K-50 & 18-55mm AL WR lens image quality

Having previously owned a Pentax Spotmatic and a Pentax P30 I recently bought a Pentax K-50 with a SMC Pentax-DAL 18-55mm AL WR lens. After my initial delight in handling a Pentax again, I was disappointed to find that the sharpness of the images was no better than my ten year old compact camera. Initially I thought that the less than positive reviews I have read about kit lenses must indeed be true, but after a while I just couldn't believe that with so much more glass the image could be relatively poor.

I returned the camera to Pentax service who adjusted the back focus. The images taken with the 18-55mm lens are now better than the compact camera, and appear to be the equal of images taken with the SMC Pentax-A 50mm prime lens from my P30.

I have read elsewhere about quality control problems with current day Pentax cameras, so if you suspect something is wrong with your new Pentax, my advice is to get straight back to them and ask for it to be fixed.

Could you share some before and after pics please?
Just interested to see the difference you are referring to.

Zoom by 100% and look at the road sign in the centre of the picture. The before picture was taken on a day with light cloud, the after one was taken on a dark cloudy day, with a slight mist, which to me makes the improvement all the more remarkable.

Hmm. I'm new to this forum, so maybe I've not done this correctly.

The images I sent were each about 7mb. The ones on the forum are 500k. With that reduction in size and resolution, I don't think you will be able to see the differences I was referring to.

may i ask was you on the same setting

if so you can tell by the beach hedge for starters

Yes the forum does downsize images; but I can see what you mean even at this size on the street name!

In both cases, everything was set to auto and resulted in:-

Before - f5.6, 1/100 sec, iso 100, 50mm

After - f8, 1/80 sec, iso 200, 50mm

Yes, on the 'before' image the street sign has an odd halo around it in addition to being blurred.

To me it looks as if all that was needed was a bit of fine AF adjust tweak - in the first frame it was front focusing. Also with that lens f5.6 is just about wide open at 50mm, the extra stop in the second shot will make a difference.

My DA18-55WR still gets used

Are you saying that they corrected the AF in addition to correcting the back focus (whatever that is) that they say they did?

There are a number of factors at work. One is that compact cameras are over-sharpened and will often look crisper than a DSLR image, which is intended for further processing. This tweaking can also be done in camera using the parameters for JPEG files.

There could also be some camera shake involved causing a softer image in picture 1, plus the lens will be sharper stopped down to f/8 compared to f/5.6.

However, adjusting the AF is commonly done these days and can make a big difference. It's not always necessary by a long way, but when it is it's worth attending to.

The need to adjust for front or back focus is NOT a quality control issue, simply a function of mass production. Camera bodies and lenses are made within certain tolerances. When you combine a body and a lens you're as likely to get back or front focus as not. Sometimes the resulting effect will be very obvious, sometimes not.

Perhaps what Pentax should do is make the likely need for adjustment more obvious and easier, as many new togs, or togs not familiar with DSLRs, simply won't know about the need to do it, or how.

Could the tolerances be made tighter by adjustment before leaving the factory? Of course. But this will result in more expensive bodies and lenses.

I would agree with John, the whole of the focus on first shot is not a patch on the second which as John suggests may suggest an element of camera shake.

The lens is a much underrated one, and you will get fine results with it.

Hi, My first post on this forum, yes I will introduce myself in the newbies section shortly.
I use my DA 18-55 AL lens on my K50 quite a bit and I like it a lot. I only shoot in jpeg as I don't have LR or any raw editing programmes.

Here are a few pics using the 18-55mm. The sunrise is two images stitched together.

Hi, yes the K50 with the kit lens is a good combination; I was also surprised to discover how good the inexpensive 50mm f1.8 lens is on this body, exceedingly sharp. I especially like your second pic, nicely framed.