Dilema

Greetings! I just picked up a K-5 for work and absolutely love it. However, I am noticing the focusing can be a bit corky. I'm not sure if it's the Tamron 70-200 f2.8 or the camera itself. Sometimes it just seems like it gets "stuck" focusing and can be a pain. However, I'm not sure if this problem would happen if we had actually purchased the top shelf Pentax lens.

Anyway, I love the camera so much I'm thinking about getting one. I currently shoot a Canon 60D and am thinking about making the switch, but since I shoot concerts, I'm not sure if the focusing problem is going to get in my way or not.

So I'm thinking.

Purchase K-5 and get 50-135 lens (Great reviews except some CA at 135)

Keep my 60D and buy a 70-200 canon f/2.8 lens and fork out the money.

Or buy a 70-200 f/4 canon lens.

Sorry of this seems like any other post, but I'm concerned.

I've also heard "problems" with the Pentax SR, but it seems to be working ok for me.

I'm pretty sure I need some sort of stabilization since I expect to shoot down to 1/60 second zoomed out.

Anyway, who do you think??

Oh, and cost is always a consideration or I'd just drop the money on a 5Dmk2 and a 70-200 IS II lens.

I don't think we can compare POentax with a tamron lens to canon with a canon lens, it needs to be Pentax with a Pentax lens to be a fair level playing field.

Plenty of people shoot concerts with all marques, and as you do that already you'll have a fair idea what it's all about. Perhaps you need to hire a camera and lens to make sure it suits you. If in the UK, SRS do this.

As for stabilisation, SR works just fine, but of course does nothing for subject movement. The high ISO performance of the K-5 would allow you to use much higher settings and still get the results you need.

Fair enough. I just wasn't sure how the k-5 does in the field with it's own lenses. I should probably upgrade the firmware too.

Greetings, I run the Pentax DA*50-135 on the K5 also. No problems here with this combination.

Even with your existing lens though, there is some diagnosis needed for you to get to the bottom of this.

Assuming this is not merely about the length of time the system takes to 'lock on', then read on... Hopefully you won't take this as someone telling you how to suck eggs...

Try it on a tripod using 2 second delay / mirror lock-up (SR will automatically switch off when this setting is used), so you can eliminate other factors - is it still happening then?
When hand-held, is your shutter speed sufficient to avoid shake at the focal lengths you use?
It would be useful for you to find out if the lens is focusing to the back or front of your intended target, and by how much.
Then, if there is some AF adjustment required, the K5 can be adjusted for focus correction on a 'per-lens' basis.

If being 'corky' is instead about AF inconsistency, then you'll need to sure about where the lens is focussing - which focussing option have you selected? Try the above tests with AF selection set to Centre rather than Auto, that way you know what the AF is homing in on.

hth

I think firstly you need to say in what situations the AF has been a bit off (not finding, or slow to find focus, or just not accurate) ? When you say for work do you mean at concerts or .... ?

The Tamron 70-200 should easily be faster than the Pentax 50-135 which is probably the second slowest SDM lens in the Pentax armoury. And the Tamron should also be faster than the beautiful Pentax DA* 60-250. If you want to trade off faster focusing for a little in the sharpness dept (not much) then go for the Sigma 70-200/2.8 instead.

The K5 should certainly outperform the 60D in concert conditions (and many other conditions) and with the Sigma you may have a winner. Another lens to consider (if you can still find one new, if not then used) is the Sigma 50-150/2.8, very sharp, quite fast and with quiet focusing.

It's not really an accuracy issue. (Though I have calibrated it to a T yet.) It's more of it getting stuck out of focus completely and me having to point it at the ground and focus..then focus back or grab the manual focus just to get it out of the "bind."

It's not a noise or speed issue either. I knew that wasn't going to be great when we bought the lens.

I'm probably going to go for the or tax anyway. The 50-135 focal length on a crop sensor is really what I want and need.

(I'm using a 50mm prime ATM.)

Could you be trying to focus on an area with no detail like a white wall or a cloud?

I did that the other day and it doesn't find focus. It will just cycle the range and then stop out of focus and let me fire.

Sorry...I didn't mean for this to turn into a troubleshooting thread.

The man to talk to is Cabstar, he seems to have nailed concert photography.

No doubt he will contribute to this threas as soon as he see's it I think I'm right in saying he mainly uses the DA*50-135.

It won't. There are a variety of situations outlined in the manual where AF doesn't work which include low subject contrast, horizontal lines like Venetian blinds and so on. This is normal behaviour.

Thanks for the info!

Only the two outer AF points on the sides have this problem, the 9 points in the middle are cross type and sensitive for horizontal lines and vertical.

I bought the K5 also for concert photography because with the K10D it was quite hard.
I use the DA*16-50 and the DA*50-135 and have no problem with autofocus with mine but that doesn't mean you don't have a problem with yours though.

Thanks, that is good to know. (I only use the center focus point anyway.

However, do you find the 50-135 to focus slow? I think someone just mentioned that.

I was also considering the Sigma 70-200 f2.8 lens. I've heard good things about it. (Even though a little longer than I would like.)