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Sony alpha 100

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Old Saturday 10th March 2007, 22:37   #26
mmdnje
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HI everyone. Denis G: could you elaborate a little more on the following statement: "The Alpha is only at its best at max f5.6/f6.3 'ish although in good light they can work at f8!!. "
I am routinely using f9-f11 and today I tried up to F22, and the camera did fine. I'm just learning about dSLR so please forgive if this is a dumb question. The attach pic was shot at f22. Jose
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Old Sunday 11th March 2007, 19:21   #27
DenisG
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Quote:
Originally Posted by mmdnje
HI everyone. Denis G: could you elaborate a little more on the following statement: "The Alpha is only at its best at max f5.6/f6.3 'ish although in good light they can work at f8!!. "
I am routinely using f9-f11 and today I tried up to F22, and the camera did fine. I'm just learning about dSLR so please forgive if this is a dumb question. The attach pic was shot at f22. Jose
Jose, that reference only refers to when autofocus will work, nothing to do with general aperture settings. Whether you use f1.2 or f64 with a normal lens and the wide open aperture is f1 to f8, no additions like telecons, autofocus should always perform well, subject to available light. This is because the lens is always wide open for focus. However, once "wide open" becomes f6.3-f8'ish then the lens struggles and focusing becomes almost impossible.

A typical case would be if you had say an f5.6 400mm lens it should work reasonably well although low light may hinder this. Now, if you add a 2x telecon you lose two stops worth of light. Therefore your f5.6 lens is now really f11, two stops greater than normal, ie: f5.6 > f8 > f11. Hope you understand that. Autofocus generally won't work when "wide open" becomes f8, often less. Again, if you puchased (or borrowed) a 500mm f11 catadioptic mirror lens you would have to use it in manual mode. Almost all cameras with autofocus are like this.

If the previous poster who asked the question was using a typical f4/f5.6 zoom lens and added the 2x telecon, autofocus would certainly not work, hense his problem.

Personally, I often use f32 on my macro lenses without problem but they are f2.8 and focus at that setting, only adjusting to f32 when the shutter button is fully depressed.

Hope you follow that

Denis.
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