helicon focus with leaf aptus and hasselblad

Kasson describes the next rule of focus bracketing as follows: 'Depending on your subject matter, the size of your intended prints, and the esthetics of the scene, I recommend using 15 µm as a default, and 7.5 µm for the parts of the image that you want to look reasonably sharp. This results in depths of field considerably smaller than typical DoF tables. The sensor pitch for a high-res camera is around 4 µm, so to achieve 'roughly equal contribution of sensor and pixel aperture blur and defocus blur, you'd set the CoC for depth of field computations to about 4 µm,' says Kasson. CoC diameter these days is measured in micrometers (µm). That's too large for modern cameras, and sticking with that standard results in blurry images. With modern high-resolution image sensors, what's an acceptable CoC? For 35mm film cameras, depth of field tables were calculated using a 0.03 mm CoC diameter. If you will forgive a bit of math, the diameter of the CoC is the amount of image space misfocus over the f-stop, but you don’t even need to know that the camera will figure that out for you.' The size of the CoCs, which are illustrated in the lower part of the above figure. Note that no matter whether the image on the sensor is front-focused or back-focused, the size of the CoC is determined by the amount of misfocusing on the sensor side of the lens (in image space). The thing that determines how much blur we’ll see in the image is the diameter of that circle. Kasson writes, 'For most of today’s lenses, that means we’re talking about filled-in blur circles called circles of confusion (CoC). It's possible to reasonably model normal photographic lenses using an image of the diaphragm opening, which is approximately a circle. These focus bracketing systems ignore the focal length of the lens and subject distance, although they do consider the f-stop.Ĭoncerning print sharpness, focus bracketing systems don't need to deal with focal length or subject distance. After all, it deals with what's happening on the image side of the lens, not the lens itself. What's significant about this is that image space has nothing to do with the lens itself. This diagram helps illustrate the importance of 'image space.' As Kasson says, ' If we concern ourselves with what happens on the sensor, or image side of the lens, we talk about image space and depth of focus.' Focus bracketing systems like Nikon's and Fuji's work in image space.

Dedicated equipment such as focusing rails can help, but that adds another layer of complexity – and cost.

It is challenging to adjust focus the optimal amount over and over. When working with high-magnification lenses up close, the depth of field is razor-thin. On the other hand, the process is tedious at best and extremely difficult at worst. Not only does focus stacking extend the depth of field of images, but the technique also allows photographers to use their lenses at optimal apertures rather than stopping way down to increase the depth of field. There's no doubt that focus stacking has helped photographers capture brilliant images.

For modern cameras with focus bracketing systems, how do they work, and are they as good as doing the focus bracketing yourself? Over at Lensrentals, photographer and all-around digital photography expert Jim Kasson answers these questions and more. Some cameras can even combine and stack images in-camera. Recently, cameras have begun incorporating focus bracketing modes to capture the requisite images for a focus stack automatically. However, this approach has required photographers to adjust focus and capture consecutive shots manually. For years, photographers have used specialized software, like Helicon Focus and Zerene Stacker.

Focus stacking, combining images shot at different focus distances to create a composite image with greater depth of field, isn't new.

Helicon focus with leaf aptus and hasselblad