Strange rainbow effect

[cuthbert]

hello all,

i have noticed a phenomena where under certain lighting conditions a rainbow/banding effect is visible.

i don't really notice this happening on lenses which have a short focal length, but longer lenses like the 100mm macro and the 135mm it's more apparent. it seems to only appear at wide apertures (like f2.8 or f2)

what i'd like to know, is what is the 'technical' name for this effect?

this is an extreme example of what i'm talking about.

 

[Ewan Hitchcoe]

do you have any other examples? that looks like an oil/petrol spill on a wet road?

 

[cuthbert]

Hello Ewan,

Here is a different shot:

 

[TheNissanMan]

Oily remnant of a fingerprint on the lens??

 

[cuthbert]

i think it's light related, the photo in the first post was taken with a different lens than the other image.

if you take a look at this image, taken seconds later from almost the same position the effect has disappeared:

 

[cuthbert]

the pictures disappeared over the weekend for some reason, but does anybody know if this is just "flare"?