10.11.2019

My Review of the Pentax HD-DFA 28-105mm f3.5-5.6 Zoom Lens.

Full frame. See 100% detail crop just below...

After looking over a fair number of images from the 28-105mm Pentax lens, when used in tandem with the K-1 body, I've come to the conclusion that it's a really good lens and if you decide to embrace Pentax's vision of a full frame camera system this might be the lens to buy. It's not the fastest of the Pentax full frame zooms being offered but it does have the most usable focal length range and it doesn't mind being used wide open, at its maximum apertures. 

Let's start with a physical description of the lens: It's small for a lens that cover the 24-36mm film gate but it feels dense, and heavier than expected, when you pick it up. It does not have an external aperture ring so you'll always be using one of the camera controls to set your f-stop. The filter ring at the front of the lens is 62mm and the supplied cap is the pinch type and it's made of thick plastic; not thin or chintzy stuff. The lens is supplied with a cloth pouch and a petal-type lens hood  that can be reversed onto the front of the lens for transportation. Please don't be a dweeb and shoot with the lens hood reversed. It just doesn't make any sense at all. If you are too lazy to use the lens hood you should just throw it away. Anything else looks lame.

There is a small, almost vestigial focusing ring positioned closest to the the back end of the lens (the camera side) and I can't imagine wanting to use it instead of the AF in one of the K series cameras. The front ring is a very long (from front to back of the lens) zoom ring which has a nice rubber grip. Focal lengths are marked on the grip at 28,35, 50, 70, 90 and 105mm. 

In deciphering the lens description from the lens barrel markings the "HD" stands for high definition and means that the lens was constructed and coated to work with high resolution digital sensors. The D-FA means it's a digital lens that covers the full 24x36mm frame. ED connotes the use of extra low dispersion glass in the optical construction while "WR" means that the lens has been made weather resistant with the application of gasketing. Finally, the lens is "DC" which means it has built in motors and doesn't depend on noisy "screw-driver" mechanical connections to the camera in order to focus.

The lens features a nine bladed, rounded aperture which generally means better bokeh, and I have found this to be the case at nearly every focal length and focusing distance. The lens weighs in at 1.33 pounds and has an optical construction of 15 elements in 11 groups. Included are two precision aspherical elements, an ED element and an anomalous dispersion element. A bit more sophisticated than a typical "kit" lens, for sure. 

I've been shooting with it in low light situations and also in bright sunlight (trying to achieve maximum performance with the lowest ISOs) and have been able to rely on the maximum apertures to delivery good to great performance (best at the wider angles but still good at the long end). I've had very little flare even in flare prone shooting situations and when I stop down one stop the performance of the lens equals that of my 24-105mm f4.0 Panasonic Lumix lens at the same f-stops; and that lens is nearly three times the price of the Lumix. The only real advantage of the Lumix lens over the Pentax is the constant aperture and a closer minimum focusing distance. 

The Pentax 28-105mm trombones (extends) as you zoom but the focusing is internal. Even fully extended, at 105mm, the barrel and extensions are tight and not at all anxiety provoking. The lens inspires confidence because it feels "right" mechanically. 

I selected this lens over the available Pentax 24-70mm f2.8 because I value the focal length range of the 28-105 more than I do the extra stop at the middle of the range or the extra two stops at the longest end. If I need shallower depth of field at the 100-105mm range I have the Pentax 100mm macro lens which is an f f2.8 and which is nicely sharp and contrasty even when used wide open. The 28-105 is just a great walking around lens for 90% of the imaging most people would do. By adding the 50mm f1.4 FA and the longer 100mm macro along with the zoom I feel like there's not a lot of general photography I can't cover well. Additionally, the K-1, at 36 megapixels, gives me room to crop and fine tune. 

The camera and lens work in concert with the camera applying lens corrections to Jpeg files and writing the corrections into the raw files. The camera is making some obvious corrects to lens geometry but once made they are largely unnoticeable and I'd rather have the camera correcting them than spend time doing it myself. Of course, I would prefer a lens that didn't require computational (my new buzz phrase) corrections but I'll gladly trade that compromise for a lens that is nicely sharp, contrasty, has great color and is fun and easy to carry around. And that's the 28-105. I'd buy it again as long as my intention was to use it with a Pentax K-1 or K-1 mk2 body. More samples below: 
100% crop from the image above the written review.











5 comments:

Eric Rose said...

Back when I was traveling with my D700 my go to walk around lens was the Nikkor 24-120. Not the greatest of lenses but when you used the sweet spot combination of FL and FS it produced some great images for me. I especially liked the last shot you posted of the merchant. Wandering both the indoor and outdoor markets in Turkey is probably one of my most memorable vacation memories. The colours, the compositional possibilities and of course the wonderful merchants and their children combined for some very nice shots.

One of my goals going forward is to do more intentional street photography. With the over abundance of tourists where ever you go these days I might as well learn how to include them in my vacation photos rather than turn myself inside out trying to eliminate them. However I am hoping all these Instagram posers will eventually tire of their quest for fame and fortune and quit crowding in front of each and every tourist attractions and viewpoint. When I visited the Trevi Fountain last week it was almost impossible to get a clear shot of the fountain what with all the Instagram models going through their repertoire of poses and costume changes.

Same thing happened when I was trying to get some nice shots of Moraine Lake by Lake Louise. It seems some log sticking out into the lake had some special Instagram significance since no fewer than twenty Instagram models where lined up to take their turn out at the end of it to do their posing routine. Naturally their Instagram photographers added to the mess. Not to mention they were all in an area closed off by the authorities.

Yes indeed I am a grumpy old man with little patience for these narcissistic fame whores.

I hope you did not run into the same problems in Montreal. As you mentioned most of the people who seemed to be on vacation there belonged to the retired demographic so I would imagine Instagram models were a bit rarer.

Eric

Kirk Tuck, Photographer/Writer said...

It was the profound opposite in Montreal. Mid-week fewer people are out and around and the threat of cold weather (which did not materialize) probably helped keep the half naked Instagrammers off the streets. I found the old town and Talon markets to be uncrowded and easy to photograph in. I love Rome and used to go there a lot but now I think I would only enjoy it in the winter. Fewer people but the natives all bundled up look so.....cosmopolitan...

Joe R said...

You might consider adding the new Fuji 16-80 f4 to your basket of lenses. I got mine a few days ago and it looks like it will become my go-to lens. Typical Fuji quality that helps produce some very nice files.

granitix said...

Pentax' use of HD is unfortunate - it refers to the optical coating method that has supplanted SMC and reviewers show it's an improvement. So many companies use HD as a label for different tech that it loses its meaning - and hey, who setles for mere HD in a 4/6/8k world?

Kirk Tuck, Photographer/Writer said...

Yeah, remember when HD meant real high definition instead of being the "step down" designation from 4K?