Advice on DOF and Portrait Lighting

rinkshots

I did a portrait shoot the other day for a client. My set up for these particular shots consisted of a single Alien Bees 400 flash unit with their giant soft box, a Canon EOS 5D with a Canon 100 f/2.8 Macro lens. I took the shot at 1/200 with the flash, and had the aperture set at f/7.1 and the ISO at 400. I focused on the people in front, as is apparent by the shots. However, the exposure was at full power for the flash, and dead on. So changing the aperture to increase DOF would have resulted in an underexposed photo. So what is my problem then? Am I simply lacking in flash power? Should I get a more powerful flash unit? I really don't want to go above ISO 400. Actually, I'd be more comfortable at ISO 100, but that obviously wasn't possible. But not having the proper DOF to maintain focus throughout the ranks is not very good either. Does anyone have an idea on how to correct this problem in the future?

Thanks,

Scott

ChatKat

You could have gone down to 125 or 160 on shutter speed and increased your dof to f8 or f11 without the change in ISO to increase dof.

All that said, I have the 100 2.8 macro and use it for single person images but not groups. It's too slow to focus for groups.

Mitchell

You answered your own question. A single AB400 is not enough for a group photo. You will need 1-2 AB800s to properly light this many people.

As ChatKat said, you could have dropped your SS down which would have helped a bit.

Scott_Quier

With respect to the previous posters, let me say a few things:

• Altering the shutter speed alters the extent to which ambient light contributes to the total exposure. It has no impact on the contribution realized from the flashes. Only adjustments to ISO and/or aperture will increase/decrease the perceived brightness of your flash. The reason for this is because your strobe/flash fires in milli-seconds. So, as far as exposure from flash is concerned, there is no difference between 1/200 and 1/60 second.
• If your AB400 was maxed out, the only way to decrease aperture and still maintain proper exposure would be to increase ISO or move your strobe closer to the subject(s).

How far from your subjects did you place your AB400? If you have the room and proper light modifier, you could decrease that distance by half and, thus, stop down your aperture by 2 stops.

You could increase the number of flash units. Get a couple AB800 stobes and, in addition to your AB400, you would have a very nice kit with which to make basic portraits.

Shane422

ChatKat wrote:

You could have gone down to 125 or 160 on shutter speed and increased your dof to f8 or f11 without the change in ISO to increase dof.

This would only help if you had significant ambient light, which at f11 indoors would probably not happen. The shutter speed only affects the amount of ambient light contribution.

There are a few things you could have done to get more from your Ab400. 1) move the light closer to the group. 2) Pull out the internal diffuser in the softbox so that the light has only the front panel to go through. 3) switch to a silver umbrella which would eat less light. 4) shoot at a wider angle (maybe 50MM) which gives you a deeper DOF at f7.1. At a subject distance of 10ft, the DOF at 7.1 for 100MM is 0.8ft, for 50MM it is 3.3ft. Check out www.dofmaster.com.

BTW, I use a Ab400 in a large softbox for groups of this size all of the time. I shoot at f8, ISO200, and about 50MM.

zoomer

I have shot groups way bigger than those with a single sb800 flash unit.
You have plenty of flash power available.

Try f8 iso 400 shutter speed 250 (max sync) then adjust the power on your flash to suit. I generally use iso adjustment to change/adjust the flash intensity/ambient mix just to keep it simple...but with the d700 I can use iso200through iso1600 with no noise which really helps.

Hard to say cause they are so small but both of those shots appear to be over flashed.

Hackbone

Watch where your focus point is. Where ever that point is generally one third in front of that and two thirds behind that will be in focus. This all depends on what your f stop is.

ChatKat

Scott_Quier wrote:

With respect to the previous posters, let me say a few things:

• Altering the shutter speed alters the extent to which ambient light contributes to the total exposure. It has no impact on the contribution realized from the flashes. Only adjustments to ISO and/or aperture will increase/decrease the perceived brightness of your flash. The reason for this is because your strobe/flash fires in milli-seconds. So, as far as exposure from flash is concerned, there is no difference between 1/200 and 1/60 second.

.

Scott,

Yes, altering the SS affects ambient light and that wouldn't affect the flash. But if you adjust the SS you can change the aperture and that will change the DOF....that is one of the issues with the photos. Too narrow DOF so you need to adjust SS to adjust Aperture to create a more crispy image.

Scott_Quier

ChatKat wrote:

Scott,

Yes, altering the SS affects ambient light and that wouldn't affect the flash. But if you adjust the SS you can change the aperture and that will change the DOF....that is one of the issues with the photos. Too narrow DOF so you need to adjust SS to adjust Aperture to create a more crispy image.

You are right if you are shooting in an environment with significant ambient light.

Agreed, stopping down the lens will, all else held constant, increase DOF.

The OP indicated that the strobe was the major (or only) light. In this situation, decreasing shutter speed, from for example 1/200 to 1/60, will not significantly increase the amount of light to which the sensor is exposed. Then, if you stop down the lens, you are now under-exposing the shot (the OP said the AB400 was maxed out).

Sam

Thanks Scott!

Not only did you beat me to the answer twice, but said it better than I could.

One think I will add is that when using my 5D with my Alien Bees I, (if I remember right) had some inconsistencies with the camera syncing at the rated 1/200. 1/200 always works with the 580 EX, but with the studio strobes I generally use 1/160, ( when the strobes are the main / only light source).

Sam

Scott_Quier

Sam wrote:

Thanks Scott!

Not only did you beat me to the answer twice, but said it better than I could.

One think I will add is that when using my 5D with my Alien Bees I, (if I remember right) had some inconsistencies with the camera syncing at the rated 1/200. 1/200 always works with the 580 EX, but with the studio strobes I generally use 1/160, ( when the strobes are the main / only light source).

Sam

I used to think that if the manual said a camera was spec'ed at a certain x-sync speed .... well it would work. It has always worked this way with my 20D and 30D cameras. But, I worked with a friend who has an XTi (I think it was the XTi, but it might have been some other XT variant) ... anyway, her camera is rated at 1/200.

Working with Sunpak 622, triggered with PWs, 1/200 would work some of the time and sometimes not.

I have yet to test my 50D cameras to see how they perform. That might be something to do in the next week or so as and when I have a spare 1/2 hour.

Nikolai

I may be too late, but...

• +1 on Scott's notes re: shutter speed (SS). While shooting indoors the SS is really your flash sync speed and nothing else. In my case it's 1/250, I never change it (although I might to get use Dogwood's wonderful trick on using partial frame:-)
• I agree, you probably maxed out on the flash. Large diffuser probably eats too much light. AB400 is not a very powerful uint in that respect. And for the large group it simply may not be enough. May be try using the ceiling as your reflector, or an umbrella, as it has been suggested...
• I *really* don't understand shooting indoor portraits anywhere above f/5.6 for such a small number of people. Even at 100mm you'll get at least 4ft of DOF if you shoot from 20ft or more (and you can't be closer to fit them all in), which is more than enough for two rows of people. Note, that yYou'll get the same 4ft DOF when shooting 50mm from 10ft, in case you don't have a large shooting space. When shooting 1..3 people I never get above f/4.

HTH

ChatKat

Variance
This is interesting because I just spent all day with John Woodard and Hanson Fong in their Beauty and the Beast workshop and in the session on DOF/SS issues. Also took Sam Puc's class on Babies and Bellies. None of them shoot below 5.6 and Hanson, in studio, shoots primarily above f8. Of course that was all applicable to using ProFoto lights and was geared to pros in studio.

Nikolai

ChatKat wrote:

This is interesting because I just spent all day with John Woodard and Hanson Fong in their Beauty and the Beast workshop and in the session on DOF/SS issues. Also took Sam Puc's class on Babies and Bellies. None of them shoot below 5.6 and Hanson, in studio, shoots primarily above f8. Of course that was all applicable to using ProFoto lights and was geared to pros in studio.

Kathy,
that's interesting indeed. Did they mention any rationale behind this choice? Because for me it's easy: I want my DOF being 1/2..1ft, hence with my 40D/50D, shooting distance of 10..15ft and my choice of glass I'm fine with f/4.0.

ChatKat

Long

Nikolai wrote:

Kathy,
that's interesting indeed. Did they mention any rationale behind this choice? Because for me it's easy: I want my DOF being 1/2..1ft, hence with my 40D/50D, shooting distance of 10..15ft and my choice of glass I'm fine with f/4.0.

Again most are shooting on the long end as well with lenses with the 70-200 4.0 as a favorite - non is. Again, like any thing - style is up the the photographer! Wide is not as flattering as long is.

Nikolai

ChatKat wrote:

Again most are shooting on the long end as well with lenses with the 70-200 4.0 as a favorite - non is. Again, like any thing - style is up the the photographer! Wide is not as flattering as long is.

Oh, I see. Well, with f/4 lens no wonder they don't go above /5.6, and primarily shoot f/8, that's their sweet spot sharpness-wise.
Thank you for the info!

LiquidAir

Sam wrote:

Thanks Scott!

Not only did you beat me to the answer twice, but said it better than I could.

One think I will add is that when using my 5D with my Alien Bees I, (if I remember right) had some inconsistencies with the camera syncing at the rated 1/200. 1/200 always works with the 580 EX, but with the studio strobes I generally use 1/160, ( when the strobes are the main / only light source).

Sam

This has been my exprience too using either the PW or STE-2 trigger and the 5D. The only way I can get reliable 1/200 sync is with the strobe on camera or a wired connection.

ChatKat wrote:

This is interesting because I just spent all day with John Woodard and Hanson Fong in their Beauty and the Beast workshop and in the session on DOF/SS issues. Also took Sam Puc's class on Babies and Bellies. None of them shoot below 5.6 and Hanson, in studio, shoots primarily above f8. Of course that was all applicable to using ProFoto lights and was geared to pros in studio.

Nikolai wrote:

Kathy,
that's interesting indeed. Did they mention any rationale behind this choice? Because for me it's easy: I want my DOF being 1/2..1ft, hence with my 40D/50D, shooting distance of 10..15ft and my choice of glass I'm fine with f/4.0.

To get the equivalent DoF on a 5D (or any FF body) you need to stop down 2/3 stop more than on a 40D/50D. f/7.1 on the 5D has the same DoF as f/5.6 on a 50D.

For family shots I typically need 18" of DoF for reliable focus. Typically I shoot those with the 50/1.4 at f/5.6, but focusing requires care to get everyone in. At 100mm you'll probably need to stop a down a touch more.

As for lights, I use a pair of 30"x40" softboxes placed together to create the effect of a bigger light (either 60x40 or 30x80). Each has a 580EX is running around half power to hit f/5.6 at ISO 100 combined at 6(ish) feet. I use fairly high quality Calumet Illuma softboxes and I am careful with the setup. It is worth doing some testing with a light meter; cheap gear or a poor setup can easily cost you 3 or more stops of light.

Nikolai

LiquidAir wrote:

...To get the equivalent DoF on a 5D (or any FF body) you need to stop down 2/3 stop more than on a 40D/50D. f/7.1 on the 5D has the same DoF as f/5.6 on a 50D.

For family shots I typically need 18" of DoF for reliable focus. Typically I shoot those with the 50/1.4 at f/5.6, but focusing requires care to get everyone in. At 100mm you'll probably need to stop a down a touch more.
...

I agree. Of course, they may also shoot 1D (non-s) series, which brings it back to almost same playing field. In any case, one must have the understanding of the properties of the particular gear. Following other's setup blindly without knowing those intrinsic details won't do much good:-)

codiac2600

Looking at the photos you did a great job with what you had to work with.

I host photography classes here in town and at nearby universities so maybe together we can come up with a solution.

Using one light is definitely not great for shooting portrait work when it comes to groups. You'll definitely need two lights, but financially speaking it's not always easy. I spent 5K on lights last year just so I could shoot everything/anything and it hurt, but it had to be done, which doesn't mean you have to spend anywhere near that so this may be a solution for you.

Purchase the largest silver reflector you can, maybe a +40" size to help give you a boost without having to drop funds for a second alien bee. Use the reflector as a second light source strategically by running your one alien bee 400 at an angle wider than 45 degrees and uses the reflector to shoot back some light towards the opposite side. If you don't mind grabbing a second alien bee then do so and place that light opposite side and at the same output. It may not be dramatic light, but it's soft simple light for groups.

Speaking of DOF I think you should have been fine with the aperture you used. It looks like you focused on the children in the front row more than the parents in the back. Remember that DOF based on where you focus is 1/3 in front and 2/3 behind. If you focused somewhere between the front row and back row you would have gotten more detail from the parents without sacrificing the detail from the kids in front.

The other option would have been to use maybe a 50mm focal length which would have allowed you to increase the DOF over the 100mm macro and also given you a faster AF lock. You will lose some blurring of the background if you go to the 50mm, but it's a tradeoff.

Hope that helps and keep working at it till it becomes second nature.

NeilL

Nikolai wrote:

• (although I might to get use Dogwood's wonderful trick on using partial frame:-)

Nik, is there a link?

Nikolai

NeilL wrote:

Nik, is there a link?

Uhm, it's somewhere, it was deep down in one of my last posts...

The idea was to go slightly beyond the sync speed and go for partially exposed frame if, for whatever reason, you do need that higher speed. For instance, in my case, I get a full frame at 1/250s, but if I go 1/320s I will still get like 5/6 of the frame (or 3/4 at 1/400s), so if my subject fits there I can frame the picture with that in mind and still get what I want.
You do need to experiment with your particular equipment to know exactly what you get at what speed.

NeilL

Nikolai wrote:

Uhm, it's somewhere, it was deep down in one of my last posts...

The idea was to go slightly beyond the sync speed and go for partially exposed frame if, for whatever reason, you do need that higher speed. For instance, in my case, I get a full frame at 1/250s, but if I go 1/320s I will still get like 5/6 of the frame (or 3/4 at 1/400s), so if my subject fits there I can frame the picture with that in mind and still get what I want.
You do need to experiment with your particular equipment to know exactly what you get at what speed.

Well, just hang on a sec while I learn your language Drofl

Seriously, many thanks Nik for your reply. I'll do a search... lazy me... it's of course not easy to describe in a sentence or two, I'm sure.

Happy New Year, Nik

Shane422

Nikolai wrote:

Uhm, it's somewhere, it was deep down in one of my last posts...

The idea was to go slightly beyond the sync speed and go for partially exposed frame if, for whatever reason, you do need that higher speed. For instance, in my case, I get a full frame at 1/250s, but if I go 1/320s I will still get like 5/6 of the frame (or 3/4 at 1/400s), so if my subject fits there I can frame the picture with that in mind and still get what I want.
You do need to experiment with your particular equipment to know exactly what you get at what speed.

I don't know if this is the link you had, but David Ziser did a nice tuturial here on cheating your sync speed by using only part of the frame.

NeilL

Shane422 wrote:

I don't know if this is the link you had, but David Ziser did a nice tuturial here on cheating your sync speed by using only part of the frame.

Thanks Shane422 for the link. I think it must be the same technique as Nik is talking about, at least it puts the 2 + 2 together in his post.

Nikolai

Shane422 wrote:

I don't know if this is the link you had, but David Ziser did a nice tuturial here on cheating your sync speed by using only part of the frame.

Shane, thanks for the link! I didn't see it before. Yes, the same idea. He's even using the same 1/400s I mentioned and darkens the sky/ground with it, thus providing a cool split ND effect (obviously you need to be outdoors for it to work, since in the studio you have pretty much have no ambient light at all).