DotTune MFA question...

[ErikH]

Hi - I just MFA my 70D using the "DotTune" method outside on a bright day with 2 of my lenses. Here are my results and my questions below:

55-250 STM

(W)ide -8 +5 = -1 (or -2)

(T)ele -5 +3 = -1

18-135 STM

W -6 +5 = 0

T -7 + 5 = -1

1) Because my adjustments are so minimal, is it even worth making the change? The reason I'm asking, is (if I'm understanding correctly) this method balances the focal plane evenly whereas typically the focal plane is thought to be 1/3 in front & 2/3 behind (speaking generally).

Since my camera has a (slight) tendency toward the minus side, could that be part of the correction DotTune is trying to make to even "things" out? (hopefully that makes sense).

Any comments appreciated!

 

[Mr Ed M]

What people have to keep in mind is that the Circle of Confusion that Depth of Field calculations ae based on a specific enlargement size (typically 8X10 or 11X14) , normal visual acuity, and standard viewing distances.

When you look at an image at 100% on a monitor you see a substantially smaller DOF than is calculated using a DOF calculator. So it is very likely that you can see the difference made by small micro focus adjustments in that situation.

p.s. The Dot Tune Method gives you your depth of focus, it is the range of values you of obtain using the Dot Tune Method.

 

[Zeee]

So if I'm going to MFA a 50mm lens 50X = 8.2 feet. 50X is Canon's minimum so even further is fine or the distance you shoot most often. Anyone can find 8 feet indoors. I would not MFA at 25X because although it is unlikely 50X is less prone to error. I'd even of further unless I was in studio and my subjects were always at 8 ft.

If I have to MFA @ 580mm lens 50X is 92.86 feet. @ 25X would be hard pressed to find enough room indoors at 46.43ft so I would have to go less. About 16X @ 29.40 ft. and I'd be squeezing behind the tripod. 15X at is comfortable. I know now that 15X will work and but more prone to error because the MFA shifts will be smaller than at the recommend 50X so I'd be extra careful and do this several times. If it wasn't Canon would not recommend a minimal of 50X is what I'm assuming. I'd double check real world shots until I could get outside and redo it at either at least 50X or the distance I normally BIF which is probably about 100 or more feet. I'll have to do guesstimate of that.

This has ben the most enlightening MFA thread for me to date.

 

[Zeee]

What people have to keep in mind is that the Circle of Confusion that Depth of Field calculations ae based on a specific enlargement size (typically 8X10 or 11X14) , normal visual acuity, and standard viewing distances.

When you look at an image at 100% on a monitor you see a substantially smaller DOF than is calculated using a DOF calculator. So it is very likely that you can see the difference made by small micro focus adjustments in that situation.

p.s. The Dot Tune Method gives you your depth of focus, it is the range of values you of obtain using the Dot Tune Method.

I use it to tell me how badly out something is and if it needs a tune up at Canon. I'm getting great images with my 100-400 MKII and 7D2 but I'm not so sure about when I add the 1.4 III.

I like to push the crops as hard as I can and I can do this easily without the TC and IQ suffers a bit using the TC. I'm not sure if I am reaching the limits of the TC magnifying the lens or not. Others have stated that the TC should not suffer. When I get a chance I'll get out and try this out with the TC, Dot Tune and at some distance. I don't have laptop so I can't use software. They need to put out something for iPads, etc or maybe there already is?

 

[Mr Ed M]

So if I'm going to MFA a 50mm lens 50X = 8.2 feet. 50X is Canon's minimum so even further is fine or the distance you shoot most often. Anyone can find 8 feet indoors. I would not MFA at 25X because although it is unlikely 50X is less prone to error. I'd even of further unless I was in studio and my subjects were always at 8 ft.

Normal shooting distance should take precedence over rule of thumb. You don't want to MFA your Macro lens at 50X the focal length. This is why you get two sets of advice from Canon. The 50X came out first as a rule of thumb, then later they clarified and said at the distance you normally shoot at. If you have no 'normal' distance for a lens, like a walk around lens, then just use the rule of thumb. For a portrait lens like your 50mm example use the normal shooting distance.

If I have to MFA @ 580mm lens 50X is 92.86 feet. @ 25X would be hard pressed to find enough room indoors at 46.43ft so I would have to go less. About 16X @ 29.40 ft. and I'd be squeezing behind the tripod. 15X at is comfortable. I know now that 15X will work and but more prone to error because the MFA shifts will be smaller than at the recommend 50X so I'd be extra careful and do this several times. If it wasn't Canon would not recommend a minimal of 50X is what I'm assuming. I'd double check real world shots until I could get outside and redo it at either at least 50X or the distance I normally BIF which is probably about 100 or more feet. I'll have to do guesstimate of that.

This is where Dot Tune shines, it can be done outside without any additional equipment. So you can MFA your 580mm lens at the distance you normally use it, and also importantly in the type of light you use it. Just set your camera and tripod perpendicular to a sign at a park and do your big lens MFA there

This has been the most enlightening MFA thread for me to date.

.

 

[Zeee]

So if I'm going to MFA a 50mm lens 50X = 8.2 feet. 50X is Canon's minimum so even further is fine or the distance you shoot most often. Anyone can find 8 feet indoors. I would not MFA at 25X because although it is unlikely 50X is less prone to error. I'd even of further unless I was in studio and my subjects were always at 8 ft.

Normal shooting distance should take precedence over rule of thumb. You don't want to MFA your Macro lens at 50X the focal length. This is why you get two sets of advice from Canon. The 50X came out first as a rule of thumb, then later they clarified and said at the distance you normally shoot at. If you have no 'normal' distance for a lens, like a walk around lens, then just use the rule of thumb. For a portrait lens like your 50mm example use the normal shooting distance.

Good info about 50X and normal shooting info. Makes sense. That is true. I would not do my macro at 50X so you have to adjust for the situation.

If I have to MFA @ 580mm lens 50X is 92.86 feet. @ 25X would be hard pressed to find enough room indoors at 46.43ft so I would have to go less. About 16X @ 29.40 ft. and I'd be squeezing behind the tripod. 15X at is comfortable. I know now that 15X will work and but more prone to error because the MFA shifts will be smaller than at the recommend 50X so I'd be extra careful and do this several times. If it wasn't Canon would not recommend a minimal of 50X is what I'm assuming. I'd double check real world shots until I could get outside and redo it at either at least 50X or the distance I normally BIF which is probably about 100 or more feet. I'll have to do guesstimate of that.

This is where Dot Tune shines, it can be done outside without any additional equipment. So you can MFA your 580mm lens at the distance you normally use it, and also importantly in the type of light you use it. Just set your camera and tripod perpendicular to a sign at a park and do your big lens MFA there

That is my plan. Thanks.

This has been the most enlightening MFA thread for me to date.

.

 

[WilbaW]

I finally got some answers I have asked about for last 5 years.

I'm interested to know what you've learned.

I believe I figured it out. DO Field and DO Focus are the exact same thing.

Not quite the exact same thing, I'd say they are opposite ends of the same phenomenon.

I broadly agree with the rest of what you wrote.

5. I have learned that Canon supports what I have thought all along. +- 3 or so MFA moves may not show any significant difference.

Depends how you look for it. I doubt you would ever see it in the whole image, but I can see a 1 click difference using the EOS Utility and deliberate defocussing.

Like I said I have been asking for 5 years why does Canon suggest 50X and others 25X and how does this impact MFA? No one could answer that.

Me too, I still want to know.

Will this help me when MFA in the future? Yes. Very much so. Distance to target has been my #1 question and now it has been answered.

Good to know you got to something worthwhile.

 

[Zeee]

I finally got some answers I have asked about for last 5 years.

I'm interested to know what you've learned.

I believe I figured it out. DO Field and DO Focus are the exact same thing.

Not quite the exact same thing, I'd say they are opposite ends of the same phenomenon.

I broadly agree with the rest of what you wrote.

OK I should have not said exact. One is the final image, etc and the other is at the sensor. There is still a variable MFA value for each. Both are much different but both change as the input changes. We have the math for one of them. It has to change on sensor if the DOF changes.

How much they change as input changes is not as important as knowing they do. See your "me too" section.

5. I have learned that Canon supports what I have thought all along. +- 3 or so MFA moves may not show any significant difference.

I won't say you can't if you say you can. There is no reason for you to provide false information. Rudy does not say you won't see them but he says you won't see drastic changes of up to 5 moves. I have folders of BIF files where the AF point is no where near the eye of the bird. On the body which is not on the same plane of the eye and the eye is tack sharp. There are times during our conversation I have wondered if you think I'm trying to discredit your or any other MFA method. I'm not.

Depends how you look for it. I doubt you would ever see it in the whole image, but I can see a 1 click difference using the EOS Utility and deliberate defocussing.

Like I said I have been asking for 5 years why does Canon suggest 50X and others 25X and how does this impact MFA? No one could answer that.

Me too, I still want to know.

If Canon, who has engineers, decades of experience, designed the system, done R&D, etc had said to MFA at last least at 50X then why are people doing it at 25X? When struggling people are told to RTFM but ignore the warnings about MFA. One being MFA is not normally required and may cause focus problems.

So far it appears the closer you are to the target when you MFA the more prone it is to error. Until someone tell me something different this is what I'm going with. There has to be a reason why Canon says 50X and not 25X, or any distance will do - whatever is convenient for you. I don't want to forget M Ed Ms' explanation about distance you normally shoot at which was updated by Canon from 50X.

Will this help me when MFA in the future? Yes. Very much so. Distance to target has been my #1 question and now it has been answered.

Good to know you got to something worthwhile.

I guess you are saying I'm the only one and wasted everyones time. Oh well. I'm one in a group, be it small, that can produce thousands of tack sharp images from the 20 to 50D, 7D and 7D2 and all the 5D's without MFA.

I read the manual and heed the warnings the people who designed the camera tell me about. I have thousands of dollars worth of highly precision equipment that I'm messing with. I'm not building a bird house. I know Canon uses far more sophisticated methods to calibrate than I can ever come close to. What happens to my images when I don't shoot at the calibrated 50X distance or not at the normal distance I MFA'd to?

I apologize to you and everyone for taking the time to try and understand something, especially statements made by Canon. It felt like all I did was battle. Lot's of fun if you ask questions and don't tow the line.

Am I banned yet? I'm surpised I got this far being such a rebel

 

[WilbaW]

each MFA click is 1/16 of the total Depth of Field.

Where is it stated that it's 1/8 of the single-sided DO focus, not 1/8 of the total DO focus?

The link to the Canon site stating this has been included a couple of times in this thread, and the text included as well.

No matter how I read that I can't make it fit your interpretation. I'm interested to hear if you're willing to explain how you get it.

 

[WilbaW]

What people have to keep in mind is that the Circle of Confusion that Depth of Field calculations ae based on a specific enlargement size (typically 8X10 or 11X14) , normal visual acuity, and standard viewing distances.

When you look at an image at 100% on a monitor you see a substantially smaller DOF than is calculated using a DOF calculator. So it is very likely that you can see the difference made by small micro focus adjustments in that situation.

Exactly.

p.s. The Dot Tune Method gives you your depth of focus, it is the range of values you of obtain using the Dot Tune Method.

I don't agree. DotTune gives you the range over which focus can be confirmed by the PD AF system. That is related to the DO field apparent in an image viewed under standard conditions, but it's certainly not the same thing.

 

[WilbaW]

5. I have learned that Canon supports what I have thought all along. +- 3 or so MFA moves may not show any significant difference.

Depends how you look for it. I doubt you would ever see it in the whole image, but I can see a 1 click difference using the EOS Utility and deliberate defocussing.

I won't say you can't if you say you can. There is no reason for you to provide false information. Rudy does not say you won't see them but he says you won't see drastic changes of up to 5 moves.

Yeah, I agree with him, I'm just adding that it depends on how you look. When he says that, he should also say how he's looking at the difference, like - you won't see drastic changes in the whole image under normal viewing conditions. I've been thinking of doing some shots to show exactly how well you can see the difference a click of MA gives. I'll let you know if it happens.

There are times during our conversation I have wondered if you think I'm trying to discredit your or any other MFA method. I'm not.

No! I never thought that, I just needed to know what was getting in the way and we worked that out.

Like I said I have been asking for 5 years why does Canon suggest 50X and others 25X and how does this impact MFA? No one could answer that.

Me too, I still want to know.

If Canon, who has engineers, decades of experience, designed the system, done R&D, etc had said to MFA at last least at 50X then why are people doing it at 25X? When struggling people are told to RTFM but ignore the warnings about MFA. One being MFA is not normally required and may cause focus problems.

Should you use the brakes to slow down? Absolutely! But when descending a slippery slope you're better off engaging low-range 4WD and not touching the pedals...

So far it appears the closer you are to the target when you MFA the more prone it is to error.

Like a foot is easier to work with than an inch? Sure, it's generally easier to judge things at an accessible scale, but I won't be convinced until I try it and find that using a close target is inherently worse than using a 50f target. (Experiment pending.)

Until someone tell me something different this is what I'm going with. There has to be a reason why Canon says 50X and not 25X, or any distance will do - whatever is convenient for you. I don't want to forget M Ed Ms' explanation about distance you normally shoot at which was updated by Canon from 50X.

Yeah, I think I said before that it wouldn't surprise me if there is no fundamental technical reason why they say 50f. For instance, I could totally believe it went like this - Tech Writer: "What distance should we tell them to use for MA?" Engineer: "Doesn't matter. Tell them 50x so they stop worrying and get on with it." Canon are always saying dumb ambiguous things that people get all bent out of shape about.

Will this help me when MFA in the future? Yes. Very much so. Distance to target has been my #1 question and now it has been answered.

Good to know you got to something worthwhile.

I guess you are saying I'm the only one and wasted everyones time.

No I was celebrating a good outcome (a rare enough event around here that it should be acknowledged).

Oh well. I'm one in a group, be it small, that can produce thousands of tack sharp images from the 20 to 50D, 7D and 7D2 and all the 5D's without MFA.

My 60D does that too.

I read the manual and heed the warnings the people who designed the camera tell me about. I have thousands of dollars worth of highly precision equipment that I'm messing with. I'm not building a bird house. I know Canon uses far more sophisticated methods to calibrate than I can ever come close to. What happens to my images when I don't shoot at the calibrated 50X distance or not at the normal distance I MFA'd to?

Probably no worse on average than if you hadn't adjusted.

Another good things I've got out of this discussion is a subtly different appreciation of the purpose of AF MA. Clearly it's there if you have an obvious error, and it's also there if you like to get the best you can out of your gear, but no-one is saying everyone has to do it all the time. I find doing it achieves two things - I get to know if there is an error, and I can do a good job of eliminating it.

I apologize to you and everyone for taking the time to try and understand something, especially statements made by Canon. It felt like all I did was battle. Lot's of fun if you ask questions and don't tow the line.

Don't be silly, you don't need to apologise for anything. Don't ever lose your curiosity!

Am I banned yet? I'm surpised I got this far being such a rebel

Well there's your problem - Rebels don't have AF MA! Ha!

 

[Zeee]

5. I have learned that Canon supports what I have thought all along. +- 3 or so MFA moves may not show any significant difference.

Depends how you look for it. I doubt you would ever see it in the whole image, but I can see a 1 click difference using the EOS Utility and deliberate defocussing.

I won't say you can't if you say you can. There is no reason for you to provide false information. Rudy does not say you won't see them but he says you won't see drastic changes of up to 5 moves.

Yeah, I agree with him, I'm just adding that it depends on how you look. When he says that, he should also say how he's looking at the difference, like - you won't see drastic changes in the whole image under normal viewing conditions. I've been thinking of doing some shots to show exactly how well you can see the difference a click of MA gives. I'll let you know if it happens.

There are times during our conversation I have wondered if you think I'm trying to discredit your or any other MFA method. I'm not.

No! I never thought that, I just needed to know what was getting in the way and we worked that out.

Like I said I have been asking for 5 years why does Canon suggest 50X and others 25X and how does this impact MFA? No one could answer that.

Me too, I still want to know.

If Canon, who has engineers, decades of experience, designed the system, done R&D, etc had said to MFA at last least at 50X then why are people doing it at 25X? When struggling people are told to RTFM but ignore the warnings about MFA. One being MFA is not normally required and may cause focus problems.

Should you use the brakes to slow down? Absolutely! But when descending a slippery slope you're better off engaging low-range 4WD and not touching the pedals...

So far it appears the closer you are to the target when you MFA the more prone it is to error.

Like a foot is easier to work with than an inch? Sure, it's generally easier to judge things at an accessible scale, but I won't be convinced until I try it and find that using a close target is inherently worse than using a 50f target. (Experiment pending.)

You should't. It is conclusion based on information attained to this point. I'm not sure how much difference you would see be between 50 and 25 but I'd bet you may between 50 and MFD. Interested in the results.

Until someone tell me something different this is what I'm going with. There has to be a reason why Canon says 50X and not 25X, or any distance will do - whatever is convenient for you. I don't want to forget M Ed Ms' explanation about distance you normally shoot at which was updated by Canon from 50X.

Yeah, I think I said before that it wouldn't surprise me if there is no fundamental technical reason why they say 50f. For instance, I could totally believe it went like this - Tech Writer: "What distance should we tell them to use for MA?" Engineer: "Doesn't matter. Tell them 50x so they stop worrying and get on with it." Canon are always saying dumb ambiguous things that people get all bent out of shape about.

There has to be but would't that be funny if it was a random number. I'd get on a plane, fly to Canon HQ and kick that person on the butt for that. People are probably wondering why I'm obsessed by this. Too many years as a technical person in manufacturing I guess. My industry had little formal training and people ran complex equipment. It was amazing what happened when we dusted off the vendors manuals and re-trained them on how to set the equipment to manufactures specs. A difference of .030 to .020 meant a day of smooth running vs a day the where the machine kept shutting down. Combine that with their years of experience and that changed everything. There are always people who are just naturally better at things than others but now the weakest operators were doing as well as the others.

Manufacturers make mistakes but we learned to follow what they said first and then you add your experience and expand.

Will this help me when MFA in the future? Yes. Very much so. Distance to target has been my #1 question and now it has been answered.

Good to know you got to something worthwhile.

I guess you are saying I'm the only one and wasted everyones time.

No I was celebrating a good outcome (a rare enough event around here that it should be acknowledged).

Thanks

Oh well. I'm one in a group, be it small, that can produce thousands of tack sharp images from the 20 to 50D, 7D and 7D2 and all the 5D's without MFA.

My 60D does that too.

I read the manual and heed the warnings the people who designed the camera tell me about. I have thousands of dollars worth of highly precision equipment that I'm messing with. I'm not building a bird house. I know Canon uses far more sophisticated methods to calibrate than I can ever come close to. What happens to my images when I don't shoot at the calibrated 50X distance or not at the normal distance I MFA'd to?

Probably no worse on average than if you hadn't adjusted.

Another good things I've got out of this discussion is a subtly different appreciation of the purpose of AF MA. Clearly it's there if you have an obvious error, and it's also there if you like to get the best you can out of your gear, but no-one is saying everyone has to do it all the time. I find doing it achieves two things - I get to know if there is an error, and I can do a good job of eliminating it.

I apologize to you and everyone for taking the time to try and understand something, especially statements made by Canon. It felt like all I did was battle. Lot's of fun if you ask questions and don't tow the line.

Don't be silly, you don't need to apologise for anything. Don't ever lose your curiosity!

Am I banned yet? I'm surpised I got this far being such a rebel

Well there's your problem - Rebels don't have AF MA! Ha!

 

[guy schlacter]

each MFA click is 1/16 of the total Depth of Field.

Where is it stated that it's 1/8 of the single-sided DO focus, not 1/8 of the total DO focus?

The link to the Canon site stating this has been included a couple of times in this thread, and the text included as well.

No matter how I read that I can't make it fit your interpretation. I'm interested to hear if you're willing to explain how you get it.

When I read it:

They indicate that it is 1/8 of DOF. Then they say that is the DOF in front of the focal plane or behind the focal plane.

this is where I get the 1/16 of the whole DOF value. (16 total increments from front to back in acceptable focus, with plane nearly centered)

 

[WilbaW]

each MFA click is 1/16 of the total Depth of Field.

Where is it stated that it's 1/8 of the single-sided DO focus, not 1/8 of the total DO focus?

The link to the Canon site stating this has been included a couple of times in this thread, and the text included as well.

No matter how I read that I can't make it fit your interpretation. I'm interested to hear if you're willing to explain how you get it.

When I read it:

They indicate that it is 1/8 of DOF. Then they say that is the DOF in front of the focal plane or behind the focal plane.

Please highlight the words that mean that in the quote.

 

[WilbaW]

People are probably wondering why I'm obsessed by this. Too many years as a technical person in manufacturing I guess. My industry had little formal training and people ran complex equipment. It was amazing what happened when we dusted off the vendors manuals and re-trained them on how to set the equipment to manufactures specs. A difference of .030 to .020 meant a day of smooth running vs a day the where the machine kept shutting down. Combine that with their years of experience and that changed everything. There are always people who are just naturally better at things than others but now the weakest operators were doing as well as the others.
Manufacturers make mistakes but we learned to follow what they said first and then you add your experience and expand.

Sure. Interested to know what you were manufacturing, what sort of machines, etc.

 

[Hokie Jack]

each MFA click is 1/16 of the total Depth of Field.

Where is it stated that it's 1/8 of the single-sided DO focus, not 1/8 of the total DO focus?

The link to the Canon site stating this has been included a couple of times in this thread, and the text included as well.

No matter how I read that I can't make it fit your interpretation. I'm interested to hear if you're willing to explain how you get it.

When I read it:

They indicate that it is 1/8 of DOF. Then they say that is the DOF in front of the focal plane or behind the focal plane.

this is where I get the 1/16 of the whole DOF value. (16 total increments from front to back in acceptable focus, with plane nearly centered)

Your earlier quote, from Canon:

"Each step is a very fine increment, equal to 1/8th of the depth-of-field you'd have with the current lens wide-open. And that 1/8th of the depth of field is only moving forward (toward the camera) or back (toward the background) from the sharpest plane of focus."

The first sentence is very clear. IMO the second one is vague, at best. I'm not sure what it is trying to say. I just thought it was an awkward way of saying each MFA increment moves you toward or away from the plane of focus. I don't think they intended to re-define the term DOF.

 

[guy schlacter]

each MFA click is 1/16 of the total Depth of Field.

Where is it stated that it's 1/8 of the single-sided DO focus, not 1/8 of the total DO focus?

The link to the Canon site stating this has been included a couple of times in this thread, and the text included as well.

No matter how I read that I can't make it fit your interpretation. I'm interested to hear if you're willing to explain how you get it.

When I read it:

They indicate that it is 1/8 of DOF. Then they say that is the DOF in front of the focal plane or behind the focal plane.

this is where I get the 1/16 of the whole DOF value. (16 total increments from front to back in acceptable focus, with plane nearly centered)

Your earlier quote, from Canon:

"Each step is a very fine increment, equal to 1/8th of the depth-of-field you'd have with the current lens wide-open. And that 1/8th of the depth of field is only moving forward (toward the camera) or back (toward the background) from the sharpest plane of focus."

The first sentence is very clear. IMO the second one is vague, at best. I'm not sure what it is trying to say. I just thought it was an awkward way of saying each MFA increment moves you toward or away from the plane of focus. I don't think they intended to re-define the term DOF.

--
HJ

HJ,

I believe both sentences need to be taken together. We must also remember this is translated from Japanese which gives some latitude of use of dof in the both sentences. Also, that is the reason Chuck Westfall clarifies it and calls it Depth of Focus, which aligns exactly with the 2nd definition from the earlier Wikipedia definition = ~ half of total dof in front, or behind focal plane.

 

[WilbaW]

"Each step is a very fine increment, equal to 1/8th of the depth-of-field you'd have with the current lens wide-open. And that 1/8th of the depth of field is only moving forward (toward the camera) or back (toward the background) from the sharpest plane of focus."

The first sentence is very clear. IMO the second one is vague, at best. I'm not sure what it is trying to say. I just thought it was an awkward way of saying each MFA increment moves you toward or away from the plane of focus. I don't think they intended to re-define the term DOF.

I believe both sentences need to be taken together.

Let's rephrase them for clarity - Each step is a very fine increment, equal to 1/8th of the total depth-of-field you'd have with the current lens wide-open. An increment moves the plane of focus forward (toward the camera) or back (toward the background).

Nothing suggests the "depth-of-field" (or focus) is intended as the single-sided depth (from the near or far limit to the plane of focus).

We must also remember this is translated from Japanese...

Rubbish. The whole paragraph is perfectly grammatical and reasonable English, using conventional terms. There is nothing to suggest that it suffers from translation errors.

which gives some latitude of use of dof in the both sentences.

DOF is always the entire depth unless specifically referred to as "near DOR" and "far DOF" or "DOF in front" and "DOF behind".

Also, that is the reason Chuck Westfall clarifies it and calls it Depth of Focus, which aligns exactly with the 2nd definition from the earlier Wikipedia definition = ~ half of total dof in front, or behind focal plane.

Yes, half of the total depth is in front of the image (or focus) plane, and the other half is behind. Both halves together make up "the depth", the total. Your assertion makes no sense and you can't explain it by reference to what you're referring to. I reject it completely.

 

[guy schlacter]

"Each step is a very fine increment, equal to 1/8th of the depth-of-field you'd have with the current lens wide-open. And that 1/8th of the depth of field is only moving forward (toward the camera) or back (toward the background) from the sharpest plane of focus."

The first sentence is very clear. IMO the second one is vague, at best. I'm not sure what it is trying to say. I just thought it was an awkward way of saying each MFA increment moves you toward or away from the plane of focus. I don't think they intended to re-define the term DOF.

I believe both sentences need to be taken together.

Let's rephrase them for clarity - Each step is a very fine increment, equal to 1/8th of the total depth-of-field you'd have with the current lens wide-open. An increment moves the plane of focus forward (toward the camera) or back (toward the background).

Nothing suggests the "depth-of-field" (or focus) is intended as the single-sided depth (from the near or far limit to the plane of focus).

We must also remember this is translated from Japanese...

Rubbish. The whole paragraph is perfectly grammatical and reasonable English, using conventional terms. There is nothing to suggest that it suffers from translation errors.

which gives some latitude of use of dof in the both sentences.

DOF is always the entire depth unless specifically referred to as "near DOR" and "far DOF" or "DOF in front" and "DOF behind".

Also, that is the reason Chuck Westfall clarifies it and calls it Depth of Focus, which aligns exactly with the 2nd definition from the earlier Wikipedia definition = ~ half of total dof in front, or behind focal plane.

Yes, half of the total depth is in front of the image (or focus) plane, and the other half is behind. Both halves together make up "the depth", the total. Your assertion makes no sense and you can't explain it by reference to what you're referring to. I reject it completely.

WilbaW,

Reject all you want. I have asked Chuck and Rudy to specifically clarify. Chuck used the term 1/8 of depth of focus, being front or back side of the dof.

 

[Zeee]

"Each step is a very fine increment, equal to 1/8th of the depth-of-field you'd have with the current lens wide-open. And that 1/8th of the depth of field is only moving forward (toward the camera) or back (toward the background) from the sharpest plane of focus."

The first sentence is very clear. IMO the second one is vague, at best. I'm not sure what it is trying to say. I just thought it was an awkward way of saying each MFA increment moves you toward or away from the plane of focus. I don't think they intended to re-define the term DOF.

I believe both sentences need to be taken together.

Let's rephrase them for clarity - Each step is a very fine increment, equal to 1/8th of the total depth-of-field you'd have with the current lens wide-open. An increment moves the plane of focus forward (toward the camera) or back (toward the background).

Nothing suggests the "depth-of-field" (or focus) is intended as the single-sided depth (from the near or far limit to the plane of focus).

We must also remember this is translated from Japanese...

Rubbish. The whole paragraph is perfectly grammatical and reasonable English, using conventional terms. There is nothing to suggest that it suffers from translation errors.

which gives some latitude of use of dof in the both sentences.

DOF is always the entire depth unless specifically referred to as "near DOR" and "far DOF" or "DOF in front" and "DOF behind".

Also, that is the reason Chuck Westfall clarifies it and calls it Depth of Focus, which aligns exactly with the 2nd definition from the earlier Wikipedia definition = ~ half of total dof in front, or behind focal plane.

Yes, half of the total depth is in front of the image (or focus) plane, and the other half is behind. Both halves together make up "the depth", the total. Your assertion makes no sense and you can't explain it by reference to what you're referring to. I reject it completely.

WilbaW,

Reject all you want. I have asked Chuck and Rudy to specifically clarify. Chuck used the term 1/8 of depth of focus, being front or back side of the dof.

That is the way I read it. I don't see any reference to Depth of Focus or anything else. If they had meant something else they should have stated it more clearly or corrected it if wrong.

If nothing suggests anything then please explain what "Canon has clearly stated" 1/8 of depth of focus then means WilbaW. No references to anything that does not exist in that document unless you research it and provide evidence that it means something else - from Canon, not Wikipedia anything else. Wikipedia did not post this. Our turn

 

[Zeee]

they were hoping they could throw something out there like "let's just tell them 50X because it sound like a good number" and no one would ask why or check the math.