Help please

Digifrog

Digifrog

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Name
Scott
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Hello

Can someone please help. I have a basic problem of elements in my images that are a bit too soft for my liking. This is an example..

5045088424_b4f4127364_b.jpg


As you can see the rocks in the middle distance are soft and before I go FF with pro glass I need to figure out what I'm doing wrong.

The image was taken with the Sigma 10-20mm (which might be part of the problem?) and was shot at 10mm. I focused on the main rock (bottom left) by pointing down and recomposing and using a tripod. The EXIF is ISO100, Manual Mode, 0.04secs, f/10.

In PP I warmed the tone up a little and used Unsharp Mask (85%).

What am I doing wrong? Is it the lens? Or could it be that it was shot at f/10? I don't think there was any movement between focussing and firing. Any advice greatly welcomed. Thank you.

Scott
 
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It looks like your lens is soft on the left side..
I can't see any focus problems as on the right side everything looks sharp at the same distances as the left.

Great photo btw :)
 
It seems to be soft on the left side all over the shot. I would want to see full res pic to draw any conclusions...

Most likely it is the lens. Sigma is well known for defective optics. Do all 10-20 photos look soft on the left? Are things sharp on the right where the distant rocks are? f/10 is pushing it a little bit.

Also have you used mirror lock up and timer / remote? If not could you shake the camera a little bit causing one soft side?

Perhaps I will conclude by suggesting D700 + 16-35mm vr at f/16 for this.
 
Blasteh said:
It looks like your lens is soft on the left side..
I can't see any focus problems as on the right side everything looks sharp at the same distances as the left.

Great photo btw :)
Click to expand...

Thanks blasteh.

That's concerning if just the left is soft. The lens took a knock a while ago and I'm wondering if it could be that now. I've also looked at an online DoF calculator and the 'hyperfocal distance'. I don't understand the calculations. I'm not one for manuals. I usually focus on the main closest subject (like that rock) and usually with a small aperture. Failing this I use the 'focus one 3rd in' guideline. I need to smarten up on the technical aspects before I upgrade.

daugirdas said:
It seems to be soft on the left side all over the shot. I would want to see full res pic to draw any conclusions...

Most likely it is the lens. Sigma is well known for defective optics. Do all 10-20 photos look soft on the left? Are things sharp on the right where the distant rocks are? f/10 is pushing it a little bit.

Also have you used mirror lock up and timer / remote? If not could you shake the camera a little bit causing one soft side?

Perhaps I will conclude by suggesting D700 + 16-35mm vr at f/16 for this.
Click to expand...

Thanks Daugirdas.

I think the problem exists in many of my shots (see stream). I have never used mirror lock up, but I do use my wireless remote sometimes to fire. As this was 0.04secs it should be OK in that respect. So you would suggest at least f/16? I'm actually worried now that the lens knock has done something.

D700? I'm waiting for its successor (if I go stay with Nikon), or the Canon 5D Mkii/iii. The lens I have in my mind is the Zeiss 21mm T*. The Nikon 16-35mm is nice but I'm thinking I should move to prime for wide use.

Scott
 
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At 10mm, you don't really need to do much math to know you have a LOT of depth of field to work with, even more so at f/10.
A lens problem would be at the top of the suspect list I think.
 
daugirdas said:
Most likely it is the lens. Sigma is well known for defective optics.
Click to expand...

Which is why they have never sold a lens and have gone out of business............:thinking:

What a sweeping generalisation, but nothing new there then.
 
Specifically yes, there are problems with that lens. But, as we all know, people rarely praise on a forum and are quick to let fly with both barrels from an early stage. Considering this specific lens has "taken a knock", then the "Sigma are well known for defective optics" (no specific in there) observation, is rather silly.
 
If you are wanting more of the picture to be in focus then understanding the relationship between aperture and DOF is essential. Using f10 at 10mm should give you plenty, however I think you may have wasted some of the range available by focusing on an area to close to the front of the picture. A general rule of thumb is 1/3 in front and 2/3 behind the actual focus point is going to be in the acceptable range. I would have focused a bit further out than the rock you mentioned. Try experimenting.
 
fracster said:
Specifically yes, there are problems with that lens. But, as we all know, people rarely praise on a forum and are quick to let fly with both barrels from an early stage. Considering this specific lens has "taken a knock", then the "Sigma are well known for defective optics" (no specific in there) observation, is rather silly.
Click to expand...

Aye, I won't disagree. Although Sigma do have something of a reputation for erratic quality control (whether it is deserved or not I can't say).

The OP needs to to some tests under controlled conditions to ascertain where the problem lies. On a tripod, take photos at different apertures and distances of a brick wall, for example, with and without the ND grad that was apparently used in the sample image. This will, at least, confirm or eliminate any problems with this particular lens.

If he's got any photos to compare with prior to the 'knock' that show it was OK then and is not now, then it would tend to point the finger at accidental damage to the lens. It may be that the design is particularly susceptible to internal movement under those conditions.
 
Is it possible to actually detect lens error from a 800 pixel photograph?........:shrug:

I didn`t like this lens much when I had one TBH.
 
Thanks to everyone who replied to my problem.

artyman said:
If you are wanting more of the picture to be in focus then understanding the relationship between aperture and DOF is essential. Using f10 at 10mm should give you plenty, however I think you may have wasted some of the range available by focusing on an area to close to the front of the picture. A general rule of thumb is 1/3 in front and 2/3 behind the actual focus point is going to be in the acceptable range. I would have focused a bit further out than the rock you mentioned. Try experimenting.
Click to expand...

Thank you. I must admit I have up to now never paid any attention to the relationship between aperture and DoF (only that the smaller the aperture the greater the DoF). The hyperfocal measurements always threw me..

Despite being a trial and error person I think it is about time I uderstood the technical aspect of this relationship. Like I said I've always focussed about one thirs in (whatever the aperture) and hoped for the best

http://www.dofmaster.com/dofjs.html
Now, using this online hyperfocus calculator I entered the required measurements...

Camera - Nikon D80
Focal Length - 10mm
Selected f Stop - f/10
Subject Distance - 2 feet (the rock I focussed on)

...and it is telling me that the h/d is 1.75 feet. Now as I focussed on the main rock (bottom right) which was about two feet away I would have (unintentionaly) used the h/d anyway? Or close enough? Am I underestimating how much DoF f/10 will give me? The 'soft' rocks extend only out to about 10-15 feet and I would have thought should have been sharper. What is more concerning is that the rocks to the left that are at the same distance into the frame as the rock I focussed on are a lot softer still.


Musicman said:
The OP needs to to some tests under controlled conditions to ascertain where the problem lies. On a tripod, take photos at different apertures and distances of a brick wall, for example, with and without the ND grad that was apparently used in the sample image. This will, at least, confirm or eliminate any problems with this particular lens.
Click to expand...

Thanks. I was thinking the same. It looks as though I am going to have to do some tests and hopefully eliminate a damaged lens. I just hope it's me that's causing the issue and not a lens fault.
 
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Digifrog said:
What is more concerning is that the rocks to the left that are at the same distance into the frame as the rock I focussed on are a lot softer still.
Click to expand...

TBH, that's what I thought you were on about. :)

It's about all I can make any sort of judgement about at 800px.
 
Nothing on the left side of the frame appears to be sharp - it looks to have a uniform softness top to bottom which doesn't really clear until after the middle of the frame.

OK, would be easier to tell on a full res, but early indications are you have a duff lens. Time for a controlled test and then maybe a trip to sigma for the lens.
 
Musicman said:
TBH, that's what I thought you were on about. :)

It's about all I can make any sort of judgement about at 800px.
Click to expand...

At first I was pointing to the rocks that are placed just behind the rockpools and beyond.

RichardtheSane said:
Nothing on the left side of the frame appears to be sharp - it looks to have a uniform softness top to bottom which doesn't really clear until after the middle of the frame.

OK, would be easier to tell on a full res, but early indications are you have a duff lens. Time for a controlled test and then maybe a trip to sigma for the lens.
Click to expand...

Yes it's worrying. has anyone passed a lensto Sigma for repair here? At £49 per hour service I was wondering how much it would cost overall for a repair to a lens that has recieved shock damage. That is, if the lens is damaged and the softness not caused by my own means.

Scott
 
Do some tests first, there's no point sending it off for repair if all it was was a smudge on the filter or lens. If a knock to a lens causes one side of the picture to be effected, then i would of thought that the result would be more dramatic than a bit of softening, but i dont really know, im just trying to be positive.:shrug:

Good luck with it:)
 
Digifrog said:
Yes it's worrying. has anyone passed a lensto Sigma for repair here? At £49 per hour service I was wondering how much it would cost overall for a repair to a lens that has recieved shock damage. That is, if the lens is damaged and the softness not caused by my own means.

Scott
Click to expand...

If it does need repair, Sigma are always very helpful and chances are would be able to slot it into tarif 6. It probably doesn't need any new parts just alignment.

Obviously test it first though!
 
Adey said:
Do some tests first, there's no point sending it off for repair if all it was was a smudge on the filter or lens. If a knock to a lens causes one side of the picture to be effected, then i would of thought that the result would be more dramatic than a bit of softening, but i dont really know, im just trying to be positive.:shrug:

Good luck with it:)
Click to expand...

Thanks for the positive thought Adrian.

RichardtheSane said:
If it does need repair, Sigma are always very helpful and chances are would be able to slot it into tarif 6. It probably doesn't need any new parts just alignment.

Obviously test it first though!
Click to expand...

Thanks Richard, I will.

Here's a question for the esteemed knowledged ones. It has been mentioned elsewhere that "focus shift" could be the problem here. Now I cant remember how I set the shot up but I possibly did this...

Say I focussed on the rock with the rock in the centre of the viewfinder then recomposed so that the rock is in the bottom right (imagine the dynamic of moving left and up to recompose), would this give sufficient "focus shift" to soften up the left hand side of the image?
 
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Digifrog said:
Thanks for the positive thought Adrian.

Here's a question for the esteemed knowledged ones. It has been mentioned elsewhere that "focus shift" could be the problem here. Now I cant remember how I set the shot up but I possibly did this...

Say I focussed on the rock with the rock in the centre of the viewfinder then recomposed so that the rock is in the bottom right (imagine the dynamic of moving left and up to recompose), would this give sufficient "focus shift" to soften up the left hand side of the image?
Click to expand...

I really doubt recomposing would cause the effect observed in your pic.
Thats if there is anything, i still think a proper test is in order.

The only step thats gonna take this forward is you doing a proper test. Leave the suppositions untill you've done the test.
















Do the test.
 
Digifrog said:
would this give sufficient "focus shift" to soften up the left hand side of the image?
Click to expand...

if it were in play, it should affect both sides of the image equally.

If elements on one side are out of focus, but other elements at the same distance on the other side not, that suggests something wrong with the lens (or that you're using a camera with movements, like a Linhof :))
 
Looks fine to me too. Surely if there was a problem it would show on the wall.

Im starting to think you had a smudge mark on your lens/filter.
Which would make you look slightly silly, but at least you wouldnt have a duff lens :lol:
 
It looks like a very basic error in that you've chosen a focus point too close to the camera. You'd have done better focusing somewhere in the centre of the furthest group of rocks.

Depth of field extends over a distance which gives you an acceptably sharp image over a range which extends two thirds behind the point of focus into the distance, and about one third in front of it, towards the camera. As a rough rule of thumb, focusing 1/3 of the way into your scene and then recomposing is good guide in most situations. As I'm sure you're aware though, you can get depth of field tables for any lens to give you a more accurate indication.

Nice shot btw. :thumbs:
 
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