F-Stop Friday: F5.6, The Friendly F-Stop

Good Evening Everybody,
Well welcome to my almost midnight post today at DigitalProTalk. Is anybody still awake?? I've been at a keyboard for 12 straight hours wrapping up my presentation I'm giving at B&H on Sunday. I hear from the boys in New York that it's going to be quite the crowd. The room holds about 70 to 80 people but I hear we have 104 registered for the presentation. I'm really looking forward to it and I'm kind of curious how I’m going to get through my 400 slide PowerPoint in five hours. I've got it --- nobody gets “potty” breaks we just go straight through:~)

Anyway, my apologies for the very late post today. My first priority was to get the PowerPoint done for my presentation on Sunday. I was planning to finish a little bit earlier today, get the DPT post up much earlier, but things are what they are.

I thought I would do another episode of our F-Stop Friday Series because it gives you some insight into why I do what I do when I'm shooting my images. So without any additional whining from me about being at the computer all day let's get right to it.

F-Stop Friday: F5.6 - The Friendly F-Stop
Back in the old film days F8 was my favorite, friendly F-Stop. With a medium format camera F8 gave us plenty of depth of field for the candid images we were shooting. When you look at the numbers below, you may not think so. But as most of us have migrated to digital 35’s, the wider equivalent focal lengths that we used on those cameras give us more depth of field at the same aperture than we had in the old film days.

Here is how that works:
An 80mm lens on a 6x6 medium format camera is equivalent to a 50mm lens on my 5D mark II and a 35mm lens on my 40D.

Now let’s look at the DOF (depth of field) numbers. The depth of field at 10 feet at F8 when shooting my 80 mm Distagon lens on my Hasselblad was 8.57-12ft or a total DOF range of 3.43 feet.

When shooting the equivalent focal length, a 50 mm lens, on my Canon 5D Mark II, my depth of field at 10 feet is significantly more 7.77-14 feet or a total DOF range of 6.28 feet.

Now look what happens to the DOF on the APS sized sensor cameras like the Canon 50D. The equivalent focal length lens is about 35mm. So on a Canon 50D fitted with a 35mm lens focused at 10 feet with the aperture at F8 we have quite a bit of depth of field 7.28-16 feet or a total DOF range of 8.69 feet.

That's why it's so easy to get by with F5.6 on our digital 35s. We actually end up with even more depth of field our full frame digital SLR and even more depth of field on our APS sized sensor cameras like the Canon 50D.

Following this logic further - we can see that we can actually shoot the Canon 50D at 35mm optic focused at 10 feet at F4 and actually have more depth of field that I was getting at with my Hasselblad fitted with its 80mm lens. I always thought it was interesting that so many film photographers as they transitioned to digital 35s continued to shoot at the same F8 aperture they used on their medium format cameras. Many didn’t even realize that they were increasing their depth of field tremendously.

That means that with our digital 35s, we can shoot a full 2 F-stops wider for the same depth of field as in the film days with the medium format cameras. That means that we need less light to make the image. This is a benefit to us, especially if you're using your on-camera flash and bouncing off of a side-wall to bring the light in from that off-camera direction that I've talked about so often here at DigitalProTalk. Combine that with our new high ISO cameras and we have all kinds of photographic possibilities open up to us. HOORAY!!

If you want to have some fun with this depth of field logic yourself, let me point you to Don Fleming's on-line depth of field calculator right here. You too can play around with a different focal length lenses on the different camera bodies and may find yourself amazed at what you discover.

The bottom line is this - I find that F5.6 gives me plenty of depth of field for all of my wedding day flash candids. As long as I shoot with the focal length between 24-50mm I’ve got plenty of depth of field to capture the action, and I'm assured that even if the auto focus misses a bit I'm still covered by my depth of field.

Hey gang that about wraps it for me today. We've got an early wake-up call tomorrow so I’ll see on the flip side of the weekend. Have a good one and remember even pixels buy their cameras at B&H Photo&Video. Adios, -- David

The Depth Of Field Myth

Everyone thinks the longer the focal length and the wider the aperture the less depth of field. Well, this is true. But let's say you first photograph your subject with a 150mm lens and then take a second shot at 24mm keeping the subject the same size in the viewfinder for both shots - here's the question - which image has the greater depth of field? The answer, much to my surprise was that both have the same depth of field!

I know, you think I'm crazy here, but over the weekend I had that same conversation with a good friend of mine, Mr. Frank Dispensa, from Wappingers Falls, NY. Frank is a great teacher and really knows his stuff. He is a regular lecturer at WPPI and does his own series of seminars too. Here is the link to Frank's site right here.

Frank watched an earlier Technique Tuesday episode entitled, "I Can't See The Forest For All The Trees" and raised the question to me about my remark about depth of field. Well, we were on the phone for 30 minutes discussing the finer points of depth of field. Most everybody thinks that there is much less depth of field with long lenses at wider apertures and that is true. BUT, when the subject is the same size, photographed at varying focal lengths, the depth of field is the same. What happens is that the longer lenses show the background as larger and hence shows the apparent softness better. In other words the perspective of the background changes and that creates an illusion that the depth of field changes. In reality it does not.

Frank sent me a list of links that illustrate the point. Check out BlueSky-Web right here for a thorough, well illustrated discussion of the facts. DVInfo.com right here has a more geeky discussion also on this same topic. DOFMaster.com right here has a great discussion on the subject, especially when the subject's size is the same as the focal length changes. It's full of charts and graphs and is a good geek read. Anyway, like I said, Frank knows his stuff - but he is so much older than me too:~) Hey Frank, thanks for the clarification and heads up info.

Hey gang that's it for me today. Be sure to tune in for tomorrow's podcast entitled, "How to Run A Million Dollar Studio." I'm interviewing my good friends Kent and Sarah Smith about their ultra successful studio in the Columbus, Ohio area. I have to say, their insights and advice truly hit this podcast "out of the park!" It is a "must listen" show. Everyone at my studio has orders to listen to every word. I hope you enjoy it. So, until tomorrow, have a great one, -David

Technique Tuesday - I Can't See The Forest For All The Trees

Today's post is very important for all portrait and wedding photographers out there. Too often a small F-stop ruins or becomes an obstacle for what could instead have developed into a beautiful image of the subject. We sometimes are too concerned with getting the subject in focus, which is indeed important, and then in effect many times put our backgrounds into too sharp of focus.

Hey gang, it's time to walk the thin line of large F-stops and shallow depth of field to make the subject really pop out of the scene. This tutorial shows you how to take some not so good looking backgrounds and turn them into a beautiful setting for a bridal portrait. I'll also show many examples as to how focal length together with aperture changes the final image for better or worse and how to get the best result on your next shoot. Enjoy! -David

Depth of Field - Short Tutorial

ArticlePhotography, a pretty cool photography blog has a nice tutorial on "depth of field." Sure it's related to photography in general, but when I make a portrait, depth of field is always an important consideration in the composition. Give it a peek right here.

So Just What Is In Focus Anyway?

I'm doing a "room shot" before the wedding guests hit the main reception ballroom. I want to show the table in the foreground and the entire background, usually remaining tables, in sharp focus. I need to use a wider aperture because I'm in a rush and I'm hand-holding the camera so I can move quickly - I choose F5.6. I've got a 10-22mm lens at 10mm on my 40D at F5.6 focused at 37 inches- what's really in focus? The answer might surprise you - everything is in focus from 18.5 inches to infinity!

Unbelievable isn't it - at 1 1/2 feet to the outer reaches of the galaxy - Carl Sagan would be impressed. OK, I know I'm a little "geeky" with this stuff, but check out DOFMaster right here - it's a link to a depth of field calculator. Just select your camera, focal length, and F-Stop and it will do the rest. You can even download it at no charge right here. Geeky or not, this is a great way to learn how your lens work at different apertures. There are lots of other goodies there too so check it out - a 5-Star find!

Footnote: I added the "Carl Sagan" link just for fun. I received his "Cosmos" DVD series for Christmas - then I hit one of the Sagan site links to the Planetary Society and found some truly stunning images under the heading "The Year In Pictures". It is a stunning collection of planetary images right here. Enjoy!