Pentax DA 55-300mm f/4-5.8
This lens has the less-than-substantial look, feel, and pricing of a typical kit zoom, but has a few important tricks up its sleeve. It offers, for starters, an extra long reach out to 300mm, significantly more than the 55-200mm budget tele zooms from Canon, Sigma, Tamron and others. Surprisingly, as we’ll see, this extra zoomability comes at little cost in image qualtiy. Streeting for only $350, this digital-only lens that coverts up to an 82.5-450mm on Pentax DSLRs, dropped nearly $50 during its first months on the market.
Much longer racked out than contracted (by almost 50%), this surprisingly long and light tele cast no shadow (sans hood) when used with a Pentax K100’s built-in flash.
Its unusually large zoom ring is easy to find, with rubber ribbing and a slightly stiff turning action. The manual focusing ring is somewhat noisy and rough-turning, but with well-marked subject distance scales (feet in blue; meters in white). The lens’s ornamental band of bright green aluminum is your cue that this is a Pentax DA (digital only) lens.
If it has an Achilles heel, it’s the autofocus which is quite loud and slow by today’s — no make that YESTERDAY’s — standards. (This lens could really have benefited from Pentax’s fast and quiet SDM AF motor.)
IN THE LAB
Sharpness and contrast were in the Excellent SQF range at all tested focal lengths — quite surprising for a lens this inexpensive and this long. (We would have expected a drop into the Very Good, even Good, ranges.) In DxO Analyzer 3.0.1 distortion tests, we found Imperceptible barrel distortion at 55mm (0.05%), and Slight pincushion distortion at 200mm and 300mm (0.29% and 0.22%, respectively). This is considerably better than, for example, the comparable Sigma and Nikon (non-VR) 55-200mm digital-only lenses which each showed Visible range distortion in 2 of the 3 tested focal lengths.
Light fall off was gone from the Pentax’s corners by f/5.0 at 55mm, by f/6.3 at 200mm, and by f/8.0 at 300mm. About what we expected.
The maximum magnification ratios at the uniform close focusing distance of approximately 55.5 inches ranged from 1:16.8 at 55mm to a strong 1:3.34 at 300mm.
If you can take the sluggish AF, this lens will reward you with unusually reach, excellent optics, and favorable pricing. Yes, you could go to a 14X super zoom like the Pentax 18-250mm, but you may not like the image quality or the higher price tag!