Telephoto Lens Cap for Canon & Nikon Camera Lenses

Archive for December, 2012

Using Focus-Stacking To Avoid Diffraction by Kyle McDougall

One of the most important parts of a successful landscape image is sharpness. This is one of those things that you HAVE to get right in camera…. there’s no fixing an image that is lacking sharpness in Photoshop. A lot of factors are at play when it comes to controlling the depth of field in an image… anywhere from the focal length of the lens being used, chosen f/stop, distance to subject and so on.

My first image I shot at f/8 which is lacking sharpness because of the close f/g subject and not a large enough depth of field.

Many people believe that by shooting with the smallest f/stop possible they will have a pretty good chance of everything being sharp from foreground to background. While sometimes this is true there are negatives to this approach, the most important one being lens diffraction. Every lens has a certain f/stop that it resolves detail best at, after you stop down past that point you start to lose sharpness. I recommend setting up your camera on a tripod and taking some test shots at different apertures so that you can see the effect in person. While the difference might not seem extreme, it’s the small details that count and when you’re printing your images every bit of detail helps. In the meantime check out this article at Luminous Landscape on lens diffraction for some examples.

With my Zeiss 21mm ZE I tend to shoot at no smaller of an aperture then f/11. Most of the time this leaves me lacking the depth of field required to cover the image from front to back. This is where focus stacking comes into play. Focus stacking is the method of “stacking” and blending a series of images that are focused at different points through a scene. Most of the time I will take three shots… one for the background, one for the middle and one for the foreground. While the thought of blending detail throughout three images might seem like a labor-intensive process, Photoshop has an automated way of doing it that produces great results almost always.

The extreme right corner of the foreground for the image focused for the foreground.

 

The extreme right corner of the foreground for the background focused image.

 

The background at 100% of the image focused for the background.

 

The background at 100% of the image focused for the foreground.

The process goes like this:
1. Open all the images in a layer stack in Photoshop, one above the other.
2. Go to Edit>Auto Align Layers
3. Once the layers are aligned go to Edit>Auto Blend Layers
4. Photoshop will automatically create layers masks for each image allowing the detail to show through.
5. You will need to crop the edges of your image slightly as there will be a slight blur from the aligning/blending.

For this particular image I used a series of four shots focused throughout the scene from foreground to background.

 

Photoshop will automatically create a layer mask for each layer revealing only the sharp detail in each.

 

The final image tack sharp from foreground to background ready to be printed.

 You’re done! This is a fairly simple process that once you get the hang of will be extremely valuable for your processing workflow. Being able to squeeze the best detail out of our lenses and cameras is key!

LC1_don_zeck_lens_cap
Kyle McDougall is a landscape photographer/workshop leader based out of Ontario, Canada.  He specializes in creating fine art images that touch on both a visual and emotional level.  When not outside exploring the land you can find Kyle online sharing his images and helping others through his instructional articles.  In 2012 Kyle was chosen by Photolife Magazine as one of Canada’s Emerging Photographers.  To view more of his work please visit his website: www.kylemcdougallphoto.com

 

Posted in: Photography Techniques

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