Problem

[yelvertoft]

Originally Posted by Susan Green LMPA

I'd like to enclose an attachment to my post, but did not figer out how.

Susan

Susan,

Below the "Quick Reply" box where you probably typed in your comment, there is a box marked as "Go Advanced". If you click on this you have many more options as to how you can compose your comment. One option is below the text entry box shown as "Manage Attachments", by using this box you can add attachments to your post.

Hope this helps.

On other matters, I'd agree with Robski that flare does not have to be hexagonal. It is often hexagonal when seen on a DSLR where the aperture blades form a hexagonal (or heptagonal, or octagonal...... etc) hole dependent on the number of blades forming the lens aperture. This kind of flare is seen when the blades of the aperture form a stray internal reflection within the lens. I agree with your advice on metering modes and methods, this will no doubt be helpful Alan with his general photography skills regardless of this specific problem.

Regards,

Duncan

[Alan.P]

I'd just like to ask if anyone knows where and if I can purchase a lens hood for my digital camera. My avartar is the camera I use a samsung S1050 so is it possible to fit a lens hood to this type of camera.

[andy153]

Hi Alan - you should not need a lens hood with this camera as the lens itself is recessed behind the lens cover - this creates a permanent lens hood. I would suggest you have a good look at the lens and carefully wipe it with a lens cloth if it looks smeared at all. I have looked at the thumbnail you posted and IMO you have a greasy? mark or some condensation on the lens which just needs cleaning off. I have looked at the specs and am impressed - a 5x Optical zoom and 10.1 mp - shake reduction etc - does it make tea as well? Anyway to repeat - lens hood is built in by the recess of the lens and remember to use that blind on the front to protect your lens.
Looking forward to many posts.

[Susan Green]

I am glad, Andy, you do agree with me that it is an orb as they are cause usually by some dirt/dust/drops of water. I found out about orbs on internet. Personally I use lens hoods too, and "nothing against them". I darkened the photo in question and did not see any strong light, just blue sky. It is not "the fix" of it, just to see more detais. If i manage i'll send it. About these orbs is a lot of interesting reading on internet and it would be nice to discuss them more.

Susan

[Susan Green]

Alms%20Houses%20cd.jpg
It looks, I did it

Susan

[andy153]

Go on Susan - tell us what you did.

[robski]

Can anybody explain why the so called orb effect is not the result of lens flare ?

The only thing I can see special about orbs is that you are dealing with pin point sources of light.
To be honest I would not describe Alan's effect as an orb after studying various photos of the effect on the net.

The "flare" effect is the result of light scattering. In the "ideal perfect" lens the transfer of light should be 100%, Sadly this is never the case therefore all optical lens suffer from flare to some degree. When light meets the boundary of a different density material its direction of travel bends. Which means that some of the light will be reflected away and some will transfer through it. The light scattering in different directions is the effect we are seeing. Whether you want to call it orbs or flare is a matter of choice and convention. Slight light scattering usually just manifests itself as a reduced contrast because the scattered light is lightening dark areas. To what extent light is reflected or transfered is dependent on the angle of light striking the boundary surface. In the case of the optical crown glass - air boundary the critical angle of when most of the light is reflected away is approx 41 degrees.

The problem with compact style of cameras is that they use a tiny sensor. This requires the use of an ultra wide angle len (typically 5 to 7mm) to get a sensible field of view. The plus side is a great depth of field and close focusing. The down side is that you are more likely to see blemishes and other effects on the lens front element.

Andy's prime suspect of a thumb print or such is a possible cause of this flare. Remember a greasy thumb print is a material of a different density.

Lens coating is about using different density materials to your advantage.

An interesting study of the behaviour of light is the science of rainbows.
http://science.howstuffworks.com/rainbow2.htm

[robski]

Attached is Alan's original image reduced to 8 gray levels.
It can be seen that shaded brick area on the right is 100% brighter than the lefthand side. This flare maybe due to a thumb print or a strong light source on the lens front element.

[miketoll]

Agree with Robski, flare can (and often does) show just as loss of detail or contrast to all or part of the picture. Robski's attachment shows this well and is something that I have to be aware of with my 70-300 DO IS Canon lens which is a bit prone to flare which is why it comes with a deep lens hood. Well Alan try shielding your camera lens in similar circumstances to the ones you have already noticed cause the problem and report back.

[miketoll]

It goes without saying that marks or any foreign matter on the lens surface will make the lens more susceptible to flare, as Robski explains so well, so keep the lens spotless (I find micro fibre cloths excellent). My understanding of 'orb' in this context is just a very specific type of flare so cleaning and shading should normally do the trick.