Off camera flash people... help me.

[CuriousMike]

I googled "beginner off camera flash" and spent about a total of 20 minutes reading and 3 minutes of youtube and figured I knew everything I needed to know.

Those 20 minutes netted me purchasing an inexpensive flash and flash remote trigger.
Yongnuo 560 flash and trigger. Pretty sweet for being cheap.
I also purchased a $35 "Cowboy studio" stand and umbrella.

I now have off camera flash.

The 3 minutes of youtube instructed me to treat the camera as exposing for the background, and use the flash for exposing for the foreground.

Easy peasy.

So, I set my camera to something like 1/200th, f8 and the flash to 1/32nd power and bang!

OK, sweet.
Now, i'm thinking, i'll be clever. I'll set the camera to 1/400th, f5.6 (or f8) with same flash power and that'll make the background darker.... my plan is to find a fast enough shutter speed to essentially render the background black.

Uh-oh - there's something deep in my memory banks about "flash sync speed", but hell if I'm going to read about it. I'll just ask everyone here if what I'm trying to do can work.
(I also went back to 1/200, but then set the aperture to something like f11 -- which darkened eveything. Then I tried pushing the flash power up more ... but I never got a black background.)

It also surprised me that, at least with my Dad, the flash resulted in no reflections on his glasses.

 

[blastingcap]

You need HSS (high speed sync... though I think Nikon calls it Auto FP HSS or something? http://www.nikonusa.com/en/Learn-An...ed-sync-to-illuminate-fast-sports-action.html) to go above the x-sync speed rating of your camera. The YN560III is capable of going very fast, well above 1/200th second, but your camera's shutter is not... at least not without communicating to a non-dumb flash about its predicament, so that the non-dumb flash can basically fire at reduced power for longer than normal.

You have a d610? The x-sync speed is 1/200 sec. So you will not be able to use the YN at any speed faster than that.

http://imaging.nikon.com/lineup/dslr/d610/spec.htm

There is a workaround for this that may or may not work: http://www.dpreview.com/articles/1653552682/high-speed-sync-with-yn560-flash

I've never gotten that to work with a Sony camera though it seems to work on my Canon and some people say it works with Nikon. If you have a flash that can do HSS, you can set the YN to optical slave mode. If you don't have such a flash, I'm not sure your built-in flash on the D610 can substitute. I know it supports wireless commander mode so give it a try.

 

[Syborg1211]

I think the issue is that the flash is hitting the background which is unavoidable with an umbrella. Flash lighting is all about ratios. If you move the flash closer to your subject, the ratio of distance between the flash to your subject and the flash to the background will go up. The bigger this ratio the more the difference you will see between the exposure of these. You can accomplish the same thing by moving your subject further from the background. Or do both together to get the best results.

If your background is lit by something other than your flash and you still want to darken the background but are being limited by the flash sync speed, your only option if you cant do HSS as mentioned above is to use a neutral density filter to knock all that ambient light out, then add light back in using flash (typically at full blast).

In the end, off camera lighting is all about placement of the flash. Typically the closer to the subject the better - usually it's right on the edge of my frame. If you're not getting the results you want you usually need to move the flash, not just adjust the power.

 

[CuriousMike]

I think the issue is that the flash is hitting the background which is unavoidable with an umbrella. Flash lighting is all about ratios. If you move the flash closer to your subject, the ratio of distance between the flash to your subject and the flash to the background will go up. The bigger this ratio the more the difference you will see between the exposure of these. You can accomplish the same thing by moving your subject further from the background. Or do both together to get the best results.

If your background is lit by something other than your flash and you still want to darken the background but are being limited by the flash sync speed, your only option if you cant do HSS as mentioned above is to use a neutral density filter to knock all that ambient light out, then add light back in using flash (typically at full blast).

In the end, off camera lighting is all about placement of the flash. Typically the closer to the subject the better - usually it's right on the edge of my frame. If you're not getting the results you want you usually need to move the flash, not just adjust the power.

The exposure triangle is addition.
Flash photography is differential equations.

I thought, in order to have the most diffuse light, you wanted the umbrella right on top of your subject.

For these photos, I had it literally as close to them as possible. I also pulled them forward from the door quite as far as the short hallway would allow.

The technique for HSS seems to indicate I need a separate flash to trigger my current flash at a higher speed... I think?

I have to re-read this. My head hurts.

 

[Syborg1211]

HSS isn't going to do much for you if the flash is what's lighting up your background. Typically black background shots are quite difficult to "create" by just limiting the light. Usually need a true black backdrop.

 

[slashbinslashbash]

If your subject is 2 feet away from your light and your background is 4 feet away from your light then the subject will be 2x as bright as the background. If the subject is 2 feet away from your light and the background is 8 feet away then the subject will be 4x as bright. It's about ratios. If you are working in standard residential dimensions then it will be very hard to get the ratio large enough to create a black background just from lighting ratios. Buy some dark velvety fabric and it will work well for a black background.

The shutter on most DSLR's is not an instantaneous thing. It is a moving curtain. At a slow speed (say 1/2 second), the top curtain opens, the whole thing stays open for the majority of the 1/2 second, then the bottom curtain closes. Then the whole thing moves back down for the next shot. Now when your shutter is set to a fast speed (say 1/1000 second) the top curtain opens, then before the top curtain has reached all the way to the top, the bottom curtain starts moving upwards as well. The two shutter curtains moving in parallel essentially create an open slit that moves across the sensor. There is no time when your sensor is fully exposed to light; the bottom part is first exposed, the slit moves from bottom to top, then the top is the last part exposed.

This is what creates the shutter sync problem. A flash can generally go off very fast (discharge >95% of its energy in less than 1/1000 of a second, sometimes 1/10,000, it will vary depending on brand and design and power settings, blah blah you get the idea but they are generally very fast. If you were in a completely dark room, with NO outside light, you could create a flash-lit photo with 1s exposure, f/8, ISO 200, that looks EXACTLY the same as the same photo with 1/200s exposure, f/8, ISO 200. Your flash essentially acts as your shutter. Even subject blur won't be an issue with the 1s exposure, because the strobe effectively freezes the motion by discharging completely within a very short amount of time. The problem is when you try getting faster than 1/200s, which is the minimum amount of time that your camera can guarantee that the entire frame will be exposed to light at the same time. If you try going to a faster shutter speed, your strobe will only illuminate a part of the frame and it will be weird.

 

[Syborg1211]

If your subject is 2 feet away from your light and your background is 4 feet away from your light then the subject will be 2x as bright as the background. If the subject is 2 feet away from your light and the background is 8 feet away then the subject will be 4x as bright. It's about ratios. If you are working in standard residential dimensions then it will be very hard to get the ratio large enough to create a black background just from lighting ratios. Buy some dark velvety fabric and it will work well for a black background.

Light drops off a lot faster than that. It goes by the inverse square law [Intensity = 1/(distance^2)]. So in your example, subject is 2 feet away and background is 4 feet away, the subject will be 4x as bright. This however does not take into account the falloff of the light source/light modifier itself. From the OP's posts it looks like the light was aimed more at the background than at the subject so that's why the two look similarly exposed. <- Feathering the light on the subject is not a bad thing but it has consequences such as sending the hot spot of your light onto the background instead of the subject.

 

[blastingcap]

OP, let me try to explain this more intuitively than the technical explanation:

Syborg is right about ratios.

If you want ambient light to be stronger (brighter background), then set shutter speed slower. This may be done by adjusting aperture, ISO.

If you want to darken the background, then set shutter speed higher. The higher you set ISO, the more work your flash does and thus the more dominating it becomes vs. the ambient light.

You can use a ND filter if you are running into the x-sync limit due to using a flash that doesn't have HSS. But this doesn't always work that well, if your flash is already getting pushed to its max.

Also, photoshop/lightroom is your friend. You can artificially darken the background if you are willing to put in the effort. It may not look as natural though. Alternatively, you can deliberately underexpose and bring up the subject, but same thing, it may not look natural and you also create apparent noise when you try to brighten as oppose to darken.

 

[slashbinslashbash]

Yes, sorry, it's proportional to distance squared, not just distance. It's been a while since I've looked at the math on this stuff. I haven't pulled out my AlienBees in over two years Moved into a new place, new baby, no real good place to set them up.

 

[virtuamike]

So, I set my camera to something like 1/200th, f8 and the flash to 1/32nd power and bang!

That's close to sunny 16. Unless you're outdoors or you're dragging shutter, there isn't enough ambient for it to factor into your exposure. At that point, treat your frame as single light source and ignore ambient.

(I also went back to 1/200, but then set the aperture to something like f11 -- which darkened eveything. Then I tried pushing the flash power up more ... but I never got a black background.)

Yah ratio, it's all relational. Changing output won't matter - your light source is too close to the background in relation to the distance to your subject for it to go black. If you want to darken the background, then move your light source closer to your subject, or move your subject farther away from the background, and adjust output / exposure to compensate.

Umbrella vs any other modifier not a factor in this case. Your issue is distance and ratio, not coverage.

It also surprised me that, at least with my Dad, the flash resulted in no reflections on his glasses.

Angle of incidence == angle of reflection.

Plenty of different tricks to get rid of reflections. Tilt head up or down, adjust height of light source or subject, etc, just go with what works for the shot.

 

[CuriousMike]

So I watched a couple of youtube videos trying to explain why I can only sync at 1/200 and how "high speed shutter flash" works and finally found a guy explaining it to me with two sheets of paper.

Now I understand - and I understand that the flash I bought is incapable of HSS.

However, some people seem to indicate that if I set my flash to maximum brightness, it might "last long enough" to fill the sensor.

I'll try that trick next time.

 

[Syborg1211]

HSS will not solve the problem in your original photos.

Your flash is what's illuminating the background in your photos. No power adjustment or HSS setting will change that. Things must be physically moved. As long as the flash is pointed in the direction of the background, there will be light hitting it.

 

[CuriousMike]

HSS will not solve the problem in your original photos.

Your flash is what's illuminating the background in your photos.

OK - I suppose I see that now.

In some of the videos I saw on "beginner off camera flash photography", they made it look as simple as bringing the camera shutter speed up to turn a white wall black -- all with the subject no more than 3 feet in front of the wall.

Certainly this has mildly inspired me to experiment more.

 

[blastingcap]

OK - I suppose I see that now.

In some of the videos I saw on "beginner off camera flash photography", they made it look as simple as bringing the camera shutter speed up to turn a white wall black -- all with the subject no more than 3 feet in front of the wall.

Certainly this has mildly inspired me to experiment more.

What direction was the flash pointed?

 

[CuriousMike]

In the photo of the man ( my Dad ), he's looking about 15' to the right of center of the umbrella. The light stand is *just* outside of the image - i had it jambed right on top of them.

Jambing it right on top of supposedly gives a softer light --- i.e., the closer the light source, the softer the light.
Which seems back-asswards to me - I would think distance would diffuse the light more.
Or maybe I misunderstood the concept.

 

[Syborg1211]

Softness of light has to do with the size of the light source in relation to the size of the subject. If the light source is farther away, it will appear smaller to the subject. The smaller the light, the less the light can wrap around your subject since the edges of the light source cannot sufficiently light the edges of your subject.

Think about it as if you were standing behind the subject. If your umbrella light is far away, you wouldn't be able to see the umbrella. This means no light will hit you directly from the umbrella. So the light won't wrap around your subject (wrapping is what soft light looks like). Move the umbrella right up to your subject, and you'll be able to see the edges of that umbrella because the umbrella is now bigger than your subject from your point of view behind the subject.

I think you're more used to natural light so here's another analogy. If you take a picture in the middle of a sunny day with no clouds, the sun is effectively a really tiny, though bright, light source because of how far it is. You get really contrasty and direct light from this scenario. Add a lot of clouds or an overcast day, and the atmosphere is effectively acting like a huge umbrella for the sun. You get much more even, wrapping light in this scenario.

 

[CuriousMike]

Softness of light has to do with the size of the light source in relation to the size of the subject. If the light source is farther away, it will appear smaller to the subject. The smaller the light, the less the light can wrap around your subject since the edges of the light source cannot sufficiently light the edges of your subject.

This actually explains it well in my mind. I need to buy a bigger umbrella.

 

[bigi]

Get fast lens and drop the flash for this kind of pictures. Don't be afraid of high ISO unless you shoot with calculator of some sort.

If you insist on using flash, bounce it off white ceiling/wall or use a good diffuser/box.

 

[CuriousMike]

Get fast lens and drop the flash for this kind of pictures. Don't be afraid of high ISO unless you shoot with calculator of some sort.

If you insist on using flash, bounce it off white ceiling/wall or use a good diffuser/box.

I already have a relatively fast lens and a very good high-ISO body.

The point is I don't want to do natural light - I want to try off-camera-flash... that's what this discussion was about.

 

[Syborg1211]

So how's the flash photography going, Mike?