Hey, I want to get a good chrome sphere for HDRI photography.
I’ve found a place that sells some apparantly pretty nice ones:

http://www.gazingballoutlet.com/

And decided to buy 2, just for the variation

I just can’t decide whether I should go for a 4” and a 6”, or a 6” and an 8”.
Anyone with any experince who could tell me what they use?

And also, any suggestions to how I mount it on a tripod? I could drill and cut a thread,
but I’m just afraid the wall thickness doesn’t allow for enough chred depth :S

sphere size is not really an issue as long as the surface is smooth. only issue is Mega-pixel count and camera sensor size [assuming this is digital]

you want to have a nice big image so you can then assign it to ither a bg map or reflection maps.

as far as the mounting i bought two cheapo tripods from wal-mart. drilled a hole in a soda bottle top and screwed it into the camera mount on one tripod. then placed my metal ball on that. used the other tripod for cam. the cap obscures just a bit of the lower area, but this is not for quicktime vr, so a little bit of occlusion never hurt anyone :)

Well I was more thinking about when there’s limited space… Like in a room, wouldn’t it be better with a smaller then?

Go to HDRI Shop: http://www.hdrshop.com/

There’s a tutorial there that has a link to a recommended ball-bearing company.  I seem to remember someone saying that a ball 2-3 inches in diameter is the way to go.

- Geoff

be careful with those mcaster-carr chrome spheres. thats what i got for my setup and the little ball started to rust about a year after having it.

i would say go for the plastic ones, only there surfaces are generally pritty warped.

the chromes are a good bet. just keep um out of moisture

The link seams to be dead :(

But I ordered the garden ornaments anyway :) They should be chrome steel balls, and they should be able to take it.
I’ll keep them inside most of the time anyway.

Anyway, I think I’ll just stick to the 4 and 6 inches :) Thanks!

hi just to let you know we are giving away a high res hdri at our website…

http://www.3six0.net

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The size requirement is really dependant on the scale of scene you are shooting. For small scale indoor stuff or close ups you can get away with a small probe. For large scale stuff a big ball can help get better resolution. Ideally the probe should be placed as near as practical to the intended position of your CG addition to the scene, and the camera shooting it in the same position as the camera shooting the background footage. If there is a long distance between them, the good news is it will minimise your self reflection on the probe. The bad news is the probe will be smaller in the frame giving you poorer resolution. Three solutions. 1 Use the highest resolution camera you can. 2 Stick the biggest lens on it you can. 3 Use the biggest probe you can. Use any or all these depending on your resources and distance/resolution requirements.
Early this year I did the animation/compositing on film for Edinburgh Trams, (see it here, it’s the one labeled “Tram Showcase")
http://www.tramtime.com/
For this the probe was always some distance from the camera. We used a Sony HDCAM (1920x1080) for the backgrounds and a Canon EOS-1Ds MarkII (4992x3328) with a big 800mm lens to shoot the probe. The probe was a 300mm stainless garden ornament form here:-
http://www.designs-in-stainless.co.uk/spheres.htm
This gave us good resolution over the distance which was better than the surface of the probe.
For the stand, the ball was a bit thin, it has a small flat disc at the base but not quite thick enough to get hold of. We riveted a small stainless disc to this and drilled and tapped a 6mm hole in it. This screwed perfectly onto the end of a cymbal stand borrowed from the boss’s music room, that was the tripod sorted.
You can see on the above site they do 100mm ones on rods they would be useful to just stick in the ground.
For smaller stuff a cheap solution is a silver Xmas bauble, highly reflective and smoothly spherical.
As for rust, always keep it clean and dry after you have been in the rain, mist, snow or under the sea.

our site http://www.3six0.net uses a spheron hdri camera to capture all our HDRI’s see link http://www.spheron.com