K5 - AF Fine Adjustment function

I am trying to get my head around the AF Fine Adjustment function on the K5 (page 126 of the manual). Is this used to sharpen images at capture where the auto-focus on some lenses can be a bit 'off' ? If so, is this preferable to (say) routine sharpening for RAW images in Lightroom ?

If anyone uses this function, what settings do you use on the K5 for the following Pentax lenses :

15-50 DA WR
17-70 AL(IF) SDM
55-300 ED

Many thanks
Nigel

It's not possible for anyone to give you the number to set because the function is there to fine tune any lens which doesn't focus spot on. In other words, to correct for manufacturing tolerances where necessary.

If you don't have a focusing problem then it doesn't need doing, but if you think your lens(es) focus a little forwards or backwards of the correct spot then you can make an adjustment for up to 20 lenses. The cameras will know which one you have fitted and will apply the adjustment.

There are a few threads already on how to do this. It is quite different to sharpening in Photoshop or Lightroom which is sharpening to make up for any slight softening of digital images. This is about whether or not you are focusing accurately.

It's even possible for the same lens to need different adjustments on different instances of the same model of Camera. I have two k-5s and some lenses require a different adjustment on each cam, while other lenses require the same adjustment. Some lenses require no adjustment.

AF Fine Adjustment is there to enable you to correct for minor focusing inaccuracies on a per lens basis (up to 20 lenses) if you need to. It does not compensate for softness.

In truth, these focusing inaccuracies are more noticeable when using fast lenses wide open, which is why the adjustment is made with images taken with the lens wide open.

It's entirely possible that you might not even notice that there's a problem with the slower lenses, in which case I'd recommend you leave them as is.

If you want to play though, it's very easy to remove any/all adjustments made and revert back to factory default settings.

Yup exactly. There's nothing to break

Hi Nigel, I agree with the posts above; if you have a lens that you feel is not quite 'tack sharp' on your camera, it's worth experimenting with the fine adjustment. I have a 55-300 lens which is very sharp, however when I first got it I was disappointed as on my K-x all the images looked very soft, even when comparing them with ones shot with a Sigma 70-300 on my son's K-m (the 70-300 is not a patch on the 55-300). I then decided to try the 55-300 on the K-m and hey-presto it was so sharp it was untrue!

This prompted me to adjust the AF on the K-x (done via a secret debug menu). Since I got the K-5, the 55-300 needs no AF adjustment on this camera and is a very reliable and sharp performer. On the other hand, I have a Sigma 50-500 which needs a +7 adjustment on the K-5. There's no harm that can be done with the AF adjustment so there's nothing to lose!

Best wishes
David

Hi all,

I have a similar issue with the 55-300, I have just moved from a KR to a K5 and am just getting to grips with it (superb camera though) but am struggling to get really sharp images with this lens, they dont seem quite as sharp as on the KR. The thing is, do I need to set the lens to a particular focal length before adjusting the Fine Focus?

Regards.

I would see what settings it needs at 55, 300 and somewhere in the middle and what they are before making a decision on what adjustment to dial in .