5D Sync Speed

Hi Gang,

Since I know it'll be useful, I went back and pulled some photos for a demonstration.

Attached is a shot at 1/320th of a second using 2 Ike SS200's and the Canon 5D. The "bottom" of the frame is dark - the right side in this instance.

Cheers

James

Here's one at 1/400th and the dark patch has moved up a lot. I think the D2x with it's smaller sensor can get away with this, but my full frame Canon cannot.

Cheers

James

The curtain problem JUST starts to appear at 1/250th, but only if the subject is right up against the side of the frame. I would say 1/200th is a max sync for the 5D setup if there is a subject at the bottom that needs to be strobe lit.

Cheers

James

Great stats, James.

I am sure that this question will be asked regularly over the coming months - and we'll be referring people to your posts here!

One factor worth considering is that you were using big strobes, probably on half or full power - meaning a long burn time. You might be able to push the synch speed a bit with a fast burning strobe like the Inon?

Alex

Hi Alex,

I admit I don't understand the mechanics very well. You'd think that a longer burning strobe would be better???? In the extreme, think of a strobe that stays lit for 1 second. It would be able to paint the whole scene as the opening in the shutter curtain passes over, right?

I don't know which way the curtain opening passes, but I'm guessing from top to bottom. In these shots, it looks like the strobe quit firing towards the end of the shot, or if the curtain moves from bottom to top, it didn't start firing in time. The latter makes more sense to me.

Perhaps Herb will chime in, he understands this better than I do.

Cheers

James

Nope you want a shorter burning strobe. From what I understand - Herb has found that he has been able to push his cameras to faster synch speeds with short burning strobes like the Inons.

This surprised me initially (until I saw the results) as I thought the issue that at speeds greater than the quoted synch speed was that the sensor was never entirely exposed at one time. In otherwords the 2nd curtain is already closing it before the first curtain has finished opening it. And as a result however fast the strobe was wouldn't matter.

Best wait for Herb to chip in...

Alex

A long burning strobe has a longer run up time to full output, in the order of a hundred msec. The rear curtain is starting to move in that time with high speed sync, so even if the sync speed can be pushed up, the area under the rear curtain does not see the full output of the strobe.

This is one of the reasons why the SS200 is not able to do preflash style TTL, the ramp up time of the tube is longer than the whole TTL process. As the DS200 IS able too (thanks to Ike's engineers and their magical pixie dust), I think you should buy two of those and give me your SS200's

All I know is that the 300D can be shot at 1/320 using the Inon Z220 on all power setting, and I've seen others post here that there is a small dark band at that shutter speed using the Ikelite DS-125.

I'm not quite sure I really understand the reason. Could be that there's a slightly longer delay in getting light out of the bigger tubes and/or it takes them longer for the full dump. If I have time this evening I'll set mine up and take a few shots of my beautiful white living room wall and report back.

Hi Craig and Herb.

I have one SS200 and one DS200 now, so I can do some comparison tests if y'all want me to. I also have some DS125's.

Cheers

James

The answer is allll...most .

At 1/250 with the Inon Z220, you can just make out a little black on the bottom edge. It's not even. It's a little darker on the lower left corner.

In doing this test, I also learned that the target light and laser on the Z220 will work with the Aquatica 5D out-of-the-box!

I was sure that I'd have to revisit this DIY project:

http://wetpixel.com/forums/index.php?showtopic=5799

to get them to work in the new setup.

Hi Harb,

Thanks for the info - that's not bad at all.

Cheers

James

For my 5D and Sea & Sea strobes I am fine at 1/250 as well. At 1/320 there is a hairline of black ( which could easily be cropped )

Thanks for posting test shot and correspondin information.

Thanks for posting this also: "In doing this test, I also learned that the target light and laser on the Z220 will work with the Aquatica 5D out-of-the-box!" FedEx man just dropped off a 5D, I have pair of Z220 strobes and will possibly go with Aquatica housing. Bonus would be working accessory lights.

Here's a test shot I took last week with the 5D at 1/250th.

(100mm lens with MacroMate & Dual Sea & Sea YS90 Autos)

You can only see the shutter in the bottom of the frame.

On another note I found it interesting that in all my shots faster than 1/200th where you see the shutter, the shutter is always a little higher on the left side. I suspect that imperfection doesn't impact the images quality thought, rigth?

Here's a test shot I took last week with the 5D at 1/250th.

 

(100mm lens with MacroMate & Dual Sea & Sea YS90 Autos)

 

You can only see the shutter in the bottom of the frame.

 

On another note I found it interesting that in all my shots faster than 1/200th where you see the shutter, the shutter is always a little higher on the left side. I suspect that imperfection doesn't impact the images quality thought, rigth?

<{POST_SNAPBACK}>

That's consistant with my shots. The black strip is slightly higher on the left side. With 2 samples we can't conclude it that way by design or just random miss alignments. It'll only affect shots at shutter faster than 1/200.

In doing this test, I also learned that the target light and laser on the Z220 will work with the Aquatica 5D out-of-the-box!

Herbko,

My dual bulkhead housing came with four pins in one connector, two in the other. Strobes work fine, but I'm curious about your functioning target light and laser. My Z220 target light and laser work with the Z220 connected to the four pin and only with the magnet in, but also stay on continuously.

Is this the same configuration and functioning of Z220 you're referring to, target light and laser work when magnet is installed and stay on until magnet is removed?

Fast strobes help if you have a camera with an exceptional high sync speed like 1/500s (I think Nikon D70 with electronic CCD shutter).

However, most of the energy is emitted very quickly at the beginning of the burning duration. Light output is proportional to capacitor’s voltage. For example, a strobe requires 1/125s for dumping a full load means you would most probably get somewhat 95% of the brightness within half of the burning time (1/250s). Theoretically, a manufacture could flat rate a strobe’s guide no. by a little amount and sell the strobe as superfast.

The visible curtain does not have anything to do with the strobe speed. The strobe could be extremely fast – but that doesn’t help if the strobe has no chance to expose the entire sensor because the shutter starts to close before it has opened entirely. Herb’s findings show that there is some margin left beyond Canon’s given specs and you can push the speed a little further before the curtain becomes visible. Canon states 10D sync. speed with 1/200s. I can do 1/250s with Z220 and DS125. DS125 is not slower here - the picture doesn't become darker. But again, this has nothing to do with the curtain. Camera's sync speed limit is strobe independant! With 1/320s my 10D already records the curtain.

Theoretically, as James said, a very long burning strobe with constant power output would enable shorter sync speeds. Canon guns use a long burning kind of strobo flash for high speed sync (up to 1/8000s). The power output is constant over the burning duration (with very high frequency peaks) and the strobe burns long enough to light every portion of the sensor while the curtain runs.

Julian

Herbko,

 

My dual bulkhead housing came with four pins in one connector, two in the other.  Strobes work fine, but I'm curious about your functioning target light and laser. My Z220 target light and laser work with the Z220 connected to the four pin and only with the magnet in, but also stay on continuously.

 

Is this the same configuration and functioning of Z220 you're referring to, target light and laser work when magnet is installed and stay on until magnet is removed?

<{POST_SNAPBACK}>

Yes. The magnet goes in the "N" hole. The light comes on in the 4th position of the mode switch, just before the "test" position. No light when the switch is in the 3rd position. The light goes off just before the strobe fires as it should.

Fast strobes help if you have a camera with an exceptional high sync speed like 1/500s (I think Nikon D70 with electronic CCD shutter).

However, most of the energy is emitted very quickly at the beginning of the burning duration. Light output is proportional to capacitor’s voltage. For example, a strobe requires 1/125s for dumping a full load means you would most probably get somewhat 95% of the brightness within half of the burning time (1/250s). Theoretically, a manufacture could flat rate a strobe’s guide no. by a little amount and sell the strobe as superfast.

 

 

<{POST_SNAPBACK}>

I think if the peak of the strobe light is delayed, as some of the older Ikelites seems to be (warm up time?), the effective xsync may be reduced. I've never had a problem using the 300D at 1/320 with the Inon strobes, but I've seen tests where a DS-125 will leave a small black line at that speed.