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Old February 4th, 2016, 07:15 PM   #1
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MFT lenses -- 3840x2160 or an upscale to 3840x2160?

I'm finishing Part 1 of my LS300 review and after weeks of calculations and recalculations it looks like if you record at UHD and set VSM to 80%(MFT) the capture window size is too small to have 3840x2160 pixels. On the other hand, if you select 89%, the capture window will have more than 3840x2160 pixels.

However, JVC's documentation warns that if you "exceed" 80%(MFT) "... the MFT lens may not perform optimally." I didn't see any problem with VSM set to 89%. Moreover, I can't think of what would cause a problem by using 89%. It seems odd the LS300 has a great VSM setup tool but if you use it with MFT lenses JVC say's you will have a problem! Worse, they don't say what the problem will be.

All other VSM values check-out perfectly, so I can no longer avoid following the math.

Current text reads:

"An alternate way to obtain a VSM setting is to use the LS300’s VSM setup tool to guide you to the correct VSM setting. After attaching an Olympus MFT zoom lens I toggled through the VSM settings. A VSM setting of 89% showed no vignetting. Others have also reported setting VSM to 89%, or even higher. With VSM set to 89%, the capture window has a resolution of approximately 8.9 Megabytes which supports both C4K and UHD."

"If JVC is recommending selecting 80%(MFT) when the camera is set to UHD, then VSM must upscale an 3316x1865-pixel capture of a 17.3 x 9.7mm MFT 16:9 video image to 3840x2160. (MFT lenses project a 17.3 x 13.0mm 4:3 image, however, when used to shoot 16:9 video, only 9.7mm of the sensor’s 13.0mm height is used.) After months with no response from JVC, I returned to using a VSM setting of 89%."

Comments from those using 80%(MFT) or 89% needed.
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Old February 5th, 2016, 12:25 PM   #2
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Re: MFT lenses -- 3840x2160 or an upscale to 3840x2160?

Yeah, Steve. I haven't shot a lot of 4K with MFT lenses, mostly with Rokinon primes. But when I have, I've always set the VSM at 89%. I can see how you might want to set it at 80% to mimic the response of another MFT camera... but that would be a rare situation.

I've shot tests with the Olympus 12-40 f2.8 in 4K and at 89% there is zero noticeable vignetting at 12mm. There may be a slight darkening in the extreme corners, but as I've said before, that's really only noticeable in stills.
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Old February 5th, 2016, 01:27 PM   #3
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Re: MFT lenses -- 3840x2160 or an upscale to 3840x2160?

You might be right about the 80%(MFT) setting. The engineers may have determined that at this setting an MFT lens will have the "expected" field of view for MFT lenses.

I've been wondering how it is that MFT lenses project such a "large" image? Do MFT lenses have a larger than we expect optical circle? If this is true then details will be the same size as when taking a photo. Only the LS300 has the ability to capture this bigger image.

Or, is mount to sensor distance longer so the projected image is larger. This would mean 89% is a match to the bigger image. If this is the case, then why the 80%(MFT) setting?

Do you have an MFT still camera? If you do you could do a quick check on the field of view.

That still leaves the warning. It must be important enough to have caused JVC to insert it into the manual. The word "optimum" may be the key. If MFT lenses project a "larger" image than we expect, it's possible/likely MFT lenses are not designed to offer maximum optical quality except in the central (normal) part of the optical circle. Thus while selecting 89% provides 3840x2160 resolution edge detail may be quality may be lower so JVC feels it is not a good trade-off.
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Old February 5th, 2016, 06:33 PM   #4
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Re: MFT lenses -- 3840x2160 or an upscale to 3840x2160?

Well, for about the tenth time I tried to attach a frame grab without success - I've never had a problem on any other site...

Anyway, it is the test I shot in 1080 with the 12-40 Olympus at 12mm and the VSM set at 92%, and it's sharp as I ever need. But you''ll have to take my word for it...
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Old February 7th, 2016, 05:41 PM   #5
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Re: MFT lenses -- 3840x2160 or an upscale to 3840x2160?

I found a review on a German site and they comment it's typical for MFT lenses to have a very large optical circle -- so not surprising we can use 89% or 92%.

So what's JVC's beef with going higher than 80%?

I've decided the best choice is 86% which is exactly 3840x2160 -- no scaling is used.

The camera really is amazing. It's features seem endless. Part 1 of my review is over 2200 words. But it must go out tonight. Then I can start Part 2.

JVC in one interview says the LS300 is the FIRST S35 camera. The $1000 reduction may be to clear inventory ahead of NAB.
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Old February 8th, 2016, 02:33 AM   #6
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Re: MFT lenses -- 3840x2160 or an upscale to 3840x2160?

I have noticed at my last wedding that the 12-35mm f2.8 panasonic lens vignettes at 12mm when I set vsm to 80% (mft)
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Old February 8th, 2016, 03:51 PM   #7
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Re: MFT lenses -- 3840x2160 or an upscale to 3840x2160?

I had a 12-35 and it vignetted slightly (darker corners, not black) on the AF100 too... The Olympus 12-40 doesn't... neither does the Zuiko 35-100. The 12-40 can just get away with 92% - if you're not too fussy - and the 35-100 is best at 89%. Some have said the the image is softer at 89% than at 80% though, but I'm not seeing it on real world clips - I haven't tried charts.
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Old February 9th, 2016, 08:34 AM   #8
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Re: MFT lenses -- 3840x2160 or an upscale to 3840x2160?

Quote:
Originally Posted by Steve Mullen View Post
The $1000 reduction may be to clear inventory ahead of NAB.
To paraphrase Mark Twain, "the reports of the GY-LS300 going away has been greatly exaggerated."

JVC continues to work on the improvement of the GY-LS300, as is evident with the announcements of the firmware updates, some of which are released enthusiastically by our product team. We are working on getting the notifications out to our user base in a more timely and direct manner.

Thank you all for your ongoing support!

Cordially,

-Craig
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Old February 9th, 2016, 09:03 AM   #9
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Re: MFT lenses -- 3840x2160 or an upscale to 3840x2160?

Well, anything better then what Sony did with their nex-ea50, bring out one firmware update with useless features and then just let the model die.

It's not that I am expecting anything but it doesn't hurt to ask again; last wedding I shot with a fixed f-stop (f2.8) all the time because I wanted that shallower dof throughout my entire recording.

Since the shutter should remain at a fixed value as well the only way to control your exposure is by adjusting the ISO on the fly and this is impossible to do with only 3 fixed iso values using the gain switch on the side of the camera.

In the menu, under "camerafunction" and "iris dial" you can assign following values to the dial on the camera: "iris", "shutter", "ae level" and "iris/shutter/ae level", if only JVC could add ISO to those options as well that would be a life saver.

My sony rx10 does this with the scrollwheel on the back which makes it so much easier to lock your f-stop and control your exposure, I"m surprised not more people are asking for this.
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Old February 9th, 2016, 10:37 AM   #10
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Re: MFT lenses -- 3840x2160 or an upscale to 3840x2160?

Careful with the promises Craig, you don't want the endless threads requesting impossible firmware updates that have plagued the Black magic forum and the old AF100 one.. I never type LOL, but you get the idea...

In my opinion the LS300 is the best camera I've ever used (and that says something when you consider I graduated from UCLA's film division in 1967)... it has it's weaknesses, but in general it's strengths far outweigh them... Starting with little things, like the deeper groove in the front of the top handle that makes it easier to carry - through to big things like the (now) remote controllable VSM and the MFT mount that should have sucked every former AF100 owner to JVC.

I would post a picture of how my camera is set up for handholding with the side-mounted Gratical and the zoom.start/stop control mounted under it, and my old Aaton grip on the starboard side - but I've never been able to upload pix on this site. Suffice it to say that it's very pleasant to work long hours with because of it's basic light weight and design.

I may buy a second one during the sale... tempting, but maybe I should wait for the improved 10 bit version? (sorry, couldn't help it)
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Old February 9th, 2016, 11:27 AM   #11
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Re: MFT lenses -- 3840x2160 or an upscale to 3840x2160?

Quote:
Careful with the promises Craig, you don't want the endless threads requesting impossible firmware updates that have plagued the Black magic forum and the old AF100 one..
Nice, so you have got what you asked for and now everyone else should stop asking? :) Eventhough I don't expect anything, it's good to see a manufacturer that is committed to improve it's product.
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Old February 9th, 2016, 12:55 PM   #12
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Re: MFT lenses -- 3840x2160 or an upscale to 3840x2160?

Oh. I want more, everyone always does... Thus the 10 bit reference... This camera would really jump ahead if it had more depth...

Understand that I'm not dissatisfied with how it handles 8 bit - until I do a long fade to black, or add a vignetting filter (which I often do for TV spots). Then banding starts to rear it's ugly head (as it does on any 8 bit camera - most, like that ol' AF100, are much worse).

I've tried (as I mentioned several months back) shooting 4K and there seems to be an improvement when it's down-converted, but there are still occasional branding issues.

This isn't a deal killer for me though, because I work around it and the images it produces are are terrific.
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Old February 11th, 2016, 06:12 PM   #13
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Re: MFT lenses -- 3840x2160 or an upscale to 3840x2160?

Quote:
Originally Posted by Steve Rosen View Post
Careful with the promises Craig, you don't want the endless threads requesting impossible firmware updates that have plagued the Black magic forum and the old AF100 one.. I never type LOL, but you get the idea...
There's a great deal of truth there, but I strive to be sensitive to both sides, our customers and our product team with no intent of making unattainable promises. We're all hard working professionals trying to bring the best product possible with what is provided to us. The LS300 was first and foremost born from the feedback we received from the marketplace. Otherwise, it would not have come to being.

When pieces come together, amazing things happen, and such is the case of JVC Log and Prime Zoom. We will continue to work on and with the LS300 to the best of its abilities. For features beyond, we will look to future concepts.

- Craig
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Old February 13th, 2016, 05:28 PM   #14
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Re: MFT lenses -- 3840x2160 or an upscale to 3840x2160?

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Originally Posted by Steve Rosen View Post
The 12-40 can just get away with 92% - if you're not too fussy - and the 35-100 is best at 89%. Some have said the the image is softer at 89% than at 80% though, but I'm not seeing it on real world clips - I haven't tried charts.
If you are shooting UHD there is no quality advantage to a setting other than 86%(4K). VSM will define a capture window that has 3840x2160 photosites. At this setting all photosites within the capture window are transferred into the camera.

When you use a setting higher than 86% you are simply capturing a wider segment of the image on the sensor. So 12mm becomes more like 10mm. But unless you need a wider angle-of-view you should NOT use a higher setting than 86%. I'm telling you this and so is JVC.

The reason is simple -- no matter how good a scaling engine is -- and JVC and Sony have some great technology -- interpolating an image from another one cause a degradation in image quality. Sure at 89% a few more photosites are captured -- but they must be squeezed down to UHD!

Why would anyone choose to this?

Were the sensor to offer a 7680x4320 capture window -- then there would be an advantage because it would provide 2X sampling. That would mean a chip with 33Mpixels.
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Old February 13th, 2016, 06:43 PM   #15
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Re: MFT lenses -- 3840x2160 or an upscale to 3840x2160?

Interesting, and I basically see this in practical shooting. However, when I do want the equivalent of 10mm it is available, and only the most dedicated pixel peepers are ever going to see it.

Using a very sharp 12mm, like the Olympus (it is surprisingly sharp) at 92% can work in a pinch, and is preferable to either having to change lenses, or using a possibly less sharp 10mm. The big downside is barrel distortion. It's pretty bad, but there are some that actually like it (those old 60s rock and roll films I shot in 35 with a horrible fisheye attest to this)..

Now that the VSM is controllable from the remote I can make my choice on the fly - although it is admittedly difficult to stop exactly where I want.

I moved my PS to another post below

Last edited by Steve Rosen; February 13th, 2016 at 06:59 PM. Reason: post script
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