Night Life

riseagainst

So i was wondering what is causing the rainbow effect around the street lights? Can someone help please it ruins all my night shots for the most part? I shoot a Canon 50d i currently don't have a filter on the lens is that the problem?

pathfinder

What lens was used for this image?

riseagainst

pathfinder wrote:

What lens was used for this image?

Canon 18-55 Shot on a tripod with a long 30 sec exposure time

LiquidAir

A filter won't help you here; if anything it would make it worse.

The first thing I'd try is cleaning the lens. My technique is to use a wet kit first and once the lens looks clean, polish it up with a lens pen.

The the next thing I'd try is experiment with different aperatures (and correspondingly different shutter speeds or ISO) to see how the aperture value affects the image.

If neither of those fix it then there is likely something wrong with the lens. If you can, borrow another lens for comparison. Better lenses will flare less, but this is extreme even for a kit lens so my guess is that it will need repair.

pathfinder

riseagainst wrote:

Canon 18-55 Shot on a tripod with a long 30 sec exposure time

Aperture? sorry but I don;t have an exif reader at work.

pathfinder

I see LiquidAir has already gone where I was going.

I think this is the lens, but seems more extreme than I would expect even with a kit lens. A filter would make this worse, as would a lot of grease, fingerprints on the front element. But this seems extreme.

The multiple reflections look like they are coming from different refracting surfaces within the lens, and seem to be due to different wavelengths/colors as well.

Was this shot wide open/ Or were you stopped down two stops or three from wide open?

Your lens should be near is optimum about 2 stops smaller than wide open, or ~ f5.6 -f8 - f11 area.

Like Ken suggested, I would try a couple different apertures and different focal lengths with this lens, to see if it improves. If not, I would submit it to Canon Factory Service for repair.


As for lens cleaner, I use Ultra Clarity liquid eyeglass cleaner sparingly if needed on my lenses without concern. You do not want so much fluid it can run behind the front element. Usually I just use a lens brush for dust, and reserve wet cleaning for real grease smears.

riseagainst

File Name _MG_7003.JPG
Camera Model Canon EOS 50D
Firmware Firmware Version 1.0.7
Shooting Date/Time 3/6/2010 8:59:45 AM
Owner's Name
Shooting Mode Manual Exposure
Tv( Shutter Speed ) 30
Av( Aperture Value ) 22.0
Metering Mode Evaluative Metering
ISO Speed 800
Auto ISO Speed OFF
Lens EF-S18-55mm f/3.5-5.6
Focal Length 18.0mm
Image Size 4752x3168
Image Quality Fine
Flash Off
FE lock OFF
White Balance Mode Auto
AF Mode One-Shot AF
Picture Style Standard
Sharpness 3
Contrast 0
Saturation 0
Color tone 0
Color Space Adobe RGB
Long exposure noise reduction 0:Off
High ISO speed noise reduction 0:Standard
Highlight tone priority 0:Disable
Auto Lighting Optimizer 0:Standard
Peripheral illumination correction Enable
File Size 5025KB
Dust Delete Data No
Drive Mode Single shooting
Live View Shooting ON

pathfinder

f 22 - A small aperture that limits resolution due to diffraction. I am not sure if that is what is responsible for all the defects in your image however.

As I said, I think you will find you lends performs better at f8 or f11.

LiquidAir

pathfinder wrote:

As for lens cleaner, I use Ultra Clarity liquid eyeglass cleaner sparingly if needed on my lenses without concern. You do not want so much fluid it can run behind the front element. Usually I just use a lens brush for dust, and reserve wet cleaning for real grease smears.

Grease smears can create effects like the ones in that shot. Its a technique I occasionally used deliberatly (on a clear glass filter, not the lens) back in the days before Photoshop.

These days the most common reason I end up wet cleaning my lens is when shooting near heavy surf. The salt water in the air can coat a lens pretty quickly but, unlike grease, it doesn't seem to result in the kind thin film which creates rainbows in the image.

pathfinder

What you are describing sounds like Vaseline on the lens - better to put the Vasline on a filter, eh?

I live in a fly over state, so I usually don't have to worry about salt deposits on my lenses. That is one time I definitely want to use a water based solution to dissolve salt deposits before using a cleaning cloth.

Salt spray is an indication for a UV filter to me, one of the few times I suggest using a filter.

ROR - "Residual Oil Remover" is great for removal of oil on lenses and is available via the web.

riseagainst

Thanks for the afeedback guys next time i shoot there i'll try some different aperture settings or a different lens!