> -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Cotty > Sent: Friday, March 26, 2004 2:13 AM > To: [EMAIL PROTECTED] > Subject: EOS Silly question about IS > > > I'm an IS ignorant. Can it be switched on and off from the lens? Or is it > a permanent feature of an IS lens? > > TIA > > > Cheers, > Cotty >
Hi Cotty, There are a couple of generations of Canon's IS, the first generation was on the old lenses like the EF 75-300IS and EF 28-135IS zooms. These were slow, mediocre performing lenses optically that were made sales successes by with addition of IS. These lenses have only one mode of operation useful only for single shots taken in one-shot AF mode of stationary subjects. I've tried to use the EF 28-135IS lens but this lens is too soft to use at wide open apertures like I can with my "L" zooms. The EF 28-135IS is also very slow optically (f3.5-5.6, the 3.5 is deceiving as it get slow very quickly as you zoom), the AF is slowish and once you get past 100mm images get soft very fast unless stopped way down to min. f/11-f/16. The first generation IS lenses also had some bad characteristics if moved while IS was on. The finder image would display jitter or shake because the lens was trying to correct for camera motion it could not compensate for. This generation also slowed down AF performance when trying to gain AF and could spuriously start jittering in the finder if moved while IS was on. I was disappointed in these lenses to say the least. The second generation was introduced in the EF 300 4L IS with the addition of mode 2 operation. This was the first professional quality IS lens design. This new version of IS was designed to allow the use of IS while panning to follow motion. This version of IS was much improved with almost none of the odd visual jitters that the first generation IS lenses sometimes showed in the finder. This lens design was an "L" class lens in build and optics but a soft when compared to the non IS EF 300 4L or EF 300 2.8L of the time. This version of IS was quickly implemented in several other Canon pro class teles and tele zooms including the EF 300 2.8L IS, EF 400 2.8L IS, EF 400 4L DO IS, EF 500 4L IS, EF 600 4L IS, EF 100-400 4.5-5.6L IS. The third generation of IS was introduced in the EF 70-200 2.8L IS zoom. This is the latest version of IS currently available in production. Canon's third generation IS features IS operation to a full 3 stop effective range, one stop more than Canon's second generation IS specs call for. This generation can also be used on a tripod without turning IS off. This is useful for tripod shooters and especially useful for monopod shooters because IS now works under all shooting conditions. When used with a stationary camera mount IS will not introduce any jitters in the finder if you leave IS on and use camera support. There are several newly announced lenses from Canon that are unknowns at this point. Which generation of IS Canon will choose to use in these new generally low-end lenses is a guess but I think they will all be third generation IS lenses. Lately Canon has been pushing its signature technologies like IS and DO downward in their lens lines to attract new buyers to the entry level Canon EOS DSLR bodies like the EOS 10D and EOS 300D/DRebel. We'll have to wait and see where Canon goes with these new lenses and which IS specs they give once they become available. A quick recap, Mode 1 is for still shots where you want maximum stabilization, say the typical handheld shot in the dark using one-shot AF. Mode 1 is also usable in AI-Servo mode but the temptation here is to follow the subject and mode 1 IS dose not like camera movement because it's trying to correct for any camera movement. Stationary camera with no movement is what works best with mode 1 IS operation. Mode 2 operation is for panning or moving shots typically with AI-Servo AF mode engaged. Mode 2 operation works in one plane only, this is to say that IS is not active in one plane but will try to will stabilize the image in the other plane when in mode 2. For example in mode 2 IS operation if you were panning left to right the IS will stabilize the image in the up and down direction and turn off the left/right correction. This allows the option for a slower shutter speed showing more motion even with very slow moving subjects while retaining maximum image sharpness of the subject even at these very slow shutter speeds. Well I hope this helps you understand what IS does and its different modes of operation. Cheers/Chip * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
