Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...

Started May 18, 2014 | Discussions
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Trevor G Veteran Member • Posts: 6,551
Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...
1

I dropped Pentax in 2011 and sold everything except for a faulty *istDS2, predominantly because their quality control is so abysmal.

Out of 20 odd Pentax lenses I had only one, the FA50 f1.4, that appeared to not be badly decentred, or suffer from skewed focus.

My K200D and subsequent K-x could not focus them accurately.

I shifted to Nikon and haven't had any sign of lens issues from the 8 or 9 I have bought.  Most were used, one or two new.

For various reasons I reacquired a K200D (OK, I like CCD output) a week ago and ordered a new DA-FT50 f1.8.  They sell for $159 on eBay via the local importers, but don't tell anyone.

I hooked it up and, you guessed it, left side is sharp on my local railway station, right side is fuzzy.  Since it's eBay I can get my money back, but I would like to think that I could buy a Pentax lens that was straight.

Does anyone else have these problems?  I know many review pages list the numerous attempts to get a non-decentred lens for their testing...

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Cheers
Trevor G
Silkypix tutorials at: http://photo.computerwyse.com

Pentax K200D Pentax K-x
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Trevor G OP Veteran Member • Posts: 6,551
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...

To be fair, here's the Nikon.  They sell for about $120 new.

They feel much better and give even results and I have never needed to do a skew test on any lens other than my Pentax ones.

Here's the Nikon 50mm f1.8D on the left:

And the right:

Even across the frame.

What gives, Ricoh??

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Cheers
Trevor G
Silkypix tutorials at: http://photo.computerwyse.com

Giklab Contributing Member • Posts: 655
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...
5

>Even across the frame.

Is this a sarcastic post?

DAVID MANZE Veteran Member • Posts: 3,962
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...
1

Yes very disheartening, both my 18-55 kit lenses were decentered, my DA*16-50 a little, however the 17-50 tamron was way off, as was the Sigma 50-150 2.8; Sigma  10-20 4/5.6,Sigma 18-50 EX 2.8 ( rubbishly), even my DA 21 3.2 was decentered( pentax sent me a new one).

Lenses I've bought that were not decentered; FA 50 1.4; S/H FA* 300 4.5; S/H 105 Macro 2.8, Samyang fisheye and a few S/H manual lenses and that's out of fifteen lenses.

In short 2/3 rds of the the lenses I've bought new or S/H were decentered and were returned.

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Richard B.
Richard B. Veteran Member • Posts: 5,585
Re: Can Pentax make A Decent Lens? Yes.

I have been shooting with:

15mm, 21mm, 40mm, 70mm limiteds, 17-70 f4, 55-300 f4-f5.8 and the 35-105 f3.5. Haven't had a problem with any of them.

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Trevor G OP Veteran Member • Posts: 6,551
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...
1

Giklab wrote:

>Even across the frame.

Is this a sarcastic post?

No.

I'd rather have a slightly less sharp image wide open that is even across the frame than sharp on one side and fuzzy on the other.

Wouldn't you?

It's wide open, by the way.

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Cheers
Trevor G
Silkypix tutorials at: http://photo.computerwyse.com

Trevor G OP Veteran Member • Posts: 6,551
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...

DAVID MANZE wrote:

In short 2/3 rds of the the lenses I've bought new or S/H were decentered and were returned.

Funny how some of us have all the baddies...

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Cheers
Trevor G
Silkypix tutorials at: http://photo.computerwyse.com

BobORama
BobORama Senior Member • Posts: 2,188
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...
8

Trevor G wrote:

Perhaps I have no idea what you are getting at, in which case I apologise in advance. Post the full image so we can get some context.

If you want a real test, shoot a completely flat surface perfectly perpendicular to the normal. Or better, shoot a star field wide open. Focus the center of the image perfectly. You will see various aberations, but they should be equal in magnitude as you get farther from the center. Any decentering will be apparent.

Star test will also reveal this issue IN the center of the image if you defocus. Find a bright star ( must be a star, not Venus ), position it in the center of the frame, then defocus till you have a large disk still visible. It should be a circle, or look like your aperture blades. IF there is actual decentering of any element, it will cause the OOF image disk to have all manner of bad structure, and not be symmetric.

Also if 19 of your 20 lenses have this issue, perhaps the issue is with the camera body.

Do all of the lenes have a right - left focus shift?   And with a top to bottom shift?

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Joseph Tainter Veteran Member • Posts: 9,394
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...

I've had two badly decentered copies of the DA* 16-50. My current one is slightly decentered, but it is only visible at 100% so I use it.

My copy of the DA 55-300 is slightly decentered, but again, it is only visible at 100%.

I've had no problems with A, F, or FA lenses. The current problem seems to have originated when Pentax switched lens production to Hanoi. Pentax clearly reduced quality control at the same time that they made this move.

In the manufacturing process, I don't understand why it is so hard to place lens elements correctly. Can someone clarify this?

Joe

Bill Robb Senior Member • Posts: 3,332
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...
3

Trevor G wrote:

DAVID MANZE wrote:

In short 2/3 rds of the the lenses I've bought new or S/H were decentered and were returned.

Funny how some of us have all the baddies...

Yeah, it is interesting how that happens.

Of the nearly 100 Pentax lenses that I own, I've had no problems that I haven't brought on myself.

jf_tea Contributing Member • Posts: 930
Please use better experiment protocol
7

shallow DOF at f/1.8

subject distance at left vs. right is significantly different.

Please use better experiment protocol.

DAVID MANZE Veteran Member • Posts: 3,962
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...
4

Joseph Tainter wrote:

I've had two badly decentered copies of the DA* 16-50. My current one is slightly decentered, but it is only visible at 100% so I use it.

My copy of the DA 55-300 is slightly decentered, but again, it is only visible at 100%.

I've had no problems with A, F, or FA lenses. The current problem seems to have originated when Pentax switched lens production to Hanoi. Pentax clearly reduced quality control at the same time that they made this move.

In the manufacturing process, I don't understand why it is so hard to place lens elements correctly. Can someone clarify this?

Joe

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Hi,

It's not a question of placing of elements correctly in the lens body, it's the doublets and triplets which are poorly aligned, ie at pre-assembly they are placed in a machine with a laser light beamed down to show alignment of the elements, the glue has a certain setting time and until the glue sets the top element is floating, often in modern production where time is at an essence the setting time is not respected and the elements misalign before the glue sets and when it does set the damage is done. Most lens manufactures supply "tested" doublets and triplets to their service departments so any decentered lenses can be corrected with new elements. Both Sigma and Tamron service centers have spoken to me on this when I pushed the question about what spares they were awaiting for. That and wobbly plastic lens bodies and you have the ideal recipe for below spec. lenses often at a high percentage ratio.

The bottom line is that it is us the customer who is the quality controller, if we say nothing, nothing will be done, so if you find yourself with a decentered lens send it back, lens manufacturers know they are making lots of below par optics so return them!

Dave's clichés

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emem
emem Veteran Member • Posts: 4,216
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...

Trevor G wrote:

DAVID MANZE wrote:

In short 2/3 rds of the the lenses I've bought new or S/H were decentered and were returned.

Funny how some of us have all the baddies...

Some people are more discerning than others.

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Mike McEnaney. (emem)
www.veritasmea.com

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Ian Stuart Forsyth
Ian Stuart Forsyth Senior Member • Posts: 2,602
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...

Trevor G wrote:

DAVID MANZE wrote:

In short 2/3 rds of the the lenses I've bought new or S/H were decentered and were returned.

Funny how some of us have all the baddies...

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Cheers
Trevor G
Silkypix tutorials at: http://photo.computerwyse.com

My second copy of the DA*16-50 also had the same problem while the first had none but had SDM failure so it went back. I lived with it as it was out of warranty and then the sudden death motor happened to the second so I just gave up.

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ozdean
ozdean Forum Pro • Posts: 23,466
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...
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At least the Pentax is sharp on one side.

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Regards Dean - Capturing Creation
N.B. All my Images are Protected by Copyright

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Younes B Contributing Member • Posts: 906
Re: Please use better experiment protocol
4

jf_tea wrote:

shallow DOF at f/1.8

subject distance at left vs. right is significantly different.

Please use better experiment protocol.

+1

Test is not conclusive of decentering.

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MightyMike Forum Pro • Posts: 35,685
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...

emem wrote:

Trevor G wrote:

DAVID MANZE wrote:

In short 2/3 rds of the the lenses I've bought new or S/H were decentered and were returned.

Funny how some of us have all the baddies...

Some people are more discerning than others.

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Mike McEnaney. (emem)
www.veritasmea.com

Yes, and some people see problems where none exist, I'm not saying the OP is one of them but there sure are hypochondriacs out there that easily imagine problems which account for some of those who keep getting multitudes of bad lenses.

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Mike from Canada
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justin23 Veteran Member • Posts: 4,347
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...

MightyMike wrote:

emem wrote:

Trevor G wrote:

DAVID MANZE wrote:

In short 2/3 rds of the the lenses I've bought new or S/H were decentered and were returned.

Funny how some of us have all the baddies...

Some people are more discerning than others.

-- hide signature --

Mike McEnaney. (emem)
www.veritasmea.com

Yes, and some people see problems where none exist, I'm not saying the OP is one of them but there sure are hypochondriacs out there that easily imagine problems which account for some of those who keep getting multitudes of bad lenses.

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Mike from Canada
"I am not a great photographer! God is a great creator! All I do is capture His creation with the tools He has provided me."
'I like to think so far outside the box that it would require a telephoto lens just to see the box!' ~ 'My Quote :)'
http://www.michaelfastphotography.com/galleries/VP-BDI_3a.jpg
http://www.airliners.net/search/photo.search?sort_order=views%20DESC&first_this_page=0&page_limit=180&&emailsearch=mighty_mike88%40hotmail.com&thumbnails=

Yeah i've not got a bad lens either, however I'm guessing if i do some rigorous testing and pixel peeping, maybe some are not perfect. I just don't notice it with my photos.

Its got to be something other than just bad luck in the OP's case. Whether its in their head a bit so they go looking for issues, emotion plays an important part in it when people are upset about something.

I'm sure there are some valid faulty lenses, but given many have 20+ Pentax lenses without fault, yet the OP who would be in the minority has mostly faulty lenses, something doesn't quite add up.

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Justin
--------------------------------------------------------
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Bill Robb Senior Member • Posts: 3,332
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...

emem wrote:

Trevor G wrote:

DAVID MANZE wrote:

In short 2/3 rds of the the lenses I've bought new or S/H were decentered and were returned.

Funny how some of us have all the baddies...

Some people are more discerning than others.

Some people have really bad camera hypochondria.

DAVID MANZE Veteran Member • Posts: 3,962
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...

MightyMike wrote:

emem wrote:

Trevor G wrote:

DAVID MANZE wrote:

In short 2/3 rds of the the lenses I've bought new or S/H were decentered and were returned.

Funny how some of us have all the baddies...

Some people are more discerning than others.

-- hide signature --

Mike McEnaney. (emem)
www.veritasmea.com

Yes, and some people see problems where none exist, I'm not saying the OP is one of them but there sure are hypochondriacs out there that easily imagine problems which account for some of those who keep getting multitudes of bad lenses.

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Mike from Canada
"I am not a great photographer! God is a great creator! All I do is capture His creation with the tools He has provided me."
'I like to think so far outside the box that it would require a telephoto lens just to see the box!' ~ 'My Quote :)'
http://www.michaelfastphotography.com/galleries/VP-BDI_3a.jpg
http://www.airliners.net/search/photo.search?sort_order=views%20DESC&first_this_page=0&page_limit=180&&emailsearch=mighty_mike88%40hotmail.com&thumbnails=

If there wasn't this thread it would have been one less post, kinda skeletal round here as it is.

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BTW. I'm not a hypochondriac; an optichondriac maybe! But it doesn't faze me, rather glass worries than health ones!

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