Pentax Ricoh Imaging has released a unique new weatherproofed lens for the 645D, their medium format camera. It is available for preorder right now, and it'll be available in retail outlets and online by the end of the month!
The world of digital photography moves ever faster! Pentax announced Thursday, March 22, 2012 that it will release a new ultra wide angle lens, a 25mm f/4. It's designed to pair exclusively with the 645 series which includes the 645D, thus far the one-and-only medium format camera made by the big, prosumer DSLR manufacturers.
Its official name is the DA645 25mm f/4 AL [IF] SDM AW lens. Kind of a mouthful, and definitely a handful! The DA645 25mm f/4 is only, as stated, an f/4 lens, so it's not a low light lens in particular, but it does have some good features, and I bet you can get it to do stunts.
The DA645 25mm has some math behind its focal lenth specification. On the 645D it has the equivalent of a 19.5mm focal length on full frame film. It's designed to cover the cropped 645D sensor (not film)
Keeping it clean and dry
The DA645 25mm sports 11 different water and dust seals and is designated as an All Weather lens (the 'AW' in its name designation). Pentax Ricoh designed it with being outdoors in mind, which is nice. I'm glad they're thinking ahead. Dust in a lens is even worse than dust on a sensor.
Also included in the package is a front element coating designed to minimize dust and grease spots on the front surface. This is a good thing for that big element because it bulges too much to put a filter on, a common design of ultra or super wide lenses.
Elements, Coatings, and Chromatic Aberration
The new 25mm has dual aspheric elements, again, a good indication that they're doing what works, and special coatings designed to control "various aberrations" (their words). The has Pentax's Aero Bright Coating, to minimize internal reflections and to produce a brighter, clearer image with good edges. This kind of coating makes a difference with digital SLRs, because it minimizes the reflection of the camera's inner surfaces on the innermost lens element.
The 25mm boasts a 95-degree field of view, which is a good FOV for landscape and architecture photographers. The news release doesn't mention distortion, but distortion is generally fairly pronounced on ultra wide lenses so there probably won't be many surprises there. If aberrations are well controlled, this lens will be very popular.
The aperture blades of the 25mm are rounded, which should give it some very nice bokeh. Personally I don't mind a little geometry in my bokeh, but I am a weird nut. From time to time I have been known to complain about angular or noisy bokeh though.
Autofocus and controls
The 25mm uses a Supersonic Direct-drive motor autofocus system, which promises to be easy on battery life and fast and accurate. It offers what is called the Quick Shift focus system, which enables fast switching between Auto and Manual focusing.
Besides the various coatings and designs, things which improve on lenses as time goes by, one interesting feature in the DA645 25mm f/4 is the integrated, in-body 40mm filter holder. Since the front element is a bit bulgy, putting the filter holder inside must've made sense. Will it increase the lens' permeability to water and dust? Pentax doesn't think so, and they might be right. At any rate, at least you can use a filter with this lens without taking it off the camera.
Many ultra wide lenses, with their bulging front elements, cannot accept filters and so if you want special treatments you have to open up the camera and put one behind the back element if it has a holder there, or you have to do gymnastics with transparencies in front of the lens (not recommended BTW), or do all your treatment in post.
Since many people consider post processing cheating, being able to use a filter will offer some relief. Actually, post is usually cheating--if you get a really nice photo with everything right there's nothing to do in post anyway.
One thing afficianados of polarizers might appreciate is a roller dial on the filter holder which will let you spin the filter into the right position--way better than taking it out again and again and again to find a good horizon on a graduated filter, for instance. I like where their heads are at on this lens.
Nuts and Bolts and Dollar Signs
This is exactly the kind of lens one expects for a great camera system and from a legendary manufacturer. It represents an improvement over previous designs, the implementation of new technology, addition of a few new ideas, and a design intent for a premium line of products. It's not a cheap lens. At US$5,000 apiece it is close in price to other medium format lenses and poised for that market. But, as many say when they get into medium format, it's not really about the money--it's about the image.
Since Pentax Ricoh aren't offering a lot of medium format lenses at the moment, despite a few good legacy lenses from the film days which are still compatible, the DA645 25mm is a good move into the marketplace. Stay tuned here on Camera-Enthusiast for a review of this lens and its performance.