How fast is my flash? - DPChallenge Forums

02/16/2007 10:23:17 AM · #1

I just got a Sigma EF-500DG Super Flash for my pentax ist DL.

I just got it two day's ago and last night I tried it at my sons basketball practice. Using the camera in sports mode I could only get 1/180 sec shutter speeds.

Any other mode, like Av I only seem to get 1/60 sec. shutter speeds.

I did not get it for shooting sports but to take portrait with, but I was thinking I could use it to stop motion too.

Now there is a "High Speed Sync Flash (FP) setting on the flash and using it with Tv on the camera lets me set the shutter speed to what ever I want but the exposure is really messed up on every photo.

Guess my question is how do I go about using my flash to stop motion with higher shutter speeds and have the exposure turn out correct?

Canon RF 24-70mm f/2.8 L IS

02/16/2007 10:25:14 AM · #2

Also what should I be looking at using for a shutter speed when taking portrait type photos?

I would like to not have to use a tripod all the time with the flash, but 1/60 of a second does not seem very fast.

Message edited by author 2007-02-16 10:25:25.

kirbic

Canon EOS R5

02/16/2007 10:31:15 AM · #3

The flash is much faster than the shutter opening. The duration of the flash depends on the flash itself, and the power setting. It's usuallly 1/1000 second or even faster (shorter). The shutter speed just determines how much of the other room light will be recorded. Longer shutter, more room light gets in.
There's a limit to how fast a shutter speed you can use with your flash, because the flash has to fire while the shutter is completely open. If the shutter is opening or closing when the flash fires, part of the frame wil be dark. The maximum shutter speed that will allow full illumination is called the flash synch speed, and it's specific to the camera model. It's usually 1/200, 1/250, or in a few cases 1/500s.

Ubersteiny

Canon EOS-5D Mark II

Sigma 35mm f/1.4 DG HSM for Canon

02/16/2007 10:47:25 AM · #4

Originally posted by kirbic:

mine is 1/250th but i can set it on highspeed flash and go to like 1/2000 when in bright areas and just using fillflash

02/16/2007 10:49:54 AM · #5

Flash photography is harder than available light photography for one simple reason.

When you use a flash, there are two exposures going on for every picture you take - and you have to control both of those exposures.

The first one, is controlled by the flash power and the camera aperture. The shutter speed has nothing to do with that exposure. There are some fundamental limits on the shutter speed (1/250s or 1/200s max for normal flash, 1/8000s or 1/4000s with high speed sync mode) but the shutter speed does nothing to control the flash exposure. More power, or a wider aperture, gives more exposure - on the thing illuminated by the flash only.

The second exposure in every flash shot is for the ambient light. This is controlled by the aperture and shutter speed. The flash power has nothing to do with this exposure. But the aperture is common to both of these exposures. This exposure affects everything in the scene, if it is illuminated by the flash or not.

So flash photography involves balancing these two exposures. Many people first use flash with little point and shoot cameras, in dark rooms, where they are essentially using the flash as the only light source and the results are terrible.

The trick to good flash photography is realising that the flash is (or should be) _always_ fill light and working out how to blend it with the ambient light, to get good exposures. As you have to juggle the 3 variables of flash power, aperture and shutter speed, it almost always pays to shoot in manual mode. The other trick to good flash photography is never having the flash on the camera, pointing straight at the subject, but that can be harder to achieve.

Many cameras in Av or Tv mode with flash, only meter for the ambient light and ignore the flash power (usually this is controlled via TTL). So your shutter speeds will often be pretty slow and just for the ambient light.

If you want to shoot handheld with the flash as the main light source, you probably need to switch to manual and find an aperture/ shutter speed that works with the flash power you are putting out, but realise you'll probably have dark backgrounds, particularly if you are shooting indoors in a gym.

ISO is the 4th part of the exposure equation but I'm assuming that's mostly constant - you can always crank it up to help increase the shutter speed, but with the accompanying increase in sensor noise.

Message edited by author 2007-02-16 10:51:12.

Canon EF 100mm f/2.8 USM Macro

02/16/2007 10:49:56 AM · #6

Originally posted by noisemaker:

mine is 1/250th but i can set it on highspeed flash and go to like 1/2000 when in bright areas and just using fillflash

Yes, that's about all the high speed shutter sync (on some flashes) is good for is fill-flash.

Spork99

OM System OM-1

02/16/2007 10:51:58 AM · #7

For the *ist DL, the sync speed is 1/180 and the flash duration for your flash is listed as "Approx 1/700 s". You should be able to set your camera in M to 1/180 and the aperture to whatever you want and the flash should adjust as long as you have the camera in TTL mode.

With flash, as long as you don't exceed the sync speed, the only thing the shutter speed controls is the exposure of the ambient light. The aperture affects both the flash exposure and the ambient light exposure.

edit: I just saw Gordon's post, and as usual, his explanation is much more comprehensive.

Message edited by author 2007-02-16 10:54:44.

Apple iPhone 5

Nikon AF-S DX Zoom Nikkor 18-55mm f/3.5-5.6 ED

02/16/2007 10:54:37 AM · #8

When I was doing a film photography course a few years ago, the tutor told us to just set the shutter speed to the sync speed when using flash. So I normally set the shutter to 1/250s and vary the aperture.

I'm not sure if this is the correct approach or not, and I'm probably missing out on a whole lot of creative stuff. But it works fine.

Spork99

OM System OM-1

Canon EF 100mm f/2.8 USM Macro

02/16/2007 10:56:45 AM · #9

Originally posted by jhonan:

That's usually where most people start off.

Try Googling the term "dragging the shutter" to see what kind of things are possible by reducing the shutter speed to allow ambient light a greater role in your flash exposures.

02/16/2007 10:56:48 AM · #10

Originally posted by jhonan:

Weirdly enough I just started a portrait class a few weeks ago and the tutor told us the complete opposite ;) His general approach when using flash is to have the slowest shutter speed he can get away with, so that he can get as much ambient as possible.

I've had others who recommend just using the sync speed and never moving, though as well. Takes all sorts ;)

02/16/2007 10:59:08 AM · #11

Awesome replies,

I am starting to understand how it works now.

It looks like it would have been best to use the camera in manual mode at the gym the other night.

At the house here this morning I can use 1/1000 and f/8 with high speed sync flash and the exposure look ok on close objects.

The flash display also shows range as 7 ft on iso 200.
If leave all setting and just change iso to 1600 the range jumps to 30 ft.

I have a much better understanding of how it's going to work now, thanks..

02/16/2007 11:02:35 AM · #12

Originally posted by John Pahl:

It looks like it would have been best to use the camera in manual mode at the gym the other night.

I'd also add that high school sports photography in a gym is about the most difficult lighting situation and technically demanding shooting circumstances that I can possibly think of.

I don't think there is any harder conditions to get consistently good results in. Maybe war photography - but at least that's usually outdoors...

02/16/2007 11:04:33 AM · #13

Originally posted by jhonan:

I see my camera shutter jumps from 1/160 to 1/200. :)
Seems odd there would not be a 1/180 shutter speed being the flash sync speed is 1/180.

I see there is going to be much more to learn about using this flash then I first thought, lol...

It's going to be a ton of fun though.. :)

edited to add, seems when flash is on I have the 1/180 show up on the camera meter, but it skips over it when the flash is off.

Yeah, lots to learn. :)

Message edited by author 2007-02-16 11:06:33.

02/16/2007 11:16:08 AM · #14

Originally posted by Gordon:

That's called dragging the shutter and is quite common in wedding photography. The trick is to get ambient exposure about 1 to 2 stops underexposed and then use the flash as the main light source (properly exposed) on the subject. That gives a nice balance to the subject to background and makes the subject really pop (without looking unnatural).

Tamron SP AF 24-135mm f/3.5-5.6 AD Aspherical IF for Canon

02/16/2007 11:17:37 AM · #15

Originally posted by Gordon:

I'd also add that high school sports photography in a gym is about the most difficult lighting situation and technically demanding shooting circumstances that I can possibly think of.

I agree... almost all indoor sports are difficult to shoot. Volleyball, IMO, is the hardest of them all, right next to basketball.

nards656

Canon EOS-300D Rebel

02/16/2007 11:21:00 AM · #16

Originally posted by fotomann_forever:

The trick is to get ambient exposure about 1 to 2 stops underexposed and then use the flash as the main light source (properly exposed) on the subject. That gives a nice balance to the subject to background and makes the subject really pop (without looking unnatural).

Thanks for reminding me of the "exact" numbers to use. I didn't realize there was a good scientific way to approach it.

02/16/2007 11:42:04 AM · #17

Originally posted by fotomann_forever:

Originally posted by Gordon:

Weirdly enough I just started a portrait class a few weeks ago and the tutor told us the complete opposite ;) His general approach when using flash is to have the slowest shutter speed he can get away with, so that he can get as much ambient as possible.

That's called dragging the shutter and is quite common in wedding photography. The trick is to get ambient exposure about 1 to 2 stops underexposed and then use the flash as the main light source (properly exposed) on the subject. That gives a nice balance to the subject to background and makes the subject really pop (without looking unnatural).

Yup, though in this case we are using it with studio lights and not going for that traditional wedding look.

Nikon AF-S DX Zoom Nikkor 17-55mm f/2.8G IF-ED

02/16/2007 11:45:56 AM · #18

Originally posted by Gordon:

Yup, though in this case we are using it with studio lights and not going for that traditional wedding look.

Hmmm... environmental portraits or "studio" type shots?

If I'm doing environmental with the studio strobes, I will drag the shutter, but if I'm doing studio type work I go lights out, so the strobes are my only light sources and set the shutter to 1/125.

justamistere

Nikon D3s

02/16/2007 11:54:39 AM · #19

I did some great indoor vollyball shots without flash. Yes the lighting was mixed from above and one wall with mostly glass bricks. I also got some interesting motion blur of the server's hand. I did get some jump shots and returns. A few did some blur in it. I was just practicing with a relative who played vollyball. I used my 70-200mm f/2.8 VR, and my 1.4 50mm lenses handheld, sitting in the top-back row of the grandstands.

Next time I'll try using flash at a slightly closer distance.
Thanks for the excellent comments on flash. Would a spotmeter like the Sekonic 778 help? Maybe to get a spot reading near the net or basket, where a lot of the action is?