Terrible results using Pentax DA 40 2.8 XS

Started Feb 12, 2019 | Discussions
Robertj_298 Senior Member • Posts: 1,345
Terrible results using Pentax DA 40 2.8 XS

This was reviewed to be a good sharp lens for the $ but mine is quite bad especially at the edges.  My DA 16-45 blows it away in the sharpness department. I'm wondering if I have a bad copy or is this just not a very good lens?

OP Robertj_298 Senior Member • Posts: 1,345
Re: Terrible results using Pentax DA 40 2.8 XS
1

Here is a 100% center crop and a 100 edge crop

DougOB
DougOB Senior Member • Posts: 1,892
Re: Terrible results using Pentax DA 40 2.8 XS
3

Robertj_298 wrote:

Here is a 100% center crop and a 100 edge crop

I don't have the XS version of this lens but I had the smc standard version and now the HD version.  There is something definitely wrong here, the lens should not be that bad.  Even the contrast is poor.

Doug

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miles green
miles green Veteran Member • Posts: 7,631
Re: Terrible results using Pentax DA 40 2.8 XS
1

DougOB wrote:

Robertj_298 wrote:

Here is a 100% center crop and a 100 edge crop

I don't have the XS version of this lens but I had the smc standard version and now the HD version. There is something definitely wrong here, the lens should not be that bad. Even the contrast is poor.

Doug

I agree, there must be something wrong.

But just so we can isolate and properly demonstrate the problem(s)  (there could be many), please post images taken at a much faster shutter speed. At 1/15, it could be many things, particularly if SR if off. In addition to the general softness and alarming lack of contrast, i think there is some camera shake. Also you should have more direct lighting, it's sometimes hard to see details in such soft light.  Please don't misunderstand me, I think something is quite wrong with the lens, a loose element or something, this does not look normal. But if you're going to send it back, you don't want to leave any room for "yes howevers".

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Miles Green
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MightyMike Forum Pro • Posts: 40,693
Re: Terrible results using Pentax DA 40 2.8 XS
2

You have a bad copy, either get it serviced or replaced

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instamatic84 Regular Member • Posts: 182
Re: Terrible results using Pentax DA 40 2.8 XS

Have you tried taking a shot in live view and comparing it with a shot taken through the viewfinder? Maybe you need to do an AF adjustment on the lens.

Mako2011
MOD Mako2011 Forum Pro • Posts: 27,014
De-centered

Robertj_298 wrote:

Here is a 100% center crop and a 100 edge crop

Looks like you may have a de-centered element in the lens.  Check the opposite corner and see if it's also bad but in the other direction (may only be able to tell by manually focusing forward and back

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OP Robertj_298 Senior Member • Posts: 1,345
Re: Terrible results using Pentax DA 40 2.8 XS

Ivan Paganacci wrote:

Have you tried taking a shot in live view and comparing it with a shot taken through the viewfinder? Maybe you need to do an AF adjustment on the lens.

I tried it on my Pentax K01 using manual focus with focus peaking and got the same results

DavidB77
DavidB77 Forum Member • Posts: 64
Re: Terrible results using Pentax DA 40 2.8 XS

I purchased a second hand DA40Ltd which produced that kind of image... It was a bad copy, send it back as soon as possible. A good (or normal) copy of DA40Ltd should produce perfectly sharp images edge to edge.

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dick eduard
dick eduard Senior Member • Posts: 1,469
Hi Robert,

The center looks bad too, did you try fine AF-ajustment?

Cheers

Dick

miles green
miles green Veteran Member • Posts: 7,631
Re: Terrible results using Pentax DA 40 2.8 XS

Robertj_298 wrote:

Ivan Paganacci wrote:

Have you tried taking a shot in live view and comparing it with a shot taken through the viewfinder? Maybe you need to do an AF adjustment on the lens.

I tried it on my Pentax K01 using manual focus with focus peaking and got the same results

OK, so that eliminates phase AF errors, good.

If you shot at faster speed (say 1/80 just to be sure you eliminate motion) and it's as bad, well, as you said, it's terrible:

Send it back.

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Model Mike Veteran Member • Posts: 3,895
Motion blur?

My first reaction was "motion blur" and note that they've been shot at 1/15 sec which is far too slow for a test shot - suggest shooting in good light and using a shutter speed 1/125 or shorter.

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Mako2011
MOD Mako2011 Forum Pro • Posts: 27,014
In this....

Model Mike wrote:

My first reaction was "motion blur" ...

In this case that would mean the center of the shot would be nearly as blurred as the corner and it is not. So we can rule out motion blur

...and note that they've been shot at 1/15 sec which is far too slow for a test shot - suggest shooting in good light and using a shutter speed 1/125 or shorter.

Not required if the shot was supported (tripod or such). And even then....wouldn't help with "the center is relatively sharp but corner is excessively blurred"

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Model Mike Veteran Member • Posts: 3,895
Re: In this....

Mako2011 wrote:

Model Mike wrote:

My first reaction was "motion blur" ...

In this case that would mean the center of the shot would be nearly as blurred as the corner and it is not. So we can rule out motion blur

On a careful second look (with both images stitched together) you're probably right, though it seems strange to shoot a test image at 1/15 sec.

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dpreviewblog Regular Member • Posts: 428
Re: Terrible results using Pentax DA 40 2.8 XS
1

IMHO... bad/decentered lens. Must be serviced or replaced.

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miles green
miles green Veteran Member • Posts: 7,631
Re: In this....
3

Imho, a defective lens AND some motion blur...

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OP Robertj_298 Senior Member • Posts: 1,345
Re: In this....

miles green wrote:

Imho, a defective lens AND some motion blur...

I believe you are correct. Here is the shot with better lighting. Center laft and right crop

OP Robertj_298 Senior Member • Posts: 1,345
Re: Terrible results using Pentax DA 40 2.8 XS

I've had this lens for quite some time. It came with a new K01 I bought quite a while back. I never really used it so I guess I'm stuck with it

DougOB
DougOB Senior Member • Posts: 1,892
Re: Terrible results using Pentax DA 40 2.8 XS

Robertj_298 wrote:

I've had this lens for quite some time. It came with a new K01 I bought quite a while back. I never really used it so I guess I'm stuck with it

Well maybe you can salvage the lens and mount caps :-/

Doug

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MightyMike Forum Pro • Posts: 40,693
Re: Terrible results using Pentax DA 40 2.8 XS

Robertj_298 wrote:

I've had this lens for quite some time. It came with a new K01 I bought quite a while back. I never really used it so I guess I'm stuck with it

Sell it to someone cheap, maybe they can fix it, I might take a crack at it for the right price

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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
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