That horrid CA

[proseak]

Steve, I had a very quick play with your image as follows;

Image>Mode>Lab color
Ctrl +1 (select Lightness)
Magic wand, contiguous & anti-alias unchecked, tolerance 40. Click in one of the light areas, in this case the sky.
Select>Modify>expand (enough to completely cover the CA, plus a bit!)
Feather>a bit less than the "expand"
Ctrl +2 (select a)
Apply Gaussian blur...experiment here!
Ctrl +3 (select b)
Ctrl +F (repeat blur)
Image>Mode>RGB color

This won't soften the detail of the image at all, and should mean that you can postpone spending any money!

HTH

Peter

[arith]

It looks brilliant to me Peter, a very clever method. cheers I was going down there today but when I woke up I thought nah can't be bothered. If I had a car I could get there in ten minutes but I'm not allowed to drive.

So this is good, the 50mm has hyperfocal distance about 25 metres at f5.6 where it is best for CA and sharpness and there is some overgrown ground behind that I think is part of the monument since everywhere else has neatly cut grass, so I won't go in it.

[proseak]

Thanks for that, Steve - the only downside that I know of is that it needs access to the LAB colorspace...which ain't in PSE. I've been looking at ways round this, but the only app(other than PS) that i'm sure carries it is the GIMP...which is free.

Time I tried it, I guess! I'll give it a try over the next few days.

[Pictus]

I prefer to:
-Change to LAB mode
-Duplicate the layer
-Apply median filter to the channels A&B
-As the median filter may take out some details, use a mask
to apply the effect only to the needed areas.

[proseak]

Yes, sounds good. It's another example of something which is easy in Lab, and otherwise much more difficult; the fact that the L channel carries the detail really does help!

But why is there so much more CA from digital cameras than analogue? Answers, on a postcard please. to...

Peter

[Pictus]

"Googling" gave this http://toothwalker.org/optics/chromatic.html

Purple fringing: lens or sensor?

Chromatic aberration, and purple fringing in particular, have received considerable
attention with the advent of digital cameras. Indeed, although chromatic aberrations can be
noticed on film (Fig. 7), they do look more intense on CCD or CMOS images. On the one hand
the digital photographer is only a few mouse clicks away from a full screen display, and few
lenses stand image inspection at high magnification. On the other hand it is possible that
digital imaging somehow renders the color fringes due to chromatic aberration more distinct.
One of the proposed mechanisms is an enhanced spectral sensitivity in the (ultra)violet and
(infra)red regimes, where lenses tend to be poorly corrected for chromatic aberration.
Purple fringing is often blamed on sensor bloom, which is odd as blooming is a quite
different phenomenon [15, 16]. In fact, there are as many arguments against sensor bloom as
there are in favor of chromatic aberration to account for purple fringing.

[arith]

That's interesting, I get it sort of implies that CA is noticed more because of higher sensitivity to certain wavelengths and much sharper images. cheers