Flash/Camera Question Please...

[acroreef]

Dear Folks,

Overview: I want the flash to go off every time I press the shutter...

I have a Sony A7R and a Sony flash(HVL F60M) that I attached to the hot shoe of the camera. I have the camera on manual mode. I have the settings at F11 and I am changing the shutter speed to get the full dynamic range of an interior scene. (From the shadows to the brightest areas). I also want to trigger the flash with each exposure. It seems that when I have the flash connected this way, I can only adjust the shutter speed so high, then it no longer changes the exposure on the camera.

I want to continue to move the shutter so the camera exposes for brightest to darkest, as with HDR. However I want the flash to trigger with each click of the shutter.

So what settings should I have the flash on and are there any menu settings on the camera that I might be missing?

(The reason for this is an experiment with exposure fusion...comparing a HDR set with flash and the same except adding a flash to each exposure).

Thanks in advance.

Dave

[Manfred M]

I suspect that your camera's default settings are what are causing the issue; once you hit the synch speed of your camera, you hit a wall it won't let you go to any faster shutter speeds. This is pretty standard to prevent blown shots.

I suggest you dive into your manuals and see how to set up your high speed synch functionality. Both the camera and flash may have to be set up to work in that mode. I assume both your camera and flash support this.

[William W]

What Manfred wrote: many modern cameras will NOT ALLOW the Flash Sync Speed to be exceeded. You should consult your User Manuals (plural - both Flash and Camera).

For some cameras there is a work around (without using High Speed Sync), but making that work around is only sensible for the purposes of:

> showing what Maximum Flash Sync is about;
> why High Speed Sync is necessary;
> why LEAF SHUTTER are very useful.

If a camera with a FOCAL PLANE SHUTTER is used with a Flash and the shutter time is shorter than the Flash Sync Speed of the Camera, then this is what happens; only part of the frame is illuminated by the flash:



*

Certainly I know that your Flash is capable of High Speed Sync, (HSS).

It just depends if your Sony camera supports HSS - AND ALSO - that particular Sony Flash is a "Compatible Flash" to that Camera.

If HSS is supported by both your Camera and Flash, then there are a few considerations that usually apply across all brands and models when using HSS.

These general considerations might not be detailed in your User Manual, so for your information, these considerations are:

High Speed Sync -

> won’t work for BOUNCE flash (i.e. flash head must be directed straight at the subject)
> will reduce the Flash’s Maximum Working Distance (MWD)
> affect on the reduction of Flash MWD, will increase as Shutter Time decreases (i.e. moves from 1/200s toward 1/8000s)
> used without adequate cool down time between shots, may cause the Flash to overheat and not work; or trigger an Automatic Cut-out; or simply fry the flash.

WW

[ajohnw]

It seems that sony do offer hight speed flash see for instance

http://community.sony.com/t5/Alpha-N...-6/td-p/166067

Before buying I would suggest you take a careful look at the flashes manual as the guide numbers drop off rapidly in HSS mode as shutter speed goes up.

Your aim seems to be a little curious to me. The flash will be running in fill in mode so if you set an aperture to avoid blown highlights at your max sync speed it will try and add sufficient light to illuminate dark areas. The catch with something like a room is that distances from the camera vary so the flash can't get everything correct. Say the flash exposed for a distant dark areas, closer areas would get too much light. If the camera and flash meter correctly the exposure will be set to avoid over exposing nearer items leaving the dark areas dark.

I just tried it out of curiosity. I bracketed to find the correct exposure for the sky seen through the window. North facing room and rather dark. The end of a settee close to me set the exposure and was clearly brightened up more than I would ideally like but not over exposed. More a case of un even illumination along it's length. Dark wooden furniture at a distance was slightly brighter and nearly recoverable providing I over exposed by around what the sky really needed by about 1 stop - leaving it flat rather than loosing all blue in between the clouds. The shaded area in the trees outside were also darker than I would like. I could probably do something with the shot given some post processing, some of that would have to be local and I doubt if the dark furniture could be bought up to the level achievable with HDR,

HDR has a catch for this sort of use. It's windy so the trees outside are waving about a little. The usual HDR software can't cope with this as there will be other exposures that show the trees in different positions. The only answer I am aware of is manual exposure blending which effectively means "selecting by hand" one way or the other.

John
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[William W]

. . . The OP already owns the Flash and the Camera.

[GrahamS]

Dave, a hotshoe mounted flash is not compatible with obtaining the "full dynamic range" of an architectural subject. The flash will "kill" any shadow detail and eliminate the effect of exposure bracketing. I would use a tripod and continuous or available light if you want to apply a HDR effect.

[dan marchant]

Dave, I agree with Graham. Using a flash to take multiple exposures for blending doesn't really make any sense.

When shooting real estate interiors there are two main approaches.
Option 1. Balance the exposure of the bright outdoor scene with the darker indoor scene by adding more artificial light (flash or strobe).
Option 2. Take multiple exposures and blend them together.

Option 1. If you are doing this you don't need to do exposure blending because you set up the lights to get a balanced exposure. If your lighting isn't giving you a balanced exposure you haven't set it correctly (or it isn't capable of doing the job - in which case you may as well not use it).

Here is an example of a single exposure that used flash to balance the exposure...


Option 2. Take multiple exposures and blend them together. If doing this then using artificial lights makes no sense as the lights either balance the exposure (in which case no blending is needed) or it doesn't - it which case it isn't helping because you still have to do the blending. The only time artificial light will help is if you specifically want to add light to part of the scene for artistic reasons (such as using a flash with a coloured gel on part of the scene).

Here are a couple of examples of an exposure blended images....

This was 3 exposures blended "manually" using photoshop/layers/masks...


and this one is three exposures blended using a trial/test version of Photomatix Pro HDR software...

[ajohnw]

. . . The OP already owns the Flash and the Camera.

Sorry about that but now it seems that the flash has to be set correctly to allow higher speeds.

Dan's flash balanced shot is interesting but I don't think it illustrates the problems. I took something similar using 24mm FF equivalent. The end of a settee was in the viewfinder and less than 1m away from me. Around 5m away there was some dark wood furniture in shadow that needed brightening up and a window behind that. The speed and aperture had been set to give a decent exposure of the scene out side the window. Single flash in TTL mode so the camera exposes at a level to avoid blowing high lights. That is set by the setee that is close to me so the dark wooden furniture hardly receives any extra light at all and has negligible effect on any shadows.

The other effect which could be processed out comes from the far end of the settee receiving light from the window and the near end perfectly exposed by the flash. So it has uneven lighting along it's length.

If I changed focal length and just framed the window and the dark furniture the results would probably be ok but that usually isn't what is needed when interiors are shot. Choosing some framing in between the 2 might work out but not over exposing bright area is always likely to win. The darker areas may be recoverable or may not.

So I'm curious how Dan took the shot and what PP was used to remove distance effects from the flash. Maybe bounce was used as the walls are white. Some wall colours can make that a none starter.

John
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[William W]

John - Thanks for acknowledging.

***

I agree with Graham and Dan that there is no apparent technical photographic rationale for making interior architectural shots with Flash as Fill with the Flash in HSS Mode.

BUT the OP stated, (bold and underlined is my emphasis)

“The reason for this is an experiment with exposure fusion...comparing a HDR set with flash and the same except adding a flash to each exposure”

I wish the OP would return to expand further on the reasons for this “experiment”.
For example, an “experiment” can be useful simply for its own purpose of doing.

Also - it always bothers me when “thanks in advance” is posted in the OP: doing so seems tantamount to suggesting that all the answers go into a void ... personally I would much rather a conversation: which IMO is more beneficial to all.

WW

[ajohnw]

I agree Bill. The only reason I posted - twice - is to try and explain why in most circumstances the use of flash wouldn't help at all. It might with a convention single shot but even that has the problems I outlined.

I'd guess the OP just wanted to try it. As I did but with no hope of it achieving anything worth while. In principle it is possible to use flash to achieve various levels of illumination on things in an interior shot but I feel it could turn out to be rather difficult. Say for instance I spot metered on the dark wood furniture in shadow that I mentioned and used TTL flash. Forgetting mid grey exposure problems this would have the desired effect of illuminating it adequately and removing shadows and could form one part of an HDR shot sequence. This would leave me wondering if a flash exposure could be locked as it's set by the pre flash and in the situation I described I wouldn't be able to frame and get the spot on the furniture.

John
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[William W]

On a totally different note:
Dan's picture of the hallway. . . the door at camera left / foreground is slightly ajar . . . that totally has me hooked - it makes the picture for me.

WW

[dan marchant]

On a totally different note:
Dan's picture of the hallway. . . the door at camera left / foreground is slightly ajar . . . that totally has me hooked - it makes the picture for me.

WW

Shhhhhh..... We don't talk about what's in there.