[Schmidt]

Hello. I just bought a Pentax K30 body and find myself in a bit of a dilemma: I can only afford one lens for now and I've narrowed it down to either the Pentax DA 18-55mm WR or the classic Pentax M 50mm.
On the one hand, a prime often delivers superior image quality and larger apertures. On the other hand, the 18-55mm seems resonably well designed and constructed, offering versatility and the luxury of auto-focus. It's also weather-sealed.
Lately I've been doing close-up portraits (human and other), and a 40mm prime (on a borrowed Canon) really did the trick; I suspect a 50mm focal length would be just as good. But... I would like to expand my repetoire to include some nature (mostly botanical) and urban (some call it street) shots, and I do enjoy experimenting with different scenery; for example, I would like to photographically document some historic buildings under certain lighting conditions. Here either lens would present its distinct advantages.
I'm stuck between the two and the one I choose will be my primary lens for the next couple of months. Any recommendations?

[Sagitta]

You can get the 50mm for almost nothing, unless you're going for a 1.2 or 1.4. If you have the cash for the 18-55mm, get that, then skip lunch for a couple days and pick up the 50mm.

[jimr-pdx]

I've had good 18-55 copies and can recommend it. Its major issues are distortion at the wide end (correctable, though it's OK by me) and copy-to-copy variation. Kit lenses don't get the full testing of higher end lenses, I presume. Get it from someone with a return policy, and enjoy what it can do! The other bonus is that it will seal your kit against common moisture, which allows for far more imaging opportunities.

And while seeking an SMC-M 50mm don't forget Sears, Rikenon and other such; I've had excellent luck with them for under $40 (f/2 for $26, f/1.7 $36).

[Sagitta]

And while seeking an SMC-M 50mm don't forget Sears, Rikenon and other such; I've had excellent luck with them for under $40 (f/2 for $26, f/1.7 $36).

I think my order went $16 (Sears 50 1.7), $15 (a differently built Sears 1.7), $15 (Sears 50mm 2.0, bundled with a camera, had a PKA 135mm and a flash unit incuded), and $33 (Pentax-M 50mm f1.4, bundled with a junky ME along with a bunch of junk lenses, - I got lucky).

So again, echoing to get the 18-55mm lens. You can get 50mm primes cheap if you keep your eye out for them.

[calsan]

There's no way the 50mm can be made useful for architecture photography, I would want at least 15mm wide angle, but the 18-55 can be acceptable. The 18-55 is very good at 18-35mm which is a useful range, beyond that, the slow aperture means there are better (albeit less convenient) options.
The quick shift focus is great feature. It also means you can manually focus in movie mode without having to remember to turn off autofocus first.

In your situation, I would get the 18-55, then get a 50mm later. Maybe consider getting a 35 or 50mm macro, because it will add a lot more versatility to your set up, particularly for nature photography, than a regular 50mm.

[Schmidt]

I am convinced. The 18-55mm comes first - despite being the more expensive option.
Thank you for your input!

[Adinfinitum]

I am convinced. The 18-55mm comes first - despite being the more expensive option.
Thank you for your input!

I agree,

I love my m50 f/1.7 - it is by far the best portrait lens I own but it isn't the most versatile. I know I still need to learn how to use it better but if you want to branch out from portraits, then you'll find more satisfaction with the zoom. Also, as others here have said, if you keep an eye out you might find a decent used M50 for lunch money

Good luck.

[prime.partisan]

Have you consider settling in the middle for a DA 35mm f2.4? I've seen great people as well as landscape pictures from that lens. It's versatile while getting great IQ. A used one goes for about $150.

[Na Horuk]

Yeah, the 18-55 is not a great lens, buts its a very useful lens. Just make sure you get the WR copy, because you have a WR camera.
A 50mm f1.7 or 50mm f1.4 will give you much better IQ than the 18-55mm, but its probably better to start with a zoom so you don't get frustrated because the lens is too tight or too wide for what you want.
What might be an even better choice is the 18-135mm WR. Slightly better IQ than the 18-55mm, much longer reach..

But I do love primes and suggest you get one right after a base zoom

[ignmar]

18-55mm is pretty good lens but if you just do human subject i'm thinking about 35mm f2.8 and 50mm f1.7 or 1.4 both got pretty low price for used tho about 50 - 60 dollar each.

[mickey]

For what you want to do with the lens, I would say the 18-55.
Whether or not that's the better lens of the two is another story, but it is more suited towards what you listed.

[wombat2go]

And consider flare when taking architecture photography into sun
I just took a couple of comparison photos into the sun, but the sun is not in the frame.
Both lenses are in good condition with no scratches etc and filters are not used here.
The lens hoods are about same length. Both lenses at f/8.

Here is the 1980 kit lens, the SMC pentax -M 1:2 50mm.
It has a Takumar 135mm hood via a 58mm adaptor
https://app.box.com/s/izcv2q8akxhdh1ajxwuk

Here is the 2004~2006 kit lens, the SMC Pentax DA 1:3.4~4.5 18~55mm
https://app.box.com/s/xnir6j5sp99sdf05g6vs

The 18~55 is a convenient lens and takes great shots but here it looks like the 25 year older -M lens has much better contrast and flare resistance when sun is in adverse position.

[Schmidt]

First of all, thanks again all who replied. You have provided me with differing viewpoints, all with a good amount of detail.

Let me begin with the 35mm prime - I'm just starting out so my facts, which have been mostly gleaned from various sites on the internet, might not be accurate: My understanding regarding focal lengths below 50mm on an APS-C system would result in facial distortions when taken close to the subject. This is why a 50mm, as far as I can tell, is considered to be good for portraiture. Intuitively I see the reasoning behind this statement, but I can also imagine a good lens of shorter length cutting down on this type distortion. Any thoughts?

I've looked at the two pictures of the house posted by wombat2go (by the way, this is what I meant by building photography - I wasn't planning on taking wide-angle shots of interiors and I wasn't clear on that point). Aside from both being good shots of a character home, the 50mm prime does seem to do a better job of retaining lighting detail, and the house looks like I would imagine in its surroundings; as expected the 18-55mm can provide better field of view. Thank you for taking the time to post the comparison, wombat2go!

As other posters have suggested each has its place. Optically, the prime looks better. Practically, the zoom might be a better option. So I just might spend my entire year's camera budget and get both. I've seen people use a combination of the Canon 18-55 kit lens and either one of the "nifty fifty" or 40mm STM primes, and never need another lens after that.

Considering a Pentax 50mm MF can be got rather inexpensively, this combination is making more sense to me. Guess I'll be skipping a few lunches, and looking forward to it.

[ScooterMaxi Jim]

I think you are approaching it very intelligently given your inexperience. I have only a few things to add for your consideration. If at all possible, choose an A-series lens 50mm rather than an M-series - it will give you easier and more-accurate metering than having to use the green button for stop down metering; and you will have the opportunity to learn all the automatic metering modes not available with the M-series. You are best off with the f/1.7 lenses (Pentax), but the f/2 will be pretty close in quality (the f/1.4s aren't worth the extra expense when you're on a tight budget).

It is great to experience both types of lenses. You are absolutely right that the 50mm is a good choice for portraits, and they are excellent for low light situations, as well. When you add a kit zoom, you'll quickly realize that they have very different uses even though both cover the slight telephoto end of it.

[Schmidt]

I was thinking this: If I were to add a circular polarizing filter to the 18-55mm lens, could I see a dramatic improvement in image quality? For example, would the polarizing filter make wombat2go's shot with the kit lens look more like the one taken with the 50mm? And how would it affect IQ throughout the entire zoom range?