Z1U, Chromatic Aberration, Zoom, and Teleconverter

[William Gardner]

Hi Everybody,

I thought I'd share some experimental results from a quick test I did.

I have a Z1 and recently purchased the Canon 1.6x teleconverter w/ step down rings to attach it to the Z1, as described in previous threads on this site. I got the teleconverter on Ebay for $20. It is far from mint condition, but it isn't totally awful either.

I've got 5 high quality JPEG frame grabs to compare, all taken of a poorly printed res chart on a music stand. :) They're all 1440x1080 grabs, so the aspect ratio isn't correct, but for these purposes they'll do. They were all taken with default PP1 settings, F4, no gain or ND.

First,
http://dsp.ucsd.edu/~wgardner/ZT50.jpg
was taken with the Zoom at the mid setting (50 on digital range from 0-99), with only the standard Z1 lens.

http://dsp.ucsd.edu/~wgardner/ZT99.jpg
was taken with the Zoom at the highest setting (99 on digital range from 0-99), with only the standard Z1 lens (physically farther back so that the framing was similar to the first image). It's not bad, but there is noticeable chromatic aberration at the edges with a green interior and magenta exterior on black items on the res chart.

http://dsp.ucsd.edu/~wgardner/ZT99wC1.6x.jpg
was taken with the Zoom at the high setting (99 on digital range from 0-99), and with the Canon 1.6x teleconverter (even farther back). There's a slight color shift. The resolution in the center looks pretty close to the first two images. However, the resolution at the edges becomes noticeably worse. The "4:3" in the upper left corner of the chart is much blurrier. There seems to be more chromatic aberration, but then it's tough to tell if this is just a blurrier version of the CA from the stock lens.

http://dsp.ucsd.edu/~wgardner/ZT90wC1.6x.jpg
was taken with the Zoom at 90 and the Canon lens on, and
http://dsp.ucsd.edu/~wgardner/ZT80wC1.6x.jpg
was taken with the Zoom at 80 and the Canon lens on. You can clearly see the vignetting effect at these settings.

Check them out for yourselves and make your own conclusions. However, my conclusions are:
1. There is mildly annoying CA in the stock Sony lens when zoomed near the max setting (though much of this can be removed with radial CA correction software, such as what I posted on this site earlier in the week).
2. The Canon 1.6x teleconverter keeps the high res of the Z1 at the center of the image, but noticeably degrades the resolution near the edges. This might be fine for some applications, but not others.
3. The Canon 1.6x teleconverter is only useable without vignetting when zoomed in almost to the max.

So, if you can tolerate items #2 and #3, then the Canon teleconverter at $20-30 is a real option to the Century converters at much higher prices. But if you can't tolerate #2 and #3, then you shouldn't bother with the Canon option.

Cheers,
Bill

[Kenn Baynard]

A very interesting and informative read. We purchased a Z1U late last year, and have been struggling with, as my boss would say "It's not sharp!", when comparing it to our obviously more expensive, more professional camera, the Ikegami HL-45 with a DVCAM deck. At first I shot video in HDV, but between the down-conversion process and the lack of apparent sharpness, we've since put the camera in DVCAM mode, which has helped a little bit, but in the end it's still not as crisp and clean as our HL-45 (and completely defeats the purpose of buying a HD camera...) I tried telling him a few days ago that he's trying to compare a $6000 camera to something that probably cost around $25k, and our HL-45 has a considerably better lense on it. My conclusions so far is that the camera itself is fine, but it's the lens that's causing our problems, and there's not a darn thing we can do about it. I've tweaked and tried almost every setting in the PP menu, including jacking the sharpness all the way up, and we're still not having much luck. What it's really coming down to is my boss was expecting great things to happen with a prosumer camera, and now he has to face the cold harsh reality that it's not going to out perform the HL-45, which takes an amazing picture.

If he had listened to me in the first place, we would've tried both the Z1U and the JVC HD100 before we decided to buy. But he bought into all the marketing hype that Sony was spewing about the Z1U, and got all excited over a bunch of bells & whistle we'll never use, and he also jumped on the "1080i is a bigger number, it must be better!' bandwagon. My comment on that is "would you rather down convert a lot, or a little to get it to SD?" We can't even edit in HD anyways, so buying a HD camera was kinda silly.. But hey, I just work here. :)

Don't get me wrong, I like the Z1U, it's a slick little camera. But at least once a week I hear "man we gotta get that camera looking sharp", and I've banged my head against the wall long enough.

Sorry if this is coming off a little ranty, I'm venting a little. :)

Back to my point, I have heard before and seen stills of CA resulting from the stock lens that comes on the FX1/Z1U, and I really wish Sony would've taken the JVC route and made the lens replaceable. All of this aside though, has anyone had any similar results of lack-of-sharpness, and if so, what you've done to correct it? After seeing the images above, I'm beginning to understand that some of our problems may lie in how far in we're zoomed when shooting.

[Boyd Ostroff]

I haven't used that Ike, but have been really pleased with my Z1 shooting in HDV and using the in-camera downconversion. I'm just editing a performance right now, and especially in the wide shots I see more sharpness where my VX-2000 and PDX-10 tended to fall apart.

But the 1/3" CCD's are going to have their limits I'm sure. And since the lens and sensors are the same as the FX1, it's really more like comparing your Ike to a $3,000 camera. But I've seen multiple threads here where people felt the Z1 held up very well against bigger cameras; here's one:

http://www.dvinfo.net/conf/showthread.php?t=54329

Originally Posted by John M. McCloskey

Where I work we have at least 12 of the Z1's and have been using them for about 10 months now. Going from the DSR 390's to the Z1's has been a big change especially in picture quality and easy transporting.

Originally Posted by John M. McCloskey

Bill, The Z1 on a nice day with an F-Stop of 5.6 or so with ND1 on put beside our old 390 there is no doubt the Z1 smokes the 390 in all around picture quality and capabilities to readily adjust the picture in many ways without pulling out the 390's 200 page manual. The Z1 at a 2.8 plus 9 gain is ok but the 390 in the same light would be around a 4.0 or better with 0 gain, in other words the Z1 awsome with good light and the DSR awsome with low light. I sure hope they make some changes in the next few years in the low light capabilities and the zoom range without a screwon vingyetting doubler. But all in all the Z1's will see way more daylight than our boxed up 390's I feel its that much better and although we master in SD we have a huge library of HDV now and it is better than SD, just keeping up with the changes. Thanks

And this: http://www.dvinfo.net/conf/showthread.php?t=38896

Originally Posted by John Poore

In short, in my opinion, the FX1 is a worthy successor to the VX2000. In comparison to the afore mentioned machine the FX1 has a much stronger (or fuller) colour balance in that the colours are deeper, the blacks look black and so on. As some have mentioned here it's a bit closer to the DSR 500/570 in picture, it certainly has a very simliar feel, despite the smaller chip.