What causes different light effects - starburst or not

[teddyt72]

Hi all,

A friend of mine too a long exposure photo on holiday - now the lights have left a trail on the same plane, whereas I tend to find starburst effect when I take the same kind of photo - any ideas what causes this? I can only assume it's the lens...

 

[Dino f]

Aperture, the smaller the aperture ie f22 etc, the more pronounced the effect will be. The different shaped starburst variation from lens to lens can depend on the shape of the blades also the amount of blades in the iris.
I think.
Dean

 

[teddyt72]

Hi Dean,

Ok thanks for the comment - a "feature" of a lens I hadn't considered before!

I am aware that using a smaller aperture exaggerates the effect but I wasn't aware of such variance in how lenses record light bursts.

 

[adsayer]

Teddy, did you friend use any particular filter infront of the lens... that type of feature of starburst (all on the same plane) I've only seen with the use of a special cokin series filter.

that or there is a HHHHUUUUGGE scratch on the lens lol.

Regards,

Ads

 

[Ian D J]

I'm pretty sure that's caused by the lens being heavily smudged caused by greasy fingerprints! Perhaps a gentle wipe with a lint-free cloth might help it.

 

[Nod]

^^^

WHS.

Parallel smears on the lens will cause that effect, especially on long exposures straight at a light source. Criss crossed smears (like you'd get from trying to clean a greasy mark off a lens/filter without too much success) will give a starburst effect. A 6 bladed iris can cause this (starburs effect)as well, especially with cheaper lenses that sometimes don't have a rounded aperture (8 bladed etc tend to be better made with some effort being put into keeping the aperture reasonably rounded).

 

[teddyt72]

Hi all,

As far as I'm aware no filter was used, and the lens is the standard kit lens with the D40. I saw some non night shots with the same lens and they looked fine so don't think it's a scratch, possible a smudge though.

Thanks for the comments