Focus fall off

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I shot a group photo, stretched across the whole frame 35mm, the center was in perfect focus but the edges were very soft almost blurry. It is just a bad lens or what....? OM1, F-Zuiko, 50mm, f1.8 at F5.6 at 1/60 Any ideas or suggestions appreciated Thanks Steve

-- Steve Mitchell (mitmad@telus.net), February 13, 2001

Answers

Steve, the rule of thumb was 1/focal length. It refers to the average person's slowest handholdable shutter speed. In other words, if you are using a 28mm lens, about the slowest you can hope to handhold your camera and get sharp pictures is 1/30 second. Some people can't hold a camera steady enough for that even, and a few can hold one even steadier. Naturally, speeds need to be faster with longer lenses, and you should probably round up if you don't have half or third stop shutter speeds. Say you are using a 300mm lens. 1/300 isn't availble on my camera, but 1/250 and 1/350 are. If I have enough light, I would use 1/350 or faster. If my camera could only select full stops, I would have a choice of 1/250 or 1/500, and would choose 1/500 if possible. If you notice you still aren't getting sharp pictures, try using a shutter speed twice as fast if you have enough light, a tripod if you don't.

-- Brad Hutcheson (bhutcheson@iname.com), February 16, 2001.

Most lenses are not completely sharp across the frame when shot at wide apertures. That being said, 5.6 should be stopped down enough at normal shooting distances (probably wouldn't cut it for macro work).

Another thing to keep in mind when shooting groups of people is that it's usually best to align them into an arc instead of a straight line. That way the people on the edges are the same distance away as the people in the middle. f5.6 might not give you enough DOF to keep everyone in sharp focus.

Finaly, 1/60 just might not be fast enough to freeze everything. Especially if your shooting handheld. In my experience the 1 / (lens focal length) rule of thumb just doesn't cut it for photos enlarged beyond 4 x 6 (if I'm extra careful and take several shots one or two may come out ok).

-- Geoffrey S. Kane (grendel.nauticom@verizon.net), February 14, 2001.


Hello Geoffery, Thanks for your reply, the tip about the circular grouping is very good.I also shoot several frames to make sure I have one. I am using a tripod and a Metz CT 45 so I think I can rule out motion although the day light was close to the flash reading.I did not get the reference to the rule of thumb you mentioned.Thanks again Steve

-- Steve Mitchell (mitmad@telus.net), February 14, 2001.

Aranging the group in an arc is the one correct answer. The problem with large groups is the the people on the ends are significantly farther away than the those in the cneter. f5.6 may not provide enough depth of field for the shot.

-- Ed Farmer (photography2k@hotmail.com), February 15, 2001.

Ed,thanks for the reply.I'm glad you concur with Geoffery, now I just have to figure how to get 50 to 100 employees of a large goverment corporation to form a nice arc at 8:15 in the morning. Really thanks for the advice it's always great to learn something new. P.S. Geoffery Could you explain the rule of thumb you alluded to in reply Steve

-- Stephen Mitchell (mitmad@telus.net), February 16, 2001.


There's a rule of thumb for 35mm photography that says that your shutterspeed should be at least the reciprocal of your lens' focal length (i.e. 50 mm lens, minimum shutterspeed of 1/50 sec, 100 mm lens, minimum shutterspeed of 1/100 sec etc.). This is to fix camera motion so it won't help if your subject is moving. If you use a tripod you can ignore it.

IMHO this rule works for prints up to 4 x 6 (maybe I drink too much coffee ;-) ), but even then I can see the difference. I think too many people take too much stock in this rule. If the tripod is possible, then I always use it.

-- Geoffrey S. Kane (grendel.nauticom@verizon.net), February 16, 2001.


Brad & Geoffery Thanks for your replies about the rule of thumb.I will continue to brace myself, hold my breath, push the shutter and pray to the photo spirits in the sky (and use a fast a shutter speed as possible) Thanks again Stephen

-- Stephen Mitchell (mitmad@telus.net), February 19, 2001.

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