Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
08-22-2011, 03:44 PM   #1
Senior Member




Join Date: Jul 2009
Location: Perth, Australia
Posts: 180
Sigma 10-20mm f3.5 hyperfocal distance

Hi everyone

I have been reading about hyperfocal distance over the last two days, and if anything I'm more confused than educated.

Can someone please explain to me in simple terms HOW to set my Sigma up for hyperfocus?

I have a K20D and want to get this method perfected before going to Canada next year on holiday.

The only distance indicators on the lens are the ft/m and infinity sign. Nothing else.

I know this topic has been covered numerous times, but I need education on the equipment I have so that I can grasp the method.

Thanks in advance

08-22-2011, 04:00 PM   #2
Veteran Member
RioRico's Avatar

Join Date: Jun 2008
Location: Limbo, California
Posts: 11,264
The bad news: There ain't no easy way, Not with AF zooms. They don't have DOF scales on them. Even manual zooms with DOF scales are hard to set hyperfocal. Manual primes are easiest.

The not-so-bad news: Google for ONLINE DOF CALCULATOR and you'll find apps that will crunch numbers for you. You can use those to build a table of apertures vs focal lengths vs distances.

If you want a rule-of-thumb, try this: On your 10-20, set your aperture to f/11 and focus to 2m. Everything from under 1m to infinity will be in focus. But if you want a DOF range that doesn't extend to infinity, use a DOF calculator. Good luck!
08-22-2011, 04:09 PM   #3
Senior Member




Join Date: Jul 2009
Location: Perth, Australia
Posts: 180
Original Poster
There is a problem....

I don't know how to use the results from the DoF calculator

What do those distances mean at a given focal length and aperture?

What is (for example) 2m at 10mm f/11?
08-22-2011, 04:14 PM   #4
Pentaxian
JinDesu's Avatar

Join Date: Jun 2011
Location: New York City
Photos: Gallery
Posts: 5,626
10mm zoom range, 2 meters is what you are focusing to, i.e. focus on an object 2 meters away

08-22-2011, 04:18 PM   #5
Senior Member




Join Date: Jul 2009
Location: Perth, Australia
Posts: 180
Original Poster
But then, there is another website which says that the 2m is the "middle" focus point and to focus on the subject HALF that distance.

I'm so confused it's not funny
08-22-2011, 04:18 PM   #6
Inactive Account




Join Date: Dec 2008
Location: Ames, Iowa, USA
Photos: Albums
Posts: 2,965
QuoteOriginally posted by CrazyNuts Quote
Hi everyone
Online Depth of Field Calculator
I have been reading about hyperfocal distance over the last two days, and if anything I'm more confused than educated.

Can someone please explain to me in simple terms HOW to set my Sigma up for hyperfocus?
Under the worst conditions, 20mm @ f:3.5, the hyperfocal distance is about 20ft according to Online Depth of Field Calculator

That means that even wide open, if you focus on something about 20 ft from the camera every thing from about 10 feet to infinity will be in focus.

For any other lens settings even more will be in focus.
08-22-2011, 04:18 PM   #7
Veteran Member
RioRico's Avatar

Join Date: Jun 2008
Location: Limbo, California
Posts: 11,264
Let's say we use this calculator: Online Depth of Field Calculator

I tell it I have a K20D, that the lens is set to 10mm focal length (its widest angle) and f/11 (that's the aperture I set via the camera), and that I've manually prefocused to 2m (set that on the lens focus ring after switching AF off). The calculator then says that my DOF extends from 0.36m to infinity. If I change the focal length to 20mm (its narrowest angle) then the calculator says DOF goes from 0.94m to infinity.
08-22-2011, 04:31 PM   #8
Senior Member




Join Date: Jul 2009
Location: Perth, Australia
Posts: 180
Original Poster
Ahhhhh I get it now

Thanks RioRico & NewArts

So I have to make sure that what's in my frame isn't closer than the NEAR LIMIT once I focus on my subject at a given distance (in this case 2m).

This will effectively give the impression that my whole image is in focus.

Riiiiiight. Think I'm starting to get the picture (pardon the pun).

The images on that link you guys provided cleared things up for me.


Last edited by CrazyNuts; 08-22-2011 at 04:54 PM.
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!
distance, k-mount, method, pentax lens, sigma, sigma 10-20mm f3.5, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Q about: Hyperfocal distance + focus scales vincechu Troubleshooting and Beginner Help 14 03-16-2011 06:05 PM
Hyperfocal Distance Correction Sticker? bigjonnee Pentax SLR Lens Discussion 8 12-08-2010 09:03 AM
hyperfocal distance stevewig Photographic Technique 26 07-16-2010 10:57 PM
Do you use Hyperfocal distance ? simonkit Photographic Technique 26 10-10-2007 03:11 PM
Hyperfocal distance regken Pentax DSLR Discussion 16 03-26-2007 05:29 PM



All times are GMT -7. The time now is 04:06 PM. | 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