Focal plane distortion

Leigh B · Mar 20, 2012

Sirius Glass said:
I tried 1/30s, 1/25s, 1/20s, 1/15s, and 1/10s multiple times slowly panning cars move 50mph perpendicular to me

Hi Sirius,

Like I said... Your shutter speeds are too slow.

To get the "sliding" effect you need a narrow slit moving across the film.

At the speeds you listed I believe the SG focal plane shutter is completely open, which will not deliver the desired result.

- Leigh

Newt_on_Swings · Mar 20, 2012

(there was a url link here which no longer exists)

I will have to revisit it again soon as the weather is nice now, I never really got the chance to do it, and when I did set it up, I didn't have a target I could get to easily to experiment with. Plus I think a motor for rewinding would provide a better/steadier flow than hand winding.

Sirius Glass · Mar 22, 2012

Leigh B said:
Hi Sirius,

Like I said... Your shutter speeds are too slow.

To get the "sliding" effect you need a narrow slit moving across the film.

At the speeds you listed I believe the SG focal plane shutter is completely open, which will not deliver the desired result.

- Leigh

Thanks, I will try it again with a smaller slit. I guess that I had bad advice before.

removed account4 · Mar 22, 2012

Sirius Glass said:
Thanks, I will try it again with a smaller slit. I guess that I had bad advice before.

i did mine at 1/15 of a second .. (the one posted) ..
i have done more than once ...
perhaps both advisements are correct ... ?

Sirius Glass · Mar 22, 2012

So if I use 400 speed film, and shoot at tension 1 and 1/8" slit [1/350] @ f/16 and my 15" lens rather than the 7.5" lens, it should work!

Ian Grant · Mar 23, 2012

Sirius Glass said:
So if I use 400 speed film, and shoot at tension 1 and 1/8" slit [1/350] @ f/16 and my 15" lens rather than the 7.5" lens, it should work!

Ideally you need a vintage racing car as well with spokes, and Dead Link Removed is the ideal place to do it

Ian

jp498 · Mar 23, 2012

I'd hardly call that a hill, despite its big name in motorsports. Still sounds like fun though.

http://www.climbtotheclouds.com/history/ Mount Washington Hillclimb claims to predate Shelsley Walsh by a year. I photographed there last year, some of it with a speed graphic. Plenty of cars with wire wheels. Didn't get the focal plane distortion I wanted; perhaps a little, but not much. I'll experiment more before returning. Spectators and photographers have to board a bus or van at 6am to be delivered to the various lookout spots along the track. You have to stay at your lookout spot (or within a few hundred feet of it) till noon when there is a break in racing runs.

E. von Hoegh · Mar 23, 2012

Sirius Glass said:
So if I use 400 speed film, and shoot at tension 1 and 1/8" slit [1/350] @ f/16 and my 15" lens rather than the 7.5" lens, it should work!

You also need a car moving at a decent rate of speed. The old pictures of old cars were taken at races, and those old cars were faster than you might realise. The Locomobile "Old 16" was capable of over 100 MPH, and was built in 1906. Try it on a car going 80 and above. The wheels on the old cars were a lot bigger, too - don't expect the same degree of distortion on a modern car going at the same speed, even when the slit travel time is the same.

E. von Hoegh · Mar 23, 2012

Ian Grant said:
Ideally you need a vintage racing car as well with spokes, and Dead Link Removed is the ideal place to do it

Ian

Napier Bentley at Shelsley Walsh http://www.youtube.com/watch?v=39dHNs7u5y4

removed account4 · Mar 23, 2012

latrigue made the photograph in 1911 ... film/plate speed was not very fast

jp498 · Mar 23, 2012

E. von Hoegh said:
Napier Bentley at Shelsley Walsh http://www.youtube.com/watch?v=39dHNs7u5y4

Doesn't a car like that just beg to be photographed with some focal plane distortion along with the smoking tires?

Ian Grant · Mar 23, 2012

jp498 said:
Doesn't a car like that just beg to be photographed with some focal plane distortion along with the smoking tires?

It's only down the road from me if anyone fancies coming along one day It's also on a Public footpath so they can only charge for car parking

Ian

E. von Hoegh · Mar 23, 2012

jp498 said:
Doesn't a car like that just beg to be photographed with some focal plane distortion along with the smoking tires?

I saw that car in person in the late 90s, when they were running it with stub exhausts and preventing the rear springs winding up by chaining the rear axle to the frame. 12 cylinders of 122 cubic inches each makes a very interesting sound.

jp498 · Mar 23, 2012

Some interesting links on the topic...

Dead Link Removed

http://www.largeformatphotography.i...3-Jacques-Henri-Lartigue-and-his-camera/page4

Sirius Glass · Mar 23, 2012

E. von Hoegh said:
The wheels on the old cars were a lot bigger, too - don't expect the same degree of distortion on a modern car going at the same speed, even when the slit travel time is the same.

Well I do have 35" tires ... will those be large enough?

Leigh B · Mar 23, 2012

This link, from post #39 above by jp498, has an excellent animated graphic that shows how the process works:

http://www.largeformatphotography.i...3-Jacques-Henri-Lartigue-and-his-camera/page4

- Leigh

E. von Hoegh · Mar 24, 2012

Sirius Glass said:
Well I do have 35" tires ... will those be large enough?

The only thing to shoot that monstrosity with is a 40mm quad Bofors.

jp498 · Mar 24, 2012

Leigh B said:
This link, from post #39 above by jp498, has an excellent animated graphic that shows how the process works:

http://www.largeformatphotography.i...3-Jacques-Henri-Lartigue-and-his-camera/page4

- Leigh

That last animated graphic is impressive, but I don't think it takes into account the upsidedown/reverse of the image at the focal plane.

Sirius Glass · Mar 24, 2012

E. von Hoegh said:
The only thing to shoot that monstrosity with is a 40mm quad Bofors.

I need someone to use my 38mm Hasselblad 903 SWC to take a photograph at that location with the Jeep completely filling the frame.

Anyone interested in a road trip to Moab?

E. von Hoegh · Mar 24, 2012

Sirius Glass said:
I need someone to use my 38mm Hasselblad 903 SWC to take a photograph at that location with the Jeep completely filling the frame.

Anyone interested in a road trip to Moab?

http://www.google.com/imgres?q=quad...tart=0&ndsp=20&ved=1t:429,r:0,s:0&tx=44&ty=77

Don't forget to pan.

Sirius Glass · Mar 24, 2012

E. von Hoegh said:
The only thing to shoot that monstrosity with is a 40mm quad Bofors.

Two problems with that:

Too heavy for the vehicle
No stereo headphones

For more appropriate platforms see:

http://staceydavid.com/episodes/larcsgt-rock

The Larc is a bit large, but Sargent York will meet your needs

In particular look at Part 4 http://staceydavid.com/emvideo/modal/3648/640/390/field_youtube/youtube/CPBfvqIexgQ

Happy Trails to You.

Leigh B · Mar 24, 2012

jp498 said:
That last animated graphic is impressive, but I don't think it takes into account the upsidedown/reverse of the image at the focal plane.

The graphic is illustrating a principle.

The specifics will vary depending on the direction of shutter movement and other factors.

That does not in any way invalidate the description of the process.

- Leigh

removed account4 · Mar 24, 2012

jp498 said:
That last animated graphic is impressive, but I don't think it takes into account the upsidedown/reverse of the image at the focal plane.

don't be such a party pooper !
you should know that jacques henri was standing on his head
when he took the photograph, or a thief was holding him by the ankles trying to
shake all his francs free from his pockets, or he held his camera upside down trying to slow the shutter
down like you can with a speed graphic to get it to be slowish ... or ...

jp498 · Mar 24, 2012

A speed graphic is easy to shoot upside down. Just gotta use your left hand to operate the shutter and darkslide. The bed makes a nice sunshade. I'd imagine a graflex SLR would be a little harder to use upside down; that's where you need someone holding you upside down.

removed account4 · Mar 24, 2012

jp498 said:
A speed graphic is easy to shoot upside down. Just gotta use your left hand to operate the shutter and darkslide. The bed makes a nice sunshade. I'd imagine a graflex SLR would be a little harder to use upside down; that's where you need someone holding you upside down.

a theif comes in handy !

"i'm not robbing him, i'm helping him take the photograph!"

Focal plane distortion

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