Half out of focus?

Roger_H · 10-04-2010, 11:53 AM

I was recently in Spain shooting with SMC Pentax DA f4-5.8 55-300mm DA. I shot a four shot panorama and on all four shot the left half of the photo was blurred and the right half sharp. I was focused at infinity with the subject landscape more than half a mile away. The lens was zoomed to 170mm and my shutter speed was 1/250. Exposure mode manual. Aperture was f 5.6 and ISO was 100. The left half of the frame on all four shots was miserably out of focus while the right half of the image was sharp. The lens was clean. I am at a loss to understand how one half an image more than a half mile away could be blurred while the other half is sharp.

Ideas?

Attached Images

Adam · 10-04-2010, 12:08 PM

This certainly isn't motion blur or lack of DOF, so I'd say that there might actually be something wrong with your lens. I'd run some controlled tests to check if that's indeed the case!

Asahiflex · 10-04-2010, 12:10 PM

It seems that your lens is decentered... And severely so.

Northern Soul · 10-04-2010, 12:10 PM

I had a 28mm Praktica lens that did exactly this because the rear element was loose, and able to pivot. As I'd only paid £20 for it, I just superglued it up.

KxBlaze · 10-04-2010, 12:27 PM

Definitely seems like something defective with the lens. Do you notice the same problem with any other lens? If not then can you return the 55-300? Because it sounds like an internal problem with one or more of the internal elements and that is not something you want to try and fix yourself.

Roger_H · 10-04-2010, 01:08 PM

The problem is hard to pinpoint. I did do a test where I shot some antennae on a hilltop about four miles away. In one shot I pushed the antennae to the right side of the image and in a second shot I pushed the antennae to the left of the image. However, both seemed sharp in the test.

Of course a loose element by the very nature of being loose would not produce consistent results.

Another thought relates to shooting position. I had my left hand on my right shoulder and the lens resting in the crook of my elbow. If I had autofocus on and it was fighting the friction of resting on my elbow, could the mechanism bind and get an element to twist slightly?

**Ex Finn.** · 10-04-2010, 04:56 PM

That is a good possibility. Would not take much torque to deflect things. But should the AF not have been done driving the lens when you took the shot?.
I know, this is not helping much.

creampuff · 10-04-2010, 05:41 PM

Sorry but your image doesn't look particularly sharp overall. Were you using a crappy tripod when shooting the pano? Seriously, before you blame the lens, check that it isn't your other gear that is the problem.

Roger_H · 10-04-2010, 07:13 PM

Originally posted by creampuff

Sorry but your image doesn't look particularly sharp overall. Were you using a crappy tripod when shooting the pano? Seriously, before you blame the lens, check that it isn't your other gear that is the problem.

The point is it was a little blurred on one side and very blurred on the other. The shot was handheld at 1/250. It was hand held because I am suffering severe arthritis and was on a 2-3 mile walk and could not carry the extra equipment.

Also I had previously done a series of night shots of 20-30 seconds duration with the camera sitting on a stone wall and tripped with an IR remote. These shots were also unsharp. You don't get much steadier than a stone wall.

Roger_H · 10-04-2010, 07:24 PM

Originally posted by Ex Finn.

That is a good possibility. Would not take much torque to deflect things. But should the AF not have been done driving the lens when you took the shot?.
I know, this is not helping much.

I agree that it would no long be driving the lens, but if it had already started to bind, I am not sure it would automatically unbind after the focus motor stopped.

Had it only been one frame and not all four, I would have blamed atmospherics. However atmospherics would not always been on the left in overlapping pano shots.

I am not a big fan of autofocus anyhow as it does a poor job of objects moving directly toward the camera

timo · 10-04-2010, 11:52 PM

Originally posted by Roger_H

I was recently in Spain shooting with SMC Pentax DA f4-5.8 55-300mm DA. I shot a four shot panorama and on all four shot the left half of the photo was blurred and the right half sharp. I was focused at infinity with the subject landscape more than half a mile away. The lens was zoomed to 170mm and my shutter speed was 1/250. Exposure mode manual. Aperture was f 5.6 and ISO was 100. The left half of the frame on all four shots was miserably out of focus while the right half of the image was sharp. The lens was clean. I am at a loss to understand how one half an image more than a half mile away could be blurred while the other half is sharp.

Ideas?

Roger I have two 55-300s and they both do this at longer zoom lengths although not as badly as your example. It is particularly noticeable wide open - at 300mm I have to stop them down to the f/8-11 range to get a reasonably sharp landscape image edge to edge. Centre is generally not too bad. Which side is blurred at what FL differs as between the two lenses. I am sure it is manufacturing tolerances, as I got one of them checked out by Pentax in Japan, who said it was 'in spec'. Try the lens at f8 or more - you may find it is better. Of course this is a pain in poor light ...

You may have to get it checked out.

Roger_H · 10-05-2010, 10:30 AM

Timo, thanks for the input, it was very useful. I will test and see what I come up with. I will also be looking at some prime lenses. Maybe I should break out the glass and use the barrel for a pencil holder.

r0ckstarr · 10-05-2010, 04:45 PM

Are you using any filters on the lens? UV or CPL?

stevebrot · 10-05-2010, 05:02 PM

Originally posted by Asahiflex

It seems that your lens is decentered... And severely so.

My first thought as well.

Originally posted by timo

Roger I have two 55-300s and they both do this at longer zoom lengths...

My friend has the 55-300 and his is acceptably sharp overall and has none of this one-sided smear.

Originally posted by r0ckstarr

Are you using any filters on the lens? UV or CPL?

Good thinking!

Steve

Roger_H · 10-05-2010, 11:41 PM

Steve, not sure where you are headed with the filter question. It is an extra element in the glass stack, but it should not have such a one sided effect. And as far as introducing an even blur, would think this would be minimal with a telephoto where the light would do far less bending than it would with a normal or wide angle where the the lens is reaching out to the sides.

I shot some tests yesterday on a tripod, but I hurried them and the method was not as rigorous as I would like, so I will try again in the near future.

I will say that over long distances no image is sharp unless the air is still, dry, and with moderate temperature.

The telephotos strength is compacting space and managing the size relationship of disparate objects. Otherwise it is best to walk or drive closer to the subject.

10-04-2010, 11:53 AM	#1
Roger_H Inactive Account Join Date: Sep 2010 Location: Arizona Photos: Albums Posts: 8	Half out of focus? I was recently in Spain shooting with SMC Pentax DA f4-5.8 55-300mm DA. I shot a four shot panorama and on all four shot the left half of the photo was blurred and the right half sharp. I was focused at infinity with the subject landscape more than half a mile away. The lens was zoomed to 170mm and my shutter speed was 1/250. Exposure mode manual. Aperture was f 5.6 and ISO was 100. The left half of the frame on all four shots was miserably out of focus while the right half of the image was sharp. The lens was clean. I am at a loss to understand how one half an image more than a half mile away could be blurred while the other half is sharp. Ideas? Attached Images

10-04-2010, 12:08 PM	#2
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,608	This certainly isn't motion blur or lack of DOF, so I'd say that there might actually be something wrong with your lens. I'd run some controlled tests to check if that's indeed the case! Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

10-04-2010, 01:08 PM	#6
Roger_H Inactive Account Join Date: Sep 2010 Location: Arizona Photos: Albums Posts: 8 Original Poster	Thanks guys The problem is hard to pinpoint. I did do a test where I shot some antennae on a hilltop about four miles away. In one shot I pushed the antennae to the right side of the image and in a second shot I pushed the antennae to the left of the image. However, both seemed sharp in the test. Of course a loose element by the very nature of being loose would not produce consistent results. Another thought relates to shooting position. I had my left hand on my right shoulder and the lens resting in the crook of my elbow. If I had autofocus on and it was fighting the friction of resting on my elbow, could the mechanism bind and get an element to twist slightly?

10-04-2010, 07:13 PM	#9
Roger_H Inactive Account Join Date: Sep 2010 Location: Arizona Photos: Albums Posts: 8 Original Poster	Unsharp Originally posted by creampuff Sorry but your image doesn't look particularly sharp overall. Were you using a crappy tripod when shooting the pano? Seriously, before you blame the lens, check that it isn't your other gear that is the problem. The point is it was a little blurred on one side and very blurred on the other. The shot was handheld at 1/250. It was hand held because I am suffering severe arthritis and was on a 2-3 mile walk and could not carry the extra equipment. Also I had previously done a series of night shots of 20-30 seconds duration with the camera sitting on a stone wall and tripped with an IR remote. These shots were also unsharp. You don't get much steadier than a stone wall.

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10-04-2010, 12:10 PM	#3
Asahiflex Pentaxian Join Date: Jan 2008 Location: Netherlands Photos: Gallery Posts: 2,795	It seems that your lens is decentered... And severely so.

10-04-2010, 12:10 PM	#4
Northern Soul Veteran Member Join Date: Feb 2008 Location: The North of England Photos: Albums Posts: 494	I had a 28mm Praktica lens that did exactly this because the rear element was loose, and able to pivot. As I'd only paid £20 for it, I just superglued it up.

10-04-2010, 12:27 PM	#5
KxBlaze Veteran Member Join Date: Feb 2010 Location: California Photos: Gallery Posts: 1,602	Definitely seems like something defective with the lens. Do you notice the same problem with any other lens? If not then can you return the 55-300? Because it sounds like an internal problem with one or more of the internal elements and that is not something you want to try and fix yourself.

10-04-2010, 04:56 PM	#7
Ex Finn. Site Supporter Join Date: Nov 2007 Location: Southern Maryland. Espoo. Kouvola. Photos: Gallery \| Albums Posts: 7,975	That is a good possibility. Would not take much torque to deflect things. But should the AF not have been done driving the lens when you took the shot?. I know, this is not helping much.

10-04-2010, 05:41 PM	#8
creampuff Veteran Member Join Date: May 2007 Location: Singapore Photos: Gallery Posts: 3,953	Sorry but your image doesn't look particularly sharp overall. Were you using a crappy tripod when shooting the pano? Seriously, before you blame the lens, check that it isn't your other gear that is the problem.

10-04-2010, 07:24 PM	#10
Roger_H Inactive Account Join Date: Sep 2010 Location: Arizona Photos: Albums Posts: 8 Original Poster	Originally posted by Ex Finn. That is a good possibility. Would not take much torque to deflect things. But should the AF not have been done driving the lens when you took the shot?. I know, this is not helping much. I agree that it would no long be driving the lens, but if it had already started to bind, I am not sure it would automatically unbind after the focus motor stopped. Had it only been one frame and not all four, I would have blamed atmospherics. However atmospherics would not always been on the left in overlapping pano shots. I am not a big fan of autofocus anyhow as it does a poor job of objects moving directly toward the camera

10-04-2010, 11:52 PM	#11
timo Veteran Member Join Date: Nov 2006 Location: former Arsenal football stadium Photos: Gallery Posts: 431	Originally posted by Roger_H I was recently in Spain shooting with SMC Pentax DA f4-5.8 55-300mm DA. I shot a four shot panorama and on all four shot the left half of the photo was blurred and the right half sharp. I was focused at infinity with the subject landscape more than half a mile away. The lens was zoomed to 170mm and my shutter speed was 1/250. Exposure mode manual. Aperture was f 5.6 and ISO was 100. The left half of the frame on all four shots was miserably out of focus while the right half of the image was sharp. The lens was clean. I am at a loss to understand how one half an image more than a half mile away could be blurred while the other half is sharp. Ideas? Roger I have two 55-300s and they both do this at longer zoom lengths although not as badly as your example. It is particularly noticeable wide open - at 300mm I have to stop them down to the f/8-11 range to get a reasonably sharp landscape image edge to edge. Centre is generally not too bad. Which side is blurred at what FL differs as between the two lenses. I am sure it is manufacturing tolerances, as I got one of them checked out by Pentax in Japan, who said it was 'in spec'. Try the lens at f8 or more - you may find it is better. Of course this is a pain in poor light ... You may have to get it checked out.

10-05-2010, 10:30 AM	#12
Roger_H Inactive Account Join Date: Sep 2010 Location: Arizona Photos: Albums Posts: 8 Original Poster	Timo, thanks for the input, it was very useful. I will test and see what I come up with. I will also be looking at some prime lenses. Maybe I should break out the glass and use the barrel for a pencil holder.

10-05-2010, 04:45 PM	#13
r0ckstarr Veteran Member Join Date: Sep 2009 Location: Texas Photos: Gallery Posts: 3,507	Are you using any filters on the lens? UV or CPL?

10-05-2010, 05:02 PM	#14
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by Asahiflex It seems that your lens is decentered... And severely so. My first thought as well. Originally posted by timo Roger I have two 55-300s and they both do this at longer zoom lengths... My friend has the 55-300 and his is acceptably sharp overall and has none of this one-sided smear. Originally posted by r0ckstarr Are you using any filters on the lens? UV or CPL? Good thinking! Steve

10-05-2010, 11:41 PM	#15
Roger_H Inactive Account Join Date: Sep 2010 Location: Arizona Photos: Albums Posts: 8 Original Poster	Steve, not sure where you are headed with the filter question. It is an extra element in the glass stack, but it should not have such a one sided effect. And as far as introducing an even blur, would think this would be minimal with a telephoto where the light would do far less bending than it would with a normal or wide angle where the the lens is reaching out to the sides. I shot some tests yesterday on a tripod, but I hurried them and the method was not as rigorous as I would like, so I will try again in the near future. I will say that over long distances no image is sharp unless the air is still, dry, and with moderate temperature. The telephotos strength is compacting space and managing the size relationship of disparate objects. Otherwise it is best to walk or drive closer to the subject.