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Silicon Imaging SI-2K
2/3" 1080p IT-integrated 10-bit digital cinema w/direct-to-disk recording.


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Old May 1st, 2010, 08:45 PM   #1
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Airshows - sigma 50-500 lens

For the sake of the curious here is a link to a test clip.


YouTube - CHIPMUNK DUO.mp4

I have normally covered such events with two smaller HDV cameras on a bar on a big Miller tripod, one camera for the wides, the other hooked up through an adaptor to a long lens.

The Sigma lens is not a motion picture lens and goes a bit soft at the long end. It is also not constant aperture which is very evident in the zooms when I go wide to hold the frame or re-aquire. It would be nicer to have a sports Fujinon on the front. 12mm - 1200mm constant aperture with a doubler? One can dream or win the lottery.

I found it much more comfortable using the side finder on the full body versus ducking down or standing tall trying to follow a rear finder or LCD.

The sidefinder is sufficently accurate in its mounting to work stereo to the other eye for at about 40mm. This is not valid for the Sigma as it falls just short of the wide-end but is close enough for binocular aquisition which is a bonus.

Last edited by Bob Hart; May 1st, 2010 at 08:53 PM. Reason: added text
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Old May 2nd, 2010, 03:24 PM   #2
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Pretty cool.

Hey, is that dirt on sensor, visible because you stopped the lens down - or is it dirt on the lens?

Also... did you consider SI2K as wide, and Canon 7D as tele - maybe with 70-200mm Canon glass? Given that you are on the tripod, you won't even need an IS version of that one.
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Old May 2nd, 2010, 03:29 PM   #3
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BTW, this guy says that Canon 100-400mm may be a better bet, since it has better sharpness/contrast than Sigma, is image stabilized, but costs a bit more. (He also says he feels Sigma in reality is close to 450mm, so shouldn't make a big diff. on the telephoto end between the two...)

Last edited by Alex Raskin; May 2nd, 2010 at 07:12 PM.
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Old May 3rd, 2010, 05:50 AM   #4
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Dirt on the sensor or on the lens. probably a bit of both. There's been a lot of putting lenses on and off the cameras playing with setting up the 3D follow-focus and zoom rig.

The Sigma lens itself is a huge air pump when you zoom and it readily sucks dust inside itself from inside a stills camera and will blow it into your eye through a stills camera eyepiece which is not so funny.

There's quite a lot of dust motes inside it now.

With the lens at f16, the dust appears. Same thing when I was using it on the AGUS35 and previously on an old JVC KY-F50, for ground-to-airs.

One of those C-Mount 12mm - 1200mm f1.8 Fujinons would suit me fine but might be a bit of a handful at about 70lbs. Used I think they are about AU$70,000. I don't think I will be ordering one any time soon.

Here's another ground-to-air clip.


YouTube - CITY LANDING.mp4
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Old May 3rd, 2010, 09:29 AM   #5
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Yes, I bumped in the same issue with SI2K sensor showing dust when lenses are closed past F12 or so.

Interestingly, C-mount lenses have this effect very pronounced, while with PL mount lenses it is far less noticeable.

In any case, may I suggest using ND Filters in front of your lens so you won't have to stop the lens itself down so much.

In your situation... you also may find the need for IR filter as 1st one before ND, if you there's some noticeable IR contamination. In general I think SI2K is quite good at NOT showing IR contamination at any noticeable level, but I don't know what will happen in such bright sunny environment like yours...
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Old May 3rd, 2010, 10:40 AM   #6
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Alex.


I couldn't use NDs because the lens is a style that "grows" and "shrinks" and I only have 4 x 4s. No gaffer tape or chance of dropping and breaking is going anywhere near them. I already lost one from flying gravel from a car departure and they are hell expensive to replace. I have some Series 9s from the CP16 but no adaptor ring.

The C-mount lenses likely have a smaller exit pupil than your PL lenses and maybe focus the dust more sharply I guess.

As for IR contamination, I have not seen it so far in blacks. There is something which comes off our laterite soil and gravel which is not quite right. The Sony sees it a bit differently too. It might just be over-exposure. In the real world it is a subtle brown-orange but seems to come out more as a brown-yellow if that description makes any sense.

On the 3D shoot in Bali, they are going to use two film lenses, matched Angenieux Optimo zooms. I don't know what filtering options there are with them.

They are taking a gadget which does all the follow focus and zoom trims in sync. Steve Rice is a braver man than I finance-wise but the stuff is marvellous to watch working and it does work a treat. It can also be set up as cordless radio remote.

Last edited by Bob Hart; May 3rd, 2010 at 10:43 AM. Reason: error
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