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DPChallenge Forums >> Tips, Tricks, and Q&A >> Blue halo
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 12/16/2003 07:57:35 PM · #1
I'm getting a blue halo around some of my subjects.

I'm hesitant to post examples because they are ones I'm working on for current challenges.

It seems to be mostly light coloured objects or recently some trees against the sky.


12/16/2003 08:00:32 PM · #2
Are you getting it straight from the camera of after some editing?
 12/16/2003 08:02:14 PM · #3
Right out of the camera.
This is daylight and studio lighting. Dark background and light.
Shooting in jpg.
 12/16/2003 08:04:32 PM · #4
Would like to see an example when you can post one.
 12/16/2003 08:07:46 PM · #5
I'm hardly an expert but it could be chromatic aberrations. The following link explains it and gives some examples. Have a read and see if that is the problem.

Chromatic Aberrations
 12/16/2003 08:24:56 PM · #6


OK,, here's one from tonight.

I won't be entering a shell! darn.
Anyway, the chromatic aberration sounds plausible.
I'll keep reading and see if they have a solution.

Oh yeah, it is whether the camera is cool or has been in use too.

It just started showing up the other day.
12/16/2003 09:06:25 PM · #7
It's the acid tracers from the 60s. I get em now and then too. hahaha No, really it looks like your sensor is out of calibration or there is a custom level set, like white balance thats too strong. Perhaps decrease the white balance down by -1 or -2 and try the same shot with the same light.
 12/16/2003 09:09:40 PM · #8
JC,
It looks suspiciously like CA, but usually there will be a cyan halo on one side, and a magenta one on the other; you can see this easily on dark objects against light background (e.g. trees against sky). If its CA (chromatic aberration) it should not just show up all of a sudden, so I suspect is not, however I have not a clue as to what else it might be.

Message edited by author 2003-12-16 21:13:07.
 12/16/2003 09:11:49 PM · #9
Originally posted by deafwolf:
It's the acid tracers from the 60s. I get em now and then too. hahaha No, really it looks like your sensor is out of calibration or there is a custom level set, like white balance thats too strong. Perhaps decrease the white balance down by -1 or -2 and try the same shot with the same light.


SHHHHHHHHHHHHHHHHHHH,,,, I'm trying to live that down! LOL

Ok I'll check that.
 12/16/2003 09:28:00 PM · #10
Nope exposure comp. doesn't help...

dang, I was hoping that was it.

next????
 12/16/2003 09:30:37 PM · #11
Have you ever (recently) applied anything to the lens surface? A residual film a few molecules thick might be enough to induce CA.
 12/16/2003 09:45:12 PM · #12
oo,, I really wanted it to be that..
I had just started using a lens pen...

But, just cleaned the lenses.. still there.

12/16/2003 09:58:59 PM · #13
Ok,, cleaned some more and it's better.
Now it's just a reddish halo. but much smaller.. I'm gonna work on the lens some more.

What do you clean with if you think the lense may have a residue that isn't going to come off with a regular lens cloth?
 12/16/2003 10:58:19 PM · #14
Originally posted by JC_Homola:
Ok,, cleaned some more and it's better.
Now it's just a reddish halo. but much smaller.. I'm gonna work on the lens some more.

What do you clean with if you think the lense may have a residue that isn't going to come off with a regular lens cloth?


The popular solution is "Eclipse" lens cleaner, which is essentially just purified methanol. I use HPLC-grade methanol, since I have it available at work...
 12/16/2003 11:27:02 PM · #15
TAADAA...
that's got it.

Phew..

What ever is on there is coming off red. (I happen to have some methanol in my studio)

The lens cloth I have is red.. Is there some way it's coming off on the lens..

I think I'll be off tomorrow to get new things.
THank you

GeneralE and kirbic.....
and everyone that responded.
 12/16/2003 11:54:59 PM · #16
Wow -- the simple solution actually worked! Is there any problem with using anhydrous 99% isopropanol instead of methanol? That's what I have around (magnetic head cleaner).
 12/17/2003 12:48:29 AM · #17
Originally posted by JC_Homola:
TAADAA...
The lens cloth I have is red.. Is there some way it's coming off on the lens..


Did nobody tell you to use rouge powder only in small amounts? LOL;)

The methanol won't harm your lens more then any cleaning solution. Accutally, it's cleaning behaviour is pretty much like a water/isopropanol mixture. But because methanol is toxic in higher dosis, it's not used for cleaning.
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