I think Gary's comments should be taken with the consideration that he is a working pro in a very challenging environment for his gear. As such he needs the best gear he can get to make his work easier and more lucrative. Unless you need to reliably bring home the bacon it may not be an issue (and if you have to - the cost of an II/IIs is probably insignificant).

I think the problems described in this post are the reasons I haven't tried to calibrate my lenses. There are so many variables (especially when using zooms), that it seems it could be an endless process. Not least the area covered by the chosen AF sensor could include areas at different distances from the camera.

I've sometimes been disappointed with general sharpness from my DA 17-70, at other times it's fabulous.

I'll have to try that! It focuses down to 0.14m (which is pretty much the front element - if not careful you'll hit the subject before you realise).

EDIT - If you think #5 is mad, I've just tried it on my Z-1 (obvious vignette probably from the hood) but I can't wait to get some film and try it. For anybody who has this lens, a suitable, cheap film body might be worth obtaining.

Thanks John. Yes I should have dropped the last one back a bit (I'd spotted that was a bit 'over' - at least the clouds do). It does show some purple fringing around the clouds, but overall very impressed with it.

Thanks for the comments, #1 is shot at 17mm and the rest at 10mm.

Smeggy - thanks for the comment, I'm using a laptop and the brightness changes depending how far I lean the screen back - the graduated bars at the bottom help a bit though.

John.

It was useful in the days of film, where your ISO was limited by the film you had loaded (particularly slide - where your latitude of error is very limited). It still is useful if you need specific shutter speeds (capturing spinning propellor blades for example). Depending on the speed of the prop, the ability to fine tune the shutter speed for the right effect is very useful.

I set mine at 0.5 because it's faster to scroll from one end to the other, and any minor corrections can be done easily in post.

John.

It'll do curves like the best of them if given a chance. In the shot below, the quay along the bottom of the frame is straight:



Canal barge by John Halliwell, on Flickr

I don't understand the issue. The only variable can be the camera body (lens mount, AF sensor & focus screen alignments). The AF system from the SFX onwards (maybe the MEF for all I know) is supposed to continually feedback to get the least phase difference between the two 'halves' of the sensor (i.e. the most 'in focus'). The only other explanations are that the AF system doesn't feedback to increase AF speed at the expense of accuracy or that the resolution of the AF stepper motor/mechanism isn't precise enough!

Any variation in the lens should be taken care of with the feedback in the above. The only difference could be whether the lens is focusing from in front or behind the subject (i.e. which edge of the DoF it hits first).

It may be that the body needs adjusting differently for different focal lengths, but this shouldn't be necessary for different copies of the same lens (unless there's something very inconsistent with lens manufacture).

The cameras and lenses are built in a very precise manufacturing environment, any variations are going to be far less than any variables introduced by a 'user' test except using the most controlled laboratory tests.

It's like paying a fortune for a new car then taking it round to your mates garage to have the suspension lowered because he knows a lot more than the manufacturers who spent millions designing and testing it in the first place!

I'm confused by the whole thing to be honest:

Two different threads for the unboxed (boxed?) lens and the flashgun. A further thread for them both together (stating possible trades with two Pentax & one Canon camera), and it also turns out the flash is on ebay...

I think the various threads should be consolidated to clarify things.

John.

Thanks Stuey,

Keeping the horizon in the middle of the frame helps, as does picking a subject that doesn't have obvious straight lines. I was surprised too, although in some you can see the distortion (outer pylon reflections in #1 & life ring post in #3, for example). I think the clouds help add interest in the sky too.

John.