Warning, Stupid(ish) question: RE. Sync Speed

BuS_RiDeR · Aug 31, 2012

I can't help but feel that I should know the answer to this... But I'm a bit confused. In my research of flashes/strobs, I have noticed that most web sites, blogs. and videos that I've seen; refer to the optimal sync speed for studio work with speedlights or strobes is 1/200th of a second.

Am I correct in saying that the sync speed is determined by the camera and not necessarily the flash/strobe that is being used?

For example: My Canon 50D does not seem to support 1/200th... However, it does do 1/250th... And my camera manual refers to 1/250th as the sync speed. So... does that mean that the camera determines the sync speed?

Ballistics · Aug 31, 2012

Sync speed is determined by the shutter system of the camera.

BuS_RiDeR · Sep 1, 2012

Ballistics said:
Sync speed is determined by the shutter system of the camera.

Thank you.

unpopular · Sep 1, 2012

Balistics is correct. With non-dedicated lights you can push the sync, but it's not always going to be reliable.

Modern TTL sync speed OTOH can be very high. I think someone here mentioned to me that some Canon units can sync up to 1/1000 with certain compatible bodies. Most non-ttl compatable lights, however, use pretty primitive capacity/coil trigger mechanisms.

IByte · Sep 1, 2012

I thought Canon sync speeds was determined by their flash, where as Nikon's sync speeds is determined by their bodies? To the internets!!

tirediron · Sep 1, 2012

Sync speed is the highest speed at which the shutter is completely open exposing the entire sensor at the same time. At speeds above sync, the shutter works sort of like a slot that passes in front of the sensor.

KmH · Sep 1, 2012

Watch this video. Learn how your #1 tool works.

Shutter/Flash Synchronization - YouTube

unpopular · Sep 1, 2012

tirediron said:
Sync speed is the highest speed at which the shutter is completely open exposing the entire sensor at the same time. At speeds above sync, the shutter works sort of like a slot that passes in front of the sensor.

I was not aware that a curtain shutter ever behaved like a traveling slit shutter, is this accurate? I thought that regardless of speed, it would always completely open and then shut.

usayit · Sep 1, 2012

unpopular said:
I was not aware that a curtain shutter ever behaved like a traveling slit shutter, is this accurate? I thought that regardless of speed, it would always completely open and then shut.

he is right..... shutters faster than sync behave similar to a traveling slit. Old cloth shutters travel horizontally and modern shutters with metallic blades travel vertically. There are two shutter curtains... one opens at the beginning of exposure... the second closes at the end of exposure (hence the meaning behind second and first curtain flash). Faster than sync, the second curtain begins to close before the first shutter completes its travel. If the flash is set above sync, the exposure will only occur at the opening between the first and second shutter which will not be the entire frame.

Studio setups that require fast sync speeds will use leaf shutters. Some would build the leaf shutter into the lens itself. Leaf shutters behave more like an iris rather than two travellng curtains.

Modern flashes with high sync capabilities will accomplish uniform exposure throughout the frame by emmitting several bursts as the slit between the curtains travels.

unpopular · Sep 1, 2012

Interesting! Does the slit size vary like it did with the old Graflex shutters?

usayit · Sep 2, 2012

unpopular said:
Interesting! Does the slit size vary like it did with the old Graflex shutters?

Not totally familiar with the graflex shutters.... I think they had avtal slits cut into the rear curtain that was spring loaded.

The slit in this case is not cut into the rear curtain but instead there are actually two curtains. The space between the curtain forms the travelling slit and the time between the first curtain movement to the second curtain movement as determined by the cameras clockwork as per the shutter setting. As such, the traveling distance between the curtains does change as the speed at which the curtains moce individually is constant.

usayit · Sep 2, 2012

PS... there was a Nikon DSLR a while back and a few others that implemented electronic shutters that were capable of syncing at higher shutter speeds with out requiring tricks like multibursts froma flash. It was accomplished by controlling the time of exposure electronically on sensor rather than relying on mechanical shutters.

unpopular · Sep 2, 2012

The old graflex shutters, at least prewar, had a cloth curtain with several slits of various sizes cut into it which would travel at various speeds. You'd have a little table which would tell you which slit and "tension number" to select to get an equivalent shutter speed.

The advantage is that you could get much faster shutter speeds than a traditional leaf shutter, you can hand hold at very slow speed provided that tension was high enough - I could get down to 1/30 on a 4x5 SLR - but because the slit was moving constantly, you absolutely could not use a flash - for flash photography you'd have to either use the leaf shutter on the lens (common with press cameras, uncommon with SLRs), or just use a small aperture and "bulb" mode with high tension.

Mike_E · Sep 2, 2012

BuS_RiDeR said:
I can't help but feel that I should know the answer to this... But I'm a bit confused. In my research of flashes/strobs, I have noticed that most web sites, blogs. and videos that I've seen; refer to the optimal sync speed for studio work with speedlights or strobes is 1/200th of a second.

Am I correct in saying that the sync speed is determined by the camera and not necessarily the flash/strobe that is being used?

For example: My Canon 50D does not seem to support 1/200th... However, it does do 1/250th... And my camera manual refers to 1/250th as the sync speed. So... does that mean that the camera determines the sync speed?

What they're talking about here is that ambient light can affect your shot if you use a low sync speed. Bumping your shutter speed up into the 200th range will take any light that you're likely to have in your studio (assuming that you are trying to control extraneous light) out of the equation. So, since the shutter speed has no affect on what you get from the strobes so long as you stay withing your sync range, staying at the top of your range is optimal.

Patrice · Sep 3, 2012

usayit said:
PS... there was a Nikon DSLR a while back and a few others that implemented electronic shutters that were capable of syncing at higher shutter speeds with out requiring tricks like multibursts froma flash.

Our old D70 will sync at all shutter speeds up to it's maximum 1/8000 sec. but only with a non-dedicated flash. I've tested this with Vivitar 285HV, Metz 45 CL-4 and Metz 45 CT-5. The connection was via pc cable. Problem was that at 1/8000 sec a full power burst was longer than the shutter and thus got underexposure. Drop down to lower powers and things got better but the ISO had to be pushed beyond the useful limits of that camera or the aperture opened to 1.8 or 1.4 and thus no DOF left.