Why is light output of automatic flashes so high?

vicmortelmans

vicmortelmans

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Hi,

I'm looking for a generic automatic (thyristor) flash that would operate on any of my hot-shoe camera's, but I'm puzzled by the limitations in the range of auto settings.

I like using available light, also indoors. In a typical evening situation (like a restaurant), the available light conditions are such that one would be able to shoot without flash, using ISO400 film and a fast f/1.4 at 1/60 speed.

Very often, the light is just a bit lower, or the light cast is wrong, so I'd like to use a flash to fill in just enough to keep the mentioned exposure settings.

BUT! All automatic flashes that I know have a minimum auto setting for ISO400 at around f/5.6, so all my available light will be gone!

Using a TTL flash, it would be possible, but I like my Canonet and the likes far better for these situations than a noise SLR.

Aren't there any (compact) automatic flashes around that can go down to coverage for ISO400 at f/1.4 or f/2 ? I would think that technically there's no issue in cutting down the power??

Groeten,
Vic
 
Perhaps the sensor becomes unreliable at such low light levels? Or putting in a more sophisticated one is not going to sell as much?

If you used something like a Metz 20 and dialled down the power to 1/8-1/16 (manual) you're looking at something like f/1.4-f/2 at 2m.
 
Lie to the flash. Tell it you are shooting with ISO 1600 film. That'll effectly reduce the light output by two stops. Non TTL flash units are pretty dumb. It will never know you are actually shooting with ISO 400 film. ;)
 
Pickett Wilson said:
Lie to the flash. Tell it you are shooting with ISO 1600 film. That'll effectly reduce the light output by two stops. Non TTL flash units are pretty dumb. It will never know you are actually shooting with ISO 400 film. ;)
Click to expand...

No, that won't work. All auto flashes that I've seen only support a couple of ISO/f combinations and the actual flash output is not affected by the ISO setting on itself.

Groeten,
Vic
 
An auto flash has to be affected by the ISO setting on it. And there are many flash units with multiple ISO's and and aperture settings. I use a Sunpak Auto 144PC with my M's and it has multiple ISO and Aperture settings.
 
if all else fails, you could tape a neutral density gel filter over the flash to reduce its output.
 
Merkin said:
if all else fails, you could tape a neutral density gel filter over the flash to reduce its output.
Click to expand...

no, that won't work either! The sensor will only switch off when enough light has been put out, so taping off the flash head will only drain the batteries, not reduce the exposure.

What I would need, is a light amplifier to put on the sensor :)

Groeten,
Vic
 
I don't use flash much nowadays but I use a big old Metz 45 CT-1, it has 5 different auto settings.

Aperture controls the amount of flash exposure and shutter speed controls the ambient light. So, use a slow shutter speed to retain some of the atmosphere.

You have a setting for this on compact p+s, it's called slow synch.
 
i still don't understand why telling the flash you are shooting at iso 1600 won't work, but your best bet might be learning to be fast with manual flash, and/or to get a flrf that gives you guide numbers for your given exposure, such as the olympus 35sp.
 
If you don't understand, then you don't understand how auto flashes work ;) If there is a minimum distance at ISO 400, then there would be a correspondingly larger minimum distance at ISO 1600.
 
Well, there are flashes with a more generous range - many pro grade Metz and Nikon flashes at least. Some even feature offset LCD display controllers with f stop settings throughout the entire aperture range...

But consumer flashes of pre TTL vintage (and their current budget priced descendants) did not have a real film sensitivity setting - their (usually three) ranges are constant and you are supposed to change the aperture to match the film. With the requirement to have at least one practically feasible power level for every supported film speed, a starting value of 2.8 for ISO 100 is fairly natural to that principle. Your suggestion of a f/1.4 start at 400 would result in a f/0.7-f/2.8 range at the formerly standard ISO 100. That would have been suicidal to the sales, since the bulk of SLR users towards which these budget to mid price hot-shoe flashes were directed did (and do) not own any lens faster than a f/3.5-5.6 zoom.
 
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I haven't used flash for decades, but I used to use bounce flash. Is that not still a possibility? I even made my own bounce - inclined the flash head 45 degrees and pasted something shiny across the top of the flash, parallel to the ground. I know it wasn't compensated for automatically, though. But it did improve my math skills on the fly! ;)
 
Pickett Wilson said:
An auto flash has to be affected by the ISO setting on it.
Click to expand...

Wrong. The usual configuration had one or three sensor sensitivity levels (the latter on early flashes usually created through switchable ND filters in front of the sensor). That is no "ISO setting device". On expensive flashes, the matching aperture and film speed for each sensitivity step could be read out from a little mechanical calculator coupled to the sensitivity switch - but film speed was a purely mechanical input into the calculator in these designs.
 
dfoo said:
If you don't understand, then you don't understand how auto flashes work ;) If there is a minimum distance at ISO 400, then there would be a correspondingly larger minimum distance at ISO 1600.
Click to expand...

I am not ashamed to admit that you are correct. I understand manual setups, but I just let my technical electro-wizard auto-flash do its job without my understanding any more than the bare basics. It always comes out looking just like I wanted, so I haven't had the need to learn yet.
 
dfoo said:
Mechanical input or not, it still changes how the auto flash detects when to turn itself off.
Click to expand...

No, it does not. The calculators on the flashes are merely a more convenient version of the little spreadsheets printed onto the back of earlier flashes.
 
Vic,

I don't have it in front of me, but my Sunpak 383 has 3 f-stop positions in auto mode. Depending on ASA (ISO) set, the maximum aperture is 2.0. The head pivots for bounce flash. Bouncing the flash reduces the f-stop by 1 or 2 stops. Turning the head away from the subject and bouncing the flash off a wall or ceiling reduces the f-stop even more. Personal testing will help you dial in some nice soft fill light from the flash.

The unit also allows manual settings down to 1/16 of full power.

Here's a thought: Don't use ASA (ISO) 400 film with flash. Plus-X, Tmax 100, Acros 100, Foma 100.........catch my hint? Sunpak 383 auto f-stops: f2, f4, f8 at ISO 100.

A flash meter would be a big help also.

Here you go:

http://www.google.com/products/catalog?sourceid=navclient&rlz=1T4HPNW_enUS311US311&q=sunpak+383+super&um=1&ie=UTF-8&cid=13474863171406220487&ei=bSH4Su7SBYum8AaknqjzCQ&sa=X&oi=product_catalog_result&ct=result&resnum=4&ved=0CBkQ8wIwAw#ps-sellers
 
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I use manual settings only on my Metz Nikon iTTL compatible flash (i also have a Nikon). I set the R-D1 to 200 ISO, shutter speed 125/s (flash sync speed) and adjust the aperture for desired DOF for scale focusing (typically a 21mm CV f4 lens at 5.6 or 8 for party type shots) and fire off test shots. Usually 1/8-1/64 strength depending og distance to subject. I use bounce flash or not at all. This gives me a P & S combination. Works more or less without adjustment the whole evening. ;)
 
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