ron@wjvax.UUCP (Ron Christian) (05/29/85)
***** >> If the aperture is changed, the camera will get more or less >> light in thru the lens and will require a shorter or longer >> exposure, accordingly, to properly expose the image. >What you have described is a sub-set of match needle called >"stop down" match needle. If the lens is coupled to the exposure >meter there is no need to stop-down to take a reading unless you >have filters in front of the lens and you don't know how to set >the ASA dial for filter factors. >BTW, on a historical note, match needle originally referred to hand- >held exposure meters. SLRs are not the be-all and end-all of photography. ***** I think what he meant to say was 'If the aperture is changed, the camera knows it will get more or less light.....' due, of course, to the coupling on the aperture ring that tells the exposure system what aperture you have chosen. Generally you don't have to do stop-down metering even on the older cameras unless this coupling is somehow missing. (An example of this is when the camera company changes the method of aperture coupling, such as in Nikon's Nikkors. The new lenses have both styles of coupling and the old ones only have the older styles. You use an old lens on a new camera, you have to use stop down metering.) I don't see how your comment about filters could be correct. If you put a filter in front of the lens, it does let less light in, but the camera exposure system compensates for this by 'recommending' a slower shutter speed for the given aperture. (Or vice-versa.) The camera doesn't know you are using a filter, it just thinks there is less available light. Of course, if you're camera doesn't have TTL metering, or you are using a seperate hand held meter, you certainly do have to take filters into account. Finally, I don't think anyone ment to imply that SLR's (with TTL metering) are the only way to take pictures. I have a pretty good (match needle) hand held meter, and I use it instead of the camera's meter when I'm doing any really serious photography. The camera and the hand held meter generally agree if I make sure they are looking at precisely the same thing. But you sometimes have to stick the meter in some tight places to get a reading off whatever you are exposing for. -- __ Ron Christian (Watkins-Johnson Co. San Jose, Calif.) {pesnta,twg,ios,qubix,turtlevax,tymix,vecpyr,certes}!wjvax!ron "What do you mean you backed it up the wrong direction???"