Strange Double Exposure

[Jeff Fillmore]

Okay aside from ME being strange- this is the strangest thing ever. ; My five year old took this Holga double exposure- one with a blue flash gel and one without. Check this out: save it to your computer- open in Photoshop (or something)- go to Adjust- Hue/Saturation and slide the saturation down. ; The blue image disappears and the double exposure is visible. ; Too weird.

 

[zackiedawg]

If I just look close enough, I can see the other exposure in there without dialing down the blue - you are outlined in red, and your right eye in the background double exposure is immediately to the right of your right eye in the blue shot. ; You're not making a tongue face, and the shot is at an angle.

It's pretty cool that dialing down the blue reveals how much information is actually still there, but just obscured.

 

[Roger]

Would make a cool animated GIF I think.

A2 didn't like that, but I tried another software and saw the results.

I know why this happened ; 8)

 

[Tim]

dude that is way cool.

 

[Jeff Fillmore]

I know why this happened ; 8)

Enlighten me please~

It's like the red channel is haunted. ; ???

 

[Roger]

C-41 Film is like Foveon: ; It has three layers (4 for Fuji) stacked on top of each other, in accordance with the color spectrum (the layers are in a specific order because of where they fall on the light spectrum). ; From the top it's blue, green then red sensitive.

Anyway, the second image, using the BLUE flash caused the blue layer to overload/overexpose, thereby becoming the primary image that was visible, but by doing so, not much of the other colors were allowed to expose on the second exposure, so the red and green channels from the previous exposure were still intact "underneath" - visible by removing the blue.

In theory you should be able to duplicate this if you process a photo in RAW rather than JPEG on digital (except for the Sigma branded Foveon sensors - they should be able to duplicate this) as RAW is supposed to allow you access to the actual Bayer sensor figures for each "group" of pixels - remember bayer is GRGB - those 4 sensors make up 1 pixel (except on Foveon, Fuji's Super CCD, and Nikon's new design - which actually uses a unique microlens system to create their own Bayer filter on the sensor rather than as a filter itself)


I may have to try this myself[nb]Of course, after I get some gels...[/nb]....and you're making want to add the Holga to my next purchase.

 

[Craig]

pretty neat,
and Wow Roger, another perfect explanation of how this stuff works!

 

[Jeff Fillmore]

Thanks for the explanation Roger- You should get a Holga. ; I got the 'CFN' model which has built-in flash gels. ; You turn the little dial on the top and it rotates a color wheel between blue-red-orange-white or you can park it in the middle of two colors and blast out a duel-colored flash. ;

http://www.bhphotovideo.com/c/product/3 ... amera.html

 

[Jeff Fillmore]

Swerving off topic:

I did find though the red flash seems to do absolutely nothing on B&W images. ; Last weekend we were stuck in the Pirates of the Caribbean ride for like 20 minutes right in front of the guy laying with the pigs. ; After that long having only the Holga with some 400 TMax in it I decided to be a rule breaker and take one flash picture. ; (I know- sue me- we were stuck!) ; Anyway- I decided to use the red gel thinking since everything in there is red anyway maybe it would look less like a dark-ride-flash-shot. ; Instead it just looked like total underexposed darkness. ; I was thinking later maybe B&W film does not expose to red? ; Kind of like a safe-light?

 

[zackiedawg]

That's interesting - I'm guessing it's the red light that is causing the problem, maybe combined with the existing red lighting in the ride might have removed all discernable contrast (highlights are already red, you flash the shadows with red...nothing left?).

Red filters are great with B&W - so it can't be the red color itself...must have to do with the light. ; I used to use a red filter on B&W film when I was shooting models outdoors as it produced a great contrasty result - really popped the tonality, for that gritty street feel.

 

[Roger]

I think that the flash just doesn't have the strength to get through the gel AND hit anything in the ride. ; Does the Holga change exposure (i.e. fixed shutter speed or something) when you use the flash?

 

[mSummers]

Very Cool! ; Roger, thanks for explaining how C-41 film works. ;

 

[Coo1eo]

That is way Cool Jeff. Great explanation Roger.

 

[Jeff Fillmore]

I think that the flash just doesn't have the strength to get through the gel AND hit anything in the ride. ; Does the Holga change exposure (i.e. fixed shutter speed or something) when you use the flash?

Maybe- although I was pretty close in the boat. ; The Holga only has two f-stops (sun and shade) and two shutter speeds (1/100 and bulb) as far as I know neither of either are cognizant of the flash.