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wide aperture and low light

Lauren M. - North Shore, MA , Sep 24, 2006; 11:15 a.m.

I can't post my samples so you'll have to take my word for it that "they stunk".

At wedding I assisted last week, I tried something I have tried before (also without luck which is why I have steered clear of it until now) - shooting with my 50mm 1.4 during reception without flash. Basically, very occassionally, I got a neat looking candid of people talking at the tables or whatever. But mostly, I had trouble with focusing. I'm not sure what my question is because I'm not sure what the problem is - the wide aperture making the in focus area small and sensitive, or the low light making it hard to auto focus? or both? and whichever the problem, what is the solution? Can it be a matter of just practicing to get the focus right? When I switched back to flash, I was able to focus and still use wide aperture.

I practiced with my dog friday, though it wasn't in low light and he mostly wasn't moving so not sure how good it was for practice and things came out as I wanted. (just first group of shots is from friday- up to his wearing glasses)


I have to stop avoiding this lens and be able to use it. What's the use of 1.4 if I can't use it-


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Robbie Caswell , Sep 24, 2006; 11:31 a.m.

beautiful dog. My little ankle biter wont stay still long enough.

A friend called desperatly with gear issues and I rushed to her aid. Loaned her my SB800's and broke out the Leica for fun since I wasn't on the clock.

Here was an attempt yesterday from my Leica. Both lense and camera date to 1959, and I think it shows.

Can't wait to get back my 90 cron shots with my other M3 body, because I know that one is in better shape.

My focusing was pretty good, even with the recession (?) shots.

see the light fall off?

Michael Church - Knoxville TN , Sep 24, 2006; 11:33 a.m.


When using these wide aperturs, you have to develop good focusing techniques. The best practice is learning how to use your selective focus points while you have the camera to your eye. Learning to use these focus points fluently, will minimize movement and will ensure focus position. The focus/recompose technique is worthless with an apeture of 1.4......simply too little DOF for the slightlest mis-focus position. Also, remember the rules of hand holding sufficient shutter speeds in natural light (shutter must be equal to the focal length) (unless using proper lighting ratios).

Ken Kartes , Sep 24, 2006; 11:37 a.m.

Hi Lauren, if I remember correctly you are shooting with the D70. They are not the best at finding focus in low light. Practice manual focusing and using the focused indicator in the bottom left of the display in the viewfinder, then reframe and shoot. I hope that answers your question.

Cindy S. - South Central Idaho , Sep 24, 2006; 12:25 p.m.

Have you looked at this site yet? http://www.dofmaster.com/dofjs.html Wide open apertures are tricky and it's good to know exactly what will be in focus at a given aperture and distance. This calculator will show you that if you focus on something 20 feet away with your 50mm lens at f/1.4 on a D70, the area in focus will be 2.75 feet. So for photographing a few people, you'll want to be at least that far away, maybe further. Write down the focus distance at certain f/stops, get familiar with them, and you'll know that lens well.

Jochen Schrey , Sep 24, 2006; 12:53 p.m.

Can't you switch your flash to some AF assist only mode? - I've seen a few PJs having their flashes riged up at no flash allowed locations.

Practicing AF spot selection is a good idea too.

Bas Scheffers , Sep 24, 2006; 01:00 p.m.

You just found out for yourself that myth of using fast lenses for low light is just that: a myth.

Fast lenses give you a nice bright viewfinder, but that's about it. There are very few good images to be had at wide open, especially in social events where more often that not you end up trying to photograph a group of people up close; one person ends up in focus but the rest are blurred. Sure, you can take a nice portrait that way or snatch a nice candid of that cute flowergirl, but in most cases the DOF is way too shallow...

(as demonstrated above, it also works well enough for a big overview shot where the focus is on or near infinity; you might just get enough DOF way out there)

Practice will help, but at the end of the day, in my opinion, f/1.4 is not that useful.

Gary Nakayama , Sep 24, 2006; 01:09 p.m.

Try setting the camera to use the center AF area. I think that one is the most sensitive. Then you have to look for something contrasty to focus on. Then practice at home in similar dim light to what you had at the reception.

Nadine Ohara - SF Bay Area/CA , Sep 24, 2006; 02:15 p.m.

First be sure your problems aren't due to handholding or motion blur. Rule that out--remember, flash freezes motion so the difference you saw between the no flash and flash shots could have been due to that fact. Once you rule out the two things I mention, decide whether to use the autofocus or use manual focus. As others have said, f1.4 has very little depth of field to use as a margin of error. If you use autofocus, use the center focus point and/or rig up your flash so that you can use the focus assist without the flash firing. I don't know how to do that with the Nikon/SB800. And practicing is good. If you decide to use manual focus, you might want to investigate getting a split prism screen.

Marc Williams , Sep 24, 2006; 02:25 p.m.

Jeff Ascough has used a Leica 50mm Noctilux f/1.0 at weddings with fairly "decent" results. I use my fast lenses wide open all the time. 85/1.2 @ 1.2 about 90% of the time, and that has a shallower DOF than a 50/1.4. My favorite lenses for hunting couples shots at a reception is a 135/2L which I can't remember ever setting beyond f/2.8. I just don't shoot them from 5 ft away.

I don't know about your Camera Lauren, but with Canons, the faster aperture lenses DO focus quicker and more accurately because the more sensitive AF points are activated ... where they are not with lenses above f/2.8. So, no matter what aperture you have selected, all modern lenses stay wide open while focusing, so a faster aperture lens will focus faster, and in some cases more accurately than slower lenses. On some older AF cameras only the center focus indicator is the "sensitive" one.

Of course IF you need more DOF (whether it's a fast aperture lenses or not), you have to stop down ... fast lenses aren't glued wide open, they do have other aperture settings to select when needed ... like when shooting a group. Conversly, a slow lens can never be set to f/1.4 when you want it.

Lauren, there are a number of things that can effect the appearance of being in focus.

Distance to subject plays a big part in depth of field even when the lens is set wide open. The further away you are the more DOF a lens gains. If you start moving closer than DOF becomes narrower and narrower.

Another thing I've seen (and done myself) is get to ambitious with shutter speeds when using a fast aperture lens. IMO, subject movement spoils the appearence of focus just as often as shallow DOF.

When shooting wide open you have to take all of the above into consideration, AND have good technique. A solid stance is necessary when shooting close up while wide open. Subject movement and your movement can combine to throw the focus area out just enough to soften the eyes for example.

Practice is the cure, and learning more about how DOF works with all lenses.

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