strange anomaly when using my DIY dolly

F

Finster

Well-known member
I have been using a DIY dolly lately with mediocre results. There's this one "hiccup" that keeps showing up in all my dolly shots, and I'm wondering if anyone out there might know the reason? Download this short QT clip.

Scrub through it quickly and you'll notice that the UCLA library in the background has a funny, up-n-down movement to it ... almost as if it's floating on waves. This anomaly has been showing up in ***all*** my dolly shots, and I'm 99.9% certain it's NOT the dolly itself. The movement on my dolly is silky smooth. Thus, I'm wondering if it's an optical thing? I'm using the Canon 5DM2 with the 24-70mm lens. Could this be a lens distortion issue? Can it be fixed in post? And is there a way to avoid this in the future?

Any feedback/advice would be greatly appreciated.
 
definately, the image isn't level, it's your dolly track, flexing somewhere down the line
 
hi finster,

i have not seen the video but it sounds like the surface you are laying the track on is not level but has undulations.

when you lay the track put a spirit level on the dolly and do a slow move....it will show you if you are level or not. the bubble must say centred for the whole move.
you may need wedges in the dips to make it level.

the tracks need to be level lengthways and widthways .
cheers
ian
 
Dang it. Maybe you guys are right. I've been telling myself it's NOT the dolly track or the dolly platform because I've tested it in 10+ different locations. Plus, I've tried using different dolly track (1" PVC pipe vs. aluminum A-frame). But this "anomaly" keeps showing up in the exact same spots.

But now you have me wondering if perhaps the DOLLY WHEELS are the culprit? I wonder if they're slightly off?

I'll try your spirit level test, Ian. Thanks for the tip.
 
Finster said:
Dang it. Maybe you guys are right. I've been telling myself it's NOT the dolly track or the dolly platform because I've tested it in 10+ different locations. Plus, I've tried using different dolly track (1" PVC pipe vs. aluminum A-frame). But this "anomaly" keeps showing up in the exact same spots.

But now you have me wondering if perhaps the DOLLY WHEELS are the culprit? I wonder if they're slightly off?

I'll try your spirit level test, Ian. Thanks for the tip.
Click to expand...


Do you have a lazer to sight down the length of the track to eliminate any wobble there.

To me, if it was uneven ground, the 'bump' would be smoother. This looks like a loose fitting, loose section joint of track, etc., or perhaps some binding with the 'wheel/track' or even perhaps a bearing in the wheels of the dolly.

Point your microphone at the wheels, and see if you here a 'clunk' as it rotates...
 
Finster said:
Dang it. Maybe you guys are right. I've been telling myself it's NOT the dolly track or the dolly platform because I've tested it in 10+ different locations. Plus, I've tried using different dolly track (1" PVC pipe vs. aluminum A-frame). But this "anomaly" keeps showing up in the exact same spots.

But now you have me wondering if perhaps the DOLLY WHEELS are the culprit? I wonder if they're slightly off?

I'll try your spirit level test, Ian. Thanks for the tip.
Click to expand...


Yes, it could very well be the wheels. When they aren't "square" with the track and each other wheel, they can climb up on the track. I've seen this before and this is why when I build skate wheel trucks, I use either steel angle iron or 1/4" aluminum alloy and a drill press to drill and tap with.

.
 
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Yeah, I'm pretty sure it's the wheels. I'm so bummin'.

Oh well. I'd rather it be my $200 dolly than my $4K camera & lens.
 
Finster said:
What would you use? After Effects? I have AE, but haven't done much with it's image stabilizer. Not even sure what settings to use. I'm sure I can find a tutorial somewhere, though.
Click to expand...

If this shot is an absolute needed shot, then, yes there are AE ways to stabilize... even manually creating motion key and manually adjusting the location of the building as it 'clunks' could be done... tedious though that may be...

However, you will have to uprez your image slighty, because no matter what you do, adjustment for the clunk will cause the top of the frame to drop down revealing whatever is in the background (typically black...). You could perhaps fudge a bit. But uprez by say 5%(Or determine exactly what amount is needed), then key for clunk, either manually or using the filter function... It's been a very long time since I've used the filter, so you'd have to search the web for a detailed tutorial... it was pretty easy to use... so it would just be a 5 minute look-see.

(In Photoshop CS5 isn't there sort of a 'fix up' healing brush tool that allowed one to fix up based on 'content aware' processing... so perhaps you could take the 10-15 frames of your 'clunk', let AE correct for the clunk, then use CS5 PS to go frame by frame 'healing' with the content aware feature...)
 
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