34 replies to this topic

[Bruno]

Hey mark- a chart test is pretty straightforward, right? Align and focus correctly, shoot.

 

It is very straight forward, but many other factors can influence resolution/sharpness. The lens used is a big factor.

It would be a straightforward test if all the cameras were done at the same time with the same chart and preferably the same lens (sharpest possible).

[markm]

Hey mark- a chart test is pretty straightforward, right? Align and focus correctly, shoot. Other than having the chart too close, errors in set up result in reduced measured resolution. In my day job I work with cameras, pixels, and math. For example, we could do an automated FFT/DCT for a groups of photographed(video) lines at various resolutions and look at the frequency bins to get an empirical measurement. For such a test, we'd want to clean up via sharpening the source frames to remove as much low-frequency information as possible (improving accutance (a form of microcontrast) as much as possible). I suspect the slashcam.de test did something similar and didn't post-sharpen the 5D3 footage, resulting in an abnormally low high-frequency measurement.

 

The charts I found looked pretty solid. Which one(s) do you feel weren't done by the book?

The problem is what you print on Your printer resolution as well as probably ink density. I guess it doesn't matter that much of you're testing all cameras with your methods The problems arise when comparing to someone else who has used a different method. There has to be standards. 

 

http://www.aig-imagi...ical-Test-Chart

[jcs]

bruno & mark - good points, in a perfect world, however no test is ever perfect. Again, worst case the measured resolution will less than actual, so we know which way the trend can go. Looking at the lines of the ISO12233 chart, it's easy to see when aliasing starts whereas extinction of detail is less clear. In the case of the 5D3, I did a very crude estimate with the ISO12233 chart, and estimated 800+ lines (using a scaled still as a reference), whereas Jason's chart was full sized and shows at least 810 lines (which matches the 1620 bitmap frame reported by the ML team). I didn't see any clear problems with the other charts. Did you? Are there test results which contradict the ones in this thread (if so- link?)?

[markm]

Hi Jcs

 

Buy some proper tests charts! I'm sure you will excel in this area and become EOSHD's resident technical resolution expert.

 

The only problem then is access to cameras.

[hmcindie]

jcs: People don't frame 100% the same. That immediately throws out some comparisons. They don't use the same lenses. That throws out even more. Or the same settings. Not to mention the printer resolution problem.

 

Also you can't just "estimate" that stuff like the 1DX is somehow sharper than the 5dmarkIII. I don't think it is. Does your thinking outweigh my thinking? That's why it has to be measured, to get rid of placebo and the human brain which is foolhardy. Some guys on the DVXuser forum think that the 5dmarkII is sharper than the 5dmarkIII which is just because the III lacks aliasing. That aliasing does increase "apparent" sharpness, same thing that is going on with the 1dx.

 

If you are going to do a proper resolution chart, do it properly. 

 

Alan Roberts from BBC rates the AF-100 at about 680/pvi

 

""Resolution is clean up to 63% of 1920x1080, where there are low-level null zones visible.  This 

means that the image has clean resolution only up to 1210x680, which is not good, given the 

strength of the aliasesResolution is clean up to 63% of 1920x1080, where there are low-level null zones visible.  This 

means that the image has clean resolution only up to 1210x680, which is not good, given the 

strength of the aliases."

 

http://thebrownings....sonic_AF101.pdf

 

http://provideocoali...n_the_charts/P2

[jgharding]

I remember having a funny debate with someone about 550D vs 7D. He just couldn't accept that there was no difference in video quality, and that in fact the 550D was better due to having Magic Lantern hacks. Actually refused to acknowledge the higher bitrate when put in front of him. Much as when one tries to argue with a religious fanatic, it was pointless.

 

The ideas were fixed and things like reason or actually seeing evidence didn't come into it.

 

It was a sign of someone being completely blinded by the religion of capitalism! More expensive must  be better right? :/

 

On the other side, as nice as resolution comparisons are though, it's the codec implementations that make more difference at the low end. Really different aesthetic feels from each company i think.

 

Alexa, for example, has lower stats than Red Epic, but I do prefer the footage on the whole. Though I hated how it looked in Skyfall, it was beautifull in The Hunt and Drive.

[jcs]

mark- lol, wish I had the free time! I'm happy to have kicked this off, hopefully the community can take over and contribute to making it more accurate and complete.

 

hmcindie- thanks for the provideocoalition link- found FS700 charts: http://provideocoali..._the_nex-fs700/

 

http://provideocoali...hd_camcorder/P3 : he states 800 TVl/ph (horizontal resolution) and 1000+ vertical resolution.

 

Another chart: http://provideocoali...he_nex-fs700/P2 .

 

From both charts, it appears the FS700 has more vertical than horizontal sampling resolution.

 

Since the straight line chart (vs. curved/trumpets) had better results, it would appear the de-Bayering and image processing may have something to do with the behavior. Note in the trumpet chart near the numbers, resolution is highest- extending past 1000 lines.

 

Thus, it would be helpful to have both charts available when testing resolution.

 

jgharding- I understand what you mean. I have an FS700 and it's hard to believe the strange trumpet chart results, but there they are. The FS700 does OK in the straight line charts, and it looks much better than the 5D3 for real imagery, so I'm happy with the upgrade. The secret to the ARRI is their color science- they've got highlight falloff and skin tone control nailed- that's why it's used so much in Hollywood.

 

Thanks for the links guys- found this which is helpful in better understanding the FS700 camera picture profiles: http://provideocoali...hd_camcorder/P2

[jcs]

FS100:

 

GH2:

 

From these charts, the FS100 has higher peak resolution but the GH2 has more area under the curve and thus better overall accutance.

 

5D2:

 

5D3:

 

Similarly, the 5D3 has more contrast at higher frequencies (peak resolution), however it has lower area under the curve. Thus the 5D2 has better overall accutance straight from the camera.

 

Sharpened 5D3 footage looks more detailed than 5D2 footage (which can't be sharpened much). Thus, overall peak accutance depends on how much the image can be sharpened in post. Sharpening increases microcontrast (but not peak sampled resolution) and will thus affect these types of tests.

 

In summary, the FS100 provides higher peak resolution, and the GH2 provides better accutance.

Out of the camera, the 5D2 provides better accutance and after post sharpening the 5D3 provides similar accutance and higher peak resolution. It might be possible to post-sharpen FS100 footage to bring accutance up to GH2 levels.

[milandirector]

What about 6D?

[gravitatemediagroup]

digital bolex not listed?

[gravitatemediagroup]

What about 6D?

6d is gonna be in the same area as mkII and mkIII

[jcs]

re: 6D & bolex please post numbers & links and I will update list.

 

GH2 & GH2 trumpet chart, both rated by reviewer as 700 lines before significant aliasing (looks like detail holds up well past 1000 though)

http://provideocoali...video_camera/P2

[jcs]

Updated top post for recent discoveries with FS100/FS700 and C100/C300.

[jcs]

http://reduser.net/f...-EPIC-and-Alexa

 

Here we have a comparison of a 5K RED sensor compared to a 3.5K ARRI sensor. At first glance one might think the RED is sharper and more detailed, and is thus better. The RED sensor is indeed sharper and more detailed: 5K pixels can sample 2.5K resolution before aliasing. The 3.5K ARRI sensor stops producing contrast changes (resolution) right where we'd expect from Nyquist- right around 3.5/2 = 1.8K. After that, the ARRI goes flat, producing almost no detail. If we look at the ring charts, we see zero aliasing for the ARRI, and lots of aliasing with the RED.

 

Thus, ARRI does an excellent job of cutting off frequencies above the sampling resolution of their sensor- this is very important to eliminate aliasing and moire. Their sensor is pretty trick as well (16-bit HDR): http://www.arri.com/...xas_sensor.html

 

Which is better in practice? For moving images, aliasing is a major give-away for a digital vs. film experience. When cost is no object, it appears ARRI is used the most. It's also the most expensive camera in this list, despite not providing the highest sampling resolution.

[jcs]

Dropped the F55, F5, and FS700 "4K" down to 2.xK estimated based on sensor photosite count and Nyquist (resolution before aliasing).

 

8.9M photosites means 3978x2237 photosites*, or max pixel resolution before aliasing of 1989x1118.

 

While the F65 comes closest to 4K, it's still not there: http://www.dvxuser.c...r-pattern/page8

 

*Computed using Wolfram Alpha: http://www.wolframal...(8.9*1000*1000)