell if my polarizer is in the optimal position to cut glare? It's so subtle that I can't be sure if it's 'on'. This also worries me as I can't always tell how much I need to open up to compensate (2 or 3 stops) thanks for any help you can offer.
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Kerry Drager |
Hi Antoinette: Some interesting questions here! Now for a few thoughts: - The "sunny f/16" rule is generally used if your metering system stops working - in other words, it's an "emergency" tool in order to keep you shooting. Otherwise, most people rely on their camera's meter for exposures. - Your in-camera exposure meter will automatically compensate when you use a polarizer or a tele-extender (assuming the tele-extender is designed for your camera/lens). Only with a hand-held meter do you need to make exposure adjustments when using a polarizer or tele-extender. - With an SLR camera, you can preview the polarizer's effect in the viewfinder as you turn the filter (remember: this unique filter rotates in its mount). You can also preview by simply holding the polarizer up to your eye and rotating the filter. This helps you determine how much - or how little! - polarization you might want. In fact, you may decide you don't want any polarization at all! Sometimes this filter simply does not work in a particular situation ... for instance, it won't have any effect if you're facing in the direction of the sun or the sun is at your back. Also, it won't affect a white overcast sky. In any case, if you do NOT see any polarizer effects while previewing, it may be that polarization is not possible in those circumstances. Hope this helps, Antoinette. Kerry
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