manual flash question - DPChallenge Forums

11/05/2006 10:42:52 PM · #1

What I understand so far is that we need to calculate the distance of the subject and take note of the Aperture recommended on the flash unit. Also, those readings are actually for ISO100. Now, what about the shutter speed? What shutter speed should I use in conjunction with the stated Aperture and distance? These are the only 2 info on the flash unit that I understand.

Less importantly also, I dont understand what are those ASA and DIN info on the unit for... can someone enlighten me?

Note: non-TTL flash. Fully manual.

11/05/2006 10:57:48 PM · #2

Shutter speed doesn't matter in flash photography. The flash will hit your subject with the same intensity no matter what you have the shutter speed at.

What you DO use shutter speed for is to balance ambient lighting with the flash lighting. A long shutter will allow for ambient lighting to fill the scene, while a shorter one will make your scene mostly flash.

11/05/2006 11:08:39 PM · #3

Originally posted by fotomann_forever:

What you DO use shutter speed for is to balance ambient lighting with the flash lighting. A long shutter will allow for ambient lighting to fill the scene, while a shorter one will make your scene mostly flash.

ah, this info wasn't easily available off the websites I read! Thanks Leroy. I usually set the shutter speed to 1/500 in hope of reducing shake/subject movement. Is that speed too fast for ambient light?

Canon EF 24-105mm f/4.0L IS

11/05/2006 11:21:00 PM · #4

Originally posted by crayon:

Originally posted by fotomann_forever:
What you DO use shutter speed for is to balance ambient lighting with the flash lighting. A long shutter will allow for ambient lighting to fill the scene, while a shorter one will make your scene mostly flash.

ah, this info wasn't easily available off the websites I read! Thanks Leroy. I usually set the shutter speed to 1/500 in hope of reducing shake/subject movement. Is that speed too fast for ambient light?

Not too fast for ambient light, but it is too fast for the flash sync speed of most cameras. You're prolly gonna want to go down to 1/200 or lower.

Anyway, shake and subject movement isn't a big issue with flash, because flash has an inherent ability to freeze motion. The quick burst of light freezes quite a bit of action.

robs

Canon EOS R6 Mk II

11/05/2006 11:22:57 PM · #5

I use a LOT less then 1/500 to let in some background light. The flash is going to freeze the foreground, so just play around a bit. Do you like what you are getting on the background? If too dark then slow it down and see what you like.

11/05/2006 11:25:18 PM · #6

Originally posted by fotomann_forever:

Originally posted by crayon:
I usually set the shutter speed to 1/500 in hope of reducing shake/subject movement. Is that speed too fast for ambient light?

Not too fast for ambient light, but it is too fast for the flash sync speed of most cameras. You're prolly gonna want to go down to 1/200 or lower.

Oh you answered the question that I didn't know how to ask. Yes, so that is what "sync speed" is about! No wonder sometimes even when I tune up the power of the flash, I get under-exposed shots. Now I know why. So 1/200 should be "safe" for most/all flash units/cameras? I think if I go any lower, subject movement might be visible?

11/05/2006 11:30:31 PM · #7

Originally posted by crayon:

1/200 should be safe for most modern cameras as the highest speed you use, unless you have a flash unit with a high speed sync.

The second question. With flash, you are not likely to see shake.movemtnt even as low as 1/30 of a second or even lower. As I said, flash has an inherent ability to freeze motion.

Now, if you are in a position of a lot of ambient light, you may see some subject movemnt.

11/06/2006 05:51:42 AM · #8

I think that the question of Flash Synchronisation has not been adequately addressed above.
The camera's shutter should be fully open when the flash fires. When the leading curtain of the shutter is fully open, the contacts for the flash close. At a shutter speed of say faster than 1/125 seconds, the trailing curtain of the shutter begins to close, even before the flash has fired, thus exposing only part of the frame. In order that the frame is properly exposed, the shutter speed should not be (typically) higher than 1/125 second, when using flash. This is called 'flash-synchronisation' speed.
The speed required for correct flash-synchronisation is usually marked in red on the shutter speed dial.

Mr_Pants

SiPix Blink

11/06/2006 07:16:28 AM · #9

Does the matter of X-sync speed even really come up with the Coolpix 800? I would have thought that it had an electronic shutter.

If you are using an 'automatic' flash, such as the Vivitar 283, you set the aperture into the flash and set the corresponding aperture on the camera (ISO, too). The flash itself then controls the amount of light given out by measuring the light reflected back to a sensor on the flash unit, so that a correct exposure should be obtained.

Message edited by author 2006-11-06 07:18:41.

Prof_Fate

11/06/2006 10:04:42 AM · #10

With a non-slr you are correct, the shutter is really just a timed capture and not a mechanical event. However, the flash event has a lag time to get started, it ramps up to max brightness and then falls off. The more light the flash needs to put out the longer this flash event (on-time of the flash bulb if you prefer). If you are triggering other flashes optically then there is even more lag time in there.

So a very short (low power) flash burst from an on-camera flash may be on the order of 1/10,000 of a second in total, so shutter speed is never gonna be so fast as to not allow all the light to get recorded. However, wne you get into full power blasts and studio strobes 1/500 to 1/800 is often the duration time of the strobe burst.

1/125 is the most common speed for studio use. For weddings most photogs shoot manual mode 1/60 and F4 or 5.6. As stated, the flash pretty much freezes any motion and the slower speed allows ambient light to keep the background form going dark.

Now if you using in daylight for fill flash, it's best to read the subject with a meter (your camera spot meter will work) and set you shutter speed a stop or so below that and use the flash to 'fill in' the difference.

Sigma 30mm f/1.4 EX DC HSM for Nikon

11/06/2006 09:08:45 PM · #11

NOTE: please disregard the Coolpix 800 listed under my name. I'm trying to learn flash use on another manual camera.

By the way, how do you read these flash unit specifications? example:
Usable lenses: 28-85mm. Range up to 16m / 53ft. G/N: 26m / 88ft at ISO 100

what do the numbers mean?

jdannels

Nikon D300s

11/06/2006 09:20:06 PM · #12

I have a flash question too, How does setting the flash angle on the camera affect shots? For example my sb 600 can go from 18-85mm. Does this constrict how wide the flash is thrown or how far the light is thrown? Lets say I have a scene where I am shooting at an 18 mm lens focal length, and I want to use the flash to pinpoint something in the scene, would it work to have the flash on 70 mm and aim the light at the object and have it only affected by the flash? Hope that makes sense.

11/06/2006 11:22:33 PM · #13

Originally posted by crayon:

These numbers are pretty easy to understand. First, the flash is suitable for lens of focal length 28 to 85 mm. Outside this range, the effective area covered by flash may not suffice. Effective distance of flash (at smallest aperture to largest aperture) is upto 16 meters (roughly equal to 53 feet).
The flash Guide Number is 26 (in meters) when using ISO 100 setting. This means that, if the flash to subject distance is 3 meters, you should use an aperture of 26 divided by 3, that is f8.6.
If the distance is 16 meters, you must use an aperture of 26 divided by 16, i.e. 1.6 (provided you have a lens of that big maximum aperture, i.e. f 1.4).

11/06/2006 11:39:18 PM · #14

OK, now I understand how to interpret those flash numbers.
I'm looking at this flash unit, it states automatic exposure.
Does it means it will auto-calculate the distance from the Aperture I set on it?

Yashica CS220 AUTO (guide no 0.22 = means 22metres at ISO100 ? )

11/07/2006 04:31:31 AM · #15

bump?

11/07/2006 09:12:38 AM · #16

Originally posted by crayon:

It means that the flash can work in both Manual as well as Automatic Flash. In Automatic mode, it will automatically control the output of the flash, depending upon the subject to flash distance. (It actually works by measuring the light reflected off the subject, and thus controls its output!).
Hope, it is clear.

No knowledge, No confusion. More knowledge, More confusion!

11/08/2006 11:14:05 PM · #17

a quick final question (I think)...
what are some good flash units that will work on a dumb hotshoe?
I was told the older Nikon SB28 works pretty well but does it work in auto mode?

11/10/2006 11:04:08 PM · #18

No idea.

11/10/2006 11:49:04 PM · #19

Originally posted by crayon:

a quick final question (I think)...
what are some good flash units that will work on a dumb hotshoe?
I was told the older Nikon SB28 works pretty well but does it work in auto mode?

Yes, the SB-28 does have an Auto Mode, will work on a dumb hotshoe and has some nice features.

Just sold mine not too long ago. Had used it with the Nikon Coolpix 950 and 8700.

Message edited by author 2006-11-10 23:50:44.

11/13/2006 11:26:55 PM · #20

What is a dumb hotshoe?