Friday, February 13, 2009

F-Stop Friday - The F-Stops Here At F4.0

Good Morning Everybody
Our bags are packed and we're ready to go, off to Vegas for the WPPI show.... - sung to the tune of "Leaving On A Jet Plane". That's right gang, LaDawn and I are ready to head west over the weekend. If you are planning to attend this GREAT Convention, plan to look me up 8:00 a.m. Monday morning in rooms 319-320. I'll be the one with the BIG cup of coffee. Hope to see you there.

Well, I'm out of camera equipment in the gear bag. I still have lighting equipment to explain, but I'm holding off for a week or two. Today I thought I'd talk F-Stops - when to use them and why. And today's F-Stop is......

Hi, I'm F-4.0 And I'm Happy To Meet You
F4.0 and I have been friends for quite a while. When I was shooting film, I dated F4.0's cousin F5.6, but since going digital I had to let the old girl go and see if I had a chance with F4.0. As luck would have it, F4.0 was perfect on my DSLR. In fact F4.0 was just as good as F5.6 was on my ol' 150mm Sonnar on my Hassey! OK, is this making any sense to anybody yet? Here is the deal.

Hit the "Read More..." link below for the rest of the story and images.

Back in my medium format days when shooting portraits, I always used my 150mm Sonnar lens. The maximum aperture was F4.0 and I NEVER wanted to use the maximum aperture of F4.0. I was a "focus freak" and thought shooting wide open would compromise the sharpness of the final print. Anyway, F5.6 gave me a really nice result with nice separation of the subject from the background - assuming, of course, the background was far enough behind the subject. All was well with the world till I switched to "digital" the later part of 2000.

Now what do I do to get the same visual effect as I was getting with my trusty 150mm Sonnar? The easy answer was - get a slightly longer lens and shoot it wider open - like at F4.0. After doing some testing, I found the "Magic Bullet" of a beautiful outdoor portrait was about 125mm to 200mm lens at F4.0 on my DSLR - I was back in business. I once again had great background separation of the subject from the background. That focal length/F-stop combo are now my default settings when ever I shoot a portrait outdoors.

There is the occasional exception, but that usually has to do with shooting in a brighter ambient light situation where I need to stop the lens to F5.6 - Yes, you can tell the difference, it's simply not as pretty.

Remember too, I'm using an off-camera flash to create my direction of light. You know, life is just easier when you add your own light. That's why I do it. But back to my friend, F4.0. F4.0 or at least within 1/2 stop either way - F3.5 to F5.0 at about 150mm is the magic recipe creating a beautiful result. You know, if you stop down too much, the background comes into sharper focus pulling the viewers attention from the subjects. Look at the images accompanying this post. This is exactly the separation I want - the wider aperture forces the viewers attention right to the sharply focused subject with the soft background receding gently in the scene.

Too many photographers are afraid to shoot at the wider aperture causing the background to come into sharper focus which then competes for attention with the subject. Back in my early film days, I had to practice focusing at the wider apertures to be sure I was sharp on the subjects. Today, there is nothing to it with the auto focus cameras we have available.

So my advice, don't be afraid to shoot at a wider aperture. Give F4.0 a try. I promise, you will love the result.

Hey gang, that's it for me today - bags to pack and planes to catch - See ya' in Las Vegas next week. And just remember while you're in Vegas , keep your pixels away from the slot machines and you'll have more fun at the trade show;~) See ya' there, -David


  1. David,
    I assume you must be back quite a ways to be shooting with a 200mm on a cropped sensor, and filling the frame with a group of 6. I don't have much experience with larger groups (esp. outdoor) but would think you might go horse yelling posing instructions : )
    Do you change it up for larger groups? 12-24? f8? I understand backing up gets you more DOF with a zoom (at a given aperture) but I could see you shooting 60 yards away for a full bridal party!


  2. Hi David. You have once again given us a great deal of amazing information. Thank you for your posts. I have shot a handful of family portraits and always start with f/4.0, mainly because I have heard you write/speak about this f/stop. I love the effect. It is so flattering and beautiful. When I nail the shot I usually think to myself I "Ziserized" the shot and then know that I am done. Thanks again!


  3. David,
    Priceless information as always! What ISO do you typically use with the 4.0/125-200mm focal length combination?

  4. Though I realized you were not a speed freak (no f/2.8 addict), I didn't thought you were a f/4 fan.
    That makes sense, but it also renders some f/2.8 supporters' reasoning useless (like "use f/2.8 for everything, as it's the only aperture that wedding photogs should use").
    You have the 70-200 f/2.8 IS, but for this type of shots, the 70-200 f/4 IS would suit just about the same, right? Sure, it wouldn't be as versatile, but I think that, for most part, it's great!
    I can't wait for your posts on this new series! :)
    Thanks for your insights!

  5. David, thanks for this post and your insight. What is your prefered distance in terms of the subject and his/her background? In the photos you have posed, they appear quite far apart. By the way, thanks for all the teaching you do.

  6. Great Post! I love your BLOG!

    My blog is far from complete, as far as setting up goes, and I really want my blog to be as informative and peaceful as yours.

  7. David, f4, is that on a cropped sensor of FF? Am I correct in thinking that the DOF on a FF will be less than on a cropped sensor? I shoot large groups 3 rows deep all of the time and was comfortable at 5.6 on a cropped sensor w/a 50 mm lens, and when I tried 5.6 on a 5DmkII and an 85mm lens I noticed a bit less DOF on the few groups I've worked w/so far, and was considering f8 for this seasons group, btw I used to love 60 sec f4 with an RZ and 180mm lens.

  8. bl, as far as I know, a f/4 (APS-C) DOF matches a f/5.6 (FF) DOF. Conversely, a f/4 (FF) DOF is equivalent to (APS-C) f/2.8.
    There was a long debate a while ago about these equivalencies in DPReview. Very interesting reading.
    Since David is generally using crop-sensor cameras, this f/4.0 post is probably about that. :)

  9. @BM...thanks, I think we are saying the same thing basically, less DOF on a FF than on a cropped sensor at the same f-stop, correct?

  10. @bl, yes, that's correct. I don't know the exact numbers, but assume it's the equivalent of around 1 stop, with less DOF on the FF sensor. Which is in line with what is know of DOF, it goes thinner the larger the sensor, at the same fstop. But I never had a FF camera, so that's just theory! ;)