“…distance, not lens length, affects perspective…”
Here’s a lens trick, based on a simple but often overlooked principle, that you can add to your bag of tricks: create a long lens compressed look with a short lens.
In photo one of model, Michelle Snow, I used a 105mm lens at a distance of
15 feet. With this lens at this distance Michelle fills the frame nicely,
however, the background power-line poles look small and far away, adding
little impact to the image. On photo two I swapped out the 105mm lens for a
300mm lens, then backed 42 feet away from Michelle to make her fill the
frame appropriately. I think you will agree, this second image is much more
interesting, notice the compression; the size relationship between Michelle
and the background has evened out somewhat making the poles appear closer
and more dramatic. Let me pose a question: is this cool compression because
I used a 300 mm lens or is it because I walked 42 feet away from Michelle?
Let’s see if my third version of the image answers the question. In photo
three I took the same picture again still at 42 feet but this time using the
105 mm lens. With this third image and the 300 mm image (for reference) open
and tiled side by side in Photoshop, the crop tool was selected to crop in
on the 105 mm lens at 42 feet image. The crop tool was set to match the
framing and resolution of the 300 mm image. Notice that the perspective
compression is identical in both shots. The underlying principle of this
compressed look is – distance, not lens length, affects perspective. As you
move away from a subject, nearer objects grow smaller at a faster rate than
do further objects. As you move toward a subject, the nearer objects grow
larger at a faster rate than further objects. But don’t take my word for it,
to see for yourself try this: with one eye closed view your hands held three
inches away from your open eye. Back your left hand away so the distance
between your two hands is about 8 inches. Observe the size difference
between the two hands. Now, keeping the distance between the two hands
constant, move them as far away as you can. Again observe the size
relationship. At the close distance your right hand appears huge compared to
the further left hand, and at far distance the right hand only appears
slightly larger, that’s perspective at work. So choose camera distance for
the 'perspective look' you desire, then choose the correct lens to fill the
frame appropriately or if you don’t have that lens, then rely on the
cropping features in Lightroom (LR), Adobe Camera Raw (ACR), or Photoshop to
crop in on your image. I like to change my mind a lot, for this reason I
prefer to use the cropping features in Lightroom and ACR rather than
cropping in Photoshop. Cropping in LR or ACR only records the cropping
coordinates and only applies them to the file rendered from the RAW file, at
any time I can go back and re-edit my cropping. With Photoshop once you save
and close the cropped file that is it, those cropped pixels have all gone to
pixel heaven.
This 'lens trick' is a great solution in a pinch and technically the only difference between the two images is depth of field and image quality. Both images were shot at f2.8 but the size of Michelle in the 105 mm version of the image is smaller in camera than was Michelle in the 300 mm version, or at least until I cropped it. The underlying principle at work here is, depth of field increases when in camera subject size decreases; the more you reduce a subject’s size from their actual size, the more depth of field you will get. As for image quality, the cropped image is made from fewer pixels, making it less resolved.
Dave Montizambert
Dave Montizambert lectures internationally on lighting, digital photography and Adobe Photoshop. He is also a published author having written two books on lighting and digital photography (publisher Amherst Media) plus numerous magazine articles on these topics in North America and in Europe. Dave also creates Photoshop tutorial CDs & DVDs for www.software-cinema.com.
Dave is available for lectures and workshops in your area and can be
reached at montizambert@telus.
net or
www.montizambert.com.
If you would like to learn more about digital lighting, check out Dave's book, Creative Lighting Techniques, available through Amherst Media and the SWPP bookstore.
Join today and receive a fantastic free gift: Apply here
