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KevinA
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« on: February 11, 2010, 06:56:54 AM »
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What exactly does it do?  As I understand you focus on the eyes, then as you tilt the camera down it holds focus on the eyes, how is that better than a choice of AF focus points? the distance from eyes to camera has hardly changed, or does it recalculate if you or subject moves forward or backwards when tilted? Is this just Hasselblads round about way of saying we can't figure out how to do multi focus points, am I doing it disservice.

Kevin.
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« Reply #1 on: February 11, 2010, 07:05:38 AM »
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Quote from: KevinA
What exactly does it do?  As I understand you focus on the eyes, then as you tilt the camera down it holds focus on the eyes, how is that better than a choice of AF focus points? the distance from eyes to camera has hardly changed, or does it recalculate if you or subject moves forward or backwards when tilted? Is this just Hasselblads round about way of saying we can't figure out how to do multi focus points, am I doing it disservice.

Kevin.


I think it is much better than multiple AF points. It allows you to focus and simply recompose. By calculating the movements it will readjust the focus back to where you had it. It makes the whole screen an AF point basically.

Sure it doesn't compensate for subject movement, it also probably doesn't compensate for lateral camera movements either. Every system can be made to fail, I think this can be made to work very nicely too.

For me the H4D is interesting because of this. Kudos for thinking outside the box with this.
« Last Edit: February 11, 2010, 07:06:23 AM by Dustbak » Logged
David Grover / Phase One
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« Reply #2 on: February 11, 2010, 07:08:56 AM »
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Quote from: KevinA
What exactly does it do?  As I understand you focus on the eyes, then as you tilt the camera down it holds focus on the eyes, how is that better than a choice of AF focus points? the distance from eyes to camera has hardly changed, or does it recalculate if you or subject moves forward or backwards when tilted? Is this just Hasselblads round about way of saying we can't figure out how to do multi focus points, am I doing it disservice.

Kevin.


Hi Kevin,

The problem with multi point AF on medium format is that placing the points so wide from the centre of the less would very much reduce the accuracy.  Especially if you wanted to use a short depth of field.  You could argue at tighter apertures that the issue would be dissolved of course.

Its not that we don't 'want' to do Multi Point AF, it is just trying to find a way that would ensure the same level of accuracy towards the edge of the optics as compared to the centre.

The off-the-shelf available AF sensors do not have wide enough spaced points for MF.  If you place a D3 AF sensor in an H4D50, you actually would get very little benefit even from the widest spaced points.  Also the AF sensor being an optical component itself is quite physically large, so tripling up the existing sensor is not possible and we would still have the accuracy issue.  Then of course you would also need to include an active LCD in the viewfinder describing which point you were using.

So right now the alternative is True Focus.  I have attached two PDF's which describe how the function is used (if interesting) and one which goes a bit more in-depth on where it matters.

I hope that helps.

Best



David



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David Grover
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KevinA
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« Reply #3 on: February 11, 2010, 07:37:36 AM »
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Quote from: David Grover / Hasselblad
Hi Kevin,

The problem with multi point AF on medium format is that placing the points so wide from the centre of the less would very much reduce the accuracy.  Especially if you wanted to use a short depth of field.  You could argue at tighter apertures that the issue would be dissolved of course.

Its not that we don't 'want' to do Multi Point AF, it is just trying to find a way that would ensure the same level of accuracy towards the edge of the optics as compared to the centre.

The off-the-shelf available AF sensors do not have wide enough spaced points for MF.  If you place a D3 AF sensor in an H4D50, you actually would get very little benefit even from the widest spaced points.  Also the AF sensor being an optical component itself is quite physically large, so tripling up the existing sensor is not possible and we would still have the accuracy issue.  Then of course you would also need to include an active LCD in the viewfinder describing which point you were using.

So right now the alternative is True Focus.  I have attached two PDF's which describe how the function is used (if interesting) and one which goes a bit more in-depth on where it matters.

I hope that helps.

Best



David

So unless the model and photographer are nailed to the ground though you are just as likely to get it unsharp on the eyes are you not.
You focus on the eyes, tilt the camera down then the model shuffles left or right an inch or two, or you lean back and it's all a waste of time right?
I thought maybe the focus on the eyes was a reference, then when you tilted down it worked out the difference then applied that with the tilt information to any new distance information. The only way I can see it being of much value as explained would be if the model was held in clamps and camera on a tripod, you would then have the advantage of being able to shoot a wet collodion for back-up.
Does it work better in practice than it looks on paper?

Kevin.
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David Grover / Phase One
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« Reply #4 on: February 11, 2010, 08:27:27 AM »
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Quote from: KevinA
So unless the model and photographer are nailed to the ground though you are just as likely to get it unsharp on the eyes are you not.
You focus on the eyes, tilt the camera down then the model shuffles left or right an inch or two, or you lean back and it's all a waste of time right?
I thought maybe the focus on the eyes was a reference, then when you tilted down it worked out the difference then applied that with the tilt information to any new distance information. The only way I can see it being of much value as explained would be if the model was held in clamps and camera on a tripod, you would then have the advantage of being able to shoot a wet collodion for back-up.
Does it work better in practice than it looks on paper?

Kevin.

Kevin,

Stinging sarcasm aside...

I thought maybe the focus on the eyes was a reference, then when you tilted down it worked out the difference then applied that with the tilt information to any new distance

AF systems don't work like that, so unless you refocused again after tilting there would be no way of knowing the 'new' distance.  This would be a very slow way of working.

But you are correct in thinking that that the change in the optimum focus point is calculated based on tilt information only.  Which leads me to my second point...

There is always an optimum point of sharpness in an image. Without Truefocus your focus error would be greater.  With Truefocus the error is reduced.

Lets say you are focussing on the eyes of a model, portrait orientation.. when you recompose, the optimum focus point will shift further back a little.  With True focus it is maintained.

Both scenarios still can't account for distance changes, the margin for error using True Focus though, is reduced.

David
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gwhitf
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« Reply #5 on: February 11, 2010, 08:29:50 AM »
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Quote from: David Grover / Hasselblad
The problem with multi point AF on medium format is that placing the points so wide from the centre of the less would very much reduce the accuracy.  Especially if you wanted to use a short depth of field.  You could argue at tighter apertures that the issue would be dissolved of course.

David,

Hasselblad must be applauded for even trying to address this autofocus issue. I can't see that it would work for me, but maybe it would for others' style.

I was shooting a job last week on the road, and this focus thing again just slapped me in the face. I am amazed that more photographers don't talk about it. Maybe it's just too embarrassing that, in the year 2010, we're still dealing with basic things like keeping the subject sharp, (even when shooting on a tripod, with a non moving subject). My setup, at that time, was a location environmental portrait. I was shooting with an unnamed 35mm DSLR (5d2), tethered, on a tripod. To give you an idea about how far away, I was shooting with a 50mm f1.2, at f8, and the subject was full length, in vertical format, but there was a good deal of room around their body. So in short, the subject was pretty damn far away. You'd think, with f8, on a tripod, with a non moving subject, the autofocus sensor could nail it. I used one of the outer squares for my focus sensor, due to how my shot was locked down, and I was trying to find some constrast in her clothing for the AF sensor to grab onto. Here is the key: You CANNOT trust what you're seeing in the Viewfinder. So many times, it looks TACK SHARP, but you shoot tethered, and you lean over and peek at the monitor, and for, the focus is slightly off. To me, this issue is The Great Unspoken issue about all digital cameras -- the Viewfinder, (even with StopDownPreview pressed), does not match, at all, what's actually rendered into the file.

But the truly scary thing is: I have spent DAYS with my assistant, and we test these cameras's focus issues, sitting there, shooting tethered, looking at every frame. The scary thing is: There is no rhyme or reason sometimes. Sometimes, you shoot a frame, it's tack sharp. You shoot the next frame, everything the same, (on tripod), and it's slightly soft. It's like there's some kind of "autofocus hunting" going on, even though you can't see or hear any hunting going on. Frame after frame. I have calibrated each lens; I have thrown salt over my shoulder; I have even tried religion. But this autofocus sensor thing haunts me. (I gave up on shooting Manual Focus last year).

Back to Hasselblad, here is the problem to me: maybe I'm missing something. I see myself shooting in this way, and it seems like this:

a. Compose the frame. Lock down tripod.
b. Unlock tripod.
c. Find what you want sharp on the subject, (and hope it's contrasty).
d. Put focus sensor then and press some button.
e. Hold down on that button.
f. Unlock tripod.
g. Recompose frame.
h. SHOOT.
i. Unlock tripod.
j. Find what you want sharp on the subject, (and hope it's contrasty).
k. Put focus sensor then and press some button.
l. Hold down on that button.
m. Unlock tripod.
n. Recompose frame.
o. SHOOT.

Over and over and over.

The reason I post this question: Are other people fighting focus too, no matter what digital camera you're using? I'm no fan of LiveView, but on the 5d2, it's pretty damn amazing: double click on the zoom thingie, and you're at 10x, and you focus, and YOU KNOW YOU GOT IT, because you're see what the sensor is seeing. But I am not fast enough shooting people's fleeting facial expressions to actually use LiveView.

It just seems that, overall, the Focus Tolerance for digital is MASSIVELY smaller than for Old Timey Film. So much so that, I just wonder why more people don't fight with Focus, even using AutoFocus. I could put up a strong argument that, with the tiny tolerances of these digital files, that it's clearly time to abandon the Ground Glass, and mirrors, and simply use an Electronic Viewfinder, in order to know that you nailed it.
« Last Edit: February 11, 2010, 08:40:54 AM by gwhitf » Logged
David Grover / Phase One
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« Reply #6 on: February 11, 2010, 08:47:28 AM »
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Quote from: gwhitf
David,

Hasselblad must be applauded for even trying to address this autofocus issue. I can't see that it would work for me, but maybe it would for others' style.

I was shooting a job last week, and this focus thing again just slapped me in the face. I am amazed that more photographers don't talk about it. Maybe it's just too embarrassing that, in the year 2010, we're still dealing with basic things like keeping the subject sharp, (even when shooting on a tripod, with a non moving subject). My setup, at that time, was a location environmental portrait. I was shooting with an unnamed 35mm DSLR (5d2), tethered, on a tripod. To give you an idea about how far away, I was shooting with a 50mm f1.2, at f8, and the subject was full length, in vertical format, but there was a good deal of room around their body. So in short, the subject was pretty damn far away. You'd think, with f8, on a tripod, with a non moving subject, the autofocus sensor could nail it. I used one of the outer squares for my focus sensor, due to how my shot was locked down, and I was trying to find some constrast in her clothing for the AF sensor to grab onto. Here is the key: You CANNOT trust what you're seeing in the Viewfinder. So many times, it looks TACK SHARP, but you shoot tethered, and you lean over and peek at the monitor, and for, the focus is slightly off. To me, this issue is The Great Unspoken issue about all digital cameras -- the Viewfinder, (even with StopDownPreview pressed), does not match, at all, what's actually rendered into the file.

But the truly scary thing is: I have spent DAYS with my assistant, and we test these cameras's focus issues, sitting there, shooting tethered, looking at every frame. The scary thing is: There is no rhyme or reason sometimes. Sometimes, you shoot a frame, it's tack sharp. You shoot the next frame, everything the same, (on tripod), and it's slightly soft. It's like there's some kind of "autofocus hunting" going on, even though you can't see or hear any hunting going on. Frame after frame. I have calibrated each lens; I have thrown salt over my shoulder; I have even tried religion. But this autofocus sensor thing haunts me. (I gave up on shooting Manual Focus last year).

Back to Hasselblad, here is the problem to me: maybe I'm missing something. I see myself shooting in this way, and it seems like this:

a. Compose the frame. Lock down tripod.
b. Unlock tripod.
c. Find what you want sharp on the subject, (and hope it's contrasty).
d. Put focus sensor then and press some button.
e. Hold down on that button.
f. Unlock tripod.
g. Recompose frame.
h. SHOOT.
i. Unlock tripod.
j. Find what you want sharp on the subject, (and hope it's contrasty).
k. Put focus sensor then and press some button.
l. Hold down on that button.
m. Unlock tripod.
n. Recompose frame.
o. SHOOT.

Over and over and over.

The reason I post this question: Are other people fighting focus too, no matter what digital camera you're using? I'm no fan of LiveView, but on the 5d2, it's pretty damn amazing: double click on the zoom thingie, and you're at 10x, and you focus, and YOU KNOW YOU GOT IT, because you're see what the sensor is seeing. But I am not fast enough shooting people's fleeting facial expressions to actually use LiveView.

It just seems that, overall, the Focus Tolerance for digital is MASSIVELY smaller than for Old Timey Film. So much so that, I just wonder why more people don't fight with Focus, even using AutoFocus.

First of all what you are seeing in the viewfinder is not the widest aperture, it will be a stop or two down from that - so if you are not confident that your mirror is correctly calibrated to your viewfinder glass, even if it does look tack sharp... it may well not be.. as you have discovered.  We use a laser system to calibrate the mirror to viewfinder glass.  There is really very little margin of error.  We are talking microns.. not 0.5mm or something.  As a 5D is mass produced I don't know how long they spend on such calibrations?

You have also rather nicely pointed out the issue with widely spaced sensors.

The reason why it 'hunts' is because the AF electronics are are comparing two different images from converging optics.  I don't know what the 5DMkII AF tolerance is but it will never wait for a 'perfect' 0 tolerance value from the AF electronics... It will reject 'out-of-focus' values until it gets within it acceptable ball park range.  As you move to the further out AF points it will accept a much wider tolerance of error.  No matter what you do, the wide AF points will never ever be as good as the centre.

There is also a difference in accuracy from Landscape to Portrait.  You will probably find landscape more accurate.  Try if you like.

As to point 'e' of your rather long list you do not need to hold the button down.  Press once, wait for confirmation (like any camera AF system) and release.

So multi AF has it faults.  True Focus is something you use consciously. There is no perfect solution yet... unless you have live view.. but that isn't much good for fast paced shooting if you want narrow depth of field.

Ideally you want a CMOS sensor comparing local contrast at any site on the sensor... but it is still slower than an optical system.

David




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David Grover
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« Reply #7 on: February 11, 2010, 08:59:07 AM »
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Quote from: David Grover / Hasselblad
There is also a difference in accuracy from Landscape to Portrait.  You will probably find landscape more accurate.  Try if you like.

Just my luck. I shoot mostly verticals for advertising stuff. Thus my questions about a Hasselblad vertical grip.

This focus thing almost makes you want to mount one of those Zacuto things on the back of the LCD and abandon the viewfinder altogether.

Thanks for your thorough answer.
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KevinA
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« Reply #8 on: February 11, 2010, 09:04:26 AM »
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Quote from: David Grover / Hasselblad
Kevin,

Stinging sarcasm aside...

I thought maybe the focus on the eyes was a reference, then when you tilted down it worked out the difference then applied that with the tilt information to any new distance

AF systems don't work like that, so unless you refocused again after tilting there would be no way of knowing the 'new' distance.  This would be a very slow way of working.

But you are correct in thinking that that the change in the optimum focus point is calculated based on tilt information only.  Which leads me to my second point...

There is always an optimum point of sharpness in an image. Without Truefocus your focus error would be greater.  With Truefocus the error is reduced.

Lets say you are focussing on the eyes of a model, portrait orientation.. when you recompose, the optimum focus point will shift further back a little.  With True focus it is maintained.

Both scenarios still can't account for distance changes, the margin for error using True Focus though, is reduced.

David

It sounds like Hasselblad have got some way there but easily could of moved on another notch. Presumedly it's a bit of trigonometry? I am no way a mathematician (I don't even have an "O" level) but it would be a short step to allow for photographer or subject forward and backward movement. If two points are recorded top and bottom from the same position every focus point on that plane would be known and the angle the camera would need to be at  to achieve that. So if the camera is at an angle and focus information shows less or greater distance than referenced previously, it could easily calculate a shift of the focus plane and the new difference of focus needed for the selected "Sharp" point. It still would not allow for a subject leaning out of plane, but much more useful that everything having to be static.
I can't believe hasselblad are not working on something like this? If it is a new idea you take up, a couple of H4D's please and a selection of lenses ta very much.

Kevin.
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« Reply #9 on: February 11, 2010, 09:10:21 AM »
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Im sorry Kevin. It just isn't possible in the way you describe without making it a very laborious process.

Attached is the trig info.

The only foolproof way would be to do it Wii style, but that would mean putting an infra red sender on top of the camera and a receiver on the models head.

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David Grover
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« Reply #10 on: February 11, 2010, 09:12:53 AM »
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PS. I will say it is worth some kind of human anthropology experiment.

If when every one recomposes they move forward/backward by a function of the distance then it would be easy to enter an offset into the calculation.

However, it is likely that we all behave a bit differently.

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David Grover
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« Reply #11 on: February 11, 2010, 09:26:11 AM »
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Quote from: David Grover / Hasselblad
If when every one recomposes they move forward/backward by a function of the distance then it would be easy to enter an offset into the calculation.

My idea is for Hasselblad to invent some kind of Sensor Receptor. It would be about the size of a quarter, and it could pin, or velcro, or stick to the person's clothing. Wherever that Receptor was, the H lens would focus on that. So let the subject move; let the subject run; let the subject dance -- wherever she goes, the Receptor goes with her, and the Hasselblad follows focus. Maybe it emits some kind of sound that's outside the range of human hearing; maybe it's painted some color that's not in the Crayola box -- something, anything, to make it unique, so that the Hasselblad is not fooled.

I'm kidding, but not really.
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KevinA
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« Reply #12 on: February 11, 2010, 09:51:34 AM »
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Quote from: David Grover / Hasselblad
Im sorry Kevin. It just isn't possible in the way you describe without making it a very laborious process.

Attached is the trig info.

The only foolproof way would be to do it Wii style, but that would mean putting an infra red sender on top of the camera and a receiver on the models head.

2 readings one for top one for bottom then a third for focus point from one camera position, quicker than getting a light reading or adjusting ratios I would of thought.

Kevin.
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« Reply #13 on: February 11, 2010, 09:52:07 AM »
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Could I just ask, if someone could explain in a few words, just exactly why is digital so much harder to focus than film? I know that it is, because I have found out the hard way with my CFV back, but none of the explanations that I have seen so far seem wholly convincing.

John
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« Reply #14 on: February 11, 2010, 11:07:35 AM »
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Quote from: John R Smith
Could I just ask, if someone could explain in a few words, just exactly why is digital so much harder to focus than film? I know that it is, because I have found out the hard way with my CFV back, but none of the explanations that I have seen so far seem wholly convincing.

John


1)  The way we view files is different.  Before - light box (scratched), Loupe (scratched), Film... hopefully not scratched.  Now 100% view on a 30" display.

2)  Pixel pitch of modern sensors is extremely small and a regular pattern.  Film grains varied in size and were an irregular pattern.

3)  The only point that the image is in focus on a sensor is EXACTLY on the surface.  Front or behind you are moving away from the optimum focus point.  Film had some inherent thickness which gave a greater latitude.  For example a sensor misplaced by as little as 50 microns (0.05mm) is enough to show a focus error on an image with shallow depth of field.  (If you were looking closely... see point 1!)
« Last Edit: February 11, 2010, 11:08:27 AM by David Grover / Hasselblad » Logged

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« Reply #15 on: February 11, 2010, 11:15:31 AM »
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I played with the H4 yesterday and have to say I was very impressed with the true focus. I used true focus with a 120 macro, focused on the eyes and then tilted the camera down until the eyes where close to the edge and they stayed tack sharp. I also liked the fact you can shoot tethered still life, and choose a spot in the image and the camera will focus on that spot. I really think Hasselblad stepped up the game against Phase. I also think Hasselblad hype was a little over the top since this was announced last year they would have this technology.  

I need to shoot a real world test, and see how the images looks against my Leaf back but this is a camera I will probably buy if the images quality is what I need.
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« Reply #16 on: February 11, 2010, 11:18:21 AM »
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Quote from: John R Smith
Could I just ask, if someone could explain in a few words, just exactly why is digital so much harder to focus than film? I know that it is, because I have found out the hard way with my CFV back, but none of the explanations that I have seen so far seem wholly convincing.

John

Viewfinders on digital specific cameras tend to be smaller and less bright (and often without focus aids like micro prisms) ... (on average - there are always exceptions).

Some argue that slight misfocus is more obvious with digital, I'm unconvinced.

And people tend to forget the things we learned when manually focusing images. Relying on AF points and forgetting to check for themselves.

[/curmudgeon]
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« Reply #17 on: February 11, 2010, 11:46:14 AM »
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Quote from: David Grover / Hasselblad
1)  The way we view files is different.  Before - light box (scratched), Loupe (scratched), Film... hopefully not scratched.  Now 100% view on a 30" display.

2)  Pixel pitch of modern sensors is extremely small and a regular pattern.  Film grains varied in size and were an irregular pattern.

3)  The only point that the image is in focus on a sensor is EXACTLY on the surface.  Front or behind you are moving away from the optimum focus point.  Film had some inherent thickness which gave a greater latitude.  For example a sensor misplaced by as little as 50 microns (0.05mm) is enough to show a focus error on an image with shallow depth of field.  (If you were looking closely... see point 1!)


Well said David , saved me the typing. Bottom line we NEVER blew a piece of film up 100 percent to view the best we did was maybe a 8x lupe and point 3 is right on the money.


Now having said all that I never trusted a AF system on any cam . Bottom line it can't think like we do. Center AF point is great if the composition stays in the center which doing people it never does we recompose which throws it off. MF it is even tougher. Shooting the S2 P40+ test in the studio tethering the P40+ we did pretty good even at F11 but we still missed. Now the S2 non tethered i was lucky to nail a couple. Not that it was the S2 fault per say but with a long lens like the 180 the DOF is so freaking thin to begin with and than recomposing than you just get lost. Getting critical focus on people is tough and trying to get a eyelash for a test is nuts. Lot's of hit and miss and this is at F11. I try to tether as much as possible in this types of situations. Honestly end of day bottom line i use AF to get me there than hit the clutch for manual and fine tune almost every time. Nature of the beast. The HD4 true focus looks interesting and I would like to try it sometime
« Last Edit: February 11, 2010, 11:48:41 AM by Guy Mancuso » Logged

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« Reply #18 on: February 11, 2010, 01:18:08 PM »
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Quote from: David Grover / Hasselblad
1)  The way we view files is different.  Before - light box (scratched), Loupe (scratched), Film... hopefully not scratched.  Now 100% view on a 30" display.

2)  Pixel pitch of modern sensors is extremely small and a regular pattern.  Film grains varied in size and were an irregular pattern.

3)  The only point that the image is in focus on a sensor is EXACTLY on the surface.  Front or behind you are moving away from the optimum focus point.  Film had some inherent thickness which gave a greater latitude.  For example a sensor misplaced by as little as 50 microns (0.05mm) is enough to show a focus error on an image with shallow depth of field.  (If you were looking closely... see point 1!)


I don't think it's any different today than it was with film, other than with digital's  instant review we attempt to shoot at wider apertures than we did with film, especially in commerce.

Commerce and film was always that fear factor of shooting a polaroid at F4, thinking yea that looks good, then the fear creeps in with the thought of well, maybe I need more of the shoulder in focus, or that model is really moving fast so I had better go up to 5.6, well let's try 8, ah to hell with it shoot it at F16 that'll do it.

With digital we preview it on the camera and/or the computer and can really get down to the bare minimum, of course when you run on the edge your always going to miss some and even if you get 200 in focus and one soft image, I can promise you the client will select that one soft image.

I think because that's the image that looks spontaneous and clients love spontaneity.

I haven't tried the hasselblad with phocus shift or whatever it's called, though I wonder how it works on moving objects.

In regards to autofocus, if you really want pinpoint sharper than sharp focus pick up a Nikon.  If you can get the focus points on the subject it will be dead ass sharp, wide open, 95% of the time in almost total darkness.

Nothing I've ever used focuses like a Nikon.  

A year ago we shot a round the world gig, of about 10,000 images, almost split 50/50 between a 1ds3 and a Nikon D3 and D700.  I used the Nikon for low light and for anything that moved quickly, the Canon with more light and any scene that was more static and the ratio of sharp focus was about 65% Canon, 85% Nikon.

Regardless, I think focus is usually somewhat overrated.  Obviously a paying client wants an image in focus and that's the goal, but do a quick tour of the galleries in New York and look at some of the world's most historically compelling images and you'd be surprised that the majority of them are soft.

Maybe it's because the subject did something unexpected, or maybe it's just because life works that way, but nobody notices a slightly soft image if it's really compelling.

For all your sharpness junkies, 10 mpx of a sharp image has a lot more detail than 60 mpx of a soft image.

Since digital, especially 20 gazillion megapixel digital all everyone seems to talk about is ultra focused, uber over sharp images, but usually the examples I see are pretty damn boring.  Sharpness and extreme detail won't save a boring photograph.

In fact I believe the first 10 years  of digital photography will be called the oversharp decade.

BC
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Nick-T
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« Reply #19 on: February 11, 2010, 01:38:12 PM »
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gwhitf

You are making the process sound a lot more complicated than it really is. When you shot H did you have the AF on the user button and focus recompose? True focus works the same way but with the addition of a rapidly calculated adjustment based on the amount of tilt. What's it's doing is correcting for the inevitable back focus caused by the change in distance.

Kevin
As you (rather sniffily) pointed out the system cannot compensate for a moving model but it is still compensating.

I have been using the system for a while and it does work albeit with the caveats that others have mentioned (moving model, moving photographer).

As for film I don't think it was ever sharp, and as David says we never looked at it as closely.

My 2c

Nick-T

Edit
Forgot to mention that I did blather about true focus in the Hasselblad newsletter might be worth a read if you are trying to get your head around how it works.
« Last Edit: February 11, 2010, 01:40:22 PM by Nick-T » Logged

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