*ist D/DS has the worst AF ever made in any (Pentax) AF-SLRs!

Started Dec 29, 2005 | Discussions thread
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RiceHigh Senior Member • Posts: 2,764
*ist D/DS has the worst AF ever made in any (Pentax) AF-SLRs!

Whilst I just wonder why I have had got so many out-focus photos with my Pentax fast prime lenses when they were wider opened, e.g., my FA 85/1.4 and also the FA 43/1.9 limited, and that my Pentax Japan "repaired" *ist DS (takes two months time) still gave me totally Front Focused and Back Focused photos when today I took photos under daylight but with the lenses, I have decided to check how this really very head-aching problems could occur from time to time. And, below is my findings which indeed is extremely shocking (but very unreasonable too for what I have found):-

1. I turned each of the prime lenses to infinity and then focus on a object at mid-distance, say, 6 feet. I attach a photo of the focus scale of my 43 Limited lens for your reference:

2. Then, for the first photo taken (AF starts from infinity), the focus of my photo appear somewhere beyond the 7 feet mark and the photo was (of course) found to be Back Focused;

3. I repeat to turn in MF the lens focus scale to the closest side and then take the photo and then found that the focus arrived at near the 1.5m mark which is equal to 4.8 ft. Of course, I got front focus photo when the lens is wide opened;

4. I then re-mounted my Limited lens to both my MZ-S and my MZ-30 (which costed me only US$180 in the Y2k) and repeated the tests above and found that the focus always arrives at about 6 feet as shown in the above picture!

5. I repeat the test for so many times and all the results are exactly the same - that is: the *ist DS always give BF and FF errors depending on the rotating direction of the AF; and that the MZ-30 and MZ-S always gave accurate and correct focus under any conditions and I must remark that the AF of my MZ SLRs achieved clearly faster than the DS too.

I MUST tell YOU ALL here that the whole case found is super ridiculous and Pentax is totally unforgiveable to make inferior products like the DS with the AF error like the above. I have a strong feeling that my money was cheated by Pentax and now that this manufacturer is simply irresponsible. Even worst, my long-time brand loyalty to Pentax plus my long time investment/selection/collection on my Pentax lenses have been all in vain.

Actually, my last on-loan DS unit was found to have exact out-focus AF errors most of the time but now that my fully checked and straightly calibrated *ist DS by Pentax Japan, i.e., the manufacturer's principal, is still having unforgiveable problem as described above. So, what's the conclusion, the design of the AF SYSTEM used in the DS (and D uses the same AF system) is VERY POOR and I think I have to use the word "junk" or "rubbish" to describe it, though I indeed feel very obliged to do so.

I now also know that it is highly probable that a very good reason for why Phil Askey always found that Pentax DSLRs to have lower resolution in his reviews and tests: - It is just because it is obvious that large AF errors can easily cause resolution drop, significant! especially when the AF errors are so large.

My heart is now fully broken with this rubbish AF system found in the two *ist DS and my 3 ex-*ist D bodies which was marketed as an advanced amateur model (I can't verfiy this with the D with exactly the above simple test, though, as I had sold my last *ist D in August).

I now have NO MORE HOPE WITH PENTAX and I shall sell all my Pentax gear and moves to Nikon or Canon very soon. I think I have given TOO MANY CHANCES TO PENTAX and WASTE too much of my valuable time during these two years with Pentax AND the WORST THING IS I HAVE GOT TOO MANY OUT_FOCUSED PHOTOS JUST BECOZ OF PENTAX DSLRS' GEAR ERRORS!

I shall write a detailed test report on the above in my homepage very soon so as to let the public and everyone on the Internet community knows that this problem exists with all the latest *ist D series Pentax cameras I have used and let anyone knows when they are deciding to get any *ist D series DSLRs or not. Or, simply I think I should let all existing *ist D/DS users to know why they got out-of-focus photos when they should see them some days (if they ever have the chance to use fast primes) and just wonder what have been going wrong all days: I can surely tell it is not the user, but just the manufacturer!

My honesty tells me that I must tell the world without any reservation for what I know, especially this is totally ridiculous for Pentax to make latest SLRs like that. I feel extremely upset for a once responsible camera maker who made quality cameras but now make stuff like that instead and have changed to a such poor commerical ethics.

Of course, I promise I shall go back to this Pentax forum to tell anyone interested in any AF problem related issues in the future and I think this is my duty to let anyone knows the truth and to help any unfortunate Pentax DSLR users when they may sooner or later face the trouble. (I now totally understand why Wally Oz still reads and posts here - he is a honest guy with good-heart afterall). But all in all, I think I must be one of the most unfortunate Pentax DSLR users here as I have used Pentax gear for near two decades and I am still forced by Pentax to leave them.

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