|
Forum: Pentax News and Rumors
04-14-2014, 06:30 PM
|
| |
There will be an image transfer software option. We will have more specifications as we get closer to shipping of the product in June.
|
|
Forum: Pentax SLR Lens Discussion
12-15-2010, 09:27 AM
|
| |
I recall bringing this one up, but I am no expert.
The DA limited 21, 40, and 70 are tessar designs. They have a smaller maximum aperture, really even sharpness across the frame, lower peak sharpness than planar, but better sharpness wide open or closed all the way down. In short, they tend to be very "even" throughout the aperture range. This lens design is a century old. In my experience, the slower tessar lenses (with modern coatings) let in slightly more light at a given aperture than their planar counterparts at the same aperture, because there are less lens elements in tessar designs.
Most other lenses are planar of some sort, although not all of them. They are a little larger, have more lens elements, are considerably faster, but also much softer wide open than tessar lenses. Peak sharpness is often higher for the planar lenses. Corners tend to be softer on planar lenses than on tessar lenses, which can actually be seen as a desirable, or undesirable, trait (depends on whether you are attempting to isolate the subject or not).
You can get really, really deep into this stuff and, arguably, it will have little effect on your abilities as a photographer. I can attest to the difference in Tessar rendering over the Double Gauss design (the FA 50 1.4)... they are very different and each have their place, really. There is no correct choice IMHO.
Boiled down: Tessar lenses are old-reliable pals. Nothing shocking about their performance, but really dependable all the way through the aperture range. Planar lenses tend to be more temperamental geniuses. They can outperform everyone when the stars align, but are more prone to producing "mistakes"... things like softness, or chromatic aberrations. However many of these "mistakes"(such as aberrations and flare) have been largely corrected by lens coatings, which explains why the planar design philosophy accounts for a very large percentage of modern lenses.
In the end, there is a good reason why Planar lenses have become the standard design of modern lenses. Tessar's are considerably more rare.
|
