I am currently looking at flashes a lot and it appears to me that camera and flash producers are making it increasingly hard to derive any value from an external flash.

I have one old flash with a guide number of 40 that has a fixed angle head sufficient for f=35mm, so it is advertised with a guide number of 40. There is an optional zoom head with its own guide number tables, having 50 at f=70mm, 53 at f=100mm and 70 at f=200mm.

Now I get to an old flash with built-in zoom reflector covering a range from f=24mm to f=100mm (basically you pull it out for longer range). That one is advertised with a guide number of 35. Consulting the sliderule style calculator on its back makes it possible to figure out that this guide number holds for f=50mm. At f=100mm, it would have about 44, at f=24mm (zoom head not extended at all) about 26. Ok, specifying at f=50mm seems sort-of a fair compromise even though the fixed-head flashes would always cover a wider angle than that (but not 24mm for sure).

So now I look at current offerings of the same manufacturer and you don't even get to figure out the guide number at all. They advertise a guide number of 36 but there is (at f=105mm) in the small print, so small that several dealers are stating that this is the guide number at f=50mm. So what does the instruction leaflet say? I mean, apart from "we do everything automatically, don't bother"? Looking at manual specification of flash power tells you you can reduce up to M/128 and with regard to the required reduction, consult a flash exposure meter.

Come again?

To make comparison and reuse harder, everyone has his own through-the-lens measuring systems. While this proliferation started in analog times already, digital has made it worse. I'd expect third-party flash manufacturers to produce multi-standard flashes, but you have to buy your flash for your particular camera manufacturer (and sometimes type). The adapter system SCA3000 is on the way out.

Now one of the main points of an external flash is being able to compose a scene which more often than not means that the external flash is not being the sole responsible light source. As a consequence, any automatism for determining its strength is likely to turn out problematic since it is looking at things it is not responsible for.

So my impression is that "modern" flashes are weak and the manufacturers don't even tell you how weak they are. If a flash is the sole light in a scene and a direct light (which makes its automatic zoom action desirable in the first place), that's sort of ok and modern sensors allow accommodation with higher ISO values without too much damage.

But as a competing light source, it has to hold its own against (at worst) the sun in backlit situations. And you cannot raise the ISO for that.

So my impression is that consumer external flashes move in a direction where they don't offer a lot any more over built-in camera flashes (short of a swiveling/tilting head) which would doom them into becoming spurious.

Am I wrong with that impression?

closed as primarily opinion-based by null, scottbb, Philip Kendall, mattdm, Dan Wolfgang Jan 13 at 22:46

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.

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    "don't offer a lot any more over built-in camera flashes (short of a swiveling/tilting head)" A swiveling/tilting head is an enormous advantage for lots of situations. – Philip Kendall Jan 13 at 18:54
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    This is just an opinionated rant in disguise. It has wrong premises, like automatic flash not being able to work as fill/main light next to other sources and wrong conclusions, like external flashes being useless for lack of comparability of guide numbers. If external flashes appear to be useless to you simply don't buy one. The comparison to built-in flashes is ridiculous. – null Jan 13 at 19:27
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    Hi. From the Help Center page What types of questions should I avoid asking?, "To prevent your question from being flagged and possibly removed, avoid asking subjective questions where … your question is just a rant in disguise: '______ sucks, am I right?'". – scottbb Jan 13 at 19:35
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    Yes, VERY wrong. And yes, rant. Don;t know what you might be seeing, but it's clear that you should look for a better grade of flash. There are exceptions, but hot shoe flash is typically 4 to 8 times more power (maybe 3 EV) at 24 mm zoom than is the internal flash, and can zoom and can tilt and can work off camera. The flash manual should have a guide number chart for zoom and/or power level. – WayneF Jan 13 at 20:00
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    I'm voting to close this question as off-topic because it isn't really looking for information. It is just complaining — mostly inaccurately. – mattdm Jan 13 at 22:30

Am I wrong with that impression?

Yes, you are very wrong. Modern flash units are not “weak”, and they are not “becoming useless”.

Today’s external flash unit have lots of power and are loaded with great features, but like anything, there is a learning curve.

Your rambling, non-sensical question seems to imply you don’t really understand how to use an external flash, and it appears you want to use your frustrations as an excuse to keep using the camera’s built in flash.

That would be a big mistake.