Using a 28-135mm IS lens with my EOS 5 (hand held), as a new user I always use "P" mode. What possible benefit could I expect to attain, other than minimal camera shake? Does the camera's program know that it is an IS lens and hence alter the "Tv" to suit? Or should I always use a slower film? Regards Garnet.

-- Garnet Cook (garnet_cook@one.net.au), July 12, 1999

Answers

I'd suggest you learn to use the Av and Tv modes. Then you can take full advantage of the IS feature.

-- Bob Atkins (bobatkins@hotmail.com), July 12, 1999.

No, the camera's program does not take into consideration the fact that you have an IS lens mounted. Follow the guidelines in the IS lens instructions. Canon states that you can safely shoot at shutter speeds two stops slower than the reciprocal of the focal length in use. My experience is that this is a conservative number and even slower shutter speeds can result in good images if you use good hand held techniques or use a monopod.

-- John McCormack (jpmccormac@aol.com), July 16, 1999.

I do believe that P mode knows and takes into consideration the focal length being used (either fixed or "zoomed"), and it will try to set a shutter speed that is roughly 1/the focal length in use (or faster) if the lens can open up enough (and some EOS cameras, like the 1st Elan model, will flash the shutter speed as a warning if it's slower than 1/ focal length) but it does not (as John said) know if IS capability is on board. With an IS lens, try shooting in Av mode (aperture priority) and evaluative metering, and choose the lens's maximum aperture; by doing so, you're allowing the fastest shutter speeds to work together with the IS fxn. Switch out of Av mode only when you need more depth of field; switch to spot or center weighted metering as needed.

-- kurt heintzelman (heintzelman.1@osu.edu), July 16, 1999.

Thank you John and Kurt for establishing that the camera program does not recognise that an IS lens is attached. My difficulty is comprehending how any program, that has calculated the amount of light into the system, can adjust for two or more stops, without utilising "exposure compensation". As I understand, the most important feature of the IS lens is allow you to use a slow shutter speed that would normally be prohibitive because of camera shake. This lower Tv would allow the use of finer grain film, hence, better images. At this time, The way that I would achieve this, leaving DOF out of the equation for the moment, is to load film (=< ISO100), switch to P-mode. [Incidently, IMHO, Tv and Av priority use the same program as the P-mode, its just that one or the other is locked. The adjusting of Tv or Av may be achieved in P-mode by moving the main control wheel to the right or left]. I would then focus etc. and read my Av and Tv. From the Av reading I would adjust so that it reads approx two stops larger. I would note the Tv, which should be slower and fire. Am I on the right track? Do you see the day where they will have the control dial reading both "P" and "P(IS)". Regards.....Garnet.

-- Garnet Cook (garnet_cook@one.net.au), July 17, 1999.

Whether the camera is in an auto mode or manual mode, it's brain & light meter is still calculating (aperture) x (shutter speed) = exposure. As far as the camera body is concerned, using (for example) the 300/4 IS lens is no different than using the 300/4 non IS lens--if you chose to use the latter lens with 100 ISO film, hand-held, at say, Tv=1/30 sec. and f/4, the camera will be happy to take the shot when you push the button, and you will likely get an unsharp photo (with the IS lens, the photo may well be quite sharp!). With the 300/4, the camera is not going to forbid a shutter speed slower than 1/focal length any more than it would with the IS lens, and it is not calculating Av x Tv = exposure any differently. THE "IS" LENS IS NOT MAKING AN INDEPENDENT DECISION TO OPEN UP OR OVEREXPOSE THE CAMERA'S (OR YOUR) CALCULATED EXPOSURE BY TWO (OR ANY NUMBER) OF STOPS, and so no exposure comp. is needed. The IS lens is gyroscopically helping to stabilize the image, but it is otherwise no different from the non IS 300/4, at least as far as the camera is concerned. Simple as that. I own the 300/4 IS, usually coupled with the 1.4 TE (that = a 420mm/5.6 L IS lens), and I can tell you that the 2 stops slower "rule" is vastly too conservative. I have obtained sharp images, hand held, at speeds as slow as 1/15 sec. with 100 ISO film. 1/30 is quite common.

-- kurt heintzelman (heintzelman.1@osu.edu), July 17, 1999.

Thank you Kurt for your prompt reply. I'll ponder your posting for a while. Regards.....Garnet

-- Garnet Cook (garnet_cook@one.net.au), July 17, 1999.

It appears the claim of "an additional two stops..." is where the confusion arises, and it is easy for some to erroniously believe that these lenses are somehow "fast" (bigger max. aperture), when in fact "all" one is gaining is several more "stops" of hand-holdability.

-- kurt heintzelman (heintzelman.1@osu.edu), July 19, 1999.

Thanks again Kurt,"The penny has droped". I understand, well explained. Regards Garnet.

-- Garnet Cook (garnet_cook@one.net.au), July 20, 1999.

Garnet: You are most welcome; glad to be of help!

-- kurt heintzelman (heintzelman.1@osu.edu), July 20, 1999.