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12-17-2006, 02:11 PM   #31
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Good luck with the 50/1.4... giving Pentax a chance through their service center to resolve the problem seems like a good idea to me..

I've tested and restested my 50/1.4 and on my K10d it worked fine (Roentarre has borrowed it too and not mentioned any problems on his k10d), so it must be able to be resolved!


Last edited by joele; 12-17-2006 at 02:27 PM.
12-17-2006, 02:12 PM   #32
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QuoteOriginally posted by joele Quote
Good luck with the 50/1.4... giving Pentax a chance through their service center to resolve the problem seems like a good idea to me..
Thanks. And thanks for all your input.
12-17-2006, 03:49 PM   #33
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Evolution,

I couldn't speak from experience for the Minolta lenses, they may indeed have a FF or BF calibration in their lenses, which can explain your experience with them. I will be interested to see if returning the Pentax 50mm f1.4 solves your problem, I have repaired them and have not found any adjutment for FF/BF.

Is your FF appearent on all focus points with the 50mm? When you shoot a plannar subject wide open with that lens (use tripod, stick newspaper on fridge, insure all is aligned, manual focus), is everything in focus on the entire image (expect a little softness on the edges, that's normal)?

The other thing to note is that in theory the Sigma 30mm f1.4 will focus better than your 50mm f1.4, as DOF gets deeper as a lens goes wider, hence masking a potential focus error.

Hope this helps....
12-17-2006, 03:56 PM   #34
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Hmm... I've only tried center focus point since typically that's the most reliable. Maybe I'll pull the lens back out and try manually focusing on a plane just to see if the whole thing's even. I hear what you're saying about the DOF on the sigma, and i will concede it's possible that the wider DOF of 30mm is masking the problem... though given my samples with the 50, it would be quite a margin to cover up. I would be very surprised if that's the case. In either case, if another 50 exhibits the same problem anyway, I will eventually get all my gear looked at by Pentax techs who can hopefully pinpoint the problem. You would think that something as simple as front/back focus adjustment would be universal on the Pentax SLRs and that service centers wouldn't need to be trained on something so basic for every new model.

QuoteOriginally posted by willc Quote
Evolution,

I couldn't speak from experience for the Minolta lenses, they may indeed have a FF or BF calibration in their lenses, which can explain your experience with them. I will be interested to see if returning the Pentax 50mm f1.4 solves your problem, I have repaired them and have not found any adjutment for FF/BF.

Is your FF appearent on all focus points with the 50mm? When you shoot a plannar subject wide open with that lens (use tripod, stick newspaper on fridge, insure all is aligned, manual focus), is everything in focus on the entire image (expect a little softness on the edges, that's normal)?

The other thing to note is that in theory the Sigma 30mm f1.4 will focus better than your 50mm f1.4, as DOF gets deeper as a lens goes wider, hence masking a potential focus error.

Hope this helps....


12-17-2006, 04:04 PM   #35
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Yep, hard to beleive so many users are reporting FF or BF. It seems like a simple enough QA test for a factory to perform.....

Anyhow, thanks for sharing your test results (if you have the patience to run through them, yet again )
12-18-2006, 04:51 AM   #36
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QuoteOriginally posted by willc Quote
Yep, hard to beleive so many users are reporting FF or BF. It seems like a simple enough QA test for a factory to perform.....

Anyhow, thanks for sharing your test results (if you have the patience to run through them, yet again )
I still do believe for the Pentax case, it is a body problem.

Rumours say that some DSLR body has an open loop AF system, e.g., people said 350D. (Only) if this open-loop AF system do exist, then the lens will "contribute" to the FF/BF errors. Otherwise, the lens has not much to do as it is *passive*. It does tell the body its focusing position but this should not be relied on for the final focus point.

As far as I know for all Pentax AFSLRs I have seen, the AF system is "close loop". BTW, an open loop AF TTL system, even if existent, doesn't make any sense to me at all!

I totally second your view that people reported about the FA50/1.4 commonly just because it has shallow DoF and it is a popular lens. If more people have tried the FA*85/1.4 or just the 77/1.8 Limited, then I think more of them would report about these "problematic" lenses too.

Luck that my FA*85 shows no big problem on my K100D for daylight. Do note that when the color temperature of the environment drops, FF will result, I find this is true for any Pentax DSLRs I've owned. See the relevant article in the "Links" section of my Blog for further details.
12-18-2006, 05:15 AM   #37
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QuoteQuote:
Otherwise, the lens has not much to do as it is *passive*
Yes, this is correct. The Pentax-FA 50mm f1.4 lens does not have a focus position sensor to tell the body where it is at in fine increments. It does have a set of contacts on the internal barrel though, to tell the body whether the focus is very close, close, medium or infinity, but nothing incremental and fine grained . I couldn't confirm this for the limited series (not had a chance to dismentle such beautiful lenses myself!). I understand the information passed to the body consists of the lens name, aperture range, maximum MTF to aid the camera in auto mode so it can make a decision on what aperture to select.

Last edited by willc; 12-18-2006 at 05:23 AM.
12-18-2006, 06:47 AM   #38
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QuoteOriginally posted by RiceHigh Quote
I totally second your view that people reported about the FA50/1.4 commonly just because it has shallow DoF and it is a popular lens. If more people have tried the FA*85/1.4 or just the 77/1.8 Limited, then I think more of them would report about these "problematic" lenses too.
While you may not be talking to me directly, I feel I should at least point out the following. I've previously used a 50/1.4 on a Canon XT and 20D with excellent results. I've also used a 50/1.4 and 85/1.4G on Minolta with excellent results. So presuming this is just error handling narrow DOF on my part would be inaccurate. The lens is consistently front-focusing. The other lenses I have for Pentax do not. There should be 2 more K10D bodies here Tuesday (for family). I will be happy to throw the 50 on those as well and see what happens. And for the record, the Sony 50 f/1.4 (A-mount) blows the Pentax out of the water for sharpness wide open (of course comparing to a manually focused Pentax shot). It's a real cracker of a lens.

12-18-2006, 07:24 AM   #39
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QuoteOriginally posted by Evolution Quote
While you may not be talking to me directly, I feel I should at least point out the following. I've previously used a 50/1.4 on a Canon XT and 20D with excellent results. I've also used a 50/1.4 and 85/1.4G on Minolta with excellent results. So presuming this is just error handling narrow DOF on my part would be inaccurate. The lens is consistently front-focusing. The other lenses I have for Pentax do not. There should be 2 more K10D bodies here Tuesday (for family). I will be happy to throw the 50 on those as well and see what happens. And for the record, the Sony 50 f/1.4 (A-mount) blows the Pentax out of the water for sharpness wide open (of course comparing to a manually focused Pentax shot). It's a real cracker of a lens.
So, for what you describe, it is either Pentax DSLR body has inferior focusing accuracy OR the FA50/1.4 is inferior except that your copy is defective.
12-28-2006, 01:45 AM   #40
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not that i'm trying to ignite any further argument here, but somebody over at dpreview supposedly received this e-mail from Pentax regarding a front-focusing 50/1.4 and K10D that were sent in for calibration:

"There is nothing wrong with your camera or lens.

Please note that Pentax analogue lenses in use with your Pentax digital camera will not give the same focus performance as Pentax DA lenses which have been specifically designed for digital use.
For best results with your analogue lenses please use lowest aperture
possible.

The above is true for all makes and brands.

You cannot expect perfect edge to edge focus on any digital camera with any analogue lens.
We will arrange for return of your camera and lens after taking the
precaution to check at no charge."

I've had 2 dud 50/1.4 lenses on 3 K10D bodies. I have 2 more on the way. If neither of them performs accurately and Pentax continues to stand behind the "there is nothing wrong" statement, I will sadly unload all my brand new Pentax gear. I love the K10D's handling and I love its features. But reduced autofocus performance with the majority of available lenses? Give me a break. Very disappointing.
12-28-2006, 04:27 AM   #41
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QuoteOriginally posted by Evolution Quote
not that i'm trying to ignite any further argument here, but somebody over at dpreview supposedly received this e-mail from Pentax regarding a front-focusing 50/1.4 and K10D that were sent in for calibration:

"There is nothing wrong with your camera or lens.

Please note that Pentax analogue lenses in use with your Pentax digital camera will not give the same focus performance as Pentax DA lenses which have been specifically designed for digital use.
For best results with your analogue lenses please use lowest aperture
possible.

The above is true for all makes and brands.
This is the most irresponsible response I have heard (again). Actually, I have heard of this before once when my DS has front focusing problem with fast Pentax prime and a guy at the Pentax service centre told me that (and then another sales guy afterwards on the phone). I do believe that he just wanted to "escape" away without doing further things to "help" me.

The tone is exactly the same and what they talked about is the same (even they said that Canon and Nikon are the same, so exactly the same here).

But then I asked them one question, they shut up immediately! "How come those lens are listed as compatible without any note on this focusing limitation on Pentax's website or in user manual? except for the multiplying factor??"

QuoteQuote:
You cannot expect perfect edge to edge focus on any digital camera with any analogue lens.
We will arrange for return of your camera and lens after taking the
precaution to check at no charge."
Do check my Blog page and you will see many reports are on DA lenses including the DA limited lenses.

QuoteQuote:
I've had 2 dud 50/1.4 lenses on 3 K10D bodies. I have 2 more on the way. If neither of them performs accurately and Pentax continues to stand behind the "there is nothing wrong" statement, I will sadly unload all my brand new Pentax gear. I love the K10D's handling and I love its features. But reduced autofocus performance with the majority of available lenses? Give me a break. Very disappointing.
My K100D proves that they are probably lying, it focuses flawlessly with my FA*85/1.4 which I do believe is the most well-known famous Pentax lens for AF problems on Pentax DSLRs, which has never been able to work reliable enough with my FA 85 at larger apertures.

See my K100D review for all the details:-

RiceHigh's Pentax K100D Full Review

Do note that the accurate AF is limited to *daylight* only. With yellow lights, it does FF. This phenomenon is somehow Pentax DSLRs specific, the original SAFOX (I) in my Pentax SFX does not have this problem! See this for more:-

Pentax *ist DS AF Dependency on Kelvin & Exposure Value

Well, SAFOX original means colour abrevation correction optics in the AF module. So, I just wonder when it comes to the latest SAFOX, things will fail again!(?)

Afterall, it boils down to the design accuracy and calibration and alignment precision of your bodies and/or lenses, but nothing to do with "older film lenses are not accurate in AF with digital bodies, regardless of brand"!

But, you can give up as you think as I bet they won't do it further for you in the end, for the response you quoted.
12-28-2006, 07:29 AM   #42
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having seen one k100 focus okay with a certain lens and another fail to do so unless the lens was stopped down it has to be a body thing.. it just shows up worse with certain lenses..

not having the money to spend on exotic auto focus "fast" lenses its not a problem that bothers me that much..

to me unless u really need them wide open they are things to be avoided.. he he

whether it can be considered a "fault" or just a limitation i dont know..

trog

ps.. mind u having said that if i did fork out big money for a pentax lens and it didnt work on a pentax camera i would be p-issed off..

Last edited by trog100; 12-28-2006 at 07:35 AM.
12-28-2006, 05:18 PM   #43
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Hi Guys,

IMHO and personal experience, the response from Pentax is not acceptable and quite inaccurate, help desk people may not be very competent...

A friend of mine lives in Melbourne (Australia) and he was able to take both his K10D and Pentax-FA 50mm f1.4 for calibration directly to CR Kennedy (Pentax rep over here). And guess what: The focusing problem can be fixed. It can be adjusted via firmware/software tweaks on the spot. In his situation, there were no mechanical/electrical problems related to the lens, the body simply needed calibration via software.

It sounds like a whole batch of K10D were issued on the market with the wrong focus calibration, chances are, swapping bodies may simply result in the same focus errors again.

Don't give up, try and hassle the right guy in your Pentax service dept and take your equipment there in person if you can.

Hope this helps,
Will.
12-29-2006, 09:05 PM   #44
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QuoteOriginally posted by willc Quote
Hi Guys,

IMHO and personal experience, the response from Pentax is not acceptable and quite inaccurate, help desk people may not be very competent...

A friend of mine lives in Melbourne (Australia) and he was able to take both his K10D and Pentax-FA 50mm f1.4 for calibration directly to CR Kennedy (Pentax rep over here). And guess what: The focusing problem can be fixed. It can be adjusted via firmware/software tweaks on the spot. In his situation, there were no mechanical/electrical problems related to the lens, the body simply needed calibration via software.

It sounds like a whole batch of K10D were issued on the market with the wrong focus calibration, chances are, swapping bodies may simply result in the same focus errors again.

Don't give up, try and hassle the right guy in your Pentax service dept and take your equipment there in person if you can.

Hope this helps,
Will.

Wow, I have backfocusing problem with my K10D and my FA 77mm no matter if it is daylight or indoor.
As soon as the holidays are past I will go to the Pentax Service Center and will hand them my precious K10D for a quick fix
I am glad that they don't need to open it's belly as a quick software "injection" will do

Thanks for giving me hope!
01-02-2007, 09:53 AM   #45
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i received my third fa 50 1.4 today from onecall. this one's a keeper. focuses perfectly in daylight, minimal fringing wide open... still has front-focus in tungsten light... but it appears that's to be expected. i can't wait to get out and actually do something with it.
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