Pentax F zoom 28-80mm f3.5-4.5

Hi Folks, hope someone can help - this has been bugging me for a while....

I own the above zoom lens, which came with my second-hand sfxn. The question is, how come there are (were) 2 versions - one labelled SMC, and one without SMC?

Having checked out Bojidar Dimitrov's Pentax K-Mount Page I see that there is a slight external difference in appearance between the two lenses. The front of the non SMC version appears to extent further, but other than that they look the same.

I've got no complaints with the performance of the lens, but am just curious to know why a non SMC version was produced. (maybe to provide a budget option?)

Thanks.

Karol

Pentax have made some non-SMC versions of their lenses over the years, sometimes with simplified optical layouts compared to the SMC lenses.

I think you've answered your own question - they are budget versions.

The clue is in the name. SMC stands for Super Multi Coating, and is Pentax's patented system for reducing flare and improving light transmission.

Although prime lenses without SMC are fine if you don't point them into the sun, the large number of elements in a typical zoom lens will progressively reduce the light throughput of an uncoated zoom, and will also give much worse flare performance.

So, non-SMC zooms are not just cheap, they're nasty.

G