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Photo Technical

We wrap up 2008 with lag time before shooting fresh into 2009 – A37

Happy New Year, and out with the old in with the new.  To finish the old I was last talking about shutter lag, making the point that in some compact digital cameras it can be a half second or longer.

What’s the big deal, well, that’s a big deal.  In photography a half second can seem like an eternity.  If you subject is your small child, pet, or a boat race, that much time between when you press the shutter button and when the camera actually snaps the photo is critical, and that special expression or the neck and neck finish will certainly be missed.

Therefore, the lag time is something you need to check on and it isn’t easy.  The sales clerk will have no idea about it and shutter lag is seldom mentioned in a ‘specifications’ list.

To date, actually, I’ve never seen it mentioned in general camera spec’s, and manufacturers only note it if it’s good news.  Try sourcing various web sites, such as www.dpreview.com or contact the manufacturer for an answer.

I buy a lot on the Internet, but at last resort you may have to find some way to try out the camera and see how it performs in this regard.  If you are learning from me, and you are a true photography buff, then yes, I find it that important.

It is important to note one other factor that causes a lag time.  It’s one that is possible for you to control and it has to do with focusing.  As you press the shutter of any camera there are two levels or stages, a sort of half way and full shutter press.

When you zero in on your subject and press the shutter button to the half way point (in pressing the shutter) the lens will auto focus on the subject.  However long this takes will effect the time it takes to snap the shot.  The camera will not expose (take) the photograph until the electronics of the camera gives an ‘all clear’ to the shutter release.

If it is dawn or dusk when the light is low, or if, for instance, you are shooting through glass were it might be harder for the camera to determine the focus, it will add a lot of lag time.  Other circumstances similar to these may cause difficulty focusing and delay exposure.

In such cases, and frankly anytime you can pre-focus you will eliminate the extra split second or more of time it takes to release the shutter.  So if only the expressions change or there is only parallel movement, in both case where the depth of field remains the same, you can pre-focus.

To take advantage of this tip you need a camera that has ability to manual focus in addition to auto focus.  This will you allow you to turn a focusing ring on the lens for a specific depth of field.  Otherwise you can let the camera auto focus and then you switch to manual focus so it stays focused to a certain depth of field, and will not somehow re-focus.  This will eliminate any extra focusing time to get your shots.

Don’t confuse shutter lag (speed) with specifications like shutter speed, frames

per second (fps), or ISO (speed) settings.

Shutter speeds for expensive and professional digital cameras can range from 30 seconds to 1/8000 of a second and Bulb.  The latter meaning the shutter stays open as long as you press the shutter.

Small compact cameras do not have such a range or bulb.  Generally they may range from 3 seconds to 1/2000 of a second or less.  This has nothing to do with lag time, and has everything to do with controlling light that’s needed to expose a photograph and stopping (or freezing) action.

A professional digital camera may allow you to take 40 jpg’s in a row at a rate (burst speed) of 8 per second.  Small compact cameras never reach such specifications, with most seldom achieving rates better then 1.5 a second.  This is due to two factors: a) the electronic processing of the photo taken within the camera, and b) the time it takes to store it to the memory card.

ISO speed settings use to be synonymous with film speed, that is, how sensitive film was to light.  The more sensitive it was the faster the film.  Today you can substitute digital chip everyplace where I wrote film.

An ISO setting of 200 is twice the speed or sensitive as 100.  This means many things, such as you can use it in lower light conditions or allow for faster shutter speeds to stop action.  These all seem like good things, and small compacts usually allow for ISO settings of 100, 200, 400, and 800 (again with a pro camera could be up to 6400), so why not just go for the 800 setting?

Wouldn’t you know it, there’s a yin and yang to everything.  High ISO settings add one very unpleasant element to photographs.  In the film days it was grain and in the digital age it translates to noise.  In general grain and noise, the latter being specks of white, black or color, are not desirable except in certain artistic applications.

That’s about it on the old speed topic.  So what’s new?  I have just been reading about face, smile, and blink detection built into new digital cameras.  So what’s this new technology all about and what’s next!?  It may be a good topic to explore next time, but for now I need permission to go ashore.