Fast "prime" lens for Pentax Digital SLR

I recently bought a Pentax-M 50mm f/1.7 lens for my Pentax K100D. It's a great lens, but I'd like

something just as fast around 30mm so that it would close to 50mm with the 1.5 factor thrown in.

I'm considering three lenses:

Sigma Wide Angle 28mm f/1.8 II Aspherical Autofocus for Pentax AF ($179.95)

Sigma Wide Angle 28mm f/1.8 EX DG Aspherical Macro Autofocus for Pentax AF ($249.95)

Sigma Wide Angle 30mm f/1.4 EX DC Autofocus Lens for Pentax Digital SLR ($419.95)

Pentax does make a 31mm f/1.8, but it retails for $779.95. There's also the Pentax 35mm f/2.0, but

it's a little slower than I wanted.

Has anyone used any of these lenses? I'd appreciate any feedback.

Thanks,

Rachel

I don't have any recommendations since I haven't used any of those lenses; but my suggestion would be not to be worried about the difference between an f/1.8 and a f/2. The difference is so slight it won't really make any difference in the real world.

I don't know what the price of the Pentax is off hand but I'd wager it would be the highest quality of the bunch.

Alan

I've been looking for one of those lenses for 2 months now in used market... Still no luck...

Sigma 30 1.4 has serious quality control problems. AF accuracy and CA can be real bad.

Sigma 28 1.8EX is decent but not fantastic. It's big and heavy.

Sigma 28 1.8 II, no one uses it. :(

Good luck and let me know how it goes.

Rachel,

I am also a fan of fast lenses, however I haven't found anything faster than f2 in a medium

wide to normal for APS-C. In my experience the 28/1.8DG and the 30/1.4 lenses are not

very good. Actually, they are pretty close to terrible wide open. I haven't used the other

lens, but can't imagine it is any better.

The best lenses I have fould are the older Pentax M28/2 and the Pentax FA35/2. The FA is

much sharper and has AF, but I find it a hair too long for my purposes. The 28/2 isn't the

sharpest of lenses, but I found it significantly better than either of the Sigmas I tried. I may

someday buy the 31/1.8, but for the moment my money is better of spent elsewhere, and I

am pretty happy with what I have.

It is worth noting, as mentioned above, that the difference between f1.8 and f2 is really

not significant. 1/3 of stop--the difference between exposures of 1/60 and 1/50--won't

really help stop motion or camera shake.

If you are using a Pentax-M 50mm f/1.7 (as I also do), you are shooting with manual focus and little exposure automation. You'll get the "normal" lens experience under the same conditins with a Pentax 35mm M or K series lens. It took me a while to find my Pentax 35mm f/2.0, but it was worth the hunt.

I personally like the tighter composition with the 50mm lenses on my Pentax DS.<div></div>

The difference between F1.8 and F2 is very small, and the Sigmas don't enjoy all that great a reputation wide open anyway. If you don't want to pay for the FA31, I'd say go for the FA35.

-Andrew

I have the Sigma 28/1.8 EX and like it just fine.

Good build quality, good image quality, and it's no heavier than a 28/1.8 should be. It's full frame, too, so it works on film bodies. Recommended!

I've used teh 30mm Sigma on a Nikon D2 camera for over a year now but I have no Pentax experience with it.

It is very good on a Nikon. At F2 it is sharper than a Nikon 35mm F2. At 2.8 it is very good and still better than the 35 Nikon. From there on they are too close to argue about. The is some CA wide open in very very contrasty light but I can't say I've ever compared it to teh 35 Nikon to see if it is better or worse.

And of course you have 1.4. At 1.4 it is at least as good as a 35 Nikon, better than a wide open 24mm 2.8 Nikon for sure.

I have no idea how it is on a Pentax. I do find the K10D very very intersting with some little DA Pancakes.

Neil

Neil

I've used the 30mm Sigma on a Nikon D2 camera for over a year now but I have no Pentax experience with it.

It is very good on a Nikon. At F2 it is sharper than a Nikon 35mm F2. At 2.8 it is very good and still better than the 35 Nikon. From there on they are too close to argue about. The is some CA wide open in very very contrasty light but I can't say I've ever compared it to teh 35 Nikon to see if it is better or worse.

And of course you have 1.4. At 1.4 it is at least as good as a 35 Nikon, better than a wide open 24mm 2.8 Nikon for sure.

I have no idea how it is on a Pentax. I do find the K10D very very intersting with some little DA Pancakes.

Neil

Neil

The 31/1.8 Limited is worth every penny. While it is pricey, you are getting Leica-level rendering out of it.

Note also that the 35/2 is superb, and it's only 1/3 of a stop slower than the 1.8's you're looking at. I'd take this as a second option.

The Sigma 30/1.4 is a good option if you can check one out before buying. Sigma QC is variable, but the basic design is excellent.

The Sigma 28/1.8 is simply too big for what you're getting. And the quality is just as variable as the 30.

The 31mm is a superb lens. If you can afford it, even afford to pay it off over a year, get it. The reviews both in the mags and user are amazing. And the photos are superb.

Now, for the rest of us. The 35mm 2.0 is a fast, and really really good clean, sharp, nice lens. For 1/3 the cost.

As everyone noted, the difference between 1.4 and 2.0 is a full stop, but the difference between 1.8 and 2.0 is neglible.

If money is a major option the 35mm is the best choice. If it's something you can manage the 31mm is a legendary lens that you'll certainly be happy with for many many years after it's paid off.

Hi Rachel,

I know you mentioned that the FA35/2 is slower than what you wanted, but I had a great experience using it wide open in available light.

Here is a photo I took with the FA35/2 @ 2.0, ISO 1600:

<a href=" to see photo</a>

It was shot RAW with a Pentax *istDS and converted with C1.