[Marc Sabatella]

Agreed - there is no way to possibly answer the question as stated. It's like asking, what's the best car, without knowing what specific attribues you are looking for. Even "sharpness" is a relative comcept, as a wide angle lens might be sharper than a telephoto in absolute terms, but that doesn't mean the wide angle lens will capture more detail when shooting a given sibject from a given position. There are just two many vairables. You need to first get a better handle handle on what your actual needs are, and then one can rationally start discussing what lenses might meets that needs the best (even then, there will likely be tadeoffs).

[sameagle]

To nikolas2012:

Congrats on your camera and for the fact that money is no object to you.

Your question is similar to asking "what is the best car?" Hopefully you are beginning to understand that.

- Sam

PS: I see Marc S beat me to the car analogy first. Damn you!

[FrancisK7]

Hello Nikolas! Welcome to Pentaxforums and congratulations on acquiring your very fine K5

From the looks of it, you might be new to photography and I recognize the fire of passion you came here with: you're anxious to get going and want the best of the best. I once approached photography like this, and we'd all love to help you, but the best of the best is something that's subjective and will change according to your needs.

Pentax has made marvelous glass over the years. Before you throw any money down on a lens you might never use because it's focal length is too restrictive (or too wide), you need to understand the basics.

-Wide-Angle lens are better suited for landscape or architectural photography (a good one is the Pentax 12-24mm DA)
-Primes are better suited for studio work, macro work, or any work that allows you to zoom in and out using your body (so the subject must be stationary). In exchange for their lack of flexibility focal length wise, they usually provide better IQ (Image Quality). Pentax has a FANTASTIC line of primes they call the limited line. They are the FA31, FA43, FA50 and FA77. The FA77 is legendary and is one of the best primes I have ever used regardless of brand. The FA77 makes many Nikon or Canon shooters jealous. It's tremendous, and totally worth the money. The FA50 1.4 is equally great because it is fast, but the FA43 has better IQ than the FA50 by a fair margin. It's also three times the price.
-Telephoto or zooms usually provide more flexibility and are better suited as walk-around lens. They have lesser IQ than primes, but really great zooms like the DA* 50-135mm or the Tamron 28-75mm are excellent lenses that are sure to provide you with great IQ and AF. The 50-135 especially has great AF abilities and is SUPER silent.
-Fisheyes have limited use and I do not recommend them to you at this stage
-Long telephoto objectives also have limited use, mostly in the professional world, so you should not consider them at this stage either

If you just got the K5 and are looking for quality glass to expand your horizons and are unsure of what kind of photography interests you, here are suggestions, in no particular order.

1. The DA* 55mm is a great prime that offers great middle range, great IQ and focusing. I know a lot of people who use it as their walkaround lens for street photography, or a day out with the kids. It is SUPER fast for indoor low light shooting (say the kid's blowing the candles on his or her birthday cake and you don't want to use flash... then take advantage of the high ISO performance of the K5 and shoot wide open at 1.4... great times)
2. The FA50 is a little cheaper and equally as fast. More compact.
3. Tamron 28-75mm is a great lens as well for everyday photography. Good and practical range. Good IQ.
4. The 50-135mm is amazing. A little long for day to day shooting, but for walking around, it's great. If you paired this up with the Tamron, you'd have 28-135mm covered with just two lenses, and both provide great IQ.
5. The FA43 or FA77 for their sheer IQ. Every Pentaxian should own the FA77 at one point or another.
6. For macro work, the DA 35mm offers true 1:1 magnification and also serves as a good wider portrait lens.

These are my suggestions. Any lens in the LIMITED, DA or DA* series is usually great glass. It's a good place to look in when uncertain. No one will be able to offer you the best because as I've said, best will depend on your needs.

Good luck and happy shooting!

[Bestzoom]

My best lens is the one that stays on my K5 and travels with me wherever i go.
For me, it is the FA 31 Ltd. I use a Sigma 50 f1.4 for portrait when i need autofocus. For portrait of my kids, i use M8 and 50mm Lux.

[RioRico]

No matter what you paid for them, the best lens is the one you use, and the worst is the one you don't use.

[bossa]

No matter what you paid for them, the best lens is the one you use, and the worst is the one you don't use.

The only way to answer that reply is to ask you to rate all of your work and see what the %'s come out to in relation to the number of shots taken with each lens. You might find that you've taken 10 all time classics with a lens you've only used 10 times and an ocean of crap with your favorite lens. I'm not speaking of you personally RR.

Answering the OP: The only way you can have an meaningful answer to your question is to buy a number of lenses, take a lot of photographs and then figure out what works for you on your own. People here offer great advice but only you will know what it means when you try it. Everything exists, or not, within the meaning.

[Chex]

Sharpness FA 43 Ltd or DA*55.. the DA*55 I would imagine has faster AF than the 43 as well.
For an overall performer it's hard to not throw in a DA 15 Ltd in the mix, some of the most amazing shots in the forums are from that lens IMHO.

[TOUGEFC]

Sharpness FA 43 Ltd or DA*55.. the DA*55 I would imagine has faster AF than the 43 as well.
For an overall performer it's hard to not throw in a DA 15 Ltd in the mix, some of the most amazing shots in the forums are from that lens IMHO.

Both the FA43 and DA*55 are incredibly sharp, honestly I cant tell which one is the sharper lens.
As for AF, the FA43 is faster but the DA*55 is more accurate and does better in lowlight and is silent. (I get more keepers with the 55)

[Ben_Edict]

Hi to everyone!! .. I am of the lucky ones who got K-5 I want to know what lens is more better for my camera.. I mean about Sharpness and Autofocus ..example like Tamron AF 17-50mm F2.8 XR LD Aspherical IF SP or smc PENTAX FA 50mm F1.4 i don't care if is zoom lens or Standard, i want the best in the market independent of the price..The best lenses made ​​from pentax....

There is no best lens.

Lens design is always a compromise. One lens may be exceptionally sharp, but has lower contrast. Or it may be ueber-sharp in the center but has severe loss of sharpness in the corners. Or it may have wonderful colours but a poor bokeh etc.

YOU need to decide, what you need that lens for. Is it your standard lens or a lens for taking portraits or for macro photography? Or do you want to make detailed shots of birds in the distance? For each occasion there might be one best lens, then.

Ben