Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
08-06-2010, 10:53 PM   #1
Senior Member




Join Date: Mar 2010
Location: Manila
Photos: Albums
Posts: 230
center focus (manual) framing

how do you guys frame our photos when using the center focus point and focusing manually?

i know center focus and recompose loses a bit of sharpness
so how'd you guys do it?

08-07-2010, 06:26 AM   #2
Senior Member




Join Date: Jan 2010
Location: Upstate New York
Posts: 203
I don't see why you'd want to use the "center focus point" when you are manually focusing, unless you want to be a slave to the focus conformation light, which IMHO is not manual focus - it's "semi auto focus". You might as well be auto focusing if you are doing that. For me manual focus (which I use 100% of the time) needs to be 100% manual and free of any such encumbrances. In fact that's precisely what makes it such a wonderful way to shoot. The framing and focusing are happening at the same time, with constant subtle adjustments to both. All the while you are "having a look" at different subtle changes without the need to keep pointing the "focus point" somewhere. The final framing adjustments are made concurrently, and it all flows together very smoothly and quickly once you're practiced at it.

Trust your eye, and practice practice practice...
08-07-2010, 06:47 AM   #3
Senior Member
dasuhu's Avatar

Join Date: May 2009
Location: Sacramento, CA
Posts: 185
I just got a k100d with manual focus lens myself a couple weeks ago, so I'm a noob. I've been using the green light confirmation as a way to real quickly find "focus", then recompose. It doesn't even seem that precise when shooting wide open, so it's up to your eye to find true focus anyways (plus taking a lot of dud shots, then analyzing where I went wrong with focus)

Earlier this week, my camera would only snap the picture when the green light focus indicator was lit. I thought something went horribly wrong and was frustrated when I thought the camera was forcing me to take what I thought were out-of-focus shots....then I realized I had actually hit the AF/MF switch on the camera and turned it to AF. Oh silly me....newbie for sure
08-07-2010, 08:03 AM   #4
Veteran Member
RioRico's Avatar

Join Date: Jun 2008
Location: Limbo, California
Posts: 11,264
If you center-focus and re-compose, one way to keep your subject sharp is to stop-down the aperture. This means to set the aperture to a higher number. In Av or M modes, set the aperture to f/8 or f/11 or f/16 -- the bigger the number, the smaller the aperture (hole), and the greater the depth-of-field (DOF).

Aperture is a fraction, the ratio of the iris' opening to the focal length of the lens. Just as 1/16 is a smaller number than 1/8, so f/16 is a smaller, narrower aperture than f/8. DOF is the distance range that will look sharp in a picture. A very 'fast' lens, with a large aperture, has very shallow DOF; if you focus on a person's left eye with a 85/1.5 lens, everything else will be out-of-focus (OOF).

Setting the aperture between f/8 and f/16 will give the greatest range of sharpness. This gives you more leeway in your focusing. There's an old photojournalist's rule: f/8 and be there; i.e., stop-down and pay attention. Stopping-down gives you the opportunity to manually pre-focus for optimal DOF, especially with a wide focal length.

The rule here is, the wider the lens, the thicker the DOF; and the longer the lens, the thinner the DOF. A 24mm lens at f/16, pre-focused to 6 feet / 2 meters, will be sharp from 3 feet / 1 meter to infinity. But a fast 85mm lens at f/1.5, focused to 6 feet, will be sharp within a range of about 1 inch. To focus and recompose with that 85/1.5 would be rather difficult, eh?
_ _ _ _ _ _ _ _ _ _

Another way to focus and recompose while keeping sharpness is, as was mentioned above: practice, practice, practice. Luckily, practice is free; snapping the shutter costs nothing. Not like film days...

08-10-2010, 09:16 PM   #5
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
QuoteOriginally posted by redeleon Quote
how do you guys frame our photos when using the center focus point and focusing manually?

i know center focus and recompose loses a bit of sharpness
As someone else mentioned, when focusing manually, you don't need the center point or any other point, nor is recomposing necessary.

And if you do decide to center your subject when focusing, unless you're shooting at f/2 or wider and are recomposing to put your subject at the extreme edge of the picture and have the world's flattest-field macro lens, the small discrepancy in focus plane that results from the rotation won't make a bit of difference.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
camera, center, center focus, focus, guys, pentax help, photography
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
K100D Super - Focus point locked to center in Manual Focus ? JGabr Pentax DSLR Discussion 2 01-25-2010 09:41 PM
Why only center point focusing for manual lenses? LightBug Pentax DSLR Discussion 19 01-01-2010 04:33 AM
Focus trap with non center focus points? RichyX Pentax SLR Lens Discussion 4 11-07-2009 09:48 PM
Macro: Handheld, Manual Focus, Manual Stop-Down Mike Cash Post Your Photos! 2 06-19-2008 07:14 AM
Different focus with non-center sensors? MNCurt-K10D Pentax DSLR Discussion 4 12-16-2007 08:42 AM



All times are GMT -7. The time now is 05:36 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top