Monthly Archives: January 2007

How To

Hacking the GN calculations when using manual flash

Here’s how to hack it when you’re stumped as to what guide number to use with a manual flash. This is useful when you’re using an analog SLR that won’t sync the flash power automatically, or you’ve got a DSLR and want to fine-tune the amount of light the flash puts out. I can’t stand having to calculate this with formulas. We all may have seen this :

Aperture (f-stop) = GN X ISO/distance (in meters)

But do any of us know it by heart, or better yet, want to know it? And are we really going to take out a tape and measure the distance to the subject? I know I don’t feel like it. So how can we hack this? Well, we use what knowledge we have to ascertain the flash power we want, and then we adjust the GN (Guide Number) up or down. It works like this:

  • Higher GN means more power for the flash and consequently, more light
  • Higher f-stop means smaller aperture, and that translates to less light coming into the camera
  • Higher ISO means better sensitivity to the light that the aperture lets in
  • Higher distance means less light (remember, we’re using a flash, and the effective distance is limited)

So, what does this mean for us? Simple: we can adjust any of the four factors listed above to get the photo we want. Need more light? Boost the GN and/or the aperture. Can’t get more light, but want a better photo? Boost the ISO, but recognize the photo may be grainy. Can’t boost ISO? Decrease the distance between you and the subject.

Of course, keep in mind that when you boost aperture (choose a lower f-stop), you’ll decrease the depth of field. Think of the focus field as a loaf of bread. When you use a small aperture (large f-stop, 16 for example), you get the whole loaf in the shot. When you use a large aperture (small f-stop, 1.4 for example), you get only a slice in focus. You can effectively think of f-stops as slices of that loaf of bread. Larger f-stops means more slices. So if you’ve got objects in this photo of yours that reside at various points of focus (more slices), to keep them all in focus, you’ll need to keep the aperture fairly small (large f-stop). If you’re only interested in a particular object, by all means, increase the aperture (small f-stop), get more light that way, and use a lower GN. You’ll get more natural colors. Flash light can be harsh and wash out the nuances if overused, so the less you can use, the better off you are.

Don’t think I’ve forgotten to talk about shutter speed. Just realize that you won’t have too much flexibility there, in particular if you’re shooting handheld. Even with a tripod and manual flash, you can’t adjust the speed that much. Too slow, and any people in the photo will be blurry. Plus, the flash will be ineffective. It can’t stay lit for several seconds or more unless you use a bulb. Too fast, and you won’t get any light. Plus, if you’re syncing the flash with the camera, you’re limited by the top sync speed, which varies by camera and usually runs from 1/180 to 1/250 seconds. You’re better off playing with the other variables in the equation.

Remember, you don’t need to go to the trouble of using manual flash unless you have to. If you need to adjust flash intensity and your camera allows it, you can easily boost or decrease it through simple menu functions. Just look this up in your camera’s manual. You can usually use the +/- button, if your camera has one.

Hope this helps!

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Places

Time takes its toll

Seen at start of Via Appia in Rome.

Time takes its toll

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Places

History

Taken March 1999 in Piazza Navona, Rome.

Commerce

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Thoughts

Digitizing my VHS library

Over the past few months, whenever I get some free time, I stick in an old VHS tape into my trusty Samsung SV5000W VCR, and using my Plextor ConvertX PVR (PX-TV402U), I digitize it. I’m really mostly interested in my library of Disney movies (feature-length animation). I have tapes from as early as 1992, and those poor things are in dire need of resuscitation. The colors are fading fast, there’s static when I watch them, and even their plastic cases have started to show signs of wear and tear, even though the only thing they’ve been doing all this time is sitting in my bookcase.

I realize I could easily purchase the DVDs, and for some of the movies, I did just that. I have the special edition Snow White and the Seven Dwarfs, for example. But it’s kind of nice to save my old VHS tapes. I have very fond memories of my Disney movies. When I started to buy them, my parents and I had just come to the States from what used to be communist Romania. That meant no access to Disney cartoons unless someone had a badly dubbed bootleg copy of some movie. We got 10 minutes or less of cartoons on Sunday afternoons around 1 pm, and that was that. If we were lucky, we got a Tom and Jerry short. If we weren’t, we got some half-baked French or Romanian cartoon, mostly stick animation. Yuck!

When I came to the States in 1991, I was starved for good cartoons. Unfortunately, we were also starving. Okay, that may be an exaggeration, but when you start from scratch, you don’t have a lot of spare cash. My parents had a hard time making ends meet in those first few years. So when I wanted to get my first Disney movie in 1992, that was a big deal. Twenty-five dollars is a lot of money to spend when you’re making minimum wage. As I started working in high school, I’d scrimp and save to have enough to buy my Disney movies. My my memories of these tapes are fond indeed. I’d wait months to be able to get one, and when I did get it, I enjoyed it very, very much — and I still do.

So here I am, dubbing my tapes to digital format. As I watch them again, bygone times come to mind. The nice experiences were all the nicer because they were in scarce supply. Digitizing my movies puts them and those times in cryogenic suspension, so to speak. They remain, in their current, fuzzy state, for as long as I keep them, always a memory of those first, few, rough years in the States.

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Thoughts

Parish Kohanim: the pursuit of beauty

Apple Pro Profiles currently features eminent photographer Parish Kohanim. With an impressive career that spans 30 years, his photographs speak for themselves. Here’s a quote:

“Every image he shoots is animated by a single urge. ‘My obsession is to capture the beauty life offers,’ says Kohanim. And despite the way contemporary critics often measure artistic significance on a scale that ranges from the merely controversial to the outright disturbing, Kohanim staunchly defends the pursuit of the beautiful.”

His philosophy strikes a chord in me. It’s what I try to do in my photography. I don’t want to focus on the ugly, the negative. I want to try and find the beauty in everything I photograph, and in my personal life as well. There’s so much ugliness to life, so much misery, that focusing on it the way some artists do is just too much.

Here’s what he believes about portraits:

“‘There’s something beautiful about everyone, whether exterior or interior,’ continues Kohanim. ‘What I love to do is draw out the beauty that is there.'”

This is what I strive for as well. Obviously, I have a ways to go in my photography, but at least I know what I want.

As for his work philosophy, I love this quote:

“‘What I admire is someone’s devotion and commitment to his or her craft,’ he muses. ‘These are the winners in our society: the people who take pride in what they do. And it could be anything. Whatever you do, do it with 100 percent of yourself.'”

Mr. Kohanim uses Aperture to manage his photo library. I’ve got to give it a try one of these days. I’ve been using iPhoto, and on the whole, I like it, although it has certain limitations, such as the inability to move photos between film roles that are months/years apart (scrolling becomes uncontrollable and drag and drop won’t work), and the impossibility of editing the EXIF data in the photographs. Another photographer whose work I love, Thomas Hawk, has just recently started using Aperture, so I look forward to seeing what he has to say about it.

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