prefocusing ruminations

Most of the time, I work at f16 and hyperfocal distance when I'm working fast on the street.

 

I was wondering how much you folks open up when doing that kind of work and what kind of luck you've had. I've

worked at f8 (with a 28 mm lens) but for the most part, I don't trust myself to get the focus "on."

 

Tips for pre-focusing?

 

Best,

 

John

Somewhere from f/5.6 to f/11 with a 28mm lens usually does pretty well if you've got a reasonable idea how to estimate

distances. I tend to have a fairly consistent range of distance from the subject- say 6 - 12 feet, give or take, so I set the

focus somewhere in there. Then once you've got your focus set if you see a subject come closer or it's further out,

sometimes you can just twist the focus ring a tad in either direction without looking at the lens, and shoot. But more

often you should just be able to set it and leave it through the shot. Of course you need to decide if you want infinity in

focus or not.

 

You've got a lot of cushion with a 28, and I wouldn't always be afraid if it happens that some of the pertinent subject

ends up out

of focus- sometimes that can look interesting- but it's not going to happen that much anyway unless you really open up

with a 28. In

general I

prefer risking focus in favor of a fast shutter speed that renders moving objects crisply. Point and shoots etc will vary

from full sized

cameras as to whatever

specific interface that allows you to pre-focus, and small sensors, wide lenses, and high ISO tend to translate to

deep focus.

I try to shoot at F8 Or F8+1/2. F16 is the worst aperture on a lens for 35mm format due to diffraction limitation. I usually set up at hyperfocal distance for f8 and if I need to focus closer, its a very easy quick move. F16 is unnecessary except for extreme shots requiring extreme depth of field. Bob Atkins(?) has a good discussion on defraction limitation on his web site it you are not a believer.

I am assuming that f16 is the smallest aperture on your lens. It is on all of my lens. If you have an aperture of f22 on your lens, then that aperture will be worse than f16. Again I am assuming small format of 35mm film or smaller digital.

I simply focus before each shot. I might as well since shooting medium format as I do I have less DOF to work with anyway. This is probably why I prefer shooting people when they are stationary...more time to focus. I also agree that if one wants the best image quality from a lens, it's best to stick to the old rule of thumb - use the middle stops like F8 or two stops in from wide open. There have been times where I wanted to blur some movement and to do this required me to stop down to f22 or smaller and I must admit that the quality seemed on par with my usual results. I would imagine that if I were to take two side by side shots with one being one or two stops in from wide open I might see a difference other then the increased DOF. I may have to try this some day for fun.

Thanks for the comments and advice. No, the lens goes to f22 and I am indeed shooting 35mm. I haven't had any image quality issues worth mentioning at f16. But today (I'm on a roll-a-day marathon this month) I'm going to get a little crazy and work at f8.

 

I'll post something later.

 

john

You'd be amazed what you can get away with if you practice, and are willing to tolerate losing some shots. I can pretty

dependably get 20-25% in focus shooting my 24/1.4 at or near wide open, sticking to a single distance (4 ft.). At this

distance f1.4 gives me 8 inches of DoF, each 1/3 stop to f2.0 gives me about another inch.

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<img src="http://www.punktures.com/photonet/EW1C9009.jpg">

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24/1.4 on FF, 1/160 at f1.6, shot from a shoulder strap, cropped a little to accomodate a rotation fix.

"Hyperfocal distance in street". That sounds odd to me: why would you insist to have infinity sharp? Are you that far from your

subjects? Move in, please, and use a wider lens than that 300mm tele, maybe a 28 mm or a 40 mm ... .

 

Where are your subjects located? Maybe 2, 5, or 12 m off but not beyond I would assume. Am I right?

 

So, please rethink your focus point and use a bit wider opening such as f/4 or f/8 on your shots and see what pleases you

better.

Frank - you're missing the point... the OP clearly states: "work at f16 and hyperfocal distance when I'm working fast on the street."

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Key word: fast. He's stopping down to increase his chances of capturing the shot he wants, and using his 28mm lens' hyperfocal distance at f16, which is roughly 5-6 feet, meaning the DOF ranges from 2.5-3 feet to infinity.

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As already suggested, f8 may be a better choice (given possible diffraction at f16, and given f16 limits you to relatively bright days) -- at f8, a 28mm's hyperfocal distance is abut 11 feet, so anything from 5.5 feet and beyond will be in the DOF range.

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I typically shoot with a 50mm, and like to shoot relatively close (<15 feet) and like the look of a relatively shallow DOF, so using hyperfocal techniques won't work quite as well for me. But I can pretty much mark 10ft (+/- 1 ft), and know that if I pre-focus my 50mm to 10ft, and either f4 or f5.6, anything within 9-11.5 feet will be in focus.

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Here's an example, taken at the Zocalo in Mexico City.

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<a href="http://www.flickr.com/photos/28873940@N06/2697513192/" title="ksp-zocalo-004 by kleonin, on Flickr"><img src="http://farm4.static.flickr.com/3127/2697513192_856a1da2a4.jpg" width="500" height="400" alt="ksp-zocalo-004" /></a></center>

I shoot in busy places so have my 50mm at 8ft. f/11 gets me 6-11ft sharp. f/8 is a little marginal which since I need to shoot a 1/250 minimum I need a reasonable amount of light to work.

 

No idea why people are using hyperfocal distance - why do you need infinity sharp in street photog? It's a waste of dof.

 

I'm pretty sure diffraction is also a moot point since you are working off a tripod with subject motion.

Thanks to everyone for their advice.

 

I actually do like to have from here to infinity in focus quite often. It creates a challenge in the sense that you really have to work with everything in front of you. But the key here was speed. Fantastic photo from the Zocalo, by the way. Not sure what you mean, mark, when you say it's a waste of dof. Is there a global shortage?

 

Thanks again to everyone who offered constructive advice.

 

John

Using hyperfocal if you don't need/want everything to infinity in focus is 'wasteful' since you could be using wider apertures and so shoot in lower light, have a faster shutter speed for moving subjects, lower iso etc. Sounds like you do though and since (as far as I know) there is no global shortage of dof, go for hyperfocal.

 

Also read this thread if you haven't already: http://www.photo.net/street-documentary-photography-forum/00QPxT

Why hyperfocal is just lazy man's zone focusing. Hyperfocal was nice for "me and Eiffel tower" sort of snaps, but in street setting focusing at closer zones might help. E.g. with 35mm lens at f/8 you can have everything from 1.5 to 4 meters in focus, vs. 2.7 to infinity for hyperfocal.