Help with wide angle lens with out of focus photos

[polarmagnus]

Here's a few photos. I processed it through Camera Raw but didn't change any settings.

I focused the middle AF Point Selection on the post.
Focal Length: 20mm
Shutter Speed: 1/160s
Aperture: f/13
ISO: 200
Shutter Speed: 7321928
http://www.photoradar.com/files/imag...us/mg-1504.jpg


Focal Length: 20mm
Shutter Speed: 1/125s
Aperture: f/11
ISO: 200
Shutter Speed: 6965784
http://www.photoradar.com/files/imag...us/mg-1525.jpg


Focal Length: 10mm
Shutter Speed: 1/125s
Aperture: f/16
ISO: 100
Shutter Speed: 4643856
http://www.photoradar.com/files/imag...us/mg-1545.jpg

[markgozz]

First of all if you want to make sure your lens isn't faulty and giving you blurred shots you should take several shots on a tripod of the same object but at different settings .
Secondly any image shot in RAW will need some sharpening in camera raw other wise they will look a bit soft .

I'm not quite sure what you mean about the f stop on the lens being different outside ?

Having said all that the images don't look like they have a focusing problem .


Mark

[jet_kit]

Originally Posted by silversnapper1

I think that jetkit may mean calibration.

No, don't think so.

Collimation is the process of aligning the elements of a complex lens to ensure proper focus at the focal plane. It's not the sort of thing you do in your shed, but lens manufacturers/repairers will have the gear to do it.

Polarmagnus.
What you need is to draw some fine lines on a piece of card about 1mm apart over a distance of about 150mm (Yup, that's a lot of them). Make the centre line thicker than the rest and that's your point of focus. Set the card up at 45 degrees (so the bottom of the card is closest to you and the top furthest away) and focus on the centre line as close-up as the lens will allow at max aperture. Load the image onto your computer and look at it @ 100%. If the lens is correctly collimated the centre line will be sharp and this sharpness will tail off in front and behind that spot. If it's out, the point of maximum sharpness will be elsewhere and you can use that image to show the shop.

[deena]

There's an interesting article here on focusing Chris. At the end of the article there is a downloadable chart. Is this relevant? I only ask because I haven't used it but knew I had it somewhere on the pc.

It would save drawing all those lines

[polarmagnus]

This might be a daft question but. Would the photos look any different if I use a UV filter?

[markgozz]

Quick answer no . As long as there's nothing wrong with it .( Damaged , scratched , scuffed )

Mark

[Cathus]

f4 - 5.6 is the widest aperture you can use, f4 at 10mm zoom but it changes to f5.6 at 20mm zoom, you can use all the other f-stops it's just they print the widest ones available on the lens

more expensive lenses have the ability to use f4 (or whatever is the widest setting)all the way through the zoom range but cheaper lenses use cheaper glass/components and can't do this.

[polarmagnus]

Originally Posted by Cathus

f4 - 5.6 is the widest aperture you can use, f4 at 10mm zoom but it changes to f5.6 at 20mm zoom, you can use all the other f-stops it's just they print the widest ones available on the lens

more expensive lenses have the ability to use f4 (or whatever is the widest setting)all the way through the zoom range but cheaper lenses use cheaper glass/components and can't do this.

Thank you. I now understand it.

[jet_kit]

Originally Posted by deena

There's an interesting article here on focusing Chris. At the end of the article there is a downloadable chart. Is this relevant? I only ask because I haven't used it but knew I had it somewhere on the pc.

It would save drawing all those lines

Hi Deena,

You're right. This is a very comprehensive article and offers a downloadable chart similar to what I was suggesting Polarmagnus makes. I use the one published by AP, but they all do the same job and are a very quick check to ensure that the problem is not a physical one.

Thanks for the input.

[polarmagnus]

Taking my camera and a work mate to Linton Falls tomorrow afternoon. I'll have my tripod too, so I'll be using that all the time.

Hopefully, it won't rain all the time. Its suppose to be sunny intervals in the afternoon, but we'll see.

I'll let you all know how I get on.