New DFA 15-30: soft edge?

johann_brehmer · 10-04-2017, 07:09 PM

Hi all,

I just got a DFA 15-30 to go with my K1. The lens is a joy to shoot, and I love both the perspective and the build quality. However, in the first test shots I noticed that the left edge seems pretty soft.

Attached you can find one of these pictures, a 100% crop of the left edge, and a 100% crop of the center for comparison.

This is at 15mm, f/11, 4s, ISO 100, on a tripod (self-timer, SR off).

Is this within the expectations for such a wide angle? At f/11 and this distance this should not be a focus or decentering issue. And since the rest of the image is sharp, I don't think this is wind or any other type of shake. The right edge does not have any distinctive sharp lines that allow for an easy assessment.

I will have time for more tests on the weekend. In the meantime, I would really appreciate your thoughts.

Thanks,
Johann

Attached Images

mikeSF · 10-04-2017, 10:11 PM

that looks problematic. send it back?

Sandy Hancock · 10-04-2017, 10:19 PM

Yeah. Not good enough IMHO. Send it back.

alpheios · 10-04-2017, 10:32 PM

Definitely looks like a decentering issue. Like the others said return it in exchange for a new one.
If you want to do some more testing there is an article about testing a lens for decentering: How to Check Your Lens for Decentering - Articles and Tips | PentaxForums.com

Lipton · 10-05-2017, 12:35 AM - **3 Likes**

I suspect motion blur, especially vertical, from looking at the trails from moving cars?
Try with a very short shutter speed in daytime as well and have a look?

Sandy Hancock · 10-05-2017, 01:02 AM - **2 Likes**

Originally posted by Lipton

I suspect motion blur, especially vertical, from looking at the trails from moving cars?

Well spotted! The light trails are jiggly when they should be straight. That does suggest some vertical movement, which would be more pronounced at the edges if the tripod wasn't absolutely solid.

More testing would be worthwhile.

alpheios · 10-05-2017, 02:06 AM

Originally posted by Sandy Hancock

Well spotted! The light trails are jiggly when they should be straight. That does suggest some vertical movement, which would be more pronounced at the edges if the tripod wasn't absolutely solid.

More testing would be worthwhile.

From the position of the lighttrails I would rather suspect they are from a boat rather than cars. If it was vertical motion of the camera then all lights would be vertical lines instead of dots. The bluriness gets worse towards the edge and is actually more of a horizontal blur rather than a vertical. This looks exactly like the kind of blur I had on one side of two decentered Irix 15mm Lenses I had. So I would still think it's decentering but just as you said more testing should be done.

Sandy Hancock · 10-05-2017, 04:32 AM

The same jiggliness is seen in a light trail in the sky high above the buildings. That one at least is very unlikely to be from something on the water....

johann_brehmer · 10-05-2017, 05:04 AM

Hi,

thank you all for the help! The jiggly lines are well-spotted, that's definitely motion blur.

Here are crops of another picture taken at 1/500s and f/5.6. I'm afraid the edge is still soft...

Cheers,
Johann

alpheios · 10-05-2017, 06:01 AM

Originally posted by johann_brehmer

Hi,

thank you all for the help! The jiggly lines are well-spotted, that's definitely motion blur.

Here are crops of another picture taken at 1/500s and f/5.6. I'm afraid the edge is still soft...

Cheers,
Johann

There’s not just blur but also some severe color fringing. You should get a new lens.

normhead · 10-05-2017, 06:04 AM

Originally posted by alpheios

There’s not just blur but also some severe color fringing. You should get a new lens.

That kind of colour fringing is often a sign the lens elements are not properly aligned. I'd exchange it as well.

tregubovav · 10-05-2017, 06:08 AM

Joann

Left corner doesn't look well still. Colour fringing exists there. But I would recommend to do additional test in more controllable environment ( a bit shorter distance to eliminate any atmosphere conditions)

Sandy Hancock · 10-05-2017, 03:50 PM

My copy was behaving like this. I sent it off and it came back (after a trip to Japan) much improved. Still not perfect, but acceptable.

Before:

This first one has been smashed with the PP bat to minimise the CA and contrast loss in the top right quadrant

Probably the most dramatic example

and after:

10-04-2017, 07:09 PM	#1
johann_brehmer New Member Join Date: Sep 2017 Posts: 2	New DFA 15-30: soft edge? Hi all, I just got a DFA 15-30 to go with my K1. The lens is a joy to shoot, and I love both the perspective and the build quality. However, in the first test shots I noticed that the left edge seems pretty soft. Attached you can find one of these pictures, a 100% crop of the left edge, and a 100% crop of the center for comparison. This is at 15mm, f/11, 4s, ISO 100, on a tripod (self-timer, SR off). Is this within the expectations for such a wide angle? At f/11 and this distance this should not be a focus or decentering issue. And since the rest of the image is sharp, I don't think this is wind or any other type of shake. The right edge does not have any distinctive sharp lines that allow for an easy assessment. I will have time for more tests on the weekend. In the meantime, I would really appreciate your thoughts. Thanks, Johann Attached Images

10-05-2017, 05:04 AM	#9
johann_brehmer New Member Join Date: Sep 2017 Posts: 2 Original Poster	Hi, thank you all for the help! The jiggly lines are well-spotted, that's definitely motion blur. Here are crops of another picture taken at 1/500s and f/5.6. I'm afraid the edge is still soft... Cheers, Johann Attached Images

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
DFA 15-30 Zoom Ring Loose?	bigoak	Pentax SLR Lens Discussion	4	05-11-2017 12:21 PM
Crunch time...DFA 15-30?	snpsht	Pentax K-1 & K-1 II	11	04-28-2017 04:23 AM
Rokinon 8mm soft at left edge: normal sample variation or bad?	Outis	Pentax SLR Lens Discussion	9	12-04-2016 07:49 AM
DFA 24-70 or DFA 15-30 for the K-1?	Hattifnatt	Pentax SLR Lens Discussion	42	10-25-2016 08:03 AM
Used DFA 15-30 2.8 at B&H for 1249.95	deepbluish	Pentax Price Watch	5	09-22-2016 11:41 PM

10-04-2017, 10:11 PM	#2
mikeSF Pentaxian Join Date: Jan 2009 Location: East Bay Area, CA Photos: Gallery Posts: 6,620	that looks problematic. send it back?

10-04-2017, 10:19 PM	#3
Sandy Hancock Moderator Site Supporter Join Date: Feb 2012 Location: Adelaide Hills, South Australia Photos: Gallery \| Albums Posts: 11,267	Yeah. Not good enough IMHO. Send it back.

10-04-2017, 10:32 PM	#4
alpheios Pentaxian Join Date: Nov 2015 Location: Bremen Posts: 410	Definitely looks like a decentering issue. Like the others said return it in exchange for a new one. If you want to do some more testing there is an article about testing a lens for decentering: How to Check Your Lens for Decentering - Articles and Tips \| PentaxForums.com

10-05-2017, 12:35 AM - 3 Likes	#5
Lipton New Member Join Date: Jan 2017 Posts: 4	I suspect motion blur, especially vertical, from looking at the trails from moving cars? Try with a very short shutter speed in daytime as well and have a look?

10-05-2017, 01:02 AM - 2 Likes	#6
Sandy Hancock Moderator Site Supporter Join Date: Feb 2012 Location: Adelaide Hills, South Australia Photos: Gallery \| Albums Posts: 11,267	Originally posted by Lipton I suspect motion blur, especially vertical, from looking at the trails from moving cars? Well spotted! The light trails are jiggly when they should be straight. That does suggest some vertical movement, which would be more pronounced at the edges if the tripod wasn't absolutely solid. More testing would be worthwhile.

10-05-2017, 02:06 AM	#7
alpheios Pentaxian Join Date: Nov 2015 Location: Bremen Posts: 410	Originally posted by Sandy Hancock Well spotted! The light trails are jiggly when they should be straight. That does suggest some vertical movement, which would be more pronounced at the edges if the tripod wasn't absolutely solid. More testing would be worthwhile. From the position of the lighttrails I would rather suspect they are from a boat rather than cars. If it was vertical motion of the camera then all lights would be vertical lines instead of dots. The bluriness gets worse towards the edge and is actually more of a horizontal blur rather than a vertical. This looks exactly like the kind of blur I had on one side of two decentered Irix 15mm Lenses I had. So I would still think it's decentering but just as you said more testing should be done.

10-05-2017, 04:32 AM	#8
Sandy Hancock Moderator Site Supporter Join Date: Feb 2012 Location: Adelaide Hills, South Australia Photos: Gallery \| Albums Posts: 11,267	The same jiggliness is seen in a light trail in the sky high above the buildings. That one at least is very unlikely to be from something on the water....

10-05-2017, 06:01 AM	#10
alpheios Pentaxian Join Date: Nov 2015 Location: Bremen Posts: 410	Originally posted by johann_brehmer Hi, thank you all for the help! The jiggly lines are well-spotted, that's definitely motion blur. Here are crops of another picture taken at 1/500s and f/5.6. I'm afraid the edge is still soft... Cheers, Johann There’s not just blur but also some severe color fringing. You should get a new lens.

10-05-2017, 06:04 AM	#11
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	Originally posted by alpheios There’s not just blur but also some severe color fringing. You should get a new lens. That kind of colour fringing is often a sign the lens elements are not properly aligned. I'd exchange it as well.

10-05-2017, 06:08 AM	#12
tregubovav Junior Member Join Date: Sep 2017 Photos: Albums Posts: 41	Joann Left corner doesn't look well still. Colour fringing exists there. But I would recommend to do additional test in more controllable environment ( a bit shorter distance to eliminate any atmosphere conditions)

Thread Tools	Search this Thread
	Search this Thread: Advanced Search

10-05-2017, 03:50 PM	#13
Sandy Hancock Moderator Site Supporter Join Date: Feb 2012 Location: Adelaide Hills, South Australia Photos: Gallery \| Albums Posts: 11,267	My copy was behaving like this. I sent it off and it came back (after a trip to Japan) much improved. Still not perfect, but acceptable. Before: This first one has been smashed with the PP bat to minimise the CA and contrast loss in the top right quadrant Probably the most dramatic example and after: