Rongnongno Loc: FL

There are several type of lenses. We will look at only two generic types of lenses usable for stacking a panorama for sharpness; Prime lenses and Zoom lenses.

Prime lens
A generic prime lens, regardless of focal length, sets two parameters you cannot change, the focusing distance and the aperture, both use a minimal and maximal limit value.
A 'Bright lens' is a lens that has a maximal wide aperture typically below or at 1.8.

Focusing
- The minimal focusing distance depends on the lens purpose. A macro lens by example will focus to a couple of inches while a telephoto can have a minimal focusing of a few feet, if not yards.
- The maximal focusing distance is usually infinity.
- Specialized lenses work best at a given distance that depends on the lens purpose.
- Optimum focusing distance depends on the design of the lens. Optimum focusing offers the sharpest capture a lens can produce at any given aperture setting. For that reason specialty lenses are not suitable for landscape photography. A macro or portrait lens are typically ill suited for long distance focusing. The long distance capture produced will be soft.
- Hyper-focusing is, simply put, the exploitation of the maximal depth of field (DoF) given for an aperture.

Aperture
Aperture is created by blades inside the lens that control the amount of light hitting the sensor. It also allows to control the DoF.
- The maximal aperture is set by the lens. The larger the 'brighter'. The DoF is shallow.
- The minimal aperture is set by the lens. The smaller the 'darker'. The DoF is deep.
- Optimal aperture is the setting that offers the sharpest image along with the best color rendition. Optimum is not the same for all lenses but will be the same for the same camera/lens combination. This is the aperture you should use when stacking images for sharpness.

Zoom lens
Zoom lenses have variable focal length by definition.

Length: Minimal/Maximal lengths are set, anything is between is variable.
Aperture: Set at the minimal length (wide angle) and maximal aperture (Wide open) is the best will get. The aperture will vary as the lens length is modified. This affects everything from focusing distance to light quality and DoF.

Due to their build there is no set optimal focusing distance. The optimal aperture is about two steps down but may vary with the focal length selected.

Note: I am leery about them as I still do not see the optical quality prime lenses have. Gene on the other hand would use zooms in their lower range. If you use a zoom, just make sure there is no zoom 'creeping'. (Creeping = Involuntary change of the zoom length)

Summary: Non specialized lenses are the best. Always use the optimal aperture as set by the selected lens.

This is written in collaboration with aellman, Bob, Gene and RGG.

BboH Loc: s of 2/21, Ellicott City, MD

Good information - know most without having to think about it, but very good to see this summary in "print"

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

My $.02.

I use a variety of lenses for pano - prime, fast zooms, and specialized tilt/shift lenses.

What I look for in a lens for pano (and in general) is consistent corner to corner optical consistency at working apertures, usually F8 to F11. But sometimes I will use a lens that can be shot wide open and still maintain image quality, when trying to separate the subject from the background, as I did in the image in this thread:

http://www.uglyhedgehog.com/t-501636-1.html

I'll get into detail on lens selection when I get back in two weeks. Until then, keep shooting!

Rich1939 Loc: Pike County Penna.

I look forward to your input.
Slàinte mhath

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

Thanks. I am putting my thoughts together as I travel through the Motherland!

Agus dea-fhortún!