08-02-2013, 04:47 PM
Hi guys,
this one's a little tricky. I would like to do a series about oversized everyday objects. For example, a huge pencil lying on a normal sized desk. I will attempt to do this with two shots, one without the object and then one with only the object but enlarged. These two shots will then be composited in Photoshop using layers.
Now the tricky bit. I can't just zoom in to make it larger, because that would change the perspective properties of the object. The normal sized object and the large version share a common set of vanishing points, which is not the case when you change the focal length. So I have to move my camera closer to the object. I must neither tilt nor pan the camera, because that again would mess up the location of the vanishing points. I am only allowed to shift the camera forward towards the object keeping the view orientation constant. This shouldn't actually be too hard. I can lock my camera on the tripod and make sure two of the tripods legs are in line with each other. My studio floor consists of wooden boards and the resulting stripes can be used as reference for the tripod legs. As long as I move the tripod with it's front legs in line, I'll be fine I think.
And the last tricky bit: When my object is in the dead center of the photo and I move my camera closer to get this magnification effect, the object will grow in all three axis (x/y/z) equaly. If that object is lying on a table like in that pencil example, I must offset the object by shifting the camera down slightly. Things get even more difficult if the object is outside of the center of the frame, because it will (apparently) grow away from the image center, in that case I have to offset the camera both in the horizontal and in the vertical plane to put it back in the original position.
I am sure there is some kind of math to calculate all of that, but I think the easiest way would be to keep the camera tethered to a computer and then alternate between shifting the camera (forward, up and down, NO TILT OR PAN!!) and go back into Photoshop to see wether I have found the right offset yet to place the object on the desired sport on the background. I might even leave some kind of markers in the background where the magified object to we located at in the end.
Maybe, just maybe I'd have to adjust the aperture as well, because the DOF will change because I am getting closer to the object and have to re-focus. But that shouldn't be too hard to figure out.
How about the change in lighting? Some of the lights might have to be readjusted, because this oversized object would be lit from slightly different angles then a normal shaped object. And if you want to get really picky, the apparent size of the lights would also change. Meaning if you make your object double the height, you have to decrease the size of the lights by half (e.g. 1x1m softbox should become a 50x50cm softbox). Especially relevant if the object to be magnified has a reflective surface. Otherwise the shadows will be too soft for an object of that size.
That's how far I got. I was wondering if anybody else has ever tried to wrap his head around this subject and came up with a workable theory on how to approach it.
Cheers,
John
www.obsoquasi.ch | Facebook
this one's a little tricky. I would like to do a series about oversized everyday objects. For example, a huge pencil lying on a normal sized desk. I will attempt to do this with two shots, one without the object and then one with only the object but enlarged. These two shots will then be composited in Photoshop using layers.
Now the tricky bit. I can't just zoom in to make it larger, because that would change the perspective properties of the object. The normal sized object and the large version share a common set of vanishing points, which is not the case when you change the focal length. So I have to move my camera closer to the object. I must neither tilt nor pan the camera, because that again would mess up the location of the vanishing points. I am only allowed to shift the camera forward towards the object keeping the view orientation constant. This shouldn't actually be too hard. I can lock my camera on the tripod and make sure two of the tripods legs are in line with each other. My studio floor consists of wooden boards and the resulting stripes can be used as reference for the tripod legs. As long as I move the tripod with it's front legs in line, I'll be fine I think.
And the last tricky bit: When my object is in the dead center of the photo and I move my camera closer to get this magnification effect, the object will grow in all three axis (x/y/z) equaly. If that object is lying on a table like in that pencil example, I must offset the object by shifting the camera down slightly. Things get even more difficult if the object is outside of the center of the frame, because it will (apparently) grow away from the image center, in that case I have to offset the camera both in the horizontal and in the vertical plane to put it back in the original position.
I am sure there is some kind of math to calculate all of that, but I think the easiest way would be to keep the camera tethered to a computer and then alternate between shifting the camera (forward, up and down, NO TILT OR PAN!!) and go back into Photoshop to see wether I have found the right offset yet to place the object on the desired sport on the background. I might even leave some kind of markers in the background where the magified object to we located at in the end.
Maybe, just maybe I'd have to adjust the aperture as well, because the DOF will change because I am getting closer to the object and have to re-focus. But that shouldn't be too hard to figure out.
How about the change in lighting? Some of the lights might have to be readjusted, because this oversized object would be lit from slightly different angles then a normal shaped object. And if you want to get really picky, the apparent size of the lights would also change. Meaning if you make your object double the height, you have to decrease the size of the lights by half (e.g. 1x1m softbox should become a 50x50cm softbox). Especially relevant if the object to be magnified has a reflective surface. Otherwise the shadows will be too soft for an object of that size.
That's how far I got. I was wondering if anybody else has ever tried to wrap his head around this subject and came up with a workable theory on how to approach it.
Cheers,
John
www.obsoquasi.ch | Facebook