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08-14-2009, 12:18 AM   #1
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Pentax AF Alignment/QC

I have finally got around to testing and calibrating my AF lenses with the k7.

They both needed adjustment:
da40 -10
da70 -3
They both seemed to front focus until adjusted. I tested then, mainly the 40, because it was useless wideopen.

I tested in sunlight and mixed(tunsten/incandesent) lights. AF performance was identical outdoors and underlights.

Anyway.... both of these lenses have a backfocus problem in my k100d body and who knows which way they would swing if i put them on my film bodies.....certainly won't be using them wide open on film.
On the k100d the 40 needed +70 and the 70 needed +30.

Someone mentioned in another post "maybe pentax lens prices are up because they realised they have to make each one twice". BTW, that is the 2nd 40mm (the first one could not be corrected with the bounds of adjustment).

I know that getting it 100% right is hard but......... isn't that what we pay for? Isn't the fact that lenses can be independently adjust in-body an confirming that 'near enough is good enough"?

Don't get me wrong, I love my pentax gear but why so much fiddling? Someone lesser skilled (in doing focus tests) will buy a 2.4 lens or even an FA 1.8 (or whatever fstop the 77mm comes in) and think it is just crap.... And they are the limited lenses.
Is that why there are so many pentax Manual focus shooters.

PS. one more thing, the K7 AF is a lot more consistent than the k100d. Nearly all shots are identical. There was a reasonable range in the k100d results.

cheers
mike


Last edited by schmik; 08-14-2009 at 12:50 AM.
08-14-2009, 01:32 AM   #2
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More thoughts on this....

Part of rant about the mis-alignment of the faster glass is the issue of trust. Certainly before adjustment I just don't trust the 40mm (and to some extent the 70) at apertures bigger than 3.2. So when you don't trust it, you rarely use it.

As the light available lowers you find yourself increasing the ISO rather than the aperture. I would open these lenses up as a last resort. That's not right is it?
Hopefully trust can be regained now that I have adjusted for their mis-alignment.

mike
08-14-2009, 01:50 AM   #3
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do you have horizon correction enabled ? try with it disabled if you do. i noticed my FA50 1.4 had a mix back/front focus AF if i had horizon correction enabled, disabled it was spot on with K-7 v1.01.
08-14-2009, 03:10 AM   #4
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Nope... definitely no horizon level.

As i said before, i am happy with my gear, and i'm sure we are more critical of our gear in the digital age... test shots are instant and free BUT i wish is was all built to tighter tolerances.

EG, focus should be within DOF. On the 70 is was nearly there but the 40 was way off.

mike

08-14-2009, 07:01 AM   #5
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Wise words.
Optical devices costs premium because theoretically it is precision equipment.
When you have to pay premium but don't get the precision equipment that should be manufactured at those costs, you star to wonder how much better it is compared to $100 point and shoot optics.
08-14-2009, 07:53 AM   #6
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Take heart in the fact that this kind of complaint seems quite common on forums dedicated to other camera brands as well. The end user is the quality control person.
Sometimes QC has to ship the camera back for adjustment.
Rather than complain about it, get used to doing it as part of the ownership experience.
08-14-2009, 10:19 AM   #7
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Cool, just another reason why I'll never touch a DA lens.
08-14-2009, 11:50 AM   #8
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QuoteOriginally posted by Wheatfield Quote
Take heart in the fact that this kind of complaint seems quite common on forums dedicated to other camera brands as well. The end user is the quality control person.
Sometimes QC has to ship the camera back for adjustment.
Rather than complain about it, get used to doing it as part of the ownership experience.
Unfortunate truth. But i cannot agree on getting used on it, because who else can make manufacturer increase their quality but buyer?

If every one thinks it is ok to expect 2 month calibration and several warranty service visits (submit item, receive it back, sometimes they ask you to come just to ask simple question they could do by phone, or need something trivial like a box) after each 500+ $ product buy don't expect it to become any better. Most likely seeing this manufacturers will lower their quality standards even more to cut costs, if the sales stays the same and no one protests actively and visible enough (like RiceHigh for example, he might be considered as a major Anti-Advertiser already, because almost every Google search will return him, many near the top of results, at the beginning i almost didn't bought Pentax because of him).

Or otherwise, if this is a clear path they choose and state that every X item can have small issues that should be serviced and are not checked prior shipping or change depending on end user configuration, then please provide simple means and few pages of description how to deal with them. I think it would pay back on item warranty shipping alone.

This is not like asking to provide means to fix de-centring problems or rewiring camera. Why cant all cameras have lens adjustment like k20d does. This is not an advanced pro feature, like high quality lens glass or scientific grade imager that adds actual cost. Just a software utility.
There are many things that can be addressed in a simple ways. If it is impossible to make perfect AF, which is fairly logical, what's so evil about split prism, that let you truly pick the object and fine focus on it.

There are two things you see now. First is internet giving the means for those who have problems express themselves searching for solution, when those without problems just keep taking pictures making the first ones majority. Second is ignorance from manufacturers, which for those having SIMPLE problems leave no viable options but disappointment in the field and cumbersome, time consuming warranty or return procedures.

I've a lens that probably needs some simple adjustment or part replacement, but no one is even willing to touch it unless i pay the same as the lens cost (the warranty is over already). And no one of them (local and foreign service centre) is giving me any warranty that they will be able to fix it first time.

08-14-2009, 12:10 PM   #9
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QuoteOriginally posted by K-9 Quote
Cool, just another reason why I'll never touch a DA lens.
??? What's the reason? Are you under the impression tha problems are more common with DA lenses than others? Do you have data to back up this impression? Seems much more likely the issue is simply that when the FA lenses were current, people never pixel peeped to the level they do now, and hence the sluight variances that have been normal since the dawn of AF went largely unnoticed. Today, people pixel peep and test obsessively, and since virtually all new lenses sold are DA lenes, any problems reported (including both real and imagined) are reported more often on DA lenses than others.
08-14-2009, 12:23 PM   #10
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Similar experience with my FA 50

As you may notice in my former posts. I have same front focus problem with FA 50 at f1.4 and I tried 2 K-7 bodies. Maybe we both got a lemon K-7. Mine was bought in Amazon and SN are: 3385138, 3386095. Could you share yours? I doubt this batch of production has that problem.

Thanks,
Tony
08-14-2009, 02:39 PM   #11
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QuoteOriginally posted by ytterbium Quote
Unfortunate truth. But i cannot agree on getting used on it, because who else can make manufacturer increase their quality but buyer?
The best option is to buy the product, note if it appears out of specification in some area and send it for warranty service. If the warranty costs become high enough that it is no longer viable to ship products out without QCing them at the factory, then the company will start doing proper quality control tests.
However, good QC is not cheap, and will ultimately add to the cost of the products.
Since we already bitch about how much these things cost (look at any thread regarding the DA*55/1.4, a significant number of posts are lambasting Pentax for the price), good QC will make the product less desirable.
In a world where people will base their buying decision on a 1500 dollar item on a 10 dollar price discrepancy, the manufacturers are in a tough spot.

Will you buy the K7 that most likely will be flawless for $1500.00, and will be fixed under warranty if it isn't, or will you opt for the one guaranteed to be flawless for $1600..?
08-14-2009, 03:12 PM   #12
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Actually i'd go for the second one. The assurance would be worth more than that. Especially for a 1600$ body.
But i'd never bought a 1600$ body. Its just not worth it.
Especially because it dosn't justifies the cost. It is more of a mostly unneeded software cost than actual technological improvements.
So 100$ difference to $500 body is another thing that may change my mind.

I guess you have not had much experience with good products turning out defective, the disappointment associated with it and following not so good warranty service.

That's what you expect when buying a product. It must have a production cycle ensuring complete product unless there are some unpredictable circumstances (like a defective part). If they need additional QC AFTER manufacture, this means the manufacturing process isn't ensuring correct assembly of product.
That's why it is still unclear to me and many others, how can AF, for example be correct for one lens but not for another.

Last edited by ytterbium; 08-14-2009 at 03:23 PM.
08-14-2009, 03:48 PM   #13
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QuoteOriginally posted by Marc Sabatella Quote
??? What's the reason? Are you under the impression tha problems are more common with DA lenses than others? Do you have data to back up this impression? Seems much more likely the issue is simply that when the FA lenses were current, people never pixel peeped to the level they do now, and hence the sluight variances that have been normal since the dawn of AF went largely unnoticed. Today, people pixel peep and test obsessively, and since virtually all new lenses sold are DA lenes, any problems reported (including both real and imagined) are reported more often on DA lenses than others.
It's not for this alone. It just adds to my other reasons why I won't buy a DA:

1-price
2-incompatibility with film cameras
3-no aperture ring
4-incompatibility with future FF DSLR's
and now 5-the focusing issues people are having with these expensive lenses

Just too many reasons and it's a safer and cheaper bet for me to go with F, A, or FA series glass.
08-14-2009, 04:25 PM   #14
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QuoteOriginally posted by K-9 Quote
It's not for this alone. It just adds to my other reasons why I won't buy a DA:
Your other reasons are valid (although price is of course lens-specific - many DA lenses are significantly *cheaper* than any similar FA counterparts). My point is just that there is no evidence whatsoever that focus issues any sort of differentiator. That is, there is absolutely no reason to believe that DA lenses are more prone than any others.
08-14-2009, 05:04 PM   #15
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I agree about the price point. A k7 + LTD lenses should not have such issues but at least they can be calibrated by the end user (unlike my k100d which has to go to debug mode and only has a universal adjustment). Maybe this is why the lense prices are going up. Too many returns.

People will have a 'melt down' if the lenses with the new prices exhibit these issues. BTW, it's not just the lenses. The sane lenses have FF issue on one body and BF issue on another body.

mike
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