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Friday, July 18, 2008

Reverse Lens Macro

An interesting technique I learned from a high school friend is the "reverse lens macro." Basically, it takes advantage of the fact that a lens works (i.e., focuses light) in both directions.

Purple Flower Close Up


This technique allows you to focus on a subject that is very close to the camera (within a few inches), closer than with a regularly-mounted lens. This can be used as an effective cheap macro solution. There are two main problems with this, which I will address: 1) Less light makes it to the camera sensor, and the camera has trouble reading exposure. 2) The depth of field becomes incredibly short, so it's hard to get enough of the picture in focus, and hard to get exactly what you want into focus.

If you have a digital SLR camera, you can try this technique. It works best with a lens with a focal length of around 50mm.

  1. Put the camera in manual mode. This is necessary because of the difficulty in metering the light.

  2. Detach lens. As I mentioned before, it's tough to get correct focus due to short depth of field. This can be fixed by making the aperture smaller (optional):

    1. Adjust the aperture (through manual mode) to around f/1

    2. Preview the aperture by pressing and holding the aperture preview button. On a Canon XTi, for example, the button is located just below the button that removes the lens.

    3. Remove the lens while continuing to hold down the aperture preview button.


  3. Hold the lens up to the front of the camera, sealing the camera's opening from any other light the best you can.

  4. Without paying much attention to the displayed exposure, take a picture of your subject (you will need to get within a few inches).

  5. View the picture you took on the camera, and adjust the exposure accordingly.


This technique is very useful for showing details that you would normally miss with the naked eye or a standard lens.

Paper Macro
Notice the texture of the paper.


Crab Close Up
Nature photos are especially interesting.


Bee
This is a pseudo-hdr reverse lens macro.


Here are some extra tips:

  1. The level of magnification of a reversed lens is inversely related to the listed focal length. If you would normally be moving the glass closer to the focal plane, you are now moving it further. Hence, if you want to magnify something in the reverse lens, change to a lower focal length. For this reason, telephoto lenses don't end up magnifying the image much, if at all.

  2. A lower regular focal length requires you to position the lens much closer to the subject. I found the following distances:

    1. 55mm = 4 inches

    2. 18mm = 1.5 inches


  3. Shoot in direct sunlight to get adequate exposure. Even in direct sunlight, you may need a higher ISO than you would normally use outdoors.

  4. You'll need to hold the camera very still since your subject is very close to the camera.


I encourage everyone to try this out if possible. Note: this can let extra dust reach your sensor, so be careful to leave the sensor open to air as little as possible. I haven't had problems, but I know that dust can easily reach your lens this way.

Additionally, I know there are converters that allow you to mount a lens onto your camera backwards, so you don't have to manually hold it.

As always, post any cool pictures you take, and contact me for more information.

Thursday, July 17, 2008

Creating a Simple Vignette Effect

I find that my pictures tend to look better with a slight vignette (when the corners are darker than the center of the picture) because it draws the attention to the center:



In this post, I'll discuss three separate ways to create a vignette effect in Photoshop, with a few pros and cons of each. I'll go over the steps briefly, so please email me or leave a comment if you want more detailed directions.



  1. Method 1: Solid Color Gradient

  2. Method 2: Levels Gradient

  3. Method 3: Burning







First of all, I'll start with the following picture as the base:





Method 1: Solid Color Gradient



The simplest way to create a vignette is to apply a solid black color over the picture and fade it out as it gets closer to the center:



To create this effect:


  1. Create a new layer above your base layer and fill it with black.

  2. Create a layer mask on that layer.

  3. Choose the gradient tool, and make a gradient that consists of the following: black from 0-50%, fade black to white from 50-100% (this will make the fade start further from the center rather than at the center).

  4. Select the layer mask. Create a radial gradient (black in the center, white on the outside) from the center to a little past the corner of the photo.




This technique tends to look bad with solid color corners (especially light colors, like the sky), because the fade from light to black looks very unnatural. It's best used on images with textured corners and already dark colors.




Method 2: Levels Gradient



This next technique uses the Levels adjustment to darken the edges while retaining image information (rather than using solid black):



For this technique:


  1. On the Layers window, create a "Levels..." adjustment layer.

  2. Set 50% (the middle slider on the Levels window) to approximately .60, or adjust based on your preference).

  3. Choose the gradient tool, and make a gradient that consists of the following: black from 0-50%, fade black to white from 50-100% (this will make the fade start further from the center rather than at the center).

  4. Select the layer mask. Create a radial gradient (black in the center, white on the outside) from the center to a little past the corner of the photo. Adjust distance to preference.




This technique is very useful for lighter colors. For example, it fades a light blue sky into a slightly darker blue color, which is much more natural than fading to black.




Method 3: Burning



The third and final technique is the most difficult, but affords the greatest degree of control. It uses the burning tool to manually darken corners and edges:



For this technique:


  1. Create a duplicate layer of your base image (burning alters the original image, so a duplicate layer allows you to easily start over if you mess up or are unhappy with the results).

  2. Choose the burning tool (it looks like a little pinching hand). Set it to midtones, approximately 5%, and a size approximately 10-20% of your image height.

  3. On your duplicate layer, click and drag over the corners repeatedly; with each pass, the picture will get darker. You can hide the duplicate layer to see the difference.

  4. Continue darkening the corners and edges until you're happy with the result.




I find that burning is usually produces the best result because of the amount of control you have, but requires the most effort. It tends to look good with any picture, whether it's solid, light corners, or dark textures. Learning how to use the burn tool (and I'm still learning, myself) can be very helpful to your image processing in general.




Hopefully this post helped you understand how to create an appropriate vignette. Let me know if you need anything clarified or would like more help. Additionally, if you have any other vignette techniques, please post them or email them to me.

On a side note, similar vignetting techniques (with circular gradient layer masks) can be used for a variety of effects:


Desaturaion



Gaussian Blur

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