Why does high speed sync exist?

Started 10 months ago | Discussions thread
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Hat Man New Member • Posts: 5
Why does high speed sync exist?

TL;DR: Read the last 2 paragraphs.

I have a sony A6000 I like to take portraits of friends with. Next weekend, I go on a trip to Tokyo, so i thought I’d step up my game a bit, and purchase an attachable flash before then.

I haven’t even bothered with the built in flash, so I’m suddenly finding myself on a crash course in flash photography. Ideally, I’d like to get a yongnuo IV for my hotshoe, and 4 yongnuo IIIs to get a basic studio setup going, but living where I live, there’s no way I can get those here in time, let alone even get a decent flash made for my modern sony camera.

So, I went to Hard Off, and bought a dirt cheap sunpak auto36SR to take with me, and learn the basics on.

Anyway, taking test shots, I learned the hard way what flash sync is. Basically, I can’t use my flash on any exposure time faster than 1/250th of a second. Even on the minimum power settings of the flash, it’s still at times too bright at that exposure time for some of the shots I try to get.

I figured out quick on my own what was going on. Upon seeing that black bar at the top of the photo, and seeing it get bigger with a faster shutter speed, it seemed to me the shutter was moving too fast, taking the photo before the flash even goes off.

This felt like a let down since that really limits my options in terms of lighting. I can’t lower my iso any further, I can change my aperature (but not without changing that sweet depth of field), I don’t have any ND or polarizing filters I can throw on the lens yet (hard to come by in the second hand stores here, and I have yet to invest in new ones), and while I can change the direction of the flash, sometimes it makes the picture look wonky when I experiment with that, and it’s iffy whether or not it’ll help matters (I usually just leave it angled up with the reflector out since that yields the most consistently decent results)... But if only I could change exposure time all the way down to what my camera can handle (1/4000s at fastest), then I could overcome all of that with a simple settings change.

This is when I started researching this “high speed sync”, and I realized that short of purchasing better flash equipment, there’s not really any easy workaround I can take advantage of.

So here’s my question:

... Why does this problem even exist? How hard would it be to put an adjustable shutter delay in the settings? Dial it in right, and you could change when the shutter goes off to meet the demands of the flash. This seems like one could easily solve this issue with software, and not have to resort to hardware.

My guess is, there’s some sort of science behind this that prevents such a simple solution (because I’m sure I’m not the first person to think this), and I’m unaware of it because I’m only just now learning how to use flashes, and am having a difficult time wraping my head around some of these concepts. What’s preventing camera manufacterer’s from including an option like this?

Sony a6000
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