Adventure of a Flash Noob: The Beginning
I’m going to learn flash.
There. I’ve said it. Now if I don’t, I will have failed, and the world will know!
I’m using (for now) the Pentax AF-540 FGZ along with my Pentax K200D. My goal is to eventually get smaller strobes and use them manually together (á la the strobist style). But for now, I’m starting with the utter basics of the equipment I already have. This is not a scientific assessment, nor will any measurements be precise. I’m writing this in case anyone wants to learn from my mistakes and to document my (fingers-crossed!) progress. I’ll be learning in the hours before I go to work every day, but work is the priority at the moment, so I can’t spend hours measuring everything and writing it down. My primary goal is to LEARN flash, not to teach others. But if they do learn anything from here, great!
I always only shoot in either aperture priority or manual. Shutter speed is some abstract concept to me that only comes into play when I a) try to exceed 1/4000th shutter speed or b) when I try to hand-hold at speeds slower than about 1/6th a second (the longest I can handhold with my lightest lenses). Otherwise, shutter speed is a non-consideration.
So today, I set out to try to “freeze” motion using the flash. I set the flash to P-TTL mode and high-speed sync. I had the 31mm on the camera and wanted to use a wide aperture for shallow depth of field. I set the flash to +1 compensation because I read last night that if you have a light subject (I’m pretty pale), then the camera and flash will try to make it darker to have a more even distribution of light and shadow. So you use a positive compensation for lighter subjects and negative for darker.
This is my setup: a really dark corner of my living room (I moved all the furniture to the other side), lit a little by ambient light and a lamp with a 40watt bulb :
Pretty dark. I’m not going to post my non-flash test shot (I look like death), but at ISO 200 and f/2.8, a properly exposed photo had a shutter speed of 1/2 second. That’s definitely not going to freeze any motion.
This part of the room is narrow, so I set the camera up about 4 feet in front of one off-white wall, and I stood about 4 feet in front of the camera against another off-white wall. I turned the flash all the way down (90° - had it been pointed toward me, if would have fired directly in my face) and rotated it a full 180° so that it would be firing against the wall behind me. The idea was that the flash would illuminate me head-on without much shadow.
In aperture-priority mode, I liked the depth of field I was getting at f/2.8, but the camera chose a shutter speed of 1/50th. This wasn’t enough to freeze the action, but I really liked the outcome otherwise:
I decided to go with shutter priority with a shutter speed of 1/180th. I missed the focus on this one, but this was more what I was going for:
Okay, enough for today. Tomorrow: lots and lots of reseach.
June 3rd, 200812:12 pm at
The trick to freezing motion with a flash is to remember that the actual pulse of light coming out of a hotshoe flash is only around 1/10,000 of a second long. That’s fast enough to freeze almost anything. If the flash is the only thing lighting up the scene (if you’re in a dark room, or it’s night time with no moon) then it doesn’t matter if the shutter speed is 1/100 of a second or 10 minutes; the pulse of light still takes the same amount of time to discharge.
You can get blur with flash when you mix ambient, natural light with the flash. In that case the image will come partly from the flash’s light and partly from the natural light. The flash part will still be crisp and frozen but the ambient part will be blurred like normal. When you mix them together you can get different effects depending on the mixture.
I used the second method for some of the photos I took at Girl Jam last month and wrote up a blog post about it at http://www.stevelosh.com/blog/2008/4/29/shooting-girl-jam.html if you’re curious.
June 3rd, 20081:15 pm at
Nice image! It’s certainly a challenge to achieve great results with a shoe-mount flash, but certainly possible as you’ve demonstrated. I always shoot in manual mode. The shutter speed will have very little effect on the image exposure if the flash is the dominant light source; The aperture essentially defines your exposure and you can adjust this to your liking.
If the flash is too low in power or the ambient light is strong enough, then ambient light plays a role. The flash will capture the image (at 1/1000th (approx.) of a second when the shutter opens), but the ambient light will add motion blur whose amount depends on the shutter speed. This blur will be opposite to natural expectations. In other words, if you’re walking laterally and the flash fires, the blur will occur after the flash fires and appear in front of the motion. You can change the way the flash fires so that it happens when the shutter is closing and the motion blur appears behind the motion, which is more pleasing to the eye.
Another trick is to try key-shifting. This is where you isolate the exposure of the subject with that of the background. Set your shutter speed to say 1/60th of a second. Then meter the background and adjust the aperture accordingly for good exposure. Adjust your flash power on the subject so that it meters at the same settings as the background. At this point you should have a nice balance in exposure between subject and background. Now start to increase the shutter speed. Your subject exposure will remain the same because it’s dictated by aperture, but the background will become darker. You can continue to increase the shutter speed up to your sync speed, which is typically 1/125 or 1/250th. This can create some nice and often moody effects. Annie Liebowitz uses this technique quite a bit.
Anyway, I’m looking forward to seeing your future flash incarnations.
Dave
June 3rd, 20086:50 pm at
I’m not sure if you saw this on my site when you were looking around but it may be an interesting read for you.
http://joshmullenite.com/?p=29
Also, if you want to try off-camera stuff I have everything you would need to get your current setup off if you’d like to use it some time to practice.