Canon CMOS Stuck Sub-Pixel/Filter Issues

[Pollywog]

So I finally have myself a proper DSLR, but after just over 2000 shots I started noticing a consistent stuck sub-pixel on the CMOS sensor in my 450D. I just got into photography within the last year and am not an expert by any means, and wanted to see if perhaps this is just a usual "luck of the draw" situation or whether it is something worth redeeming warranty for. In raw it turns up as a solid green pixel, whereas after a conversion to JPEG it turns into a white star over a few pixels..

Examples:


Upper right:





Upper right:


What can I do? I've heard about some sort of "pixel-fixing/remapping" feature that Canon has, but I am having trouble finding it within any of my included programs or on the Camera itself..

Secondly, I have been using a UV filter on one of my lenses as a cheap lens protector. After having used it on my 18-55 for a while I have noticed intensified lens flare as well as random "blooming" of some sort in my photos. As soon as I take it off, the pictures lose the horrid glare marks - so what is causing it? I wasn't under the impression that this was a usual side-effect, but I am guessing that light is somehow bouncing between the filter and the outermost lens.. My polarizing filter (HOYA - Japan) doesn't do this at all, however is it because my UV filter (CANON - USA built) is of horrid quality?

Example:

You can also spot the pixel issue in the middle of the upper 1/5..






Thank you kindly for any help!

[HiSpec]

off topic... how did you achieve that "star shape" effect on those lamps?

[Pollywog]

Originally posted by HiSpec
off topic... how did you achieve that "star shape" effect on those lamps?

Happens naturally, especially with longer exposures - however I'm sure one of the pros here will be able to give you a much better explanation. I actually wish it wasn't so dramatic to be honest.

[mboldt]

I think this is a common problem with long exposures.. Do you have any other daytime fast exposures to show? or do you only shoot night time long exposures?

I have this problem with my D700 even... I think I have with every camera.

[blitz]

You get the star shapes with lower apertures (f18ish onwards), from my experince, the lower aperature the more pronounced the star shape.

As for the filter, it's a common effect, even on the high quality ones. I use a UV filter on all my lenses, but take them off if I've got a big light source in the frame.

[KKY]

The hot pixel issue was discussed recently. you can take a look for a bit more info
http://forums.beyond.ca/showthread.p...hreadid=286688

There are many different grades of UV filters. The better ones have multiple anti-reflective coatings that help reduce the flaring issue.

[Pollywog]

Originally posted by mboldt
I think this is a common problem with long exposures.. Do you have any other daytime fast exposures to show? or do you only shoot night time long exposures?

I have this problem with my D700 even... I think I have with every camera.

Unfortunately, it doesn't matter the iso/exposure/aperture - its always there.

[Pollywog]

Originally posted by blitz
As for the filter, it's a common effect, even on the high quality ones. I use a UV filter on all my lenses, but take them off if I've got a big light source in the frame.

Ahhh, alright well I think I will stop using it as a lens protector atm.

Originally posted by KKY
The hot pixel issue was discussed recently. you can take a look for a bit more info
http://forums.beyond.ca/showthread.p...hreadid=286688

There are many different grades of UV filters. The better ones have multiple anti-reflective coatings that help reduce the flaring issue.

Thank you for the link and info on reflective coatings. I've seen single and multi-coated filters and did not know that this was one of the things it combats.

[AccentAE86]

Yeah, your shots were like 13 and 6 seconds long. Almost all cameras will show some of those hot pixels with those exposure times. Nothing too alarming. Some people say that the camera can map those pixels out by running the mirror locking sensor cleaning function with the lenscap on for about a minute, but I've never tried nor cared to try. It won't fix them, it'll just map them out.

The filter is probably what's causing the weird glare. Canon filters suck. They are made by Tiffen and are low quality. Hoya filters are much better than the Canon branded ones, especially if you get the HD, HMC, S-HMC, or Pro-1 filters. I like to use filters, but I would rather use none than use a Canon branded filter.

The "star" shape is a natural effect of your aperture and exposure value. There isn't a magic aperture where this will happen, but it is easier to get it to happen at smaller apertures; but you HAVE to be stopped down somewhat to get this effect. The exposure value on the point light source has to be within a reasonable range to get a good star effect. So depending on your ISO or shutter speed, you can generate a star at F/8 and NOT get one at f/16. But it definitely is easier to produce the star effect at small apertures. Just don't overexpose the light sources too much.

A lens with an EVEN number of aperture blades will generate a star with the same number of points as blades. A lens with an ODD number of aperture blades will generate TWO points on the star for each blade.

In reality, both even and odd aperture bladed lenses generate TWO points for each blade, but the even bladed lenses have two stars that are superimposed on top of each other so it only looks like it has one point per blade.

The star points are actually diffraction spikes due to the non-circular shape of the aperture. That's why you cannot create this when wide open. The more you stop down, generally, the less circular the aperture is, which is why it's easier to generate this at smaller apertures. This is also the reason why this effect shows up at wider apertures in lenses that have less blades due to the fact that it is less rounded right from the start.

[Pollywog]

Originally posted by AccentAE86
Yeah, your shots were like 13 and 6 seconds long. Almost all cameras will show some of those hot pixels with those exposure times. Nothing too alarming. Some people say that the camera can map those pixels out by running the mirror locking sensor cleaning function with the lenscap on for about a minute, but I've never tried nor cared to try. It won't fix them, it'll just map them out.

Even on short-exposure day shots I am getting a solid green pixel in the upper right, solid red and a green on the left + a few others.. Is this still considered normal?

Originally posted by AccentAE86
The filter is probably what's causing the weird glare. Canon filters suck. They are made by Tiffen and are low quality. Hoya filters are much better than the Canon branded ones, especially if you get the HD, HMC, S-HMC, or Pro-1 filters. I like to use filters, but I would rather use none than use a Canon branded filter.

The "star" shape is a natural effect of your aperture and exposure value. There isn't a magic aperture where this will happen, but it is easier to get it to happen at smaller apertures; but you HAVE to be stopped down somewhat to get this effect. The exposure value on the point light source has to be within a reasonable range to get a good star effect. So depending on your ISO or shutter speed, you can generate a star at F/8 and NOT get one at f/16. But it definitely is easier to produce the star effect at small apertures. Just don't overexpose the light sources too much.

A lens with an EVEN number of aperture blades will generate a star with the same number of points as blades. A lens with an ODD number of aperture blades will generate TWO points on the star for each blade.

In reality, both even and odd aperture bladed lenses generate TWO points for each blade, but the even bladed lenses have two stars that are superimposed on top of each other so it only looks like it has one point per blade.

The star points are actually diffraction spikes due to the non-circular shape of the aperture. That's why you cannot create this when wide open. The more you stop down, generally, the less circular the aperture is, which is why it's easier to generate this at smaller apertures. This is also the reason why this effect shows up at wider apertures in lenses that have less blades due to the fact that it is less rounded right from the start.

This is why I ask questions here. This is super informative!

Edit: And thank you, I am now looking into the mirror lock-up/lens cap fix at the moment.

[AccentAE86]

Originally posted by Pollywog


Even on short-exposure day shots I am getting a solid green pixel in the upper right, solid red and a green on the left + a few others.. Is this still considered normal?




This is why I ask questions here. This is super informative!

Edit: And thank you, I am now looking into the mirror lock-up/lens cap fix at the moment.

If it's still happening in short exposure shots, then it might need a trip to Canon. They won't fix it, they'll just map it out. It's a standard procedure and not a "cop out". I'm sure I have DOZENS of pixels that are mapped out on all my bodies.

[Pollywog]

Originally posted by AccentAE86


If it's still happening in short exposure shots, then it might need a trip to Canon. They won't fix it, they'll just map it out. It's a standard procedure and not a "cop out". I'm sure I have DOZENS of pixels that are mapped out on all my bodies.

Believe it or not, your tip about the mirror lock-up + lens cap actually fixed almost every stuck sub-pixel, and now my problem has been reduced to only one red pixel. I can't thank you enough!

Both problems solved, thanks beyond.

[AccentAE86]

Glad to hear it worked out for you!