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Old 07-02-2011   #41
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Any DOF calculation is arbitrary. And, sharpness is subjective. Fuji isn't "wrong," they are just taking a more conservative approach to DOF. Most calculations for DOF use the Zeiss formula, circle of confusion = 1/1700 of the image diagonal; the math is solid but 1/1700 part is completely arbitrary.

This camera resolves better than that, so it's appropriate to use a more conservative forumla.
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Old 07-02-2011   #42
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Quote:
Originally Posted by M4streetshooter View Post
I did manage to talk with an engineer at Fuji.
He admitted there was a mistake made as they used a 35mm to compute the scale.
Now, that is actually scary. A US Mars mission crashed because somebody messed up a formula (by using feet vs. meters).
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Old 07-02-2011   #43
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Originally Posted by Jamie123 View Post
No, the DoF stays the same for a given focal length no matter what size the sensor is. But the smaller the sensor, the shorter the focal length (with less DoF) you need to use in order to achieve the same FoV.
Sigh. People still don't get this.

The depth of field at the film plane stays the same, it's a physical property of the lens and aperture. But that's not what depth of field scales on lenses are refering to. DOF scales on lenses are refering to the CoC when magnified as an enlargement (a print) and viewed at a specific distance.

And so the whole issue is about the enlargement factor from a u4/3 image to an 8x10 print.

Remember, any time you refer to a DOF lens scale, you have to take into account CoC, enlargement factor and viewing distance of a print; that's what the numbers on the scale are calibrated to.

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Old 07-02-2011   #44
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If you view a 16 x 20" print at museum standard of
60" center height, about 38" away and even at 180 pix, not needed as your eye can't see more than that anyway, the dof for the x100 far exceeds the scale they give you.

It's a mute point already. You either believe or you don't.
Try the camera using a calculator and be surprised.
I used calculators for my 8x10 for years and they never failed me.

Last edited by M4streetshooter : 07-02-2011 at 13:11.
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Old 07-02-2011   #45
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Sigh. People still don't get this.

The depth of field at the film plane stays the same, it's a physical property of the lens and aperture. But that's not what depth of field scales on lenses are refering to. DOF scales on lenses are refering to the CoC when magnified as an enlargement (a print) and viewed at a specific distance.

And so the whole issue is about the enlargement factor from a u4/3 image to an 8x10 print.

Remember, any time you refer to a DOF lens scale, you have to take into account CoC, enlargement factor and viewing distance of a print; that's what the numbers on the scale are calibrated to.

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Sigh. Some people just don't seem to be able to read. My comment clearly had NOTHING WHATSOEVER to do with DoF scales or CoCs. I replied to Eric T (as indicated by the quote box), in regards to the effect (or lack thereof) of sensor size on the DoF for a given focal length.

Remember, any time you reply to someone on RFF and quote them, you have to take into account that your comment might be totally irrelevant to what they wrote.
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These are true facts Jamie
Old 07-02-2011   #46
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These are true facts Jamie

It is funny how folks cannot grasp this, and refer others to tables that are using arbitrary CoC's from the manufacturers tables so their online calculator matches the manuals.

If enough folks here complained to their favorite online dof web site, the site would correct for 23mm and make many folks happy.

Ray - by using 35 instead of actual 23, you're actually making it a bit hard on yourself with focus, but if you can do it, it's just the equivalent of using one stop more conservative, which is a good thing anyways, in this day of fine grain, large prints, and pixel peeing. Oops, I mean peeping.


Quote:
Originally Posted by Jamie123 View Post
No, the DoF stays the same for a given focal length no matter what size the sensor is. But the smaller the sensor, the shorter the focal length (with less DoF) you need to use in order to achieve the same FoV.
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Old 07-02-2011   #47
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Quote:
Originally Posted by Jamie123 View Post
Quote:
Quote:
Originally Posted by Jamie123 View Post
No, the DoF stays the same for a given focal length no matter what size the sensor is. But the smaller the sensor, the shorter the focal length (with less DoF) you need to use in order to achieve the same FoV.
Sigh. Some people just don't seem to be able to read. My comment clearly had NOTHING WHATSOEVER to do with DoF scales or CoCs. I replied to Eric T (as indicated by the quote box), in regards to the effect (or lack thereof) of sensor size on the DoF for a given focal length.
Sorry to say, but you were still completely wrong. DOF indeed does depend on the sensor size, leaving all other image parameters unchanged. Try it out yourself, for example using the Silverlight DOF calculator (http://www.silverlight.co.uk/resources/dof_calc.html) - dial in a focal length, an aperture and a distance and watch DOF change. Just try it out yourself, but be rigorous about changing only one parameter (sensor size) and leaving the other parameters unchanged (focal length, viewing distance, aperture) as per your first posting above. Preferably don't use DOFMaster for trying this out, because DOFMaster changes the underlying CoC assumptions when you change format and hence is not rigorous enough. There is a mathematical reason for why this is how it is, but this is not the place to go into formulas; refer to the article quoted below if you're interested.

You could also take a look at the DOF scales of a medium format and a 35mm lens of the same focal length and wonder why they're so different, but you didn't want to talk about DOF scales.

DOF is not some kind of inherent property of an image - it comes about because our brain percieves things as sharp as soon as they're small enough. Hence it does not make sense to talk about DOF without talking about things like circles of confusion, viewing distances and print sizes. It seems to be surprisingly difficult to accept that DOF indeed does not correspond ty physical reality (in the sense that a picture indeed does not have one single unique DOF, no matter if you look at it in 400x600 pixels on-screen or at a 40x60" print of it), and that in-camera and on-lens DOF scales are based on solely conventions and assumptions about print sizes and enlargement rations, making DOF a highly volatile thing dependent on a lot of non-obvious parameters like the acceptable circle of confusion. This seems very counter-intuitive to many people who think that an image either is in focus or it isn't. People don't like mathematics, and they also don't like to change their mind on what seems obvious to them, and hence DOF discussions tend to go bad rather quickly.

Nevertheless, that's how it is, and any advanced photography textbook (and even the Wikipedia article on DOF) will contain a highly mathematical section on how DOF comes about and why it is so relative.

This is my last post in this discussion, because I've seen many DOF discussions; they all tend to go pointless and angry at some point, and I'm on RFF for fun after all.
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Old 07-03-2011   #48
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Quote:
Originally Posted by rxmd View Post
You could also take a look at the DOF scales of a medium format and a 35mm lens of the same focal length and wonder why they're so different.
Anyone with camera systems of different sensor/film size... Go shoot some samples. It was an eye-opener for me. Shoot the same scene with DX, FX, and 6x9. Quick: With lenses of comparable view, what f-stop on DX will give the same DOF as f/4 on 6x9? Try it.
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DOF scale is quite accurate!
Old 08-06-2011   #49
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DOF scale is quite accurate!

Quote:
Originally Posted by M4streetshooter View Post
Ok, first off ... We can safely assume that this forum has many members that understand RF cameras. They also understand about DOF scales and how to use them. Many also use the X100.

So, if you use a DOF calculator, set to 23mm (22-24 will work), you will find that the scale in the camera is off.
It's off very bad on the close end of hyperfocal distance.

It appears that Fuji used a 35mm to design the scale.
Of course we all know that's just wrong.

Does this bother anyone or should I just drink another shot of single malt.
Hi there. After several tests using measure tools and comparing the DOF indication with the one present in pictures, I can confirm the DOF scale is very accurate. The same applies also to the hyperfocal setting using the same DOF scale. All tests done in MF mode, of course. The 35mm is just a concidence.
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Old 08-06-2011   #50
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Sir, it is accurate for a 35mm lens. My X100 has a 23mm on it.
Do the test at that focal length, check the images...
Eureka.
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Old 08-06-2011   #51
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There is no standard for DOF. It all comes down to what you regard as sharp enough or not sharp enough.
My Jupiter 8 (50/2) says hyperfocal distance for f/16 is 4m. My Minolta 50/2 says 5m, a Tessar 50/2,8 claims 3m ... who's wrong? Truly an international issue...
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Old 08-06-2011   #52
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Quote:
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There is no standard for DOF. It all comes down to what you regard as sharp enough or not sharp enough.My Jupiter 8 (50/2) says hyperfocal distance for f/16 is 4m. My Minolta 50/2 says 5m, a Tessar 50/2,8 claims 3m ... who's wrong? Truly an international issue...
Dear Andreas,

You are of course absolutely right, but it is truly astonishing how many people look for a precision that isn't there, and then get really upset when their unexamined prejudices are not confirmed.

Cheers,

R.
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Old 08-06-2011   #53
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But whats great about this is that the OP has experimented and determined what sort of apertures produce acceptable DOF for his applications. The end result of Fuji's error/conservatism is that the OP now knows more about his camera and how to use it than he would had they got it right/been less conservative. Sounds like a happy ending to me!
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Old 08-06-2011   #54
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Quote:
Originally Posted by M4streetshooter View Post
Look above ... that's a heck of a margin!
Seems to me you are confusing hyperfocal distance (Fuji's numbers) and depth-of-field at hyperfocal distance (DOF program's numbers).The latter always is from half the former to infinity.

So—what numbers exactly are you comparing with one another?
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Old 08-06-2011   #55
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hmmmm, I just might be that OP guy. Look, i'm no cherry to DOF scales. I've been on Leica M's for well over 40 years. Never in my history with any other shooter has anyone questioned the DOF scale on a Leica lens! Why is it that we now do digital and things change. Nope...bunk pure rubbish.

Will anyone here with an M9 and a 35 Cron state that the scale is wrong? I doubt it. Why? Because there are certains constants that stay constant in the photo universe.
The scale on the X100 is wrong. I know it, Fuji knows it and verified it to me and many others. Why then the un-acceptance about this issue that really gives you more than what you think.
Isn't that another shape of the Inverse Square Law.
All anyone has to do is check it, make some images and then realize that the old DOF that worked for centuries still holds constant.

Turtle, thanks you kind sir!
Shooter
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Old 08-06-2011   #56
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Quote:
Originally Posted by ka7197 View Post
Seems to me you are confusing hyperfocal distance (Fuji's numbers) and depth-of-field at hyperfocal distance (DOF program's numbers).The latter always is from half the former to infinity.

So—what numbers exactly are you comparing with one another?
I'm not confusing anything. I'm questioning the scale on the X100. It's wrong, simple as that.
I'm using the X100 the same way I always used my M's. The prints verify what I am discussing.
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Old 08-06-2011   #57
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Originally Posted by M4streetshooter View Post
I'm not confusing anything. I'm questioning the scale on the X100. It's wrong, simple as that.
Oh, yes ... sorry. After some googling, I found a remark in dpreview.com's X100 review stating that Fuji obviously had used a focal length of 35 mm rather than 23 mm in their calculations when they designed the X100's DOF indicator. So it seems Fuji's engineers simply are too dumb to tell actual focal length from equivalent focal length. Or they designed the DOF indicator for pixel peepers, not for those looking at prints.

Maybe it will get better after the next firmware update ...
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Old 08-06-2011   #58
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But DOF scales are not infrequently 'varied' and sometimes mystifying. The Mamiya 7 lenses, for example, are (for my uses) wildly optimistic and you will find plenty of blurb on that issue online. I would not dream of relying completely on a DOF scale on a lens. Validation through use is the only way to be sure.

Leica DOF scales might work nicely for you, but others might find them conservative or optimistic depending on how big they prints and their subjective opinion on whats acceptably 'in focus.'

You know how to interpret the cameras numbers and relate that to what you do, so you are all set, right? I am sure you are used to having to put your own input into lots of aspect of photography, such as interpreting various meters in different light, film speeds under different conditions etc. Surely this is the same. You can achieve the DOF you want at, say f8, when the camera says F11 or f16. With my Mamiya 7, I stop down one to two more stops compared to what the scale tells me (depending on needs) and it works fine. I can't say it has soured my view of a phenomenal camera system.
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Old 08-06-2011   #59
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Well, heres the crux of the issue. This is confirmed by Fuji.
Let's just look at the scale issue. If it's off at the near end, this is confirmed, could it then be off on the other end. So, maybe infinity is not really infinity.

Your getting ready to do an image. You WANT the foreground OUT of focus to make a soft blur and use the scale... If the scale is wrong then your blur is in a different place.

Set the camera up for DOF preview and use the EVF. Go by the scale setting and see what happens.
This scale is a key feature for this camera. With the OVF it's the only way to see your DOF at any fstop. Maybe I'm just old but then that means the Fuji Engineer is also.

It will be fixed hopefully in the next update.
The camera is designed for street and this is the real issue.
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Old 08-07-2011   #60
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Originally Posted by M4streetshooter View Post
hmmmm, I just might be that OP guy. Look, i'm no cherry to DOF scales. I've been on Leica M's for well over 40 years. Never in my history with any other shooter has anyone questioned the DOF scale on a Leica lens! Why is it that we now do digital and things change. Nope...bunk pure rubbish.

Will anyone here with an M9 and a 35 Cron state that the scale is wrong? I doubt it. Why? Because there are certains constants that stay constant in the photo universe.
The scale on the X100 is wrong. I know it, Fuji knows it and verified it to me and many others. Why then the un-acceptance about this issue that really gives you more than what you think.
Isn't that another shape of the Inverse Square Law.
All anyone has to do is check it, make some images and then realize that the old DOF that worked for centuries still holds constant.

Turtle, thanks you kind sir!
Shooter
Uh... Yeah...

I normally use the next set of d-o-f scales down (e.g. f/5.6 when shooting at f/8) if I reckon the pic might be run big. But mostly I rely on experience.

This is a song I've been singing for a very long time. From http://www.rogerandfrances.com/subsc...e%20focus.html, written some years ago:

Manufacturers' d-o-f scales are not uniform. They are based on the manufacturers' assumptions of what the camera's users will regard as 'acceptable'. . . . There is however an easy way around this. If you find that your camera is not giving you the d-o-f that you want, just use the next scale down, e.g. if you are shooting at f/11, use the d-o-f scales for f/8, and if you are shooting at f/8, use the d-o-f scales for f/5.6.

Cheers,

R.
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It's Hardly An Exact Science!
Old 08-07-2011   #61
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It's Hardly An Exact Science!

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I normally use the next set of d-o-f scales down (e.g. f/5.6 when shooting at f/8) if I reckon the pic might be run big. But mostly I rely on experience.

Manufacturers' d-o-f scales are not uniform. They are based on the manufacturers' assumptions of what the camera's users will regard as 'acceptable'. . . . There is however an easy way around this. If you find that your camera is not giving you the d-o-f that you want, just use the next scale down, e.g. if you are shooting at f/11, use the d-o-f scales for f/8, and if you are shooting at f/8, use the d-o-f scales for f/5.6.

Cheers,

R.
I think some people go looking for a degree of precision that isn't there and was never intended to exist. Most of the lenses I've had over the years had a DOF scale on them that gives a reasonable approximation of the zone of acceptable focus. I've never used them for more than a rough guide and if the subject was important I've always gone for a reduction at least half of the next scale marking.
What is the "zone of acceptable focus"? Generally I've found with all of the lens markings that for shop prints of 6x4 the focus is most acceptable; for prints from the same negative of 10x8 some softness is frequently observed and at 16x20 it's often not acceptable. Since the fall-off of sharpness is gradual there's no "tipping point" beyond which the result is or is not acceptable. You just have to make a judgement call and, as Roger says, if in any doubt, use a tighter scale.
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Old 08-07-2011   #62
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Gentleman, thanks for your interest and post.
I surrender.
Don
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Old 08-07-2011   #63
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As this camera is the first I have seen to have an electronic DOF scale, it would be easy for Fuji, even in a firmware change, to allow a user-assigned CoC and allow the user to adjust the DOF scale to suit their own purposes.

Surely that would make us all happy?
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Old 08-07-2011   #64
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Quote:
Originally Posted by yanakis View Post
After several tests using measure tools and comparing the DOF indication with the one present in pictures, I can confirm the DOF scale is very accurate. The same applies also to the hyperfocal setting using the same DOF scale. All tests done in MF mode, of course. The 35mm is just a concidence.
Thanks, yanakis, for reporting this test result. It sounds like you, and the camera, have a high standard in assessing DOF.

The pop culture saying fits here: "Different strokes for different folks."
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