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DE&i

Blurred Edges

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DE&i

On the day you can find plenty of shark’s teeth from Walton-on -the Naze. But to really bring them to life and to give them the credit they really deserve I decided to up the stakes with my new camera.

The slight blurring around the edges becoming a recurring problem at the moment would anyone have any suggestions to eliminate this problem please.

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Edited by DarrenElliot

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jpc

google 'photo stacking'.

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Auspex

This is mostly a depth of focus issue. More light (resulting in a smaller aperture) should help.

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snolly50

painshill is indeed correct (and fast). Stop down your camera, use a smaller aperture. This will help. Of course, like everything, this is a trade-off. You'll need more light. I think your photos are just fine as they are. But you are right, there is softness at the edges. Vignetting is the label for the phenomenon, Google that, if you wish. Good luck, have fun.

Edited by snolly50

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DE&i

Guys what I can say…as I keep telling family and friends “it’s not just about the fossils”.

“Right then I’m going in armed with my notes”

Regards,

Darren.

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painshill

Without wishing to nit-pick, there’s only very minimal vignetting on your pictures. As Auspex said, there’s a “depth of field” issue resulting in loss of sharpness for parts of the subject which are nearer or farther away from the focal point of the lens. Vignetting manifests itself as a difference in contrast or saturation of the edges of the image – usually apparent as dark/muddy corners or what looks like a darker ring around the image. It’s barely noticeable here, not unusual and normally a sign that a lens is being used at or close to the limits of its design capabilities – a zoom lens at its shortest focal length and widest aperture for example. When severe or obvious, it’s a sign of a cheap or inferior lens.

It also happens when SLR enthusiasts who already have a good selection of lenses purchased in the past for a non-digital camera believe that these are OK for use with a digital body because they have the same fitting. Although you can still mount these lenses on a digital body, and some of the automatic linkages may work, they aren’t optically matched to the sensor and again you’ll likely get vignetting.

A mismatch between angle of flash coverage and focal length of lens will cause it too.

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Harry Pristis

Try elevating the object a few inches on a piece of window glass. Illuminate the object and the background (I often use a sheet of typing paper) equally. In the image, the object should look like it's floating in air with no shadowed edges. Use a minimum of two color-correct light sources.

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snolly50

Without wishing to nit-pick, there’s only very minimal vignetting on your pictures. As Auspex said, there’s a “depth of field” issue resulting in loss of sharpness for parts of the subject which are nearer or farther away from the focal point of the lens. Vignetting manifests itself as a difference in contrast or saturation of the edges of the image – usually apparent as dark/muddy corners or what looks like a darker ring around the image. It’s barely noticeable here, not unusual and normally a sign that a lens is being used at or close to the limits of its design capabilities – a zoom lens at its shortest focal length and widest aperture for example. When severe or obvious, it’s a sign of a cheap or inferior lens.

It also happens when SLR enthusiasts who already have a good selection of lenses purchased in the past for a non-digital camera believe that these are OK for use with a digital body because they have the same fitting. Although you can still mount these lenses on a digital body, and some of the automatic linkages may work, they aren’t optically matched to the sensor and again you’ll likely get vignetting.

A mismatch between angle of flash coverage and focal length of lens will cause it too.

painshill is indeed correct to imply, as did auspex; that a razor thin depth of field is a vexation in all "close-up" photography efforts. However, the softness I am seeing (picture 1, look at the corners) is due to vignetting. That is, I am assuming your background is flat; therefore it all (including the soft corners) must be in the same plane in relation to the camera's sensor. The softness may well be caused by limits of the lens employed and not an "operator error." As painshill suggests, focus drop-off at the edges may be a characteristics of the optics employed. Little can be done about that beyond switching equipment. Unfortunately, flawless lenses come at a hefty price. As I said, to my eye the fossils themselves in your shots are acceptably sharp. In picture 1 for example, I do see some softness at the root margin where it touches the background. This is certainly a depth of field issue and could be avoided using jpc's original post suggesting "stacking" software.

I am intrigued by the floating technique offered by Harry Pristis. I will experiment with that at the first opportunity.

I appreciate your efforts to post better pictures and the member's comments to support that effort. I wish everyone (myself included) would make an extra effort to get quality images. I find one of the great pleasures of the Forum is the chance to "see" great fossils; that I will probably not see in person. An excellent photo certainly enhances that experience.

Hmmm, my post appears with odd boxing around the text...curious!

Edited by snolly50

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ssholly

I think a very important part of any question a member asks in the photography section is to include the name and model of their camera as well as the lens (or lenses) they are using.

The replies to the initial question have all been very good except it might not be applicable to that particular situation due to a limitation in the camera and/or lens and thus might be very confusing. In fossil photography, most issues seem to revolve around depth of field (focus depth) that is easy to address with most dSLRs on the market today. Many people, however, have cameras that advertise being an "advanced optic system" but in fact lack the ability to capture images that people expect from their cameras.

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xonenine

now that you have Photoshop there is also the post processing option of using the "Unsharp Mask". It's often ideal for minor fixes such as this.

http://en.wikipedia.org/wiki/Unsharp_masking

:)

also sometimes I will try to leave "canvas" available so that I can recrop an image when I'm done, as the edges can often suffer various issues from this step as well

Edited by xonenine

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Sagebrush Steve
On 5/7/2014 at 11:51 AM, painshill said:

Without wishing to nit-pick, there’s only very minimal vignetting on your pictures. As Auspex said, there’s a “depth of field” issue resulting in loss of sharpness for parts of the subject which are nearer or farther away from the focal point of the lens. Vignetting manifests itself as a difference in contrast or saturation of the edges of the image – usually apparent as dark/muddy corners or what looks like a darker ring around the image. It’s barely noticeable here, not unusual and normally a sign that a lens is being used at or close to the limits of its design capabilities – a zoom lens at its shortest focal length and widest aperture for example. When severe or obvious, it’s a sign of a cheap or inferior lens.

It also happens when SLR enthusiasts who already have a good selection of lenses purchased in the past for a non-digital camera believe that these are OK for use with a digital body because they have the same fitting. Although you can still mount these lenses on a digital body, and some of the automatic linkages may work, they aren’t optically matched to the sensor and again you’ll likely get vignetting.

A mismatch between angle of flash coverage and focal length of lens will cause it too.

Painshill is correct, this is a depth of focus issue, there is no vignetting.  Take a look at the first photo.  You will see that the background at the top and bottom of the photo is blurred, and at the center of the photo it is in focus.  This is because the camera was tilted with respect to the background sheet. The top of the sheet was farther from the camera and the bottom of the sheet was closer to the camera than the distance of optimal focus.  This is a classic way to demonstrate the concept of depth of focus.  If you stop the lens down to something like f/22 you will see a broad range across the center of the image that is in focus.  If you open it up to something like f/5.6 there will only be a narrow line across the center that is in focus.  You can improve things by making sure the camera is aligned precisely parallel with the sheet.  Then stop the lens down to around f/22.  You can't do this if your camera only has an automatic setting, which is why you see recommendations to get more light onto the subject.  If you have a DSLR mounted on a tripod, set it to "aperture preferred" and set the f-stop to around f/22.  The camera will then automatically set the correct exposure time for the amount of light.  It needs to be on a tripod to prevent any movement during the exposure.  One more recommendation is to not stop the lens all the way down to its smallest opening because then another effect called diffraction comes into play, making your entire photo just slightly less crisp.  Back off one or two stops to get the sharpest image.

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