Again very interesting, the Olympus must have been a real knife edge design.

Steve

John, I agree with your comment, but at the time of these test in the early 80's I think people paid far more attention to these figures and so you would presume that the manufacturers were very diligent in ensuring that 'good' copies were sent for test. Also 28mm was a very popular focal length at the time, so considering the volume sold I would have expected the manufacturing process to be very well tuned.

Do you have anymore comparisons 85mm , 135 ect ?

Regards - Steve

Interesting as my personal experience with the 'M' and 'A' series 28s has been slightly dissappointing. I used to have a K mount Vivitar that I much preferred. John do you have decentering figures for the 28s ?

Regards - Steve

I am surprised by this as I thought it was the other way round, i.e primarily Tokina designs with input from Pentax. Were not the lenses available in other mounts before the Pentax versions were released?

In terms of coatings I really do wonder nowadays if there is a significant difference in coatings. If Pentax are supplying the glass, which I believe to be the case, then it would make little sense to run separate production processes. Volume has a huge effect when it comes to lens manufacture. It is why pricing lenses beyong the reach of most of your user base is such a flawed strategy.

I am pretty sure that the Pentax badged Tamron 18-250 was assembled from Tamron components. It explains why Pentax made it obsolete when Tamron replaced their version with the 18-270. Pentax have used Tamron designs in the past 28-105 version 2 and the 28-200. It is my understanding that the arrangement with Tamron is tactical, lens specific and one that Pentax utilises periodically to fill a gap in their range. I am not sure if the arrangement is Tokina is really a joint venture, but it is certainly more strategic and I am sure whoever takes the lead that information flows in both directions.

Going back to the point made in the original post I would be all in favour of Pentax manufacturing a range of primes in other mounts as it would/should drive down manufacturing costs, lower prices for Pentax users and increase profits, which in turn would fund R&D and marketing.

Regards - Steve

Thanks for that John, I admit to being a data junkie and these sort of things really interest me.
It is this sort of in depth information that I would dearly like to see in the lens database that I mentioned in the 'mentoring thread'

Regards Steve

I have said this before but think that a great number of commonly recuring questions/problems could be handled with a revised/revamped sticky section.

Thinking about this further I will throw out a few ideas

1. Camera Setup, it has always struck me as odd that manufacturers do not include a setup video in the box. How many questions do we get asking 'how do I set this up' or where do I find that option. Plainly lots of people have problems with manuals. If bandwidth is a problem then maybe we can create a PentaxUser DVD, which users can buy for a nominal charge.

As a starting ponit it should not be too difficult to create a video for each Pentax model.

2. When I think of video I think of Don over in Winnipeg. How great would it be to have Don guide you through some of the improvised setups that he has shared with us. I am sure that there are a whole range of subjects/topics that could be included.

3. Structured Meets, following on from John's idea. For example, a topic is chosen and one or more people agree to hold a masterclass. A venue/venues is/are chosen and members can then register to attend. A charge could be levied to reimburse the 'mentor' for his time and to cover costs.

4. I too like Peter's idea, but I will throw in another twist. What if the poster asks for replies via pm or to their email address (this would allow attachments to be sent). The original poster can then read through the responses in private, without fear of embarrassment. The stipulation being that he/she should then compile a post that summarises what was useful, so that it then becomes available as a reference source for all users of the forum. Due acknowledgement to contributors should of course be included and their permission obtained prior to posting. This might sound complicated at first, but it is quite simple to setup. I have created several 'Word' documents with snippets from threads that I have found useful.

5. Following on from the point above and on a similar theme I see great benefit in expanding and building upon the work Matt did with his Flash and Silkypix guides.

6. Finally and I know this has been mentioned before, but I really do feel that it is time that this site had it own lens database, that allows users to post comments to.

Regards - Steve

For your information

I rechecked focus on FA 31, FA 35, FA 50 and FA 16-45 lenses at the weekend.

Camera on tripod
SR off
3 second remote delay
Centre spot metering
Natural daylight
Lenses manually turned to extremes of focus and then refocused using the remote.
Focus confirmation 'beep' on and heard before every exposure.
DA 16-45 tested at both extremes of focal length.
Latest Yvon Bourque charts used

My focus setting from previous adjustment was +10um.

With the exception of the FA 31 all lenses showed the slightest degree of front focusing. If it had been just one lens then I might dismissed the results, but with 3 lenses showing very similar results, I changed the camera back to +/= 0um. This leaves me with a Fa 31 that is backfocussing, but a repeat of the test at F4 and the results are acceptable, so I can live with that.

Steve

I echo the comments above and respect your choice. Good luck with your future endeavours

Regards - Steve

Thanks for posting the link Amin.

The review is pretty balanced and unlike most I have read provides accurate factual information. The guy obviously used the camera before writing the review.

Looking at the example shots I am most impressed by the shot into direct sunlight.

Regards - Steve

This item is now provisionally sold.

Regards - Steve