Does the camera Lie?

Dec 31, 2009
906
87
48
Matsumoto
#1
Look at the spokes. Is this what is happenng or is this an optical illusion. Never mind the cross chain and thank the photographer for not showing the pain of the rear derailleur being bent and streched over the cogs like a painful midevil torture device, never mind that at all.
 

jdd

Maximum Pace
Hardest Crash
Jul 26, 2008
2,519
650
133
Kanazawa
#6
stanc has it right. The same thing happens with propellers on planes.

Certain types of shutters create this (side to side, vs. iris), and it's also related to shutter speed (as related to the speed of what's being photographed, again as stanc pointed out very high speeds reduce it). Add camera movement--pan or dolly--which can also create some strange artifacts.

on edie: http://www.tessive.com/ <<--for a cinema work-around. They don't talk specifically about bent spokes, but the other issues are similar.
 

Mike

Maximum Pace
Sep 24, 2007
1,066
9
58
Kanagawa
#9
Sorry to rain on your parade techies, but it's my pure power doing that! Now I know why I break so many back wheel spokes!
 

jdd

Maximum Pace
Hardest Crash
Jul 26, 2008
2,519
650
133
Kanazawa
#10
And tangentially, the same thing (similar thing?) applies for sampled sound. The 44.1kHz of CDs can capture something less than half that frequency only reasonably well (and that "reasonably well" is open to interpretation). The higher sampling rates of SACD, and so on, do a much better job on the aural 'picture'--i.e, they include fewer "bent spokes" in the representation of the music.
 

GSAstuto

Maximum Pace
Oct 11, 2009
945
242
103
tokyo
www.roadfixie.com
#12
I'll side with Mike on this one! Outside the optical illusion, you may be surprised at the amount of spoke 'wind up' and deflection that does occur on a wheel. Especially wheels that are radial spoked on at least 1 side and have reduced spoke counts, heavy load, high wattage, etc etc. It's very challenging, actually, to get a stiff , responsive wheel when you need to raise spoke tensions into the 150-200kgf range just to keep them from pretzeling!

Sorry to rain on your parade techies, but it's my pure power doing that! Now I know why I break so many back wheel spokes!
 

jdd

Maximum Pace
Hardest Crash
Jul 26, 2008
2,519
650
133
Kanazawa
#13
Caused by the shutter motion of the camera. As the shutter moves across the film/sensor the spokes move round and hence appear curved. A faster shutter speed makes this go away to a degree. Some finish line photos you show this very dramatically. At random this one for instance http://www.letour.fr/2006/TDF/LIVE/us/300/index.html
So, Tim, how do you account for the supposed flex in that pic?

And in the front wheel in that pic?

It's an artifact of the photography. Spoke wind-up? On the front wheel?!?! While the rider is in that position??

And how do you account for the different directions of the 'bending' on the leading and trailing spokes. It is a photographic artifact, not something real.

Sorry to be persistent on this, but I can't accept that spokes are stretching as much as these photographic artifacts are supposedly/illusionarily presenting.
 

GSAstuto

Maximum Pace
Oct 11, 2009
945
242
103
tokyo
www.roadfixie.com
#14
The photo effect is well known and not at all contested. I'm merely bringing attention to the fact that a significant amount of spoke and wheel deflection does, in fact, occur while riding under certain conditions. That's what makes wheels a very dynamic and variable part of the machine. We are not sitting on infinitely solid disks.

When I hit the road dividers a couple weeks at a fairly high rate of speed, my front wheel delaminated in 3 sections, the tire blew and I felt the front go very 'soft' while absorbing the full force of the collision against the rim. A slow motion camera would have probably captured a visually exciting event.

After the less-than-a-second near heartattack - I inspected my bike and found that the wheel was still basically true! And with a tube of sealant , was able to complete the ride, in spite of the wheel being damaged in several locations. Ahh, the spoked wheel!

So, Tim, how do you account for the supposed flex in that pic?

And in the front wheel in that pic?

It's an artifact of the photography. Spoke wind-up? On the front wheel?!?! While the rider is in that position??

And how do you account for the different directions of the 'bending' on the leading and trailing spokes. It is a photographic artifact, not something real.

Sorry to be persistent on this, but I can't accept that spokes are stretching as much as these photographic artifacts are supposedly/illusionarily presenting.