Lens Spotlight: K500 - Jason Doss

Lens Spotlight

smc Pentax-K 500mm f/4.5

This is a large lens.  A really large lens.  One large enough that I had to get it its own backpack so I could haul it and its tripod around when I want to haul it around.  It needs support.  This means a solid tripod or a solid support with a thick towel or a beanbag under the lens for support and protection from abrasion.  The lens is large.  I said that already but it is large.  The front element diameter is 128mm, which is just over 5 inches across.  That's bigger than an Impossible Whopper.


Why do I have this 500mm lens?  I don't know.  It is my least used lens, because I don't have an adequate tripod.  I have another tripod on order, but I fear that one may not be adequate either.


The tripod I'm talking about the Peak Design Tripod, rated for 20 pounds.  I pledged for the tripod upon reading the specs, but now they say they made up the weight rating, and all reviews thusfar have said that 20 pounds is likely a huge overestimate.  I have not found anyone who's used a large lens like this on that tripod.


The other option is a beanbag, or a pillow, or a thick towel.  I've used each of these on solid concrete walls and have managed better images than I'm about to show you.  So the lens is capable of very good images, just not me with this particular tripod.


The lens has some cool features, including a huge retractable lens hood, a gun sight (!), a secret compartment where you can put a 52mm filter in, and a rotating lens mount.  The lens does not have an automatic aperture, which means that when you set the lens to f/16, you look thru the viewfinder and see the image at f/16.  All other lenses in my collection will show you the image at wide-open aperture, then stop down in an instant before the shutter opens, and open back up after the shutter has closed.  This is good and bad, in my opinion, since now one can use auto-ISO with a manual lens.  However the viewfinder is darker when stopped down.  Unless you use live-view, which compensates for brightness to a large extent and therefore levels everything out.  Since I use live view with this lens most of the time, I guess the lack of an auto-aperture is good for me, overall.


The lens is 3370g (7.4lb) and, focused at infinity, 440mm long (17.3 inches) and has 10 aperture blades and can accept 52mm filters in an internal compartment at the rear of the lens. The fast aperture of f/4.5 is about fairly fast for lenses of this focal length. The lens bears the usual aperture ring and has a rubberized grip for manual focusing. Minimum focus distance is 10mm (32.8 ft) producing 1:16.7 reproduction ratio (0.06x).

As focal length increases, the difficulty in getting a good, solid, and sharp photo increases proportionally. That's keeping all things equal, so if your lenses are all the same size, shape, and operate the same, then that would probably be mathematically accurate. But add five pounds to the lens weight, and make it unwieldy as this K500 is to use handheld, then you have to add an order of magnitude to that math. What I'm saying is that getting good shots from this lens is difficult, but good shots can be obtained because this is a very good lens.


So, besides the size, weight, and requirement for support, what is not to like about this lens?  I can only think of two things.  First, the filter threads are found inside the lens barrel, and to remove or install a filter requires unscrewing the rear quarter of the lens and detaching it completely.  This is not that significant most of the time, since you'll either want to keep the filter in or not for your entire shoot.  In other words, you're fine so long as you don't need to access the filter a lot.  If you're using filters that might need to be installed and removed often (ie, ND filters) or adjusted often (ie, circular polarizer), then this may present a problem.  However, it should be noted that all shots included here were taken with a circular polarizer installed.  My technique was to open the lens, install the filter, and view the sky thru the viewfinder and rear segment of the lens only while dialing in the sky color I hoped to get in my photos.  I'm confident that mechanism will work, but these shots might not be the best examples of that success.


One other thing comes to mind that affects usability.  The manual focus ring is between the camera and the helicoid.  What does this mean?  This means that when you focus the lens while mounted on a tripod, the camera and your hand will move closer to your face.  If your lens is mounted on a solid surface with a beanbag, then you will have to move backwards (or forwards) as you focus. This is a minor issue, but one that is noticeable and unfixable.


All of the photos shown here are from the top of Round Top Mtn in Jasper.  I chose to shoot some landscapes because of the potential detail that might result (and did in some shots), because of the fall color (which was late-stage waning), and because landscapes are typically not the first application that comes to mind when one considers a 500mm lens.  Plus, it was an easy target and one I'd been thinking of doing with other lenses anyway, but it was the K500's turn this day. 


Again, click any photo to see larger versions, and comments can be left on this page or under each photo if you are so inclined.


That's all I have for now... See you next time.


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