photography101: what's ISO and why do I care?


Finally some sunny skies and warm weather - and it's week 3 of photography101!

Today's topic is ISO (or ASA) - basically, it's your film speed.  Of course, with digital, "film speed" isn't technically correct, but the principle is basically the same.

A lower ISO is ideal, as it produces images with a finer "grain", meaning there is very little digital "noise" in the details.  Shooting in sunlight or on bright days will warrant a low ISO because there is so much available light already - so an ISO setting of between 100 and 400 will be just fine.  But, when shooting in lower light situations, you will likely find that you need to change to a higher ISO to compensate for the lack of existing light around you.  Pushing your ISO to between 800 and 1000 will allow you to continue shooting with the available light, even if there's not much of it!  But, this means that you will begin to notice more "noise" or "grain" in your details.

Here is an image that was taken with an ISO of 400 (and a closer look at 100% zoom).  You'll see that there is very little grain in the details!

ISO 400

ISO 400

Now look at the image again, this time photographed with an ISO of 6400.  Again, make sure to look at the detail shot, where the grain is now extremely noticeable in the details!

6400 ISO 6400 ISO

Most cameras have a default ISO somewhere between 200 and 400.  Again, that's perfect for MOST situations and I would recommend not going much higher if you're photographing portraits or nature.  But for events like concerts or wedding receptions or anywhere with lower light, if you want to avoid using flash, you're going to need to bump up the ISO.  In situations like those, I like to start at ISO 1000 and adjust as necessary.

I once had a friend come to me with her PAS camera, asking if she needed to buy a new one because no matter what she did, all of her images were coming out "noisy".  We took a look at it and realized she had somehow changed her ISO to 4000, and her camera was set there, regardless of where she was shooting and what time of day.  Knowing your ISO is important for just that reason!

…Now…I hinted at it a bit on Facebook this week….

Announcing the Photography101 Challenge Giveaway's!

photography101 giveaway

On select weeks, I will be giving away these prizes to those of you who do your homework!!  Posts that are eligible for the giveaway prizes will be announced at the top of the post, as well as the coinciding prize!  The Photojojo DIY book, iPhone Holga lens, vintage film pack and Bloom Theory camera strap are just among a few of the sweet prizes available!

Now, I'm not officially saying that next week's challenge will definitely be eligible for a prize….but…I will say….get your cameras ready for some homework…..  :)