Digital camera accessories

[bdery]

One of the things I love about the Pentax system for DSLRs is that older lenses can still be used with modern cameras. I had been using a manual focus (auto exposure) 50 mm lens for some time with great results, but I recently found a deal for an autofocus equivalent. I thought the comparison between older and newer designs was interesting enough to warrant a few pictures.

For the record, the older lens has an aperture of f1,4 while the newer has an aperture of f1,7, which explains the difference in diameters.







For the record, here is an even older design from Pentax of a 50 mm lens, this one fully manual :



Isn't evolution nice?

[ShutterbugGail]

Great information!

Just curious. Do you miss the f1.4?

[bdery]

Great information!

Just curious. Do you miss the f1.4?

That was my only real interrogation regarding the switch. I ran a little benchmark test today to compare the performances of both lenses. I set up my tripod in front of a bookcase and took a series of pictures at various apertures with both lenses.

The f1,4 was always distinctly softer at its widest aperture and contrast was lower. It improves at f1,8 and from f2 towards smaller aperture it's as sharp as it goes.

The f1,7 is sharper at its widest aperture than the f1,4 at f1,8 (many numbers in this sentence!). So while I could never rely on the f1,4 at the widest aperture, I'm confortable using the f1,7 at the widest. In other words, I use the same actual apertures on both lenses, so no, I don't miss the half-stop I ost.

For the record, when I say the f1,4 was not perfect at the widest apeture, it must be mentionned that it's still better than many other lenses! But it's not on par with the best it can offer.