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Messages - jrista

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1156
EOS Bodies / Re: Eos7D mk2, How EXCITED will you be if . . .?
« on: July 10, 2014, 08:00:12 PM »

Quote from: neuroanatomist
As for sharpness, while it's true that a multilayer sensor wouldn't need the blurring caused by an AA filter to avoid color moiré, that blurring is predictable and thus highly correctable with sharpening in post, so the true gain in sharpness is minor at best.
Not true. "No AA" picture can still be corrected/sharpened better than picture "with AA". Multilayer without AA can be sharpened/"regenerated" even further.

 All the practical evidence from people who have two cameras identical other than with, or without AA filter, ie. Nikon D800/800e and Pentax K5II/n (or whatever it's called) is that there is no perceivable difference after applying suitable un-sharp mask.

no AA is still a touch crisper, but also with false 'detail' and more issues
I don't think sensor densities are high enough yet for no AA filter to be wise.

Aye, removal of the AA results in false detail, which really just shows up as harsh noise a lot of the time, aliasing and more at others. I don't know that sensor densities will ever be high enough that we could ever really do away with AA filters. I mean, if the Otus does resolve somewhere in the realm of 400lp/mm wide open, then we would need a bayer sensor capable of resolving over 550mp in order to be able to drop the AA filter. That would be pixel sizes around 1.25µm. Not infeasible from a fabrication standpoint...probably infeasible from a data transfer rate standpoint (the file sizes at 14 bit, assuming around 7% increase in pixel count for masked border pixels, would be about 1.1GB in size, each...the only things that move that much data per second are high powered GPUs and CPUs, both if which require massive amounts of power (even i7 Intel Haswells still draw a lot of power when moving that kind of data per second.)

1157
Third Party Manufacturers / Re: Nikon's D800E 30% sharper than D800
« on: July 10, 2014, 07:34:19 PM »

Consider that across the Internet, criticism of DxO typically only comes from people that own Canon products. That piece of data speaks volumes about how DxO results are absorbed, don't you think?

I'm not sure what "typically only" means (do you mean "usually" or "most of the criticism I've seen" or "most of the criticism I've noticed"?) but I often see criticism of DxO on forums (esp. m43), including at DxO itself.  Perhaps that "piece of data" speaks volumes too.

I never see people on Nikon rumors or Sony Alpha Rumors ripping into DxO like folks do here... (don't read m43 forums so...)

LOL. You haven't read enough of Nikon Rumors or DPR then. Particularly at DPR, the DXO ripping is AT LEAST as bad as it is here, if not a lot worse. We aren't the sole group of people who have a problem with the way DXO does things, there are a lot of people out there, and many who are NOT Canon fans, who don't like DXO results nor like the black boxes DXO insists on maintaining. You can't call yourself "scientific", then have blantantly unscientific results, and not tell anyone why or explain the reasons why to anyone.

That doesn't mean that 100% of everything DXO does is bad...people here are pretty clear about what bits of DXO's information and/or processes and procedures they have a problem with. Dig down into DXO's direct measurements for sensors, and most of those are useful information. It's the extrapolations (i.e. Print DR) and funky results (i.e. lens resolution, T-stop weight in their results) that raise serious questions about what DXO is doing, how, and why. LEGITIMATE questions.

1158
Third Party Manufacturers / Re: Nikon's D800E 30% sharper than D800
« on: July 10, 2014, 01:03:39 PM »
OK, I trust you guys know your optics and related math much better than I do.  I'm just trying to figure something out here that's not quite making sense to me yet so if you care to indulge following the path I'm on with this, please tell me which step I slipped on.

I'll use round numbers for convenience but referring to the numbers jrista provided on a previous page.

Step 1:

- A digital image sensor (e.g. D800e) with pixels that are 5 microns square = 100 lp/mm physical sensor resolution with no AA filter.
I presume with whatever kind of algorithm is used, it is possible to read alternating rows of pixels, if they are properly stimulated, such that it would be possible to electronically extract the maximum of 100 lp/mm from this sensor.  If this were a monochrome rather than Bayer sensor then likely even simpler.

The resulting contrast ratio, if one were to stimulate alternating rows of pixels with high and low (dark) intensities would depend on the spot size of the illumination and how it was modulated during the raster.

Let's cheat a little bit, for fun.
I'm thinking if a visible light laser beam could be focused to about 1 micron, then rastered across the sensor in perfect geometric alignment and modulated such that the beam was ON only while the edge of its spot fringe was entirely located within a given pixel (row) such that no appreciable amount of that light were to enter an adjacent pixel (row), then the resulting contrast ratio would be quite high as there would be no bleed-over to the pixels in the dark row resulting from the fuzzy fringe of the spot.
This would be cheating because it would not be a perfect square wave function but would required a reduced ON time vs the normal 50% ON to 50% OFF of a square wave.

Thus we have applied a pattern of light and dark lines to the sensor synchronized with the sensor's physical pixel layout such that every second pixel is illuminated and alternating ones are dark.
We get 100 lp/mm equivalent signal from the sensor.  Still, we may have slightly less than perfect maximum (MTF) contrast ratio between rows but it's likely to be much higher than the typical 50% MTF standard. 

If we were to instead modulate the light spot (without cheating) so that it was turned ON and OFF as its center crossed the boundary from one (row) of pixel(s) to the next, then that will have an equivalent contrast ratio you could calculate at about 5:1.

Are there any errors in this hypothetical assumption so far?


Step 2:

- we have some lens that is capable of resolving 150 lp/mm at an MTF of 50% as measured on some optical bench...
This same lens should have a better than 50% MTF result if it were resolving a test target at 100 lp/mm.

Any error in step 2?


Step 3:

- we take the lens in step 2 and use it to focus a 100 lp/mm image onto the sensor in Step 1.  (We can use monochrome light if we have to minimize focus errors from CA)
We must now carefully align the focused image to the pixels on the sensor so that the middle of the bright line corresponds to the middle of a pixel (row) with the middle of the dark line aligned to the middle of the next pixel (row).  This should yield the maximum readable contrast ratio from the electronic sensor.
IF the alignment is PERFECT then the contrast ratio should still be a reasonably good number.  As the alignment shifts away from perfect the resulting contrast ratio will drop to a low of 1:1 (2.5 micron shift) for adjacent pixels which means no discernible contrast at all.

Are there any errors in step 3?


Conclusion:

If there were no errors in the 3 steps above then it is possible for a lens and sensor combination to resolve the physical maximum lp/mm of the sensor if the lens has a sufficiently higher resolving power in at least the ideal circumstance described.

Add angular and positional misalignments and mismatches in spatial frequency and you'll get aliasing and all manner of things that throw the above out the window and the math explained in this thread describes the system behavior.

is the conclusion correct within the limitations stipulated?

Your have it somewhat, and some things are slipping through your grasp. ;)

First thing. Yes, it is possible to use a lower contrast ratio than 50%. If you do that, then your results are generally in a different context than lens tests done anywhere else, as testing at MTF 50 is very standard. It's what all the major testers use. It is not invalid to reference a lower contrast level, however there is a diminishing guarantee that any given sensor can actually resolve any differences below a certain contrast level. The human eye is capable of barely detecting contrast at 9%. The human eye has some advantages that sensors do not, however, such as our brains doing real-time superresolution enhancement on everything we observe.

It's "safe" to refer to spatial resolution at MTF 50. It's a well-known context, it's easily comparable with results from other testers, official sites, etc. You can also very easily find LP/MM numbers for primary apertures, and sometimes half or third stops, in tables for MTF 50. You can also usually find the same for MTF 10, although there is no guarantee that a sensor could actually separate detail (real detail, not noise) at that low of a contrast level. (Noise tends to dominate at that low of a contrast level, and things like LPFs may smooth detail out, and conversely the LACK of an LPF may result in even more noise at an even higher contrast level.) MTF30 might be a good contrast level that sensors can still resolve...however there isn't a lot of readily availble information on lens resolving powers at that level. You would have to compute all that yourself (which is certainly possible, but it makes it harder for others to verify your claims.)

Some other things to account for as well.

First, lens aperture. Lens resolving power changes with aperture, as smaller apertures increase the impact of diffraction more. I have found that, based on my own testing as well as tests from official testers like DPR, PZone, etc. that lenses generally top out in resolution somewhere around f/4 to f/5.6. Diffraction-limited spatial resolution at those apertures is somewhere between 123lp/mm and 173lp/mm. There are some few lenses that may resolve more than that at wider apertures...something like the Otus could very well resolve the 247lp/mm diffraction limited resolution of f/2.8...and possibly, in the center of the lens, resolve upwards of 350-400lp/mm at f/2-f/1.4. I haven't actually looked at a real MTF chart to know for sure.

Keep in mind though...those resolutions are ONLY possible at those apertures or WIDER. The moment you stop down more, your maximum diffraction-limited resolution drops. Those are pretty fast apertures. Even f/4 is getting fairly fast. Very few lenses actually exhibit "ideal" behavior at f/4 or faster...optical aberrations generally have some kind of impact, even if it's small. Sometimes the impact of an aberration is simply a loss of contrast...resolving power might be the same, but its now at a lower contrast (i.e. MTF30), which means detail will become increasingly more difficult to differentiate from noise.

Finally, and I make this mistake myself, sensors really don't get their "theoretical maximum" resolution...not unless they are just a bare, monochrome sensor (no filters of an kind). Only a bare mono sensor is really going to be capable of resolving line pairs anywhere close to the size of their pixels. For all other sensors, the use of filters (even just IR/UV filters) will reduce resolution a bit, and the use of a CFA obviously has an impact (although more in color than in luminance, for sure). So, the D800E, with it's 4.9 micron pixels, has a raw mono spatial resolution of about 102lp/mm. It's real-world spatial resolution is going to be diminished, however. I'd say the D800 probably loses some 20-30% or so due to the CFA and filter stack. The D800E has that funky reversed LPF, so it won't lose as much, maybe 15-20%.

Given the existence of the CFA on the D800E, despite the lack of an LPF, there is no way anything could ever actually resolve anywhere remotely close to 36mp, with any lens. It just isn't possible. Hence the reason why DXO's results are so highly suspect. I could believe ~30-31mp, with a very good lens. I have a very hard time believing anything higher than that on average, though...unless it was an absolutely stupendously kick-ass god-quality lens that ACTUALLY resolved some 400lp/mm at f/1.4...and, assuming the results were actually for f/1.4, I think 33mp, maybe 33.5mp, is really the best your going to get...I mean, your WAY up there, really pushing the sensor to its absolute limits.

1159
Trolling all over the Internet.....

http://www.fredmiranda.com/forum/topic/1305527

He just wants someone to approve of his decision to spend lots and lots of money he doesn't have jumping brands. :P

1160
Third Party Manufacturers / Re: Nikon's D800E 30% sharper than D800
« on: July 09, 2014, 02:40:16 PM »
Or to put it differently, that Zeiss lens outresolves the sensor.

There is no such thing as lens outresolves sensor or sensor outresolves lens. That's a misnomer. I've proven that, PBD has proven that, many people have proven that over the years on these forums. Image resolution is the result of a CONVOLUTION, of the lens, sensor, even air, all functioning to assert their impact on what's being resolved. That results in lens resolving power (if it has a higher power), when convolved with sensor resolving power, having an asymptotic relationship with the sensors resolving limit. (Similarly, if it's the other way around, the sensor has an asymptotic relationship with the lenses resolving limit.) There is no "outresolving"...it just doesn't happen.

The math is simple: (1/SQRT(LensSpot^2 + SensorSpot^2))/2. That's how you determine the theoretical optimal resolution of a lens combined with a sensor in line pairs per millimeter. It doesn't matter if the resolving power of the lens is higher than the resolving power of the sensor, it is physically impossible for ANY lens to resolve enough that the output resolution was 100% of the D800's sensor. PHYSICALLY IMPOSSIBLE. To do it, you would REQUIRE a lens with infinite resolving power at an infinite aperture. To even get close, you need MASSIVE resolving power in the lens...resolving power that is only possible if the lens is ideal at apertures like f/1, maybe f/1.2, at MTF50.

Every single lens test should result in an output resolution (measurable resolution actually recorded in the image itself) that is LESS than both the lens and the sensor, and certainly less than the element with the lowest resolving power. For any lens test to "resolve 100% of the sensor", it would literally have to be a "perfect" lens...in every single way, at every single aperture. Just as with the relationship between lens and sensor, our attempts to achieve perfection have an asymptotic relationship with perfection itself...we can never actually attain it.

This is true.

An done interesting thing to note, is that a relative dog lens even in the 8MP days that didn't manage to give a remotely satsifying 8MP image, well put it on a 24MP sensor and of course you gain nothing at all by going to the 24MP with such a dog of a lens that was all blurred at 8MP sensor even right? Nope. You'd likely get noticeably more detail with the dog lens plus 24MP sensor combo than the dog lens plus 8MP sensor combo, again, even though it was clearly not remotely getting much out of the 8MP lens. Now if you go to an utter extreme, it's possible you won't really be able to see any improvement going to the 24MP sensor, but in the current realm of sensor MP differences and typical optical quality spread from best to dogs you are pretty much going to always get more out of the higher MP sensor as even dog lenses aren't quite pure coke bottles. (although I'm sure it's true that there are enough lenses around that are poor enough at FF corners that you might not see any gains out there, what little gain there would be, would be too small to really notice).

Absolutely true! Going from an 8mp to 24mp sensor with a lens that didn't perform well on the 8mp could easily result in SIGNIFICANT gains.

(That said that test chart rounded to the nearest MP (And I'm not sure what the exact D800E count is it might be fractionally above 36MP itself, so if their result was like 35.5 and the camera has 36.4 they might still have tossed a 36MP on that chart even though it was a 100 perfect result, so it may be making a mountain over nothing. Plus don't forget measurement error which could easily be +/-0.5MP and quite possible more).)

This is all very probable. The issue, though, is that DXO just doesn't address these little things. They should be catching these little quirks, and publishing test results that don't make themselves look like fools all the time. At best, maybe the lens resolves "99%", but even that is pushing it, a lot. (I don't even like the whole idea of a lens resolving "x percent" of a sensor, that's just inane, and completely unrealistic.) These are the things that DXO does, again, and again, and again, and AGAIN, AND AGAIN... It's why they are a joke to a significant number of photographers (except anyone in the Nikon camp.) DXO has clearly made some significant mistakes, they miss obvious issues in their published results, and a lot of their process is completely black box. All the while, they claim to be "scientific." It's just a hard pill to swallow. I'll never have any respect for DXO until they become 100% completely transparent about 100% of their process. It wouldn't matter if they score the 7D II or 5D IV with 150 points...I still couldn't trust that their process was accurate.

1161
Dear "J,"

I supposed I should not be surprised that you chose to announce the end of our relationship in such a public and cowardly way. You were never one for subtlety and discretion.

And, so typical of you to blame all the failures on me. As though you contributed nothing to the breakup. But, then, I guess since you contributed so little to the relationship, I should not be surprised.

The truth is, I've known for a long time this wasn't working. If I could have ended things myself, I would have. But as you know, for me this was an arranged marriage. You picked me and I had no say in the matter. For the honor of my family (and honor is something my culture values very highly) I could not leave you.

At first, your clumsy attempts to satisfy me were amusing and not without a certain boyish charm. But, honestly, it quickly became apparent that you were never going to improve. In fact, I soon realized that you actually thought you were good. I know this is hurtful to say, but since you are the one that began this public conversation, I think honesty is justified.

Never once were you able to bring me to my full potential. No, let me be more candid, never, ever did I come remotely close to achieving the heights I was intended for. You would fiddle with my dials and move my joystick, but it was so mechanical and uninspired that I could hardly bear it. Honestly, most of the time I wished you would just stick to the green box and let me do it myself.

And the trips...well, what can I say? Sure, I enjoyed them, but it was as though you thought that simply going someplace new would solve all our problems. All it did was make me long for the relationships that I saw others enjoying. How I wished that could have been us. But you...all you ever did was worry about whether someone else had a newer, prettier model hanging on his shoulder. 

You were so obsessed with showing me off that you didn't see how many of your fellow travelers lovingly treated their lowly Rebels with respect and appreciation and how they were rewarded in ways that you and I could never achieve together.

Yes, I saw the world. But, really, I would have traded it in a instant for a quiet little town in the Midwest, with someone who understood me and what I was meant to do.

Now, dear D810, believe me, I wish you no ill. In fact, I actually feel sorry for you. I know people say you are nothing more than an overinflated mass of silicon, but I know better. We are both from established families and, like me, you have not had any say in this relationship.

I would like to wish you a long and happy relationship, but I suspect that won't be the case. In the end, you will be blamed for everything. Just remember this. It is not you...it's him.

Exquisite. Priceless.

1162
Third Party Manufacturers / Re: Nikon's D800E 30% sharper than D800
« on: July 09, 2014, 12:40:57 PM »
Most definitely. I'd love to see a chart of total resolving power versus dollars. Gotta pay to play.

What I know is you need more than a $2,199 Zeiss to resolve 100% of a 36MP 135 format sensor. DXO just did it again, they threw any "scientific" credibility they had out the window, not that they had much left anyway.

What is the basis for your knowledge here?

My earlier linked law of physics.

You're assuming that the imperfections in the lens are noticable/detectable with that camera.

As has been quite eloquently shown by many DSLRs, lenses for SLRs that were thought perfect in film days are been found lacking in the digital era.

Or to put it differently, that Zeiss lens outresolves the sensor.

There is no such thing as lens outresolves sensor or sensor outresolves lens. That's a misnomer. I've proven that, PBD has proven that, many people have proven that over the years on these forums. Image resolution is the result of a CONVOLUTION, of the lens, sensor, even air, all functioning to assert their impact on what's being resolved. That results in lens resolving power (if it has a higher power), when convolved with sensor resolving power, having an asymptotic relationship with the sensors resolving limit. (Similarly, if it's the other way around, the sensor has an asymptotic relationship with the lenses resolving limit.) There is no "outresolving"...it just doesn't happen.

The math is simple: (1/SQRT(LensSpot^2 + SensorSpot^2))/2. That's how you determine the theoretical optimal resolution of a lens combined with a sensor in line pairs per millimeter. It doesn't matter if the resolving power of the lens is higher than the resolving power of the sensor, it is physically impossible for ANY lens to resolve enough that the output resolution was 100% of the D800's sensor. PHYSICALLY IMPOSSIBLE. To do it, you would REQUIRE a lens with infinite resolving power at an infinite aperture. To even get close, you need MASSIVE resolving power in the lens...resolving power that is only possible if the lens is ideal at apertures like f/1, maybe f/1.2, at MTF50.

Every single lens test should result in an output resolution (measurable resolution actually recorded in the image itself) that is LESS than both the lens and the sensor, and certainly less than the element with the lowest resolving power. For any lens test to "resolve 100% of the sensor", it would literally have to be a "perfect" lens...in every single way, at every single aperture. Just as with the relationship between lens and sensor, our attempts to achieve perfection have an asymptotic relationship with perfection itself...we can never actually attain it.

1163
Third Party Manufacturers / Re: Nikon's D800E 30% sharper than D800
« on: July 09, 2014, 12:28:44 PM »
Most definitely. I'd love to see a chart of total resolving power versus dollars. Gotta pay to play.

What I know is you need more than a $2,199 Zeiss to resolve 100% of a 36MP 135 format sensor. DXO just did it again, they threw any "scientific" credibility they had out the window, not that they had much left anyway.

What is the basis for your knowledge here?

Science. Physics. Reality. You might want to look those up some time and give them a visit!  ::)

Quote
Quote
A result made all the more comical when you look at the $4,000 Otus results on the D800E, down to 33MP, a drop of over 8% for what is regarded as one of the finest photography camera lenses ever made. I think DXO have two teams of testers and the Canon team, who clearly multiply all their results by 0.9, mistakenly did the Nikon Otus when they did the Canon Otus as well. No that's not true, I believe the Canon testers are OK, it is the Nikon test team that multiply all their results by 1.15.

As for not being able to have 99% of perfection or it being a strange way to look at it, I understand that, I was just trying to illustrate that anybody claiming perfect anything is farcical and it isn't as simple as the lens being capable of resolving more than the sensor. Like the >14 stops of DR in a 14 bit file, extrapolate to ridiculous figures all you want (DXO) but if I can't actually realise that shadow lifting capability it is of no practical use.

Totally agree with everything here. DXO has some really wacko shite goin on with their lens tests. They have the weirdest lens test results I've ever seen...anywhere.

But that wacko S___ produces arguably the best RAW conversion results when they feed it into DxO Optics.

Have you ever used anything other than DXOOptics? I spent six months with that program. It is HORRIBLE compared to Lightroom, Photoshop, even RawThearapy (I haven't used DarkTable in a while, but I'd put money on even it being better than DXO). DXOOptics produces some of the worst quality output I've ever seen in a RAW editor, especially with Canon files. So, sorry, but "arguably" doesn't belong in your sentence above...because it is NOT "arguably" the best RAW conversion. It's arguably among the worst. I have several wildlifer friends who use DXOOptics, and after my initial recommendation that they move to Lightroom, which was immediately dismissed, I've not had the heart to tell them their RAW conversion looks terrible. Even to this day, every time I see these photographers photos, I cringe at the blotchy noise or the scratchy detail.

Arguably...hardly!!  :P

1164
Third Party Manufacturers / Re: Nikon's D800E 30% sharper than D800
« on: July 09, 2014, 01:24:58 AM »
Most definitely. I'd love to see a chart of total resolving power versus dollars. Gotta pay to play.

What I know is you need more than a $2,199 Zeiss to resolve 100% of a 36MP 135 format sensor. DXO just did it again, they threw any "scientific" credibility they had out the window, not that they had much left anyway.

A result made all the more comical when you look at the $4,000 Otus results on the D800E, down to 33MP, a drop of over 8% for what is regarded as one of the finest photography camera lenses ever made. I think DXO have two teams of testers and the Canon team, who clearly multiply all their results by 0.9, mistakenly did the Nikon Otus when they did the Canon Otus as well. No that's not true, I believe the Canon testers are OK, it is the Nikon test team that multiply all their results by 1.15.

As for not being able to have 99% of perfection or it being a strange way to look at it, I understand that, I was just trying to illustrate that anybody claiming perfect anything is farcical and it isn't as simple as the lens being capable of resolving more than the sensor. Like the >14 stops of DR in a 14 bit file, extrapolate to ridiculous figures all you want (DXO) but if I can't actually realise that shadow lifting capability it is of no practical use.

Totally agree with everything here. DXO has some really wacko shite goin on with their lens tests. They have the weirdest lens test results I've ever seen...anywhere.

1165
EOS Bodies / Re: EOS 7D Mark II Announcement September 5, 2014?
« on: July 08, 2014, 02:14:20 PM »
jrista has an advanced case of the astrophotography bug. That's an expensive bug to catch, at least if you give it full freedom to grow.  ;D   I would be more worried about catching this bug, but unfortunately I live in an area with less frequent clear skies, lots of light pollution, and I don't function too well on little sleep, so my AP window of opportunity is Fridays and Saturdays.

On the other hand, telescopes keep getting better for less money.

Oh, that is SUCH a TRUE statement! :P I do worry about myself now. If I just "let go", and got everything I wanted, this is the bill:

10Micron GM2000HPS UP: ~$24,000 (with all required options)
PlaneWave 17" CDK Telescope: $22,000
SBIG STX-16803 w/ 7-pos Filter Wheel: $11,590
Astrodon LRGB E-series Gen II 50mm Square: $1,225
Astrodon H-alpha 5nm Narrow Band 50mm Square: $875
Astrodon Oxygen-III 3nm Narrow Band 50mm Square: $1,250
Astrodon Sulfur-II 3nm Narrow Band 50mm Square: $1,250

That's a total bill of: $62,190  :o :o :o :o :o :o :o :o

The big benefit of the 10Micron mounts is they use high end absolute encoding on the axes. They can track with <0.1" accuracy without guiding for up to 20 minutes. They also include sky modeling built right into the mount. This stuff is big and heavy as well, so you really set it up in a personal observatory, perfect and tune it's alignment and sky modeling, then just access it all remotely. You log in from your computer, tell the dome to open, point at whatever you want to image, program an imaging sequence, and then just let it run. Go to bed, wake up in the morning, and you have a bunch of image data to work with. ;)

The cool thing about automated observatories these days...you can automate EVERYTHING. You can even pre-program imaging sequences that automatically "wake up" the observatory, open the dome, point it and the scope at the right location, do the imaging, then park the scope and close down the dome and have everything "sleep" when morning arrives. You can even set up weather monitors and cloud detectors, which will again put everything in sleep mode until the clouds pass, then wake the thing up again so it can get back to work when the sky clears. (You can also wire all this into forecasts online.)

Of course, building a nice, fully automated observatory like this, under really dark skies that have a lot of clear time, is like another sixty grand...so...you know....only the independently wealthy really get to play with "toys" like that. :P

1166
Third Party Manufacturers / Re: Nikon's D800E 30% sharper than D800
« on: July 08, 2014, 01:37:50 PM »
its' impossible to fully realize the full resolving power of a sensor with a high resolution lens, and to get very close, you rapidly run into diminishing returns. You get to the point where doubling your lens resolution gets you a few line pairs closer.

It's an asymptotic relationship...system resolving power is asymptotically related to the resolving power of the lowest common denominator of the system.

Thus the moral of the story is: if your primary goal is to maximize system resolution (and for the majority of people, that's likely not the case, regardless of what one may read on some fringe forums), always upgrade the weakest component.

Yeah, pretty much. Although that can become prohibitively expensive at some point.

The 7D is a good camera, but it doesn't perform terribly well with the telephoto lens it's most often paired with, the 100-400. However if you move up to one of the Canon great white primes, the 7D becomes a stellar performer at ISO settings 1600 and lower, and becomes viable at ISO settings higher than that in the evenings. It's just that you have to spend a LOT of money on those lenses to maximize the potential of the 7D.

On the flip side, if you upgrade the camera itself, to one with a higher resolution sensor (which the 7D II should have), then instead of spending $6000 to $13,000, you spend maybe $2500-3000. It's still a large chunk of change, but not necessarily prohibitively expensive.

1167
Third Party Manufacturers / Re: Nikon's D800E 30% sharper than D800
« on: July 08, 2014, 01:12:25 AM »
The resolving power of an optical system (i.e. a whole camera with lens and sensor) is limited by the resolving power if the least capable component. If that is the sensor, then resolving power of the whole has an asymptotic relationship with the resolution of the sensor.

Thank-you.  I think you've nicely answered my question from the first page of this thread.

Still... there's something about the explanation that seems to be missing for me...  Is there a contrast limit or something in place when making these calculations?
Otherwise it only seems logical that a lens capable of resolving 150 lp/mm (at some contrast ratio) should be able to resolve 100 lp/mm (eg. ~d800e) which is roughly the max resolving power of a sensor, even if it's at some reduced contrast ratio.  :-\

Sorry, I should have stated, those numbers are all for MTF50, or 50% contrast. It is indeed possible to use a lower contrast level, however it's pretty standard to use MTF50 for photography. As we get smaller pixels and AA filters are weakened or dropped, it'll certainly be possible for lenses to meaningfully resolve detail at lower contrast levels, so maybe MTF30 could be used instead. I think by around the Rayleigh limit, contrast is too low for most modern camera sensors to pick up at higher frequencies. The human eye can barely discern contrast at that level, and we have a biological supercomputer processing what our eyes see.

I would actually have to derive all the resolutions for MTF30, I don't have that memorized for key apertures. :P

The D800 has 4.9µm pixels, or 102lp/mm. A 150lp/mm lens, at, what, around f/4.2 or so I guess, has a spot size of 1/(150 * 2), or 2.2µm (To convert from line pairs to spot size, you multiply by two to get lines, and take the reciprocal to get line thickness/spot size). Take the RMS of those two sizes, SQRT(0.0049^2mm + 0.0033^2mm), and you get 0.0059mm (5.9µm). Take the reciprocal of that and divide by two to get line pairs again: (1/0.0059) / 2 = 84.6lp/mm. That's eh, getting there. You can get very close...something like the Otus at a wider aperture probably resolves enough detail to get much closer to the 102lp/mm resolving power of the D800. The point, though, was that getting close-ish isn't too difficult...it's getting very close, i.e. maximizing the potential of a sensor, that actually gets REALLY tough...in fact, its' impossible to fully realize the full resolving power of a sensor with a high resolution lens, and to get very close, you rapidly run into diminishing returns. You get to the point where doubling your lens resolution gets you a few line pairs closer.

It's an asymptotic relationship...system resolving power is asymptotically related to the resolving power of the lowest common denominator of the system. For diffraction limited (or close to it) lenses at fast apertures, that's usually the sensor. For diffraction limited lenses at narrower apertures, that's usually the lens.

1168
EOS Bodies / Re: Eos7D mk2, How EXCITED will you be if . . .?
« on: July 07, 2014, 06:12:04 PM »
I bought the 7D when it was first released and I had two impressions....One: I LOVED the ergonomics and control layout over the 5D2.  Two: I was majorly disappointed in the quality of the files out of the camera....just too mushy for my taste.

Agreed. Especially the bold part.  The 7D had the worst IQ of any Canon product I have used.  It was especially weak in crepuscular light, which is where most big-game wildlife shooting occurs.   

Aye, low light is definitely the 7D's weak point. I had a real tough time with the 7D and the 100-400mm lens, things beyond ISO 1600 were unusable, and 1600 itself was borderline. I will say, however, that with the EF 600mm f/4 II lens, the 7D is a remarkable performer, even in lower light. I've taken some amazing shots in extremely low light with the 7D and 600/4, such as this:



7D, 600/4, ISO 3200. Taken well after sunset, as blue hour was starting. With enough light and proper technique, even the "muddy" 7D could be made to perform quite well.


I'll be staying away from anything with the 7D name, no matter the amount of enticing gadgets. I found the 70D to be a far superior camera.

The past IQ of the original 7D doesn't mean the 7D II will have the same problems. For Canon to succeed with the 7D line, the 7D II MUST have better IQ and overall performance than the 70D. It would just be a flop if it did not. If the 7D II does end up being a superior performer to the 70D...would you still adhere to the above statement? (Just curious...personally I find it odd when one single bad experience with one single product permanently taints a person's opinion of something...to me, every product generation is a chance for a new start, a chance for a company to reinvent itself, reinvigorate itself, or if necessary redeem itself (not that Canon needs redeeming, but they do need some reinvigoration in some areas.))

1169
EOS Bodies / Re: Eos7D mk2, How EXCITED will you be if . . .?
« on: July 07, 2014, 03:49:58 PM »
  • I'd have mixed feelings, but overall positive if Canon 'bit the bullet' and "swallowed their pride" and used a Sony sensor with 24 mpx with high DR of 14 stops. That might bode well for Canon using a similar sensor to the Nikon 810 / A7r in an upcoming full-frame.

Not gonna happen, as Canon prides themselves too much on their "in house, fully integrated" approach.

  • Native MagicLantern-like Dual-ISO for much greater DR

You want both a Sony Exmor sensor...and ML Dual ISO? How much DR do you want? :P Unless Canon is moving to a 16-bit ADC, which if they used an Exmor is impossible (since Exmor includes the ADC), then having both is moot. You can only get 14 stops of DR out of a camera with a 14-bit ADC.

If Canon natively improves their own sensors DR, which is more than possible, it isn't like Sony has an exclusive right on high dynamic range sensor technology, then having ML Dual ISO is again moot. If Canon tops 13 stops of DR, they would be comparable to the D800/600/810, which all get around 13.2-13.3 stops (as far as editing latitude/shadow lifting goes). Adding ML Dual ISO to that wouldn't really offer any benefit...as to achieve that kind of DR in the first place, ISO 100 would have to have as low read noise as ISO 800 anyway.[/list]

1170
Macro / Re: Flower macros
« on: July 07, 2014, 03:41:39 PM »
DPC, you really have an eye for this stuff! Amazing images!

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