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Old Sep 14, 2004, 1:31 AM   #1
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I am living in China and while my Chinese is improving my vocabulary specific to photography is limited to: "camera", "digital camera", and "take a picture". For this reason I have found going to the store to learn about flashes a bit on the difficult side. I am wondering what some things are to look for in a external flash, for a camera with a hot shoe (Fuji S7000 to be specific). I am new to photography, but would like to buy decent quality right at the beginning rather than needing to upgrade (although I don't need the top line quality either). So the question is:

What are important things to look for in an external flash?

In looking on websites it seems that it is good to ahve a flash that can be set on an angle for the "bounce" effect (I believe this is "vertical bounce"). I have also seen the following mentioned:

Guide #

# of f-stop settings

Auto thyristor circuitry

zoom flash head

sufficient light indicator

calculator dial

remote sensor capable

Which of these (or others I have not mentioned) do you think are important. For those which may have different settings and levels, what level do you think is best to buy (Guide #, f-stop settings, etc).

Thank you in advance for your help!

Rob Goll
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Old Sep 14, 2004, 12:35 PM   #2
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Guide number: describes the theoretical maximum flash power. Since you're intending to get an external flash, it means the built in one on your camera is insufficient, hence look for higher GN. However, it's more useful to look at the maximum range of the flash unit.

# of f-stop settings: refers to the automatic calculation capabilities of the flash unit. This is usually irrelevant if your camera has fancy auto flash metering, and you have a compatible (usually same brand) flash unit.

Auto thyristor circuitry: marketing gimmck IMHO. A flash works by charging a thyristor capacitor with the batteries and then discharging it quickly to produce that short duration bright light.

Zoom flash head: meaning the light output angle of illumination changes with your camera's zoom. Not really useful, but check the widest setting (eg. 28mm or 24mm) is at least as wide as what your camera is capable of. ie. if the flash covers down to 28mm wide, and your camera is capable of 24mm field of view, the flash may not light up the extreme outside edges of your image.

Sufficient light indicator: ??

Calculator dial: probably to do with setting manual flash output. Simplifying that Guide Number dividied by aperture giving you flash range formular. Back in the 70s it was important to manually calculate how much flash power was needed, but today I don't think it's important if auto is available.

Remote sensor capability: probably off camera flash functioning.


One important spec I'd suggest look at is flash recycle time. This prescribes the minimum time (in seconds) of firing the flash between pictures, which dictates how fast you can take pictures with flash. Usually in the region of 4-6 seconds,lLower is typically better.
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Old Sep 14, 2004, 1:12 PM   #3
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Quote:
Guide number: describes the theoretical maximum flash power. Since you're intending to get an external flash, it means the built in one on your camera is insufficient, hence look for higher GN. However, it's more useful to look at the maximum range of the flash unit.
The guide number varies with the price you pay, what you have to check is at what focal the given GN number correspond to ( ie at what focal length, or at what angle coverage) to compare on the same basis.(manufacturer tends to give the GN at full tele to have a big GN)


Onyx wrote:
Quote:
# of f-stop settings: refers to the automatic calculation capabilities of the flash unit. This is usually irrelevant if your camera has fancy auto flash metering, and you have a compatible (usually same brand) flash unit.


In this case, the flash will be operated at auto mode or manual (not dedicated), so it is an advantage to have many aperture choices (usually , 3 to 6), as well as many partial manual power settings.

Onyx wrote:

Quote:
Auto thyristor circuitry: marketing gimmck IMHO. A flash works by charging a thyristor capacitor with the batteries and then discharging it quickly to produce that short duration bright light.


Auto thyristor designation, also called "auto mode" is the globally accepted term to designate the aperture set (commanded) flash output control , since the film camera old times. (flash burst is stopped when it reach the correct output suitable for the selected aperture, measured by the own flash sensor)


Zoom ... Well depends on what you need, some even add separate zoom head to reach further with long tele. But Ithink alsothat the wide end is the most useful with normal indoor shot.

Some flash may have a "winder mode" ( film camera related term) offering a reduced power mode that can keep up to 4, 5 FPS (frame per second)

Battery choice may be important depending on your use , AA? or proprietrary ? can they recharged, or you have depend on alkaline?

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Old Sep 14, 2004, 1:16 PM   #4
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I thinka betterapproach is that you give 2 or 3 choices (available for you locally) and we can give comments
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Old Sep 14, 2004, 5:02 PM   #5
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rgoll wrote:
Quote:
sufficient light indicator
- Confirmation that the output has reached the minimum detected by the Auto thyristor circuitry (ie the flash burst was OK). This is useful because sometime the subject is too far out or when doing a bounce, the flash fired, but the picture is still underexposed!



Quote:
remote sensor capable
- Attachment for a photo-eye which can be slaved to other flash(es).



* More important than the angle of coverage, is how even the flash beam is; Otherwise the resulting picture is bright in the center, but dim at the edges. Inexpensive flashes always do this by concentrating the light so it's projected further out boosting their GN!
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Old Sep 19, 2004, 12:48 PM   #6
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If you hold your camera side-ways, for a portrait of one person for example, youmay want a flash that both bounces and swivels. Also, this is useful to find the nearest and whitest wall for bouncing off.

Bouncing the flash is great for giving a natural light. You'll need a pretty powerful flash, however; the good news is that the even spread of light from the flash is not important because the wall/ceiling diffuses it anyway.
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