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11-23-2009, 02:38 AM   #16
Damn Brit
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Moved to lens forum, this isn't about Photographic Style or Technique.

11-23-2009, 05:42 AM   #17
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dear god, If I had a dollar ever time I heard this question i would me f*king loaded....
11-23-2009, 11:27 AM   #18
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QuoteOriginally posted by Digitalis Quote
dear god, If I had a dollar ever time I heard this question i would me f*king loaded....
X2...

Steve

BTW...I don't know why Gary moved this thread. DOF is a general photography topic in my mind.
11-23-2009, 02:40 PM   #19
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QuoteOriginally posted by stevebrot Quote
X2...

Steve

BTW...I don't know why Gary moved this thread. DOF is a general photography topic in my mind.
Something to do between changing poopy diapers! laugh

11-23-2009, 03:17 PM   #20
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Yes DoF is affected by focal length, as you can see it on many DoF calculators.

Practically, on the same sensor, it is canceled out by the distance you have to move to get the same framing as shown by the Luminous Landscape tests.

In addition, changing the distance will change the perspective and relative sizes of the objects and what is in the background, giving the illusion of shallower DoF.
11-23-2009, 09:08 PM   #21
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by not moving away from the subject how do you get ALL in focus? aside from increasing aperture, moving away and wider focal length
11-23-2009, 09:39 PM   #22
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QuoteOriginally posted by rustynail925 Quote
how do you get ALL in focus?
You don't.
11-24-2009, 12:14 AM   #23
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QuoteOriginally posted by rustynail925 Quote
by not moving away from the subject how do you get ALL in focus? aside from increasing aperture, moving away and wider focal length
One word...tilt. Cameras with movements, and to a lesser extent, tilt/shift lenses are the most practical way to attain extreme DOF while managing perspective. There is a reason why so many incredible landscapes with foreground subjects are taken with view cameras.

See this thread for a few example pics using a Samsung GX20 coupled to a modified view camera:
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/80872-ilford-m...onversion.html
Steve

11-24-2009, 01:21 AM   #24
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my thoughts on this one is clearly as follows.

1. it is impossible to replicate the field perspective of two lenses with different focal lengths, unless you are shooting your subject up close with it's back against a plain white wall (no apparent or visible background) or in a different scenario, shooting a distant scenery which doesn't show involve a noticeable foreground. although there is an FOV difference, this can be solved by either cropping or segmented panoramic solution.

2. although DOF can be the same, brightness all over the image varies due to the lens difference. can be solved during post-processing or adjusting the shutter speed.

3. there is a need to buy a lens to cover a focal length for particular shots.

Last edited by Pentaxor; 11-24-2009 at 02:55 PM.
11-24-2009, 02:23 PM   #25
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It took me awhile to find them, but here are two images with similar composition, un-cropped, taken from different positions using different focal length lenses. They were posted as part of a similar thread about 18 months ago.







One was taken with a 50mm and the other with an 85mm. Both lenses were at f/5.6. The challenge put forth was to label which was the 85mm without peeking at the exif. (Hint: You can tell from the difference in perspective...)

Steve
11-24-2009, 02:46 PM   #26
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QuoteOriginally posted by stevebrot Quote
It took me awhile to find them, but here are two images with similar composition, un-cropped, taken from different positions using different focal length lenses. They were posted as part of a similar thread about 18 months ago.







One was taken with a 50mm and the other with an 85mm. Both lenses were at f/5.6. The challenge put forth was to label which was the 85mm without peeking at the exif. (Hint: You can tell from the difference in perspective...)

Steve

this is very easy Steve. basing from the OOF background, the first pic is the 85mm while the 2nd pic is the 50mm.

btw, what you did here is a tough task since you needed to recompose the photo at a certain angle that it would look the same with the other photo.

with a definite background as a basis, one could easily identify which lens is which. but this task however is difficult to judge if the background is plain single colored wall or the the subject is completely isolated by wide open aperture brightness.
11-24-2009, 02:53 PM   #27
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btw, specifically I easily identified the fl due to the wider FOV background of the 2nd pic. point of reference are the lateral location OOF flower petals on the right side of the frame. also the additional flower petal at the right edge of the frame. there are 2 OOF petals (right side) in the first pic versus 3 OOF petals (same side) on the 2nd one.
11-24-2009, 03:05 PM   #28
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QuoteOriginally posted by Pentaxor Quote
btw, specifically I easily identified the fl due to the wider FOV background of the 2nd pic. point of reference are the lateral location OOF flower petals on the right side of the frame. also the additional flower petal at the right edge of the frame. there are 2 OOF petals (right side) in the first pic versus 3 OOF petals (same side) on the 2nd one.
Good work!

Steve
11-24-2009, 03:09 PM   #29
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QuoteOriginally posted by Pentaxor Quote

...btw, what you did here is a tough task since you needed to recompose the photo at a certain angle that it would look the same with the other photo...
It did take a few tries to get it right, but the results were worth it.

The interesting thing was that before doing this comparison, I was of the opinion that the 85mm would show greater DOF based on its focal length. The original intent of the exercise was to demonstrate that. Boy was I wrong!

Steve
11-24-2009, 05:21 PM   #30
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QuoteOriginally posted by stevebrot Quote
Good work!

Steve
thanks ! the secret there is to look beyond the foreground.
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