Question regarding flash sync speed on X-T1

[lmirante]

Hi.  I have a question regarding flash sync speed on an X-T1.  I'm using a Canon speedlite.

 

I know the sync speed is at 180 but I did some tests at 250 and I didn't see any issues.  At 500 I started seeing a darker bottom half with a gradual fading to properly exposed.  Has anyone else done this successfully or am I missing something?  Consider me an intermediate photographer, comfortable shooting on manual with a manual flash but definitely still learning the nuances.

 

Thanks for any help anyone can give here.

 

 

 

 

[Vladimir]

Hi.  I have a question regarding flash sync speed on an X-T1.  I'm using a Canon speedlite.

 

I know the sync speed is at 180 but I did some tests at 250 and I didn't see any issues.  At 500 I started seeing a darker bottom half with a gradual fading to properly exposed.  Has anyone else done this successfully or am I missing something?  Consider me an intermediate photographer, comfortable shooting on manual with a manual flash but definitely still learning the nuances.

 

Thanks for any help anyone can give here.

You are not missing anything. At 180/1" manufacturer guarantees (or at least has to ) no issue with synchronization. On most cameras it's can be higher where black bar start appearing. As well it depends on the triggering system you use and the chain of them (pocket wizard activates younguo which activates Cactus). My XT1 works 90% at 1/200" with my Canon's 600EX and Profoto's. And sometime the bar is very slim and its easy to crop

[craigk49]

The black bar is the shutter starting to close. On my X-T1 I can get away with 1/200th no problems. If you are getting 1/250th that is a bit better. Other people I've talked to can't go above 1/80th. Most likely the small variation is due to minor manufacturing differences. Fuji, probably only tests shutters to the 1/180th standard for flash synch. As long as it passes that test, it passes and is used.

 

Similar variances occur with most mechanical devices coming off of assembly lines. No surprise, but it is nice when your copy does a bit better than it should. 8-)

[flysurfer]

Hi.  I have a question regarding flash sync speed on an X-T1.  I'm using a Canon speedlite.

 

I know the sync speed is at 180 but I did some tests at 250 and I didn't see any issues.  At 500 I started seeing a darker bottom half with a gradual fading to properly exposed.  Has anyone else done this successfully or am I missing something?  Consider me an intermediate photographer, comfortable shooting on manual with a manual flash but definitely still learning the nuances.

 

Thanks for any help anyone can give here.

 

If your flash is fast enough (e.g. due to low output), 1/250s is perfectly possible.

[lmirante]

Well, lucky for me I guess.  The weird thing is I'm not getting a dark bar.  It's more like a soft graduated ND filter.   I wasn't aware the output of the flash would make a difference here.  I knew it helped refresh time but I didn't know it would impact this.  Since this is shooting outside with a low fill flash, it should be consistent.

 

Thanks for your responses. 

 

[korbasiewicz]

If your flash is fast enough (e.g. due to low output), 1/250s is perfectly possible.

 

Actually it is complete opposite - if your flash lasts for time long enough 1/250s is perfectly possible (that's why with continuous light you can use any shutter speed, because it lasts long enough).

 

Let me explain now - when you have SS set to 1/180 or lower, second curtain starts to close after the first curtain is fully opened. So let's say we have very fast flash - sequence looks like this:

 

1. First curtain starts to open

2. First curtain opens fully

3. ZAP - flash just had been triggered and it lasts 1/2000s

4. Second curtain closes

 

With SS set to 1/250 :

1. First curtain starts to open

2. Second curtain starts to close after 1/180

3. First curtain opens fully

4. ZAP - flash fires for 1/2000s (but a small bit of flash is already covered that's why we have thin black bar)

5. Second curtain closes

 

If we will set SS to 1/250 and rear curtain flash we will have:

1. First curtain starts to open

2. ZAP - flash fires for 1/2000s (but a small bit of flash is already covered that's why we have thin black bar)

3. Second curtain starts to close after 1/180

4. First curtain opens fully

5. Second curtain closes

 

Basically black bar should be at the top or bottom of the frame (in panoramic view) depending on the sync type - whether flash is triggered after first curtain is fully open - scenario 1 - or right before the second starts to close - scenario 2).

 

Now let's think about hypothetical flash which lasts for 1s:

 

With SS set to 1/250 :

1. First curtain starts to open

2. Second curtain starts to close after 1/180

3. First curtain opens fully

4. ZAP - flash starts

5. Second curtain closes

6. Flash stops 

 

We still have black bar

 

If we will set SS to 1/250 and rear curtain flash we will have:

1. First curtain starts to open

2. ZAP - flash starts

3. Second curtain starts to close after 1/180

4. First curtain opens fully

5. Second curtain closes

6. Flash stops

 

Only in this hypothetical situation we end up with fully exposed frame.

 

 

[flysurfer]

Wow, quite a long explanation for something that isn't correct, but who cares, anyway.  

 

(If you know German, have a look at the Wikipedia article covering the topic.)

[x-tc]

 

Actually it is complete opposite - if your flash lasts for time long enough 1/250s is perfectly possible (that's why with continuous light you can use any shutter speed, because it lasts long enough).

 

As the name implies its about synchronization.   i.e. When the flash goes off relative to when the respective shutter areas are open.  When the exposure time is shorter then the X-sync speed, areas are expose in a partial slit like manner; i.e. not exposed all at once.   This slit is created by tracking the rear shutter behind the front shutter.  The separation distance between the two determining exposure period for each area.  The flash must deliver same amount of light when each area of the sensor is being exposed by the shutter gap that tracks across the frame at the rate of X-sync.  The X-sync speed of the X-T1 is 1/180. 

 

https://en.wikipedia.org/wiki/Flash_synchronization#X

 

Here is what happens when lighting is not the same and shutter speed is faster than the X-Sync. So its not just about duration. Its also about constant intensity over each area when the shutter speed exceeds X-Sync. 

 

https://en.wikipedia.org/wiki/Focal-plane_shutter#/media/File:Lightning_rolling_shutter.jpg

[hrk]

For some reason I can only use 180 on the 35mm, but I can go to 250 when using the 56mm

[romi.gilles]

it's a reason why some people use the flash right on the hot-shoe or with a sync cable. wirelessly, isn't fast enough. i'm hoping the XP2 introduces HSS to the Fuji X system.

 

For some reason I can only use 180 on the 35mm, but I can go to 250 when using the 56mm

^

hmm.. maybe the narrower angle is missing the curtain.

 

 

(Sent from another Galaxy via Tapatalk)

[flysurfer]

HSS should be easy to implement via firmware. It's already there technically, as the Nissin i40 works with HSS in manual mode. However, you need a strong flash for HSS, and since Fuji still has to provide new (stronger) flash hardware, the software apparently has to wait until the hardware announcement. Fuji wants to sell Fuji flashes, not Nissin flashes after all.

[lmirante]

HSS should be easy to implement via firmware. It's already there technically, as the Nissin i40 works with HSS in manual mode. However, you need a strong flash for HSS, and since Fuji still has to provide new (stronger) flash hardware, the software apparently has to wait until the hardware announcement. Fuji wants to sell Fuji flashes, not Nissin flashes after all.

 

Is there something specific about the Nissin i40 that makes it work with HSS?  I was using a Canon Speedlite when I originally found this disparity so I obviously was shooting in manual mode.  If there's something I could apply to the Canon that would be great.  I would consider getting a Nissin i40 if that specifically works in HSS.

[flysurfer]

Well, then get one. I actually like its warmer color temperature. That came in very handy for wedding party shots on the dance floor.