70-200 f/2.8 IS II should shoot at ISO200

TonyUSA · Nov 26, 2016

Some of youtube recommend to shoot at ISO 200 with this lens. He said something like should shoot at ISO 200 because of the length of the lens. Been using ISO 100 all the time. Is that true?

Thank you,

Derrel · Nov 26, 2016

Using ISO 100 ALL of the time is quite honestly, often a mistake. ISO 100 is often too low in marginal lighting conditions. It is now 2016: if you have a modern camera, using ISO 200 to get a faster shutter speed, or a smaller lens aperture, can be a good thing. The basic rule to getting a SHARP photo in the real world means the shutter speed MUST stop movement: of the camera, or the subject, or of both. MANY people will shoot at slowish speeds, like 1/100 second, and end up with blurred photos, or at speeds like 1/160 second, and same thing-- blurred photos, photos that are not quite fully sharp, photos that seem "Meh....".

Do some experimenting on your own. Try ISO 200, or ISO 250, or ISO 320, or ISO 400.

See what happens once you get your shutter speeds up into the 1/320 second to 1/400 second range on a consistent basis. See what happens. It is VERY different from being stuck in that 1/50 to 1/160 second range all the time.

Really SHARP-SHARP images of several types of scenes start to occur at around f/5.6 and 1/500 second; where I live, that exposure cannot be achieved during most of the year at ISO 100. Again, let me just say this: Using ISO 100 all of the time is quite honestly, often a mistake.

With a Canon 5D-III, ISO 200 ought to give pretty good dynamic range and pretty good image quality. TRY IT, and see what happens.

tirediron · Nov 26, 2016

There are no absolutes in photography; sometimes ISO 100 will be fine, other times you will need ISO 3200! The rule of thumb is that you could keep ISO as low as you can, while still getting the shot. As Derrel mentioned above, people often take that too far and with modern cameras an extra stop or two of ISO is not issue. I routinely shoot at ISO 800 - 1200 with all my lenses in lower light conditions simply because it makes life easier.

Overread · Nov 26, 2016

It is likely that either you or the youtube video creator have either gotten the wrong end of the stick or simplified things to the point where the actual reason has become lost.

For any lens when you hand hold it the general rule of thumb for getting a sharp shot of a static (non-moving) subject is:

1/focal length of the lens = minimum shutter speed

So for the 70-200mm at the 200mm end the slowest shutterspeed for a sharp shot whilst handholding would be 1/200sec.
Of course if you set it to 70mm then it would be 1/70sec (or as close as you can get it).

However in the real world there are other factors that come into play including:
a) Good shooting posture (eg elbows in, arms held firm, legs braced slightly apart)
b) Physical fitness of photographer
c) Wind or other conditions
e) movement of the subject in the shot itself.

These might mean that some can handhold at slower shutter speeds and other people will need faster shutter speeds to get a sharp handheld shot.

For a moving subject you'll need a faster shutter speed no matter the focal length.

Thus it is likely that the suggestion to use a higher ISO has come from the idea that the user needs a faster shutter speed in indoor conditions or lower lighting; even if the lens has IS to aid in handholding. It could also be that there's been a mistake and the video creator meant to say at least 1/200sec shutter speed and instead said ISO.

ISO can have an influence on sharpness as very high ISO values will induce more noise which will affect the quality of sharpness that a shot shows. However these days the differences between 100 and 200 are tiny to the point where most can't tell them apart (reduced clarity of detail and crispness of sharpness tends to become more of an issue at very high ISO values - 1600 and greater).

NOTE it is my observation that the 1/focal length rule has a few niche situations where it fails:
a) some suggest that it should be 1/(focal length multipled by crop factor) because the rule was developed for 35mm film and as such as you reduce the film/sensor size the shutter speeds required go up.

b) Very short focal length lenses (ergo wide angles) can often be hand held at much slower speeds and still get a sharp shot because the relative amount of body sway (ergo handshake) is much less- they also tend to be shorter lenses so even if they are heavier the weight is closer to the holders own centre of mass, making them easier to hold steady.

c) Long focal length lenses (I would say those of around 300mm and longer) typically get longer (moving centre of mass away from the core of the body) and much heavier (esp higher quality ones). This puts additional strain on the photographer and thus often puts the min shutter speeds required up - ergo you might need 1/400 or even 1/640sec for a heavy 300mm f2.8 lens.

TonyUSA · Nov 26, 2016

Thank you so much guys for value knowledgeable info.

Went back and look at photos that I took at the swim meets and mostly shutter speed were at 1/4000, ISO 100, f/2.8, average time of the day is around 11:30 am. I was using Aperture priority. Next meet I will try ISO 200, but wondering if shutter speed is going to be too hight?

Overread · Nov 26, 2016

Why use ISO 200 in that situation?

You're in good lighting at f2.8 and not showing any desire for greater depth of field (and thus using a smaller aperture); meanwhile you're getting 1/4000sec which honestly should be more than fast enough for that kind of photography.

So all raising the ISO to 200 will give you is an increase in your shutter speed; but I doubt you'd get a gain from a faster shutter speed.

Derrel · Nov 26, 2016

Swimming is a "slow" sport.... 1/1250 second will freeze human motion pretty well. Your zoom lens is NOT at its best at f/2.8--NO zoom lens is best wide-open. Stopping down just a little bit, to say f/3.5 with that lens will yield probably just about the beginning of its maximum sharpness range on many newer cameras (no serious diffraction at f/3.5). Your Canon zoom is a fine, fine lens; at f/4 to f/4.5, it will give you a little bit more in-focus at typical sports distances....f/2.8 gives you no focusing leeway for error.... 1/4000 second is simply "wasted speed" in a sport like swimming, which is "slow" compared to say archery and arrows in flight, or motorsports, or baseball, where the ball can move at 100 miles per hour or more. DIVING might benefit from 1/4000 second, but not so much regular swimming events.

For human sports (not motorsports), shutter speeds of 1/1250 second are usually about right to freeze motion with a 70-200mm lens on an FX camera. On HIGH-magnification shots, where people are moving very rapidly, you might need to go to 1/1600 or 1/2000 for an absolutely crisp, frozen action on the hands and feet of people moving at top speed (running). A little bit of blurring on the hands or feet can sometimes be helpful. But 1/4000 second? That's typically "wasted speed", and it might be better to have a smaller f/stop, like f/4.2 or so, rather than being at f/2.8 at 1/4000 second.

Gary A. · Nov 26, 2016

The the lowest ISO which reflects your previsualized image. If you previsualized a shot with a lot of DOF, then set your ISO high, (in harmony with your other settings), in order to attain/capture your previsualized image. If your previsualized image has shallow DOF, then set your ISO low, et cetera.

Typically, image content/Image Impact will go farther to making your photo successful than Image Quality.

Gary A. · Nov 26, 2016

For swimming I'd set my speed where I want it ... then the aperture where I want it ... then adjust the ISO to make that work. If the ISO is at 800 or under I wouldn't give it another thought.

TonyUSA · Nov 26, 2016

Thank you Thank you Thank you.

Overread · Nov 27, 2016

Just a further thought - the suggestion to use ISO 200 in the video might also have come from someone who is used to working in slightly dimmer conditions. Thus as a result they might start the day with ISO200 as their default starting position.

That way they turn up with a rough setting that might give them the ideal shutter speed and aperture; they then adapt that to suit the exact lighting that they are in.

I do much the same, if the day isn't as bright I might start at ISO 400 or even 800. It's a way of thinking that aims to get you out of the "ISO 100 all the time" mentality.

OF course if I turn up and the light is really bright chances are I'll start at ISO 100. Remember this is before the action happens, before the swimming starts in your case. It's when you point the camera where the swimmers will be and see what the meter gives you. It's purely a starting point for settings when you leave the house to head out.