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CA - purple fringing
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PostPosted: Fri Jul 03, 2009 2:46 pm    Post subject: CA - purple fringing Reply with quote
Hi all

I've been really struggling with purple fringing with my Tamron SP 60-300 and Tamron SP 70-210 19AH. Well, specifically, bright blue fringing in sunny conditions.

I read somewhere that attaching a UV filter might resolve the problem, and luckily I had a 62mm UV filter discarded in a box! I tried it and it stopped nearly all CA! Very Happy

My only concern now is that filters might degrade the resolution...it's a Hoya so shouldn't be too bad, but I'll report back after my holiday Smile

Thought this might be useful for someone.


PostPosted: Fri Jul 03, 2009 3:05 pm    Post subject: Reply with quote
Yes, very usefull at least for me.

I hear two thing about UV filter

1- Like all the filters, degrade the image quality.

2- As it eliminates the UV waves, reduce the blue/purple fringing, and improve the IQ.


How much it degrades and how much improve the IQ?

Rino.


PostPosted: Sat Jul 04, 2009 10:12 am    Post subject: Re: CA - purple fringing Reply with quote
Shrek wrote:
Hi all

I've been really struggling with purple fringing with my Tamron SP 60-300 and Tamron SP 70-210 19AH. Well, specifically, bright blue fringing in sunny conditions.

I read somewhere that attaching a UV filter might resolve the problem, and luckily I had a 62mm UV filter discarded in a box! I tried it and it stopped nearly all CA! Very Happy

My only concern now is that filters might degrade the resolution...it's a Hoya so shouldn't be too bad, but I'll report back after my holiday Smile

Thought this might be useful for someone.


Useful info, I'll give that a try.

Don't worry about IQ, there will be no measurable degradation of image. That goes for pretty much any filter you buy, even the cruddy Jessops ones. The Hoya HMC have better than 98% light transmission (as will most coated ones) and the uncoated ones will be in the region of the upper 90s%. apart from that, they only need to be perfectly flat, and that's been easy to achieve in optical filters for years Wink


PostPosted: Sat Jul 04, 2009 10:36 am    Post subject: Reply with quote
Filters however (even the best ones) may cause internal reflections.
I suggest care in using them in potential flare situations (shooting against the sun, or with a light source in or near the visual field).
It also becomes more important to control the lateral parassite light with a hood (a good habit also without filters).


PostPosted: Sat Jul 04, 2009 9:25 pm    Post subject: Reply with quote
Orio wrote:
Filters however (even the best ones) may cause internal reflections.
I suggest care in using them in potential flare situations (shooting against the sun, or with a light source in or near the visual field).
It also becomes more important to control the lateral parassite light with a hood (a good habit also without filters).


yes, Orio... Smile - - but you must admit that the carrying of hoods is not being done by us particulary Smile -- they are always forgotten at home .. Smile

tf


PostPosted: Wed Jul 29, 2009 12:13 pm    Post subject: Reply with quote
Knowing that my lenses are not going to get scratched is almost worth a slight decrease in image quality. Although I have to say that it is always on my mind that MAYBE the pic would have been nicer without the filter. I think I need to stop obsessing...


PostPosted: Wed Jul 29, 2009 12:36 pm    Post subject: Reply with quote
conor12 wrote:
Knowing that my lenses are not going to get scratched is almost worth a slight decrease in image quality. Although I have to say that it is always on my mind that MAYBE the pic would have been nicer without the filter. I think I need to stop obsessing...


I always use my lenses without filter. Scratches are not as much degrading the image as you might think. See for yourself:

http://www.lensrentals.com/news/2008.10.30/front-element-scratches

Now, of course I do take care of my lenses, but I would not pass up a rare lens with a scratch on the front lens.


PostPosted: Wed Jul 29, 2009 1:27 pm    Post subject: Reply with quote
Well, CA (purple fringing) can be stopped / reduced using an UV/IR Cut filter which cuts into the deep blue (violet) starting at about 410-420nm. That gets hardly noticed. A very common practise in astro-photography btw.


PostPosted: Thu Jul 30, 2009 8:13 pm    Post subject: Re: CA - purple fringing Reply with quote
Shrek wrote:
Hi all

I've been really struggling with purple fringing with my Tamron SP 60-300 and Tamron SP 70-210 19AH. Well, specifically, bright blue fringing in sunny conditions.

I read somewhere that attaching a UV filter might resolve the problem, and luckily I had a 62mm UV filter discarded in a box! I tried it and it stopped nearly all CA! Very Happy

My only concern now is that filters might degrade the resolution...it's a Hoya so shouldn't be too bad, but I'll report back after my holiday Smile

Thought this might be useful for someone.


Do you use Photoshop?

Jules


PostPosted: Fri Jul 31, 2009 3:20 pm    Post subject: Reply with quote
So what is all this hoopla about purple fringing in California? Laughing

Interesting thread... Wink


PostPosted: Sat Aug 01, 2009 3:11 pm    Post subject: Reply with quote
Katastrofo wrote:
So what is all this hoopla about purple fringing in California? Laughing

Interesting thread... Wink


Haha very good! Laughing

Jules - yes I do use photoshop. But I took a load of shots of seagulls recently with a blue sky background, and found that I couldn't remove the fringing without making the sky go grey. Perhaps I should have used the colour replacement tool. Either way, it sucks!

I'll post some examples up as soon as the sun comes out, with and without UV filter. The filter certainly helped produce much better photos with my Tammy SP 60-300!


PostPosted: Sun Aug 02, 2009 1:29 am    Post subject: Reply with quote
Shrek wrote:
Katastrofo wrote:
So what is all this hoopla about purple fringing in California? Laughing

Interesting thread... Wink


Haha very good! Laughing

Jules - yes I do use photoshop. But I took a load of shots of seagulls recently with a blue sky background, and found that I couldn't remove the fringing without making the sky go grey. Perhaps I should have used the colour replacement tool. Either way, it sucks!

I'll post some examples up as soon as the sun comes out, with and without UV filter. The filter certainly helped produce much better photos with my Tammy SP 60-300!


I have a great piece oif software that I will send you. I've used it for years and it gives total control over what you want messed with, however, my computer is in pieces at the mopment and it will take a few weeks to get it to you.

Hang in there.

Jules
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