Each one was AU$2.20 each, so a full set of 9 would be about AU$20.00 or about Euro13.20.

I'd never noticed a shim in my K10D previously either, but I just checked it and sure enough there is one there!

The shims should be available from Pentax UK? I have purchased them from Pentax Australia and should receive them this week. I have purchased a set of 7 from .10mm to .40mm inclusive in .05mm steps, there are also .45mm and .50mm available.

I never knew that they had the shims until Rachael pointed it out to me and it is fantastic that they do, so now we can calibrate the whole focus system to correlate with each other. We can adjust AF via the AF Adjustment feature, and now the focus screen via shims.

Perfectly explained, Richard!

Here is a diagram of the various focus paths. To get correct sharpness in the VF that corresponds to the sensor image, L1 and L2 need to be exactly the same length. To achieve correct sharpness from auto focus, L3 needs to equal L2. For all to work together correctly, L1, L2 and L3 all need to be identical.

Pentax provide the AF Adjustment feature for calibrating L3 to correspond to L2. We now see that they also provide a way to calibrate L1 via shims.

Shims are inserted between the focus screen and the bottom of the pentaprism. A .05mm difference of shim thickness can be detected by a suitably fast lens, so I am told.

Here is a good link for explanation:

http://www.focusingscreen.com/work/test-fsen.htm




Here is the shim from my K-7:

Apparently, this has been discussed here before, but I thought I would post my experiences with my K-7 with regards the focus shims and Katz Eye screen. I never knew there were focus shims used for calibrating the focus screens of the Pentax DSLR's. I did know there was a shim for the DS(?), but I thought that was just a locating shim or some such thing. Anyway, I posted this over at the "other forum"

I just purchased a Katz Eye focus screen for my K-7 and received it yesterday. The screen is a ground glass screen with 1/3rd grid lines for composition and Opti-Brite treatment. There are no other focus aids other than the ground glass screen, there is no split prism or microprism collar.

This screen is wonderful as it is simple and very effective for getting that "snap intop focus" look throught he VF.

I did some preliminary tests as far as exposure and manual focus accuracy. Exposure looks spot on but I noticed an issue with the manual focus accuracy. When the focus is correct in the VF, the resultant recorded image on the sensor was focused in front of the intended target. This was using the A50mm f1.2 lens which will obviously have very narrow DOF and allow such accurate focusing ability.

My first thought was that the focus screen is too thick and therefore the image was being focused in front of the correct focus plane, but on reflection and talking to Rachael Katz from Katz Eye, this is of course an incorrect assumption. Silly me!! The focus screen thickness is irrelevent as the focusing takes place on the ground glass surface which is on top of the screen next to the pentaprism, just the same as the original screen focus would be and therefore has no bearing on the issue.

My second thought was that the pentaprism is out of calibration, but Rachael Katz advises that there is a shim between the focus screen and the pentaprism bottom face and these shims come in various thicknesses so as there is adjustment available!

I removed my shim and measured it and found that it was .40mm. When removed, the resultant image target recorded on the sensor was now behind the focused target image in the VF by about the same margin as it was in front with the shim installed.

So, it would appear that the correct shim thickness should be about .20mm to .25mm and this is borne out by what Rachael Katz has found with her dealings with the K-7. Apparently, some K-7's are shipped with the .40mm shim and some with .20mm and .25mm. It looks as though mine should have been with the .20mm or .25mm shim and this is why it is out of calibration.

Rachael also states that using the Katz Eye screen due to it's excellent focusability, you can see where even as little as .05mm can make the difference whether you have the focus accuracy exactly spot on! I would suggest that you need a very fast lens to utilize this sort of focus accuracy with the Katz Eye screen, probably sub f2.

What I did notice is that the DA*16-50 f2.8 lens was less susceptible to slight focus inaccuracies due to the extra DOF, but it would still be advantageous to have the correct focus shim applied. I think my point here is that you are less likely to see focus inaccuracies with an f2.8 lens or slower than if you used a faster lens(obviously).

The Katz Eye screen seems to give better focus "snap" and therefore better focus accuracy, me thinks. I mean, I never really noticed that I had any focus inaccuracies previously, but using the Katz Eye certainly pointed it out quite easily. Maybe this is why a did get a few ever so slightly misfocused shots (but within realms of acceptibility) previously and put it down to user error. The "inaccuracies" may be, and probably are, masked by the extra DOF afforded by using smaller apertures like f4 etc.

If your shim is incorrect, this may also play a part in any focus anomolies experienced when trying to adjust for AF Adjustment and why some people find it difficult to accurately get correct AF using the AF adjustment feature. I am not saying that the shim issue is prevalent, but it may be worth checking if you are having any issues with focus and discount this part of the equation.

It is a reasonably simple exercise to swap shims and not much different to changing the focus screen, if you are reasonably competent. I would be very careful when doing it as you may damage the bottom of the pentaprism if you are not careful. Use a plastic set of tweezers rather than anything metal. Katz Eye supply an excellent set of plastic tweezers for swapping the focus screen, so you can utilize this for the job.

Wow! That is very impressive. One of the most beautiful cities, except for Sydney, and my favourite city to visit.

John, yes you are correct, I forgot about the round diaphragm of the new lens.

I went from the K20D to the K-7 and couldn't be happier. I love the smaller camera and slightly better build quality of the K-7, plus the better user interface of the menu system and the 100% VF. There are slioght speed advantages too. I also just sold me K20D, so the upgrade cost was not too painful

As far as I know, the DFA100 f2.8 WR is exactly the same lens formula as the previous DFA100 f2.8 macro which has superb sharpness and excellent bokeh. I would say that the bokeh should be the same.

Yes, as Mongoose states, any attempt at magnification is at the expense of brightness.