spreadsheet showing why M8 and FF have same DOF

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rxmd said:
But what happens to DOF in the infrared?

And what about redshift? Particularly as the topic moves away from photography at high speeds? How does that affect DOF?

Nice camera BTW. A true classic. I think all cameras should have a hard disk and a SCSI interface. If I were a collector I'd have to have one. Got a DCS100, too?
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I'm just tankful no one brought up dark-matter, that would start the whole dark-energy thing off ... and at some point someone will have to say "where there's dark-energy there must be dark-light"

Which would be silly ... because bokeh would work backwards and people would argue about the in-focus bits of pictures
 
in camera cropping

in camera cropping

The only cropping the M8 is doing for me is by giving me a 3:2 JPG, it's giving me 10.3 effective pixels, instead of the native 11.2 total pixels.

Compare that with say the M9 which has a native 25MP, but gives a output of 18MP for the 3:2 image.

A Gibson Les Paul guitar has a scale length of 24.5" compared with a Telecaster's scale length of 25.5". Is one better than the other because of that? Some folks have preferences, and most folks can adjust to either with ease.

Do you refer to an M9 or Canon 5D as a cropped S2?

And then the S2 as a cropped large format?


rxmd said:
You don't have to, after all; the M8 does it for you.



From the technical side, just as one man's "overscan" is another man's crop, this just about answers its all.

And from the picture taking side, I suggest following the example and not concerning oneself with it too much.

Now I think we can return the discussion to Wang CLAs and nixie tubes, I liked that part better anyway. While I'm still here, I need to try and find myself some of the old Soviet calculators, such as a C3-07 or a B3-34.
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ampguy said:
A Gibson Les Paul guitar has a scale length of 24.5" compared with a Telecaster's scale length of 25.5". Is one better than the other because of that?
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Well, how would you like your your guitar service tech to place your new frets for the Tele at Les Paul distances? 😀

ampguy said:
Do you refer to an M9 or Canon 5D as a cropped S2? And then the S2 as a cropped large format?
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I don't, usually, but I don't see why I couldn't. And I don't see why you don't get it. And I'm not sure I want to pursue this further... it feels too much like Galilei trying to make the churchmen actually *take a look* though his telescope...
 
rxmd said:
But what happens to DOF in the infrared?

And what about redshift? Particularly as the topic moves away from photography at high speeds? How does that affect DOF?

Nice camera BTW. A true classic. I think all cameras should have a hard disk and a SCSI interface. If I were a collector I'd have to have one. Got a DCS100, too?
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I waited for the DCS200 to come out, passed on buying a DCS100. I handled one when they were first introduced, but the suitcase sized computer connected via umbilical cord was a show-stopper. Within a year ot so, the DCS200 was announced. It was $12,400 for the body. They go for about $50 now on Ebay.

with a Micro-Nikkor 55/2.8, I've never had to worry about the IR Focus shift. other lenses- noticeable. Same with ED series lenses and mirror, no need to adjust for IR.
 
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I'd love it

I'd love it

I do that all the time, keeps me in tune for jazz parts ...

kossi008 said:
Well, how would you like your your guitar service tech to place your new frets for the Tele at Les Paul distances? 😀



I don't, usually, but I don't see why I couldn't. And I don't see why you don't get it. And I'm not sure I want to pursue this further... it feels too much like Galilei trying to make the churchmen actually *take a look* though his telescope...
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We have physicists here?

I always thought a light-year was 12 months that was less filling, more taste. Bud I was wrong.
 
ampguy said:
My test results are here:

http://matsumura.smugmug.com/Journalism/M8-and-M6-depth-of-field/12529753_UJFd5#898702880_f85d9

Over 30,000 views, no one can see any difference between the M6 film and M8 DOF, except for Finder, and I've talked with dozens of folks who've magnified 10-400x to examine.
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If you're still interested in testing the DoF of your lenses, here's a technique that's quite informative: photograph a ruler or yardstick which is tilted towards the camera. The Auspicious Dragon photoblog did some Sonnar tests using this method, to demonstrate focus shift:

http://www.auspiciousdragon.net/photowords/?p=953
 
rulers

rulers

The issue that I have with those tests are that the markings have no meaning other than whether you're focused on a point subject or not focused there.

The blog author mentions that the yardstick is about 40 deg. from the wall, but what angle is his camera film/sensor plane at?

In his 2nd image, nothing is in focus, which I realize may be his point for that photo, but the numbers don't mean anything, the subject could have been anything.

I like my usage of figurines since I know exactly where they are relative to the sensor/film. Other users like yourself can also see, for example, with the first Hexar that I was not indeed focused or indexed on my target (good eyes), but evaluating DOF can still be done by closely looking at where the point of focus was at.

I do have an 8" artist triangle at 30/90 angles, which along with colored tape, can be useful for SLRs/Macro, or RFs with say 50/75 wide open tests, but it can't encompass the steep depth of ~24cm at 4cm intervals at 1m with a full 3d subject to evaulate at each step.


antiquark said:
If you're still interested in testing the DoF of your lenses, here's a technique that's quite informative: photograph a ruler or yardstick which is tilted towards the camera. The Auspicious Dragon photoblog did some Sonnar tests using this method, to demonstrate focus shift:

http://www.auspiciousdragon.net/photowords/?p=953
...
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ampguy said:
I like my usage of figurines since I know exactly where they are relative to the sensor/film.
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You could also incorporate the ruler into the figurine setting, to confirm that the focus distance is correct.

I guess my basic point is, to measure DoF, you have to treat the photograph like a scientific experiment, and try to be accurate as possible with all the details.
 
where should the ruler be placed

where should the ruler be placed

for example in my figurine/condiments setup, where should a yardstick lie, and at what angle to the film/sensor plane?

My take is that this was a personal project that I urge others to do on their own.

If someone thinks my measurements are wrong from film plane to figurine eyes and other objects like the Tabasco bottle, that's fine, please do your own tests with your own measuring gear.

However, a ruler shot at an angle, needs some index, ideally in the self-documented image, for what angle it is lying at, in relation to the film/sensor plane.

antiquark said:
You could also incorporate the ruler into the figurine setting, to confirm that the focus distance is correct.

I guess my basic point is, to measure DoF, you have to treat the photograph like a scientific experiment, and try to be accurate as possible with all the details.
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ampguy said:
for example in my figurine/condiments setup, where should a yardstick lie, and at what angle to the film/sensor plane?
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Set the ruler at a 45 degree angle, and position it so that the Tabasco label is exactly at, say, the 20 cm mark on the ruler. Then you can use the ruler as a calibration to confirm that the Tabasco bottle is exactly in focus.

ampguy said:
If someone things my measurements are wrong from film plane to figurine eyes and other objects like the Tabasco bottle, that's fine, please do your own tests with your own measuring gear.
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Then we'd end up with two conclusions: DoF equations are true, and DoF equations are false. (Also, I don't have enough lenses to run that test.)

ampguy said:
However, a ruler shot at an angle, needs some index, ideally in the self-documented image, for what angle it is lying at, in relation to the film/sensor plane.
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If the ruler is at a 45 degree angle to the film plane, then you can divide the markings by 1.414 to get the actual depth.
 
Ted, I'm not writing you off as a quack, so I'm going to try to help you. If what one is trying to accomplish is to discern whether or not there is a difference in the DoF between 2 lenses, then absolute measurements are not necessary, only that the conditions (like the angle of the ruler) are consistent. It is a classic experimental setup where the only variable is the one one is comparing (in this case the DoF of 2 different lenses) but all other variables are constant. Set up the apparatus, take a pic with one lens, switch lenses without changing anything else, and take a second pic. The camera should be on a tripod and not move between pics, the lenses should be at the same (widest) aperture and the angled ruler should not be moved. This is the only way you are going to be able to convince me of your hypothesis, Ted. The testing method that you used is flawed and the results/conclusions are invalid, IMO.
 
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