Unable to Focus on both foreground and background

sterretje · 09-29-2011, 09:39 PM - **1 Like**

Originally posted by vass

Hi, Just gone through the DOF Master Hyperfocal Chart and gained a little knowledge on 'Hyperfocal distance'. Thanks to Hambino for posting the link. My doubt is, I'm using older lens on my Pentax K-r and I was told that I've to use a multiplication factor ,1.5(don't know exactly what's this, why to use and by what name it's called). So, say, my 50mm lens become 50*1.5=75mm. In this case which length should I consider? whether 50 or 75??
Regards,
Vass.

RioRico explained it well. The field of view changes, not the focal length. Assuming that you used the dof calculator that I referred to, they also clearly state

Quote:

Use the actual focal length of the lens for depth of field calculations. The calculator will automatically adjust for any "focal length multiplier" or "field of view crop" for the selected camera.

Maybe a picture says more than a thousand words and here are two that I found
post #32 on https://www.pentaxforums.com/forums/pentax-dslr-discussion/119867-equivalent-field-view-3.html
post #8 on https://www.pentaxforums.com/forums/pentax-dslr-discussion/132694-some-about-...-negative.html

Both images show that only part of what the lens 'outputs' (the circle in the first link) is picked up by the sensor.

Hope that those make it a bit clearer.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Startrails with lit lighthouse in foreground	kswier	Photographic Technique	13	06-30-2011 07:01 AM
Unable to fire	azngirlLH	Troubleshooting and Beginner Help	8	03-03-2010 05:16 PM
lighted background black foreground	iasonis	Troubleshooting and Beginner Help	9	06-15-2009 12:03 PM
Front focus issue, but unable to correct - What now?	enoxatnep	Pentax SLR Lens Discussion	11	12-28-2008 10:34 PM
aperture settings for detailed foreground and background	lordson	Photographic Technique	4	11-10-2007 08:16 AM

09-29-2011, 09:39 PM - 1 Like	#16
sterretje Veteran Member Join Date: Dec 2008 Location: Roodepoort, South Africa Photos: Gallery \| Albums Posts: 3,561	Originally posted by vass Hi, Just gone through the DOF Master Hyperfocal Chart and gained a little knowledge on 'Hyperfocal distance'. Thanks to Hambino for posting the link. My doubt is, I'm using older lens on my Pentax K-r and I was told that I've to use a multiplication factor ,1.5(don't know exactly what's this, why to use and by what name it's called). So, say, my 50mm lens become 50*1.5=75mm. In this case which length should I consider? whether 50 or 75?? Regards, Vass. RioRico explained it well. The field of view changes, not the focal length. Assuming that you used the dof calculator that I referred to, they also clearly state Quote: Use the actual focal length of the lens for depth of field calculations. The calculator will automatically adjust for any "focal length multiplier" or "field of view crop" for the selected camera. Maybe a picture says more than a thousand words and here are two that I found post #32 on https://www.pentaxforums.com/forums/pentax-dslr-discussion/119867-equivalent-field-view-3.html post #8 on https://www.pentaxforums.com/forums/pentax-dslr-discussion/132694-some-about-...-negative.html Both images show that only part of what the lens 'outputs' (the circle in the first link) is picked up by the sensor. Hope that those make it a bit clearer.