December 17, 2014, 06:36:33 PM

Author Topic: Estimating extra reach (resolving power) of crop vs FF  (Read 12792 times)

Valvebounce

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Re: Estimating extra reach (resolving power) of crop vs FF
« Reply #45 on: August 30, 2014, 07:46:41 PM »
Hi Neuro, Northstar.
The ostrich never flew, it just walked up the tree when when it was frightened by the bald eagle!

Cheers, Graham. 

I'm standing on the side of the road on a sunny day and I'm looking at a bald eagle that is 75 meters away sitting at the top of a tree.
same situation...except I'm looking at an Ostrich.  Which camera do I grab.

Doesn't matter, but you'd better be on the phone to the Guinness Book of World Records, the local news media, and the tabloids to report your flying ostrich!!!
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Re: Estimating extra reach (resolving power) of crop vs FF
« Reply #45 on: August 30, 2014, 07:46:41 PM »

Andyx01

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Re: Estimating extra reach (resolving power) of crop vs FF
« Reply #46 on: September 02, 2014, 02:48:16 PM »
The 7D.

Are we assuming the 'scene' is un-important and the "final image that fills the frame" is to consist of just the bird itself?

The 7D will have more pixels on target, but on a cropped field.

If your cropping the image down, the 7D will have more 'resolution' - but it might not be useful resolution depending on dozens of factors.

I had a 7D, and have a 5D III.  I did some tests where I cropped the 5D III to APSC frame-size and although lower in resolution, I saw no decernible differences with my sharpest lens.


Andyx01

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Re: Estimating extra reach (resolving power) of crop vs FF
« Reply #47 on: September 02, 2014, 02:53:15 PM »
This really has me baffled.
85mm f1.8 @ f4, 1/1250. ISO 100
Shot on 5DII and 1100D. The crop camera down sampled to match 5D as that camera works out at about 8.5 mp when cropped and the 1100D is a 12 mp aps camera. Hand held, but had to resort to live view focusing as I couldn't believe the results.

100% crops from each camera.

Crop-A appears to have less dynamic range / poor shadow detail.

What can't you beleive about the results?

Skulker

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Re: Estimating extra reach (resolving power) of crop vs FF
« Reply #48 on: September 02, 2014, 04:26:07 PM »

The 7D will have more pixels on target, but on a cropped field.

If your cropping the image down, the 7D will have more 'resolution' - but it might not be useful resolution depending on dozens of factors.

I had a 7D, and have a 5D III.  I did some tests where I cropped the 5D III to APSC frame-size and although lower in resolution, I saw no decernible differences with my sharpest lens.


That's what I find. I don't see the "extra reach of crop vs FF" in the real world. I see lots of people who are convinced and try to prove it. But I have no regrets about having sold my 7D.


The 7D was and is a great camera but I get better results from the 5D3 and the 1Dx. 
If you debate with a fool onlookers can find it VERY difficult to tell the difference.

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Re: Estimating extra reach (resolving power) of crop vs FF
« Reply #49 on: September 02, 2014, 04:30:29 PM »
This really has me baffled.
85mm f1.8 @ f4, 1/1250. ISO 100
Shot on 5DII and 1100D. The crop camera down sampled to match 5D as that camera works out at about 8.5 mp when cropped and the 1100D is a 12 mp aps camera. Hand held, but had to resort to live view focusing as I couldn't believe the results.

100% crops from each camera.

Crop-A appears to have less dynamic range / poor shadow detail.

What can't you beleive about the results?

I remember being able to see the difference in resolution between an eight mp APS camera and a twelve mp, but in this instance when comparing 8.5 of the 5DII against the 12 of APS there is no appreciable difference.

Don't read too much into shadow detail etc, the cameras were not identically matched.

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Re: Estimating extra reach (resolving power) of crop vs FF
« Reply #50 on: September 02, 2014, 04:31:02 PM »

The 7D will have more pixels on target, but on a cropped field.

If your cropping the image down, the 7D will have more 'resolution' - but it might not be useful resolution depending on dozens of factors.

I had a 7D, and have a 5D III.  I did some tests where I cropped the 5D III to APSC frame-size and although lower in resolution, I saw no decernible differences with my sharpest lens.


That's what I find. I don't see the "extra reach of crop vs FF" in the real world. I see lots of people who are convinced and try to prove it. But I have no regrets about having sold my 7D.


The 7D was and is a great camera but I get better results from the 5D3 and the 1Dx.

Are you sure you aren't compensating for the reach difference? Most of the claims about full frame being better are just personal feeling about how their photos actually turn out. I suspect most of the time, framing, and therefor pixels on target, is a bit better with full frame than with APS-C, thus negating the issue. I know that with my 5D III, I'm now using 1200mm f/8 more often, which completely negates any reach advantage the 7D had. Total amount of light falling on the sensor is just a little more than the 7D, so overall noise is similar...but the greater pixel count ultimately results in sharper, crisper detail in the end. (The greater pixel count also means NR is more effective, as it can be utilized more appropriately.)

Now, when it comes to shooting at 600mm f/4 on either camera, my 7D definitely resolves more detail, no question. However, I'm also definitely reach limited at that point unless I risk scaring off my subjects to get closer.

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Re: Estimating extra reach (resolving power) of crop vs FF
« Reply #51 on: September 02, 2014, 04:58:15 PM »

The 7D will have more pixels on target, but on a cropped field.

If your cropping the image down, the 7D will have more 'resolution' - but it might not be useful resolution depending on dozens of factors.

I had a 7D, and have a 5D III.  I did some tests where I cropped the 5D III to APSC frame-size and although lower in resolution, I saw no decernible differences with my sharpest lens.


That's what I find. I don't see the "extra reach of crop vs FF" in the real world. I see lots of people who are convinced and try to prove it. But I have no regrets about having sold my 7D.


The 7D was and is a great camera but I get better results from the 5D3 and the 1Dx.

Are you sure you aren't compensating for the reach difference? Most of the claims about full frame being better are just personal feeling about how their photos actually turn out. I suspect most of the time, framing, and therefor pixels on target, is a bit better with full frame than with APS-C, thus negating the issue. I know that with my 5D III, I'm now using 1200mm f/8 more often, which completely negates any reach advantage the 7D had. Total amount of light falling on the sensor is just a little more than the 7D, so overall noise is similar...but the greater pixel count ultimately results in sharper, crisper detail in the end. (The greater pixel count also means NR is more effective, as it can be utilized more appropriately.)

Now, when it comes to shooting at 600mm f/4 on either camera, my 7D definitely resolves more detail, no question. However, I'm also definitely reach limited at that point unless I risk scaring off my subjects to get closer.


Yes I am sure. That's why I said it and yes I am sure I am not mis compensating for reach difference. You do make some rude comments and that was one of them. You are very arrogant to imply I am incapable of making a valid comparison.

If you debate with a fool onlookers can find it VERY difficult to tell the difference.

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Re: Estimating extra reach (resolving power) of crop vs FF
« Reply #51 on: September 02, 2014, 04:58:15 PM »

Stu_bert

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Re: Estimating extra reach (resolving power) of crop vs FF
« Reply #52 on: September 02, 2014, 05:36:36 PM »
This stuff just gets too technical for me, so let me ask a question.

I'm standing on the side of the road on a sunny day and I'm looking at a bald eagle that is 75 meters away sitting at the top of a tree.  In my camera bag is my 300mm 2.8 lens, a 7D and 5D3.

I'm shooting handheld.  I don't dare move closer for fear that I scare him off.

If I'm trying to produce a final/edited image that "fills the frame" with as much detail, sharpness, and overall IQ as possible, which body do I attach to the 300mm?

A fully grown bald eagle is 1 m long. The size of the image on the sensor for a 300mm lens 75 m away is 4 mm. corresponding to 930 pixels on the 7D or 640 on the 5DIII. 300mm is too short for a decent image. I would use the 300 mm + 2xTC on either camera as 1860 px on the 7D or 1280 on the 5DIII would give an excellent image. You didn't have the 2xTC in your bag, I know but that is bad planning.

Alan - out of curiosity, what's the maths behind subject size, lens, distance, size on sensor please? I've always wanted to be able to calculate this.

Is it focal length/(distance/subject size) = size on sensor?

Thanks in advance.
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Re: Estimating extra reach (resolving power) of crop vs FF
« Reply #53 on: September 02, 2014, 06:44:36 PM »

The 7D will have more pixels on target, but on a cropped field.

If your cropping the image down, the 7D will have more 'resolution' - but it might not be useful resolution depending on dozens of factors.

I had a 7D, and have a 5D III.  I did some tests where I cropped the 5D III to APSC frame-size and although lower in resolution, I saw no decernible differences with my sharpest lens.


That's what I find. I don't see the "extra reach of crop vs FF" in the real world. I see lots of people who are convinced and try to prove it. But I have no regrets about having sold my 7D.


The 7D was and is a great camera but I get better results from the 5D3 and the 1Dx.

Are you sure you aren't compensating for the reach difference? Most of the claims about full frame being better are just personal feeling about how their photos actually turn out. I suspect most of the time, framing, and therefor pixels on target, is a bit better with full frame than with APS-C, thus negating the issue. I know that with my 5D III, I'm now using 1200mm f/8 more often, which completely negates any reach advantage the 7D had. Total amount of light falling on the sensor is just a little more than the 7D, so overall noise is similar...but the greater pixel count ultimately results in sharper, crisper detail in the end. (The greater pixel count also means NR is more effective, as it can be utilized more appropriately.)

Now, when it comes to shooting at 600mm f/4 on either camera, my 7D definitely resolves more detail, no question. However, I'm also definitely reach limited at that point unless I risk scaring off my subjects to get closer.


Yes I am sure. That's why I said it and yes I am sure I am not mis compensating for reach difference. You do make some rude comments and that was one of them. You are very arrogant to imply I am incapable of making a valid comparison.

It was a general statement, not about you personally, but people in general who make general claims that they see no difference in FF resolution without actually comparing FF and APS-C in a valid context. What in the world was rude about that?

Jack Douglas

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Re: Estimating extra reach (resolving power) of crop vs FF
« Reply #54 on: September 02, 2014, 11:54:33 PM »
Jon, I don't think that was rude unless a person chooses to take it personally based on other issues.  When there is disagreement it's challenging to keep everyone happy.

You now have the 5D3 which is resolution-wise pretty similar to me with the 6D and we're both wondering about a 7D2 primarily with respect to its IQ.  I'm trying to settle into what really is the truth relative to the reach advantage.  It's pretty clear there is no where near a 60% advantage relative to being reach limited and choosing FF or crop, but I'm prepared to believe 20% is realistic.  Would you be willing to offer what you consider the various deciding factors that would sway you for or against a 7D2 purchase when it arrives.  Let's assume frame rate and AF are acceptible.

Jack
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Re: Estimating extra reach (resolving power) of crop vs FF
« Reply #55 on: September 03, 2014, 12:36:24 AM »
Jon, I don't think that was rude unless a person chooses to take it personally based on other issues.  When there is disagreement it's challenging to keep everyone happy.

You now have the 5D3 which is resolution-wise pretty similar to me with the 6D and we're both wondering about a 7D2 primarily with respect to its IQ.  I'm trying to settle into what really is the truth relative to the reach advantage.  It's pretty clear there is no where near a 60% advantage relative to being reach limited and choosing FF or crop, but I'm prepared to believe 20% is realistic.  Would you be willing to offer what you consider the various deciding factors that would sway you for or against a 7D2 purchase when it arrives.  Let's assume frame rate and AF are acceptible.

People are choosing to take offense at all kinds of stuff lately, and a lot of it seems to come from "sparse" reading of my posts, leading to misinterpretation. I guess that's their prerogative. Seems once you mention DR and put Canon in bad light, everything gets misinterpreted, everyone gets pissy.

As for the 7D II, I'm only really interested in it as a gauge for where Canon is technologically on the sensor front. If it really does only get a very, very modest bump to 20.2mp, no DR improvement, etc. then I really don't have much interest in it in general. I'm not unhappy with the 7D when I need the reach and resolution. I also like the 7D for imaging smaller nebula at a tighter image scale.

Now, if the 7D II gets something like a 24-26mp sensor, along with a DR improvement, then for me it would at least be a good indicator that Canon has been doing something quietly behind the scenes. That would mean that the next 5D or 1D model should have even more improvements. I still don't think I'd be getting a 7D II. I've got the hang of using the 5D III with the 600/4 and 2x TC now. Both on a tripod and handheld. It ain't good at all for BIF, but it's really nice for when I want to keep a greater distance from birds (which the 7D+600 did pretty well, but with actually fewer pixels on subject.) Because I'm now skilled enough to get pretty nice head shots with the 5DIII/1200mm combo, I don't see as much need for the 7D II personally. With a 24mp or higher resolution sensor, it would offer a nice resolution improvement for astrophotography...however DSLRs, while very easy, REALLY lack the sensitivity and total resolution that a mono CCD with filters offers. So it really wouldn't be all that useful to me for that either.

So...yeah. The 7D II is pretty much just a milestone marker for Canon sensor tech. They have either done something on that front...or not. DPAF, even if it gets that sensitivity boost their latest DPAF patent describes, just doesn't interest me enough to matter yet. I don't think it's a viable replacement for PDAF, and won't be for a while still. I'm looking to the 7D II to tell me what the 5D IV might be like. I hope it tells me something good.

I seem to be getting a lot of airplane trails in my Elephant Trunk nebula images. I'm not sure what's going on, but it's like an airport outside right now, and I gotta go figure out who is doing what in the airspace right on top of my house...  >:(

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Re: Estimating extra reach (resolving power) of crop vs FF
« Reply #56 on: September 03, 2014, 01:05:02 AM »
Thanks Jon, great comments as usual.

Jack
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Re: Estimating extra reach (resolving power) of crop vs FF
« Reply #57 on: September 03, 2014, 02:11:43 AM »
Jon,

"DPAF, even if it gets that sensitivity boost their latest DPAF patent describes, just doesn't interest me enough to matter yet. I don't think it's a viable replacement for PDAF, and won't be for a while still."

I thought the 70D used DPAF in a two pixel phase detect format (PDAF), so could you please clarify.  Apparently, the dual pixels covering most of the sensor can function as selectable AF points.  What's holding this technology back relative to the anticipated 7D2?  It's really hard to believe the 7D2 will actually be a ho hum camera.

Jack
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Re: Estimating extra reach (resolving power) of crop vs FF
« Reply #57 on: September 03, 2014, 02:11:43 AM »

ChristopherMarkPerez

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Re: Estimating extra reach (resolving power) of crop vs FF
« Reply #58 on: September 03, 2014, 04:10:02 AM »
Here is a way of calculating the effective extra reach or resolving power of a crop body versus FF, which will amuse the geeks among us...

MTF is not a measure of resolution, it is a measure of a lenses ability to transmit contrast of the original scene through a lens.  That's all it measures.

If what you really want is true image resolution, then there are two correct ways of measuring it.  The first is a measurement of the performance of the lens itself.  This measurement can be found in using something like a USAF resolution test chart and a microscope to perform aerial inspections of the image of the chart after it has passed through the lens.

Problems with this approach include difficultly in setting up a test bench (it's not easy at all).  Additionally, the final result will not include measurements of chromatic aberrations, image distortions, field curvature, etc.  The most important missing element in this kind of test is the exclusion of the imaging system itself.  However, if the question is about real optical resolution, this test will give you the right answer.

Which leads to the second way of measuring, well, actually calculating real image resolution.  This is diagnostic and very simple to perform.  Simply take the number of image points ("pixels") in your file, divide by the size of your sensor (in millimeters), and divide by two.  This number will represent the number of Line Pair per Millimeter (the measure of the ability to go from one white line to one black line) that your sensor can resolve.

This is rather interesting in that you can quickly see that a Canon 7D 18 mpixel sensor is capable of resolving 116 line pair per mm.  The Canon 5D MkII is capable of 78 lppmm.  As a comparison, Sony's 36mpixel FF sensor is capable of resolving 102 lppmm and Phase One's monster 80mpixel IQ180 returns 97lppmm.

Taking this a step further, look carefully at the physical limits (as in optical physics) of optical resolution, as measured in lppmm.  You see that at f/2, an optically correct lens will return 695lppmm in the center of the scene where the light's wavelength is 589.3mu (green).  At f/11, an optically correct lens will return 123lppmm, dropping off to 92lppmm at 25 degrees off-axis tangential.

Looking at this over the years, I have come to realize there is seldom a lens resolving so poorly that a sensor (or old film for that matter) could out-resolve the lens.  Sure, there are other important optical effects we need to consider, but we are talking pure resolution here.  Nothing more.

Think about this for a moment.  MTF does _not_ measure optical resolution.  While useful, it does _not_ tell the story of resolution, no matter how much "math" you throw at it.  Secondly, and perhaps most interestingly, optical physics show diffraction limited resolution at f/11 EXCEEDS currently manufactured sensors ability to return that resolution in all cases. 

Rather shocking, don't you think?

Back to the original poster's point: Canon's 7D sensor outresolves (using the correct application of the word "resolution") the FF sensors from any manufacturer.  It does so, however, for reasons other than those that were brought up.

Correct application of rational thought and real world science can help us properly understand and identify the errors and misleading comments widely published by marketeers and critics of optical imaging systems.
« Last Edit: September 03, 2014, 05:04:34 AM by ChristopherMarkPerez »
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Re: Estimating extra reach (resolving power) of crop vs FF
« Reply #59 on: September 03, 2014, 05:08:11 AM »
Here is a way of calculating the effective extra reach or resolving power of a crop body versus FF, which will amuse the geeks among us...


Which leads to the second way of measuring, well, actually calculating real image resolution.  This is diagnostic and very simple to perform.  Simply take the number of image points ("pixels") in your file, divide by the size of your sensor (in millimeters), and divide by two.  This number will represent the number of Line Pair per Millimeter (the measure of the ability to go from one white line to one black line) that your sensor can resolve.


what about the bayer pattern?

a pixel in the image file is interpolated from photosites on the sensor.
so a bayer pattern sensor has to be worse than what you wrote?

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Re: Estimating extra reach (resolving power) of crop vs FF
« Reply #59 on: September 03, 2014, 05:08:11 AM »