Friday, June 20, 2008

Friday Tip

TGIF! Continuing on from the last photo tips, we'll talk about ISO and histograms, and get into f-stops a little more. As with last week, rolling over the photos will reveal the settings used, and clicking will display a larger photo.

The ISO setting on your camera is essential to getting proper exposure. Lower ISOs are less sensitive to light, and are what you would use outdoors on a sunny day. Shooting in dim light - especially indoors - presents a problem for your "normal" camera settings, so the ISO is there to save the day. You want to use the lowest ISO you can get away with, as the higher your ISO gets, the grainier your photos will be. Start out with your ISO set at 100, or 200 if that's as low as your camera goes. If your photos are unacceptably dark, then change your ISO to 400. You should notice an instant improvement! I try to rarely shoot over 400 because my camera (a Canon 10D) is an older model and doesn't do well at all at high ISOs. But give yours a try at 800 if 400 just isn't cutting it and see what happens!

One thing you should keep in mind when using a digital camera is that it is very easy to blow highlights out. Once a highlight is gone, it can't be brought back. On the other hand, shadows still retain some details that can be brought out in processing. If you want to stay really safe, keep your photos a touch on the dark side, and lighten them up when you get them on your computer. Try not to go overboard with this technique though, as lightening photos after the fact results in lower quality images. This is where the histogram comes in!

Histograms are little graphs that some cameras and photo editing programs will display. Check your camera manual to find out how to show the histogram, since they typically won't just show up with the preview image. A histogram is an analysis of the light composition of a photograph. Spikes on the left indicate dark pixels, while spikes on the right indicate light pixels. The rest fall somewhere in between. Depending on how busy your backgrounds are and the color of the horse, the majority of horse pictures you're going to take will have a histogram that looks like a hill (or a few hills) in the middle of the graph. Some bars falling off to the dark (left) side are fine, but you want to really watch out for clipped highlights - bars falling off to the light (right) side. My camera has a neat function where the blown out portion of the photo blinks black and white, so it is very easy to tell if the settings need adjustment. Check to see if your photo blinks in the histogram view on your camera! For reference purposes, it's ok if the sky is blown out, as it frequently will be on overcast days. But if that clipping has anything to do with the horse, then you need to adjust your exposure.

To wrap up, let's revisit f-stops a bit. Carol asks:
One question for ya -- if the horse is farther away, you can get away with using a lower f-stop, can't you? For instance, if you're 5-10 feet from the horse and using f 2.8, some parts might be out of focus, but if you're 25 feet away, as long as you're focused on the horse, you should be okay. Is that right?

That's a great question Carol, and really the lower f-stops can't be avoided in some situations, especially for people photographing horses in low lighting situations like arenas. (Why are they always so much darker than they seem?? Grrr.) Yes, that is correct - the farther away you are, more of the horse will be in focus (if he is angled towards or away from you). But there is a caveat... It becomes more difficult to precisely get the focus on the horse the farther away it is, and when the focus slips off onto say, a fence rail, the horse will be out of focus. This of course happens with higher f-stops as well, but the margin for error is much greater with lower f-stops if the horse is a bit away from the background. I had a really difficult time finding an example since I delete most of my bad photos, but this one is an approximate demo. Of course in this situation, even a higher f-stop wouldn't really have helped since the horse is so far away from the fence, but you get the idea...


Marianna said...

I like that you posted a photo of the hottie dutch guy! ;)

Mel Miller said...

Wellll, it was just a convenient photo. ;-)