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05-16-2009, 10:14 AM   #16
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QuoteOriginally posted by sholtzma Quote
...
Is something like the following scenario possible and feasible? Your autofocus lens sends info about aperture and distance-to-focused-subject to the camera. The camera's processor calculates a depth of field range, which shows in the viewfinder. ...
In my mind, the "high tech" solution is a properly implemented LiveView. Why throw numbers at the photog when the cam can give you WYSIWG. Such a technology already exist, it is called video camera. You simply turn the aperture ring, and voila, you see the DOF effect on the display screen immediately. No distance scale to think about, you just focus on your raw visual creativity.

05-16-2009, 11:30 AM   #17
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QuoteOriginally posted by song_hm Quote
In my mind, the "high tech" solution is a properly implemented LiveView. Why throw numbers at the photog when the cam can give you WYSIWG. Such a technology already exist, it is called video camera. You simply turn the aperture ring, and voila, you see the DOF effect on the display screen immediately. No distance scale to think about, you just focus on your raw visual creativity.
The problem with that approach is the size of the screen. *Everything* looks sharp when you downsample to fit a 3" VGA screen. In order for it to be useful, the screen would need to match the resolution of the sensor - not gonna happen anytime soon...
05-16-2009, 01:01 PM   #18
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QuoteOriginally posted by OregonJim Quote
The problem with that approach is the size of the screen. *Everything* looks sharp when you downsample to fit a 3" VGA screen. In order for it to be useful, the screen would need to match the resolution of the sensor - not gonna happen anytime soon...
Your argument certainly is true when comparing sharpness within the area of focus. But the OP is interested in hyperfocal calculation, which is really about the differential between the out-of-focus and the in-focus area. No matter which down sampling algorithm used, it can't bring blurred areas back into focus.

The best way to illustrate is with an image where a near object is OOF, while mid to far objects are in focus. Unfortunately, I can't seem to find one in my collection. So here is the next best thing.



The left is 800x534, the right is downsampled to 240x160. To your argument, one sharp spike on the left end up three on the right. To my point, the guy in the red shirt, and the ball on the post are OOF in both. For visual hyperfocal functionality, this is good enough. And if it is critical to get the exact boundary right, just add some slop factor.

Also, with a properly implemented LiveView, one can digitally zoom in, this reduces the downsampling factor potentially up to 1:1.
05-16-2009, 01:10 PM   #19
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song_hm,

Your sample pictures serve to illustrate my point.

In the larger image, the 4th post from the front is clearly the only one in focus.

In the smaller image, the 3rd, 4th, and 5th posts all look sharp.

The apparent DOF has changed significantly.

05-17-2009, 01:21 AM   #20
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Yess and this is even more pronounced with larger DOF's and hyperfocal. Where everything in viewfinder might look sharp, something on a computer scren may have some 10..20 pixel blur wich can be very disturbing if the subject has to be sharp (like a persons face).
Can you tell from the smaller picture that the flower in foreground is out of focus, where exactly focus is and what DOF do you have with 10mpix camera?

P.S. With such DOF function it would be nice to have adjustable circle of confusion (or colored Megapixel scale as one stated above).
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05-17-2009, 11:56 AM   #21
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QuoteOriginally posted by ytterbium Quote
Can you tell from the smaller picture that the flower in foreground is out of focus, where exactly focus is and what DOF do you have with 10mpix camera?
What's more interesting about this is that your larger picture represents the screen resolution most new DSLRs will have. The real question might be your eyesight and viewing distance, not the screen itself.
05-17-2009, 09:03 PM   #22
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QuoteOriginally posted by OregonJim Quote
song_hm,

Your sample pictures serve to illustrate my point.

In the larger image, the 4th post from the front is clearly the only one in focus.

In the smaller image, the 3rd, 4th, and 5th posts all look sharp.
Yes, I don't disagree with this, and it is already mentioned below my sample picture. However, you can't deny it is visually apparent that the red shirt guy, and the ball post are blurry even down sampled. Not everything looks sharp on a 3" screen as you stated.

QuoteOriginally posted by ytterbium Quote
Can you tell from the smaller picture that the flower in foreground is out of focus, where exactly focus is and what DOF do you have with 10mpix camera?

P.S. With such DOF function it would be nice to have adjustable circle of confusion (or colored Megapixel scale as one stated above).
With my bad eyes, I would not be able discern that the very front part of the white flowers are OOF. BUT, I can tell the background are NOT in focus, in fact, I can detect that the far left edge of the table cloth is starting to look soft.

Notice the rear half of the white flowers are in focus, this means the hyperfocal front edge is only inches behind the OOF front part. Now answer this, after consulting hyperfocal charts, can you reliably estimate the hyperfocal edge is in the middle of the pot?

Both your argument boils down to this. Because of the inherent problem associated with downsampling, LiveView based DOF visualization is pointless, therefore we should just stick with hyperfocal charts and numbers.

I don't accept that. As stated already in my previous post #18, with a properly implement Live View, all one has to do is digitally zoom in, this will reduce the download sampling ratio. Eventually, you will get to a zoom setting where the front part of the pot is visually obvious to be OOF.

To ytterbium credit, you are seeing some of the possibilities. Playing with the CoC is an interesting idea. I don't know it feasible to digitally manipulate CoC, it could well be the implementation approach to Hyperfocal Mode the mattdm suggested. In fact, why stop there, you can have a Hyperfocal Mode distinct from DoF mode.

Last edited by song_hm; 05-17-2009 at 09:10 PM.
05-18-2009, 06:19 AM   #23
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Live view wont give you a distance to work with. If you want your hyperfocal to start 67 ft away, how would you know it is starting at that distance? It's just a simple math calc and X is your near limit. You want that limit displayed somewhere...


Unless you get a number and focus lock indicator to work with, you just dont know. I emailed pentax about adding the feature 2 years ago; their reply was to use mtf hyper drive.

05-18-2009, 09:51 AM   #24
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QuoteOriginally posted by Mike Cash Quote
I can't figure out why you're all searching for a high-tech solution to a low-tech problem:
Mike, my understanding is that the DOF scale for 35mm is not accurate on Pentax digitals.
For instance using the same 50mm lens set at f16 on both cameras:

Focus at 10 ft:
35mm - DOF = 6.35 ft to 23.6 ft
Digital - DOF = 7.23 ft to 16.2 ft

Focus at 20 ft
35mm - DOF = 9.26 ft to infinity
Digital - DOF = 11.3 ft to 88 ft

Hyperfocal distance at f16:
35mm - 17.3
Digital - 25.8

According to the charts on Hyperfocal Distance this is due to the circle of confusion being 0.030mm for 35mm and 0.020mm on all Pentax digitals from the *ist D through the KM/K2000.

You can download the DOFMaster Hyperfocal Chart Download and set the parameters to print out a hyperfocal chart to keep in your bag.

Speaking of confusion, all this math has given me a headache. I think I will go take two aspirin and a shot of vodka. On second thought, maybe I'll skip the aspirin.

CW
05-19-2009, 08:26 PM   #25
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QuoteOriginally posted by attack11 Quote
Live view wont give you a distance to work with. If you want your hyperfocal to start 67 ft away, how would you know it is starting at that distance? It's just a simple math calc and X is your near limit. You want that limit displayed somewhere...

Unless you get a number and focus lock indicator to work with, you just dont know. I emailed pentax about adding the feature 2 years ago; their reply was to use mtf hyper drive.
In pre-computerized cameras, you have no choice but to resort to manual math computation. The main problem is, the primary input to the math equation starts with that 67 ft. Short of actually taking out a physical measurement, what usually happens is a guesstimate.

With computerized camera, why do manual math, why guesstimate the desired distance. Why not just let the camera show you a visual preview of where the OOF areas are?

QuoteOriginally posted by straightshooter Quote
According to the charts on Hyperfocal Distance this is due to the circle of confusion being 0.030mm for 35mm and 0.020mm on all Pentax digitals from the *ist D through the KM/K2000.
The dofmaster site allow you to customize the CoC used to arrive at a custom chart.

QuoteOriginally posted by straightshooter Quote
You can download the DOFMaster Hyperfocal Chart Download and set the parameters to print out a hyperfocal chart to keep in your bag.
Ha ha, I have one in the bag, but everytime I need it in the field, the chart either can't be found, or have a crease in the wrong place

QuoteOriginally posted by straightshooter Quote
Speaking of confusion, all this math has given me a headache.
My point exactly. This is happening when you are at home sitting in front of your computer. Now imagine you are out in the field, that once in a lifetime shot about to slip away, do you want a hyperfocal chart and math, or a visual feedback from the camera?
05-20-2009, 10:27 PM   #26
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ok, so based on the only variable the user would change (aperture), how would you present the user with the near limit distance? that's what matters. a guess is a guess, you can't automate hyperfocal based on a scene; 'cause what if the user wants A and the camera thinks B is ideal?

you could automate it sorta by having the user select the near limit distance, and then the camera does everything .. but that's still an interface nightmare.
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