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A55 & wireless flash with HSS : UNusable

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Just to be sure one more time:
  • You mount the flash (42 or 58) and set camera and flash to 'fill'.
  • Turn on HSS on the flash.
  • Manual mode on camera.
  • Set the shutter speed faster than the sync speed - say 1/500 sec.
  • Every thing works fine - good exposure.
  • Remove the flash.
  • Set the camera and flash to WL (flash IR sensor starts blinking).
  • Flash still has HSS on.
  • Pop up the on board flash.
  • Set the flash where the IR sensor can see the pop up flash.
  • Both the on board flash and the 42/58 fire.
  • Black picture.
If the above is true, it's broke.

BTW - You seem to be implying that you think there is a big difference in HSS flash between 1/250 sec and 1/4000 sec. Te flash duration/number of pulses is almost the same and therefore the power will be almost the same. The flash has to stay open the entire time the curtain is moving. The second curtain will follow a little sooner with the fast shutter speed, but it still takes nearly the sync speed for the curtains to move.

TF
 
OldClicker said:
BTW - You seem to be implying that you think there is a big difference in HSS flash between 1/250 sec and 1/4000 sec. Te flash duration/number of pulses is almost the same and therefore the power will be almost the same. The flash has to stay open the entire time the curtain is moving. The second curtain will follow a little sooner with the fast shutter speed, but it still takes nearly the sync speed for the curtains to move.

TF
Click to expand...
The instruction manual shows the following:

normal sync full power guide number (105mm zoom setting) = 58m
At HSS 1/250 GN = 22.4m
At HSS 1/500 GN = 15.9m
At HSS 1/4000 GN = 5.6m
At HSS 1/12000 GN = 2.8m

I used to understand (and actually be able to explain) why this happens, but right now I am drawing a blank (real long day). Ok, I think i've got it. At the slower HSS speeds, the open shutter slit is larger than at faster times, so the frame gets exposed to more light (the pulses fire at a fixed rate) as a wider slit crosses at the same speed a narrow slit does.

Remember at just faster than normal sync speed, the opening will be almost the full frame height (second curtain starts to move just before the first curtain reaches the end of frame). But at the fastest speeds, the slit will be much smaller (second curtain starts to close almost as soon as the first opens a gap).

tom
 
OldClicker said:
Just to be sure one more time:
  • You mount the flash (42 or 58) and set camera and flash to 'fill'.
  • Turn on HSS on the flash.
  • Manual mode on camera.
  • Set the shutter speed faster than the sync speed - say 1/500 sec.
  • Every thing works fine - good exposure.
  • Remove the flash.
  • Set the camera and flash to WL (flash IR sensor starts blinking).
  • Flash still has HSS on.
  • Pop up the on board flash.
  • Set the flash where the IR sensor can see the pop up flash.
  • Both the on board flash and the 42/58 fire.
  • Black picture.
If the above is true, it's broke.
Click to expand...
The above is true.

Actually it is not a black picture, but a picture very underexposed. But the flash does something and if I manually set its power, it can even overexpose the picture in WL HSS.

If something is broken, it is not the wireless system which is working but the exposure metering or "power signal given" for WL HSS.

It would be really helpful if someone else could confirm whether it works or not.
tom55604 said:
BTW - You seem to be implying that you think there is a big difference in HSS flash between 1/250 sec and 1/4000 sec. Te flash duration/number of pulses is almost the same and therefore the power will be almost the same. The flash has to stay open the entire time the curtain is moving. The second curtain will follow a little sooner with the fast shutter speed, but it still takes nearly the sync speed for the curtains to move.

TF
Click to expand...
I agree with tom, my flash needs more power at 1/4000 than at 1/250 (keeping the same ISO and aperture). This is based on my observations.

--
http://www.photo-production.net/vincentpham
 
tom said:
OldClicker said:
BTW - You seem to be implying that you think there is a big difference in HSS flash between 1/250 sec and 1/4000 sec. Te flash duration/number of pulses is almost the same and therefore the power will be almost the same. The flash has to stay open the entire time the curtain is moving. The second curtain will follow a little sooner with the fast shutter speed, but it still takes nearly the sync speed for the curtains to move.

TF
Click to expand...
The instruction manual shows the following:

normal sync full power guide number (105mm zoom setting) = 58m
At HSS 1/250 GN = 22.4m
At HSS 1/500 GN = 15.9m
At HSS 1/4000 GN = 5.6m
At HSS 1/12000 GN = 2.8m

I used to understand (and actually be able to explain) why this happens, but right now I am drawing a blank (real long day). Ok, I think i've got it. At the slower HSS speeds, the open shutter slit is larger than at faster times, so the frame gets exposed to more light (the pulses fire at a fixed rate) as a wider slit crosses at the same speed a narrow slit does.

Remember at just faster than normal sync speed, the opening will be almost the full frame height (second curtain starts to move just before the first curtain reaches the end of frame). But at the fastest speeds, the slit will be much smaller (second curtain starts to close almost as soon as the first opens a gap).

tom
Click to expand...
You are referencing the exposure, not the power required from the flash. The exposure is less because the slit is narrower - just like ambient. The same kind of reductions in GN numbers would be seen at those shutter speeds with a constant ambient light (or 'power').

The sync speed is the time it takes the first curtain to get all the way across the frame. Think of the extremes to visualize.
  • If the time of the first curtain was instantaneous, there would be no sync speed limit because no matter how soon the second curtain started, the first would already be all the way across.
  • If the first curtain took 1 minute to go across, it wouldn't matter how soon the second curtain started after the first because the flash would have to pulse for a full minute. The pulse duration determines how much power it can put out.
Terry
 
I can see that how I presented it (1/250 vs. 1/4000 sec) would confuse the issue since the exposure certainly does change. This post that shows the incorrect conclusions by the OP:

“By not changing any other setting, shooting with WL in Manual mode, ISO 100 :
F2.8 1/125 : image correctly exposed
F2.8 1/200 (HSS thus) : image completely dark”

This is to be expected since at 1/125 sec SS, the flash duration (depending on the manual setting) will be on the order of 1/5000 sec. At 1/200 sec, the flash has to pulse for the full 1/200 sec plus (as it also does for the 1/4000 sec.).

I just tried it with an A350 and I get the same result the OP did.

TF
 
Just curious what version firmware does your a55 show?
--
Sony a700 with HVL56AM
Sony a55 ( Wife )
Sigma 10-20mm
Minolta 50mm F1.4
Minolta 28-75 F2.8 Japan
Sony 18-55 ( Kit )
Tamron 70-200 F2.8 Di
Tamron 28-105 F2.8
Tamron 28-200 3.5-5.6
Tamron 200-500 5-6.3 Di
 
" shallow depth of field with no ambient light in the image"

HSS pops the flash synced to the moment that the shutter curtain is open across the whole frame before it starts to close. The flash duration is necessarily very short. If you shoot at 1/125 sec, the exposure time will still be an action-freezng 1/4000 sec (or thereabouts).

These images were taken at 1/125 at f/8 and f/10 respectively.





I can expose the same scene at 1/30, 1/60 or 1/25 with no change in exposure since the brevity of the flash pop itself dictates exposure time. Variations in exposure are controlled by flash distance/power and aperture.

Hope that helps.

--
Dave Pierce

http://www.pptphoto.com
http://www.pbase.com/pierce324
http://pierce324.zenfolio.com/

The early bird may get the worm...
but the second mouse gets the cheese!
 
HSS is only available when the FLASH is ON camera not wireless and it cannot be bounced it has to be "DIRECTLY" pointed at subject.

HSS should be used for OUTDOORS when direct SUNLIGHT is flashing on subject. This is to avoid the HARSH shadows that would be otherwise introduced to subject.

This has been the same since HSS was introduced for MINOLTA FILM bodies back in the late 80's...
oddjobb57 said:
Hi,

Just bought this camera today. Doing my first tests, I found out that pictures taken (indoor) with wireless flash & HSS are completely underexposed, almost dark... :-(

I am doing studio shootings and here is one of my set up which I won't be able to do anymore in the same conditions than before :

F1.4 1/4000 wireless flash (this is mandatory when I want to achieve a shallow depth of field with no ambient light in the image).

I didn't have this issue with my old A550 and don't see how the SLT technology can limit this usage ?

I hope there will be a firmware update soon for this point.

P-S : I saw a similar thread mentioning that the A55 can't be properly used with studio stobes. Here I am talking about using the flahes F58AM and F42AM in wireless HSS, I don't have the issue with the viewfinder becoming dark (although the final image IS).

--
Click to expand...
--
-Alex

From the minds of Minolta to the imagination of Sony, Alpha, like no other.

http://www.pbase.com/lonewolf69
 
lonewolf69 said:
HSS is only available when the FLASH is ON camera not wireless and it cannot be bounced it has to be "DIRECTLY" pointed at subject.
Click to expand...
Lonewolf,

That is not correct. One major reason for me going with Minolta/Sony on digital was wireless HSS, while it is not intended to be used in bounced mode, it works very well when it is aimed directly.

On Canon 7D onboard wireless flash cannot do wireless HSS, but all Sony's (including A100) can :)

Cheers,

N
 
lonewolf69 said:
This has been the same since HSS was introduced for MINOLTA FILM bodies back in the late 80's...
Click to expand...
No, that is not true. the 5400HS came in 1993, and the 5400XI that was before did not support HSS. (Guess what HS in 5400HS means)

--
The world just does not fit conveniently into the format of a 35mm camera.
  • W. Eugene Smith
 
DPierce said:
I can expose the same scene at 1/30, 1/60 or 1/25 with no change in exposure since the brevity of the flash pop itself dictates exposure time. Variations in exposure are controlled by flash distance/power and aperture.
Click to expand...
Yep, but in your case your only light source is the flash. The OP says there's ambient light too, which would ruin the shot if taken like yours, and he gets rid of it by using fast shutters.

But IMO the natural way to solve that would rather be to get rid of that unwanted light in the first place instead of playing tricks to avoid it. He mentions studio shots, but the whole point of a studio is to make it a controlled environment you can light how you wish - i.e where ambient light doesn't get in the way. Dim/turn the lights off or buy some shades...

But yeah, still seems like an issue.

--
http://kilrah.dynalias.net/gallery
http://www.rc-tech.ch/aviation
 
Kilrah said:
Yep, but in your case your only light source is the flash. The OP says there's ambient light too, which would ruin the shot if taken like yours, and he gets rid of it by using fast shutters.
Click to expand...
Actually, the area was lit by ambient room light that was not all that dim. The flash simply overpowered the ambient.

I get the same effect using my 5600(s) wirelessly in a macro situation where I need ambient light to focus.

--
Dave Pierce

http://www.pptphoto.com
http://www.pbase.com/pierce324
http://pierce324.zenfolio.com/

The early bird may get the worm...
but the second mouse gets the cheese!
 
Guys this is funny, almost 2 pages of debate about the flash power & speed which could explain my issue and now some advices (I know you want to help :-) ) on how or where I should shoot.

I would try to answer to these points with 1 picture I took a couple of months ago.

Shot with a Sony A550, ISO 200, 85mm, F1.4, 1/4000s, Wireless flash with a F58AM in a softbox :



If I believe all the people who said "there is not enought power with HSS at that speed", then how come this picture was made ?

Regarding now the settings, YES I WANT to shoot at wide aperture F1.4 and control the depth of field I want, NO I don't want to cut the natural light of my room (i.e. dim it by any way) - the autofocus would suffer as well - or move to another place ;-) ... and for all these reasons in a case like that I NEED to be able able to shoot at 1/4000s (remember F1.4 + ISO 200 + some natural light on a sunny day in my room).

I will answer to the other questions in another post.

But the point is that there IS an issue with Wireless flash HSS and the A55. I went to the shop today and asked to try another model --> same problem.

The isssue is NOT due to my settings unfortunately. My shooting techniques could be appreciate or not, but I think that the real debate is, for the A55 is there an issue with this feature which needs to be fixed with a firmware update (if possible) and I would answer yes.

--
http://www.photo-production.net/vincentpham
 
Lets hope that this is just a software bug that will be fixed in a firmware release.

I am just about to replace my Nikon D40 with a Sony A55 and a HVL-F42AM and would like to have working wireless HSS. Especially since I will miss the 1/500 x-sync speed of my D40 when buying the Sony.
 
lonewolf69 said:
HSS is only available when the FLASH is ON camera not wireless and it cannot be bounced it has to be "DIRECTLY" pointed at subject.

HSS should be used for OUTDOORS when direct SUNLIGHT is flashing on subject. This is to avoid the HARSH shadows that would be otherwise introduced to subject.

This has been the same since HSS was introduced for MINOLTA FILM bodies back in the late 80's...
Click to expand...
The xi series introduced wireless flash limited to 1/60 sec, 1/45 if ratio

The si series (and 4500HS) introduced HSS flash, but only on camera flash and not bounced. Wireless shutter speed was still limited to 1/60.

The Maxxum 7 introduced wireless flash up to the full normal sync speed of the camera (instead of the 1/60 sec limit) when using the 3600HSD and 5600HSD flashes. It also introduced wireless HSS when using the 3600 and 5600 HSD flashes. The difference between the 2 wireless modes is that the guide number for wireless HSS is reduced depending on shutter speed.

tom
 
I just made a comparison between the A55 and A850 (with F20AM as the flash trigger). Images were only resized, EXIF are still there.

The set up - Flash & camera on tripod, around 1m from the subject :



A55 - ISO 100 - F2.8 - 1/160s (NO WL HSS) -> correct exposure :



A850 - ISO 100 - F2.8 - 1/160s (NO WL HSS) -> correct exposure :



A55 - ISO 100 - F2.8 - 1/250s (WL HSS) -> underexposed :



A850 - ISO 100 - F2.8 - 1/250s (WL HSS) -> correct exposure :



A55 - ISO 100 - F2.8 - 1/500s (WL HSS) -> underexposed :



A850 - ISO 100 - F2.8 - 1/500s (WL HSS) -> correct exposure :



A55 - ISO 100 - F2.8 - 1/1000s (WL HSS) -> underexposed :



A850 - ISO 100 - F2.8 - 1/1000s (WL HSS) -> correct exposure :



Last test for the high shutter speed sceptics at 1/8000s, yes 1/8000s ! (still ISO 100, opened at the widest aperture F1.4)....

A850 - ISO 100 - F1.4 - 1/8000s (WL HSS) -> correct exposure :



--
http://www.photo-production.net/vincentpham
 
Now there is some breaking it down! Hey can you link me to that flash holder on your flash stand? I never seen any with Sony Hotshoe

--
Sony a700 with HVL56AM
Sony a55 ( Wife )
Sigma 10-20mm
Minolta 50mm F1.4
Minolta 28-75 F2.8 Japan
Sony 18-55 ( Kit )
Tamron 70-200 F2.8 Di
Tamron 28-105 F2.8
Tamron 28-200 3.5-5.6
Tamron 200-500 5-6.3 Di
 
oddjobb57 thanks for your testing with the A-55. I have a friend who has just acquired the A-33 this week. If he brings it with him tomorrow, I shall do your test with my 42am flash. I believe you are onto the same findings with hss wireless as some others have posted about the A-55 in studio settings with studio flashes. Even though these are not meant for studio photography (in general) this shouldn't be the case for hss flash on-camera and wireless! Hopefully this will get addressed with a firmware update soon.
--
Glenn

I'm kinda partial to video, but I'm hangin!
 
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