What causes this wierd flaring?

K

KayJay

Give us a Tena
Suspended / Banned
Messages
5,783
Edit My Images
Yes
I was having some issues last night which I've not experienced before with some of my night images and was wondering if anyone can offer some advice or help.


Exposure: 13 sec (13)
Focal Length: 10 mm
ISO Speed: 400
Aperture: f/11.0
Do I have dust particles on my lens and what causes the strange flare on the top left of the police box.


Exposure: 4 sec (4)
Focal Length: 10 mm
ISO Speed: 400
Aperture: f/4.0
And with this one what causes the strange flaring effect from the light all the way across the sky?

Hoping someone can offer some advice and help on this as it's frustrating to come home and find that on my piccies :'(
 
You can expect to get these flare effects sometimes when you're shooting straight at light sources - in this situation a lens hood is no protection. In the first shot the hexagonal shapes are the shape of the diaphragm reflecting back and forth off the internal elements of the lens. If you were using a protection filter it could add to the problem in this situation.

In the second shot the flare effect is caused by two artificial light sources shining right into the lens. If you'd used a smaller aperture (and longer shutter speed) - you'd have got a sharper, more pronounced star filter effect from the lights, which is probably preferable to the softer effect you have here.
 
I'm guessing you were using quite a small aperture to get those exposure times so my suggestion would be a combination of:
1. Light defraction off the edge of your aperture blades
2. Exagerated lens flare from over-long exposure
3. Simply a bright light bouncing off your open sensor, onto your lens, and back onto your sensor

Keep the aperture a little wider and the exposure a little shorter to minimise the issues, sadly its unliekly you'll ever illiminate thenm so focus on the mitigation.

Most effective is a small piece of black card to block the edges of scene (which are out of shot) to prevent stray light spilling in. The lens hood on the 10-20mm is not the biggest .

HTH :thumbs:
 
oops, beaten by CT - with a much more concise answer :lol:
 
In the first one it's the sensor reflecting light back onto the rear optic of the lens which in turn reflects back onto the sensor. It is the reflection from the double street lamp to the left of the police box. The second one looks like reflection from a filter, do you have a filter on the lens? What lens did you use for these shots?
 
Thank you both for the advice. I'm going to go out again tonight and apply those techniques. I did get some good shots last night but a couple of them I was questioning.

Thanks again :)
 
Also CT, I did have a protection / UV filter on the camera all night. I was using the Sigma 10-20mm.


This one came out better.

 
I don't use protection filters, but in this situation, why not just remove it while you take the shots? :)

Yep - that 2nd shot is better - I'd guess a smaller aperture? Try using a smaller aperture still, the star effects can look pretty good then.
 
Yeh. The first one with the flaring was f/4.0 and the second one which is a bit better is f/5.6.

From now on I'll take off the filter. I guess it makes sense when taking the shots as I'm not likely to scratch or damage the lens.

I've linked to these helpful comments from the flickr page for those images. Hope you folk don't mind, some other people will find them helpful. :)
 
We never mind being linked to other sites. ;)

Always use a lens hood - which is good protection against most accidental knocks..
 
You must log in or register to reply here.
Back
Top