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Author Topic: Will 1/3*mm impact megapixel count?  (Read 2316 times)
dreed
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« on: January 31, 2011, 10:04:58 PM »
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In the story on the 80MP back from Leaf and Phase One, Michael remarks how the increased sensor resolution now begs for 1/3*mm for a sharp shot. Shooting at 100mm requiring 1/300 or faster when hand held. Hmmm.

If I calculate this correctly, the IQ180 is 3.6MP/cm2. Smaller compact cameras have a higher pixel density and seem to be ok at less than 1/3*mm ... there's got to be a better algorithm for determining safe hand held speed than just an arbitrary x for 1/x with camera y. And with Cameras like the 2D Mark2 doing SRAW1/SRAW2 (effectively increasing pixel size), why can't I use that as an additional axis of freedom when choosing settings for a shot? (ISO, shutter speed, aperture, raw capture size) I suppose the point here is, let me fix the shutter speed and aperture, let the camera choose ISO for exposure and pixel count for clarity using the focal length and shutter speed to calculate.

Whilst prime lenses such as various 50mm 1/1.2's and so on sell as being great for low-light, if the MP in your camera requires 1/150 (or better) in order to be sharp when hand held, is the benefit lost? (Consider that low-light rarely means 1/150 is possible, except with ISO of 3200 or more.) A 35mm DSLR with >31MP is going to be at the same pixel density as the IQ180. Is it useful for me to have a camera that requires 1/3*mm for a sharp picture when I'm walking through the city streets? Or does that shift the focus back to ISO above 100 or 200 being necessary for non-tripod work with such cameras?

In part, image stabilisation will provide some compensation here but the kicker there is that the lens typically has to have IS built in - unless you've got a Sony Alpha ... and I'm stating to guess that in this, Sony has figured out the long game better than Canon/Nikon as the requirements of the IS are driven by the MP of the sensor.

It may be that Phase One's market is predominately studio-based or those who can unpack the tripod from the car that's a few feet away, so there's nothing to worry about for them and perhaps for those that want such a back to walk about with, the answer is an IQ140. But if the MP count keeps going up, then how long before it becomes impractical to use some cameras hand-held simply because of the image blur on the sensor?
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ErikKaffehr
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« Reply #1 on: February 01, 2011, 12:04:13 AM »
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Hi,

It has been clear very long that it takes excellent technique to fully utilize today's sensors. I would suggest that MFDBs are mostly used on a solid tripod or in studio with flash that is freezing action.

A while ago I made a series of exposures with and without MLU. At intermediate times like 1/15 - 1/125 I lost about half the resolution, essentially turning that 6 MP DSLR into a 1.5MP camera. The images still looked decent, although the resolution was not there.

On the other hand, increasing pixel count is really a win/win situation if done within reasonable limits. A higher resolution sensor will exhibit less aliasing, interpolate better, respond better to sharpening. Making the senseless to small will affect DR negatively, but less than would be expected.

Check these two articles:
http://www.dxomark.com/index.php/en/Our-publications/DxOMark-Insights/More-pixels-offset-noise!
http://www.luminous-landscape.com/essays/dxomark_sensor_for_benchmarking_cameras.shtml


Achieving full resolution on a small pixel sensor makes very exacting demands:

- Stable plattform
- Vibration elimination (MLU/self timer/remote release)
- Exact focusing which is very hard without live view
- Finding very good lenses
- Having everything aligned
- Using optimal aperture

That said, perfect focus is possible in a single image plane. That plane can be tilted using the Scheimpflug principle, but it's still a plane. Extended depth of field is possible with techniques merging several images with different focus into a single image, using Helicon Focus or similar.

It would be very nice if the industry came up with the concept of focus bracketing.

Best regards
Erik




In the story on the 80MP back from Leaf and Phase One, Michael remarks how the increased sensor resolution now begs for 1/3*mm for a sharp shot. Shooting at 100mm requiring 1/300 or faster when hand held. Hmmm.

If I calculate this correctly, the IQ180 is 3.6MP/cm2. Smaller compact cameras have a higher pixel density and seem to be ok at less than 1/3*mm ... there's got to be a better algorithm for determining safe hand held speed than just an arbitrary x for 1/x with camera y. And with Cameras like the 2D Mark2 doing SRAW1/SRAW2 (effectively increasing pixel size), why can't I use that as an additional axis of freedom when choosing settings for a shot? (ISO, shutter speed, aperture, raw capture size) I suppose the point here is, let me fix the shutter speed and aperture, let the camera choose ISO for exposure and pixel count for clarity using the focal length and shutter speed to calculate.

Whilst prime lenses such as various 50mm 1/1.2's and so on sell as being great for low-light, if the MP in your camera requires 1/150 (or better) in order to be sharp when hand held, is the benefit lost? (Consider that low-light rarely means 1/150 is possible, except with ISO of 3200 or more.) A 35mm DSLR with >31MP is going to be at the same pixel density as the IQ180. Is it useful for me to have a camera that requires 1/3*mm for a sharp picture when I'm walking through the city streets? Or does that shift the focus back to ISO above 100 or 200 being necessary for non-tripod work with such cameras?

In part, image stabilisation will provide some compensation here but the kicker there is that the lens typically has to have IS built in - unless you've got a Sony Alpha ... and I'm stating to guess that in this, Sony has figured out the long game better than Canon/Nikon as the requirements of the IS are driven by the MP of the sensor.

It may be that Phase One's market is predominately studio-based or those who can unpack the tripod from the car that's a few feet away, so there's nothing to worry about for them and perhaps for those that want such a back to walk about with, the answer is an IQ140. But if the MP count keeps going up, then how long before it becomes impractical to use some cameras hand-held simply because of the image blur on the sensor?
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dchew
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« Reply #2 on: February 01, 2011, 03:52:07 AM »
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I think you are mis-interpreting what is being said by Michael and others.  If you shoot handlheld at 1/focal length, a higher resolution sensor doesn't make the handheld shot any worse than a lower resolution sensor. I think Michael is saying you cannot get the most out of what the camera has to offer in regards to resolving power unless you go to a shutter speed that is 3x the 1/focal length. 

In other words, the image quality potential is much higher with a high resolution sensor.  You just wont see that higher image quality unless you use different / improved technique.  Using a smaller RAW size file will not improve the image at any shutter speed / focal length ratio.  The high resolution sensor raises the bar of what you can achieve, but you must be very diligent in order to get there.

Dave

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John R Smith
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« Reply #3 on: February 01, 2011, 05:56:11 AM »
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The image quality that you get for any given shot, whatever your technique / shutter speed / aperture, is the exactly the same no matter what sensor you hang off the back of the camera. All that changes, even if you had a 200 MP sensor, is the magnification at which you see the image when zoomed in at 100%. The difference between 40 MP and 80 MP is similar to cranking the enlarger head up the column in the darkroom. Sure, your image will look softer the more that you enlarge it - but it always did, with film just the same as digital.

And if you print two pictures, one from 40 MP and one from 80 MP, taken of the same subject using the same camera and lens, they will look identical at 10x8 all other things being equal.

John
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dturina
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« Reply #4 on: February 01, 2011, 06:10:17 AM »
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Good technique makes the major part of image quality in any case. I recently looked at my old pictures absolutely shocked with the mistakes I made - for instance stopping down to f/20 with a four thirds sensor just because I needed longer exposure in daylight in order to blur the water. The pictures, of course, are hopelessly soft. Also, pressing the shutter button with my finger (while using tripod) blurred all the shots. Now I use a wired release, mirror lockup and 2s delay, and it's that modification of technique that made my pictures sharper, not the change of lenses and cameras. So I'd say larger format gear is good because it makes you brush up on your technique, which was overdue anyhow. Smiley
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Danijel
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« Reply #5 on: February 01, 2011, 07:28:16 AM »
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[...]Smaller compact cameras have a higher pixel density and seem to be ok at less than 1/3*mm[...]

Are you taking into account the fact that smaller sensors require shorter focal lengths in order to achieve the same field of view?.
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Rob C
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« Reply #6 on: February 01, 2011, 02:15:59 PM »
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You know, this is all taking people further and further away from the fact that regardless of the technical ideals, pictures are made in the mind and caught via the camera.

For example: I'm probably leaving the house in half-an-hour to go to a bar and shoot some images of a small blues combo. All the theory in the world won't make the work any better or worse than the ability I may or may not still have to hand-hold a camera. I can only open up to f1.8 (my max) and set the thing at around a 125th and the ISO on Auto and pray nobody bangs my arm at the tickly bit. I won't use a flash, and if the available ain't enough, too bad - I'll have a coffee and drive home. That's the reality, or it is if I want to come home this freezing night with anything to make the drive and the cold worth the dare. I have three cameras: one film and two digis. The film is a no-no and so is the D200, so the D700 it is. The D200 would have been long gone if trade values were realistic but they are not. So to what point all the theoretical hype in threads such as this one?

I think the difference is between getting an image of something and not getting an image because the tech details don't fit some imaginary ideal that exists only in chat pages and photo magazines. This is a relatively new malaise that didn't exist in the bad old days when folks just got on with it and did the best they could with what they had.

Rob C
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dturina
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« Reply #7 on: February 01, 2011, 02:59:06 PM »
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I think the difference is between getting an image of something and not getting an image because the tech details don't fit some imaginary ideal that exists only in chat pages and photo magazines. This is a relatively new malaise that didn't exist in the bad old days when folks just got on with it and did the best they could with what they had.

If the image I got isn't technically good enough for its intended use, I can hardly say I got it. And yes, I do shoot all of my closeup work hand-held, but the same applies. It's either sharp enough and focused on the right part of the bee, or not. The bee is either in the depth of field or not. If it's not, then I didn't get the image.
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Danijel
douglasf13
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« Reply #8 on: February 01, 2011, 03:00:00 PM »
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Good points, Erik.  Iliah Borg just made an interesting post in regards to the importance of tripods and 24mp cameras.

http://forums.dpreview.com/forums/read.asp?forum=1021&message=37552546
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Ray
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« Reply #9 on: February 01, 2011, 05:36:09 PM »
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You know, this is all taking people further and further away from the fact that regardless of the technical ideals, pictures are made in the mind and caught via the camera.

Rob,
I am surprised at such an attitude  Grin . It's a given that any picture usually appears in the mind before the shutter is pressed, otherwise one wouldn't know what one was shooting. But in order to 'catch' via the camera what has previously appeared in the mind, one needs an appropriate shutter speed, otherwise the result will likely be considerably different from the picture in the mind.

Isn't the 1/FL rule as old as the hills? (Well, at least as old as the 35mm format).

Of course, if one suffers from Parkinson's in one's old age, it doesn't apply. One might then have to create a new rule such as 1/4FL or even 1/10FL.

One factor of the '1/focal length' guide for minimum shutter speed, which is sometimes overlooked, is that it relates specifically to the 35mm format.

If one applies the rule to other formats, one should use the 35mm equivalent of focal length, so a cropped format camera with a 50mm lens requires an 1/80th sec minimum shutter speed, and presumably an MF camera with standard 80mm lens requires a minimum 1/50th.

If that doesn't sound right, it's because one has perhaps overlooked another factor. The 1/FL rule relates to a requirement for acceptably sharp prints at an 8"x10" size (or 8''x12" without cropping), because that size used to be considered by many as the maximum size print for 35mm photography without grain becoming objectionable.

Clearly modern DSLRs and MFDBs are capable of much larger prints than 8"x10". The larger the print, the faster the shutter speed required for a hand-held shot to be acceptably sharp.

Of course, the new technology of Image Stabilisation changes the situation. Whereas a shutter speed of 1/FL using a 24mp DSLR is clearly inadequate if it is intended to produce a large print, a shutter speed of 1/FL in combination with VR or IS may be perfectly adequate.

This is a situation where you should make your own rules because each invidual's capacity to hold a camera steady will vary, and the style of camera and method of holding it will also affect the result.
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dreed
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« Reply #10 on: February 01, 2011, 06:41:13 PM »
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The image quality that you get for any given shot, whatever your technique / shutter speed / aperture, is the exactly the same no matter what sensor you hang off the back of the camera. All that changes, even if you had a 200 MP sensor, is the magnification at which you see the image when zoomed in at 100%. The difference between 40 MP and 80 MP is similar to cranking the enlarger head up the column in the darkroom. Sure, your image will look softer the more that you enlarge it - but it always did, with film just the same as digital.

No.

If the 40MP back has pixels that are twice the size of the 80MP back then quite clearly the 40MP back can move twice as far as the 80MP back when the shutter zips across.

How do I explain this... for example, if my picture has a horizontal line through it that is 10 pixels wide on an 80MP back, if during the taking of the photo the camera moves enough to cause the line to paint an area 11 pixels wide, at 40MP it should be a line that is 5 pixels wide and that same extra movement might not be enough to cause it to be 6. So at 80MP, the picture has blur and at 40MP it does not.
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EricV
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« Reply #11 on: February 01, 2011, 07:58:40 PM »
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If the 40MP back has pixels that are twice the size of the 80MP back then quite clearly the 40MP back can move twice as far as the 80MP back when the shutter zips across.
If you care about image blur in pixels, then your argument is correct.  But isn't it more important to consider physical object blur?  Then the original poster is correct, pixels do not matter.  For example, if I take a photograph of a newspaper, and I shake the camera enough to blur the text by the width of a single letter, the blur on a print will appear the same independent of the pixel size, provided I have enough pixels to resolve the text in the first place.
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Ray
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« Reply #12 on: February 01, 2011, 09:27:10 PM »
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John R Smith is essentially correct, provided one eliminates variables such as the ease with which one may hold one type of camera steady as opposed to another type which may be more difficult to get a grip on.

And provided one normalises print or viewed image size.

On the basis that all cameras are capable of producing an 8"x10" print without interpolation, if one applies the rule of 1/FL35mm for the shutter speed, then all cameras will employ the same shutter speed for the same field of view.

For example, the P&S camera with a standard 6mm lens may be 50mm in terms of 35mm format equivalent. The MF format with standard 80mm lens will also be 50mm in 35mm format terms.

If one uses a shutter speed of 1/50th with all 3 cameras, and one downsamples the images to a size suitable for viewing or printing at 8"x10", then any blur due to camera movement will be the equally apparent in all images.

However, it should be understood that in practice the blur due to camera shake is never exactly the same twice, but may be approximately the same.
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EduPerez
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« Reply #13 on: February 02, 2011, 05:47:03 AM »
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You know, this is all taking people further and further away from the fact that regardless of the technical ideals, pictures are made in the mind and caught via the camera.

For example: I'm probably leaving the house in half-an-hour to go to a bar and shoot some images of a small blues combo. All the theory in the world won't make the work any better or worse than the ability I may or may not still have to hand-hold a camera. I can only open up to f1.8 (my max) and set the thing at around a 125th and the ISO on Auto and pray nobody bangs my arm at the tickly bit. I won't use a flash, and if the available ain't enough, too bad - I'll have a coffee and drive home. That's the reality, or it is if I want to come home this freezing night with anything to make the drive and the cold worth the dare. I have three cameras: one film and two digis. The film is a no-no and so is the D200, so the D700 it is. The D200 would have been long gone if trade values were realistic but they are not. So to what point all the theoretical hype in threads such as this one?

I think the difference is between getting an image of something and not getting an image because the tech details don't fit some imaginary ideal that exists only in chat pages and photo magazines. This is a relatively new malaise that didn't exist in the bad old days when folks just got on with it and did the best they could with what they had.

Rob C

In general, I tend to agree completely ("There is nothing worse than a sharp image of a fuzzy concept"), but motion blur (when caused by camera shake) is particularly annoying to me; I can stand noise or lack of sharpness / definition, but camera shake can ruin a photograph for me.

Knowing how low I can "safely" go with the shutter speed is important, or else I risk coming home with a card full of unusable images.
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dturina
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« Reply #14 on: February 02, 2011, 11:02:00 AM »
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In general, I tend to agree completely ("There is nothing worse than a sharp image of a fuzzy concept")

Except maybe a fuzzy image of a sharp concept. Smiley
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Danijel
fredjeang
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« Reply #15 on: February 02, 2011, 01:16:35 PM »
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I have no doubt that any significative increment in MP has applications and needs, specially big prints for fine arts, museums etc...
I think they target the LF users that still resist to enter digiland.

I have serious doubts on a commercial basis. For most of commercial works, this is like killing a mosquito with an atomic bomb. I think we all agree that 40 ish is a great balance and top reso.

Then, the cost almost drives you to raw video, and video, and raw video in particular, is an equipment that will need to invest more and more pros simply because of the increment demand in this area and the less demand for still imagery (not less demand but vastly ocupated by snappers and semi-pros). It's prety much one choice or the other.

But if they want to go 500MP I'm fine with that.
« Last Edit: February 02, 2011, 01:18:50 PM by fredjeang » Logged
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