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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Leica Lens Resolution test...

5K sine zone plate. Trumpet charts are traditional, but are very hard to measure resolution with accurately and don't allow you to plot MTF.

Graeme
 
Thanks Graeme.
Now we have just to find a 5K sine zone plate to work with Imatest.
 
Jannard said:
Don't just read this post. Come to RED Studios and ask to see the 700 reel. Everyone is welcome. See for yourself why Ridley Scott choose RED. He sat in Stage 4 and saw for himself. So can you.

Jim
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Jim. Jim. Jim. This is why you are my idol. I will happily see you next week. Said it before, but it's worth repeating: RED is the end of the line for me. Thanks for the invitation.
 
Graeme, it's thoughtful posts like this that make all the noise on this forum worth it.

Thank you for helping us sell your magic :)
 
Should we expect more lens to be tested in the future? Im curious how Canon EOS L glass fairs on the 1-10 scale? I would hope its above 7 but considering the price difference I would not be surprised if it was between 5-7 on your scale. Thanks for the heads up on the Leica's, very good news.
 
Graeme (or anyother left brain type who knows how to talk to right brainers), I'm still not quite ready to give you a gold star yet. First, what does "MTF" stand for and why do we care? Next, I follow your line about the swing of the lines, but what about the distance between the verticle lines? Red is much closer (or is that an illusion?). Is that because they are being measured differently, a change in axis (I can't read mine too well), or what? The red line shown as "alasing" means what? That Alasing starts here and throughout the rest of the chart or at this point only? If at this point only, so what is the significance? What's the signifance of the large fall off on the Red at the end? No such fall off on the other charts. Does the bottom axis say "distance"? If so, distance from what to where?
 
Pulling an all-nighter Monday night (2 Epic Ms shoot!), but I'm going to drag myself out of bed to come down on Tuesday... See ya'all there!
 
James Brundige said:
Let's see this test with a Nikkor 35 mm G (no need to put it on the Alexa, because the pathetic resolution says nothing about a good lens.)

It would be interesting to see how close it would be, optically speaking.
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+1. (for the 50mm 1.4 G)
 
Today we did some resolution testing (with adult supervision) to see how well the new Leica lenses perform for an upcoming feature. Of course the Alexa was included in the tests as required by law.

The Leica lenses perform better than any lens we have tested to date... beating the Master Primes and RED Pro Primes by just a bit.

Jim
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Super impressive, I can't wait to have mine. This is the camera of my dreams.
 
I just love that test chart!!!!




Jannard said:
Today we did some resolution testing (with adult supervision) to see how well the new Leica lenses perform for an upcoming feature. Of course the Alexa was included in the tests as required by law.

The Leica lenses perform better than any lens we have tested to date... beating the Master Primes and RED Pro Primes by just a bit.

Jim

1304136624.jpg
Click to expand...
 
The good news about these charts is that they translate directly to images. You can see this clearly on the big screen... as we will demonstrate on Tuesday.

Jim
 
Even the aliasing looks cleaner on the Red chart. At the point that Alexa loses it the Red is still equal or better than most of the Alexa range.

No wonder you want to show it off.
 
I'm just puzzled by these charts. It looks like they show a totally non linear sensor response. Sensor should have a linear response until it reaches the resolution limit and than it cuts off.
If that's the case the plot for alexa should be about the same latitude as the Epic and then cut off at the res limit. Epic would just continue. Here it looks like the sensor (MTF) response drops gradually in non linear manner and it drops to almost zero as the limit is reached. I know it true for lenses but sensor "doesn't know" what resolution hits it and responds the same until the resolution approaches the pixel pitch (aliasing)and then it can't "see" anymore.
I may be misunderstanding this plot....
 
You are not misunderstanding the plot, only physics.
You are not looking at something digital, this is an optical system with physical lenses and an analog sensor. In the ideal camera, which Graeme mentioned, but which doesn't exist, you would be right. In reality, we have this gentle and not even completely regular falloff into noise (not even zero). What you imagine is a theoretical idealization.

Even the lens alone would produce such a plot, but the OLPF is shaping it further.
 
You can forget lenses- they used the same lens. we are only looking at the sensor response here. S/n ratio for sensors depends on saturation(fill) factor(amount of light that hits it)- not resolution as they are ultimately digital. Alexa is also known for decent dynamic range so the gradual drop is even more puzzling...
 
understanding lens resolution testing

understanding lens resolution testing

If I understand the test that is shown here, you can't forget about the lens, or OLPF filter, or the sensor, or the original chart for that matter. The graph shows a response which is the product of all of those things (and perhaps more besides, if anything in the post-sensor electronics affects spatial frequency response.)

Note also, if you had a theoretical perfect "brick wall" frequency response of 100% up to the frequency limit, it would be a really bad camera for normal imaging (awful moire patterns on fine detail). As far as I know, the graph you see is the general thing you want for "natural" appearing images.

I should add, I really don't know any details of their test- what exactly is measured on the vertical axis, and is it linear, log, or some other scaling law.
 
The OPLF filter seems consistent throughout both the ranges. One is geared to a different range than the other.

The proof in the pudding is how the image looks. The edges mean less than the meat in the middle. What's the S/N ratio?
 
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Again- forget the lens- if it performs better on another camera(Epic) it means it 's not a limiting factor for Alexa.
OLFP is more secretive but a whole point of OLFP is that it cuts off selective frequencies(or is it?). Otherwise you could just put a diffuser there... If that's the OLFP response OMG- that's bad...by the time you get to 1K lines the DR drops to 1/3 value...that's like 20 lp/mm....
Also forget the chart, lighting, MTF plotter, etc. the only thing that changed was the camera.

Signal to noise ratio?
 
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