Chromatic ab. worse in macro?

Some of my macro shots have noticeable chromatic aberration. Is there something about the optics of macro that makes this happen? Perhaps it's only that I shoot more white things with macro, whereas larger scenes tend to be multicolored.

An example of white things: Fly eggs on chard leaf. These are 0.7–0.8 mm long. G15, Av mode, 1/50 sec., f/7.1, ISO 800 (Auto: cloudy day, late afternoon), AWB, no EC, macro setting with no added lenses. I see blue and yellow at edges in the image, where they shouldn't be.

I'm not sure what lens your using, but one thing that makes CA worse is adding more glass, especially the cheap diopter type filter lenses. You need to start off with good glass. Extension tubes are better than the add on lenses because they don't have any glass.

CA varies from optical system to optical system. some diopters can add dramatic amounts of CA. Using tubes/bellows will magnify the CA already present in the lens being used with them making it more noticeable. Using a lens on lens system aperture placement can alter CA through out the image field. Using a dedicated macro lens CA is what it is at a particular aperture. For tubes, bellows, and normal macro lenses the best you have to fight CA is stopping down the lens.

For your set up I would stop down the lens on the camera, 1.8 is wide open and will experience CA worse than other apertures.

For those two shots, just the lens that's part of the G15, nothing added.

Okay. For bugs, I usually use Av and choose a small aperture to maximize DoF. The second photo above was taken at night (poor indoor light) for the Super Macro Guessing Game in the Competitions forum here, and for that purpose CA didn't matter.

On the G15, I would guess the CA would be worse in the macro setting since the lens is not designed specifically for macro.

Macro lenses themselves are not generally worse at close distances, but non-macro lenses with extension tubes and/or focused at MFD are usually a lot poorer optically than at longer focusing distances.

I have no idea what is normal for the G15 though. I assume in the eggs one, the eggs are in the center of the image, which makes it a little unnerving, but then if you cropped it significantly I would not be too surprised. Actually if you didn't crop it severely then it looks pretty low resolution.

ejenner wrote in post #15734221
I assume in the eggs one, the eggs are in the center of the image, which makes it a little unnerving, but then if you cropped it significantly I would not be too surprised. Actually if you didn't crop it severely then it looks pretty low resolution.

Any subject that small, I have to crop severely. I'm using only the center of the frame most of the time. That's all I can do until I get a real macro lens.

Original photo, no PP except reducing the total size:

OhLook wrote in post #15734388
What about the eggs being in the center makes it unnerving?

I expect CA away from the center, but would generally expect no CA in the center at the focus plane. In an SLR lens this would suggest to me a possible decentering issue - where one of the lens elements is not exactly on-axis.

If you don't see it at normal distances with high-contrast subjects then it could just be what is going on in the lens to make it focus very close though.

I don't really have much experience with the lenses in those types of cameras though. I guess I don't expect my S95 lens to be all that great and haven't scrutinized iamges that closely. It definitely has CA, but I haven't noticed it in the center.

I think I'm catching on. Close distances between camera and subject don't intrinsically increase CA, but a lens not optimized for close distances does when used for such shots; and pushing buttons to get a macro setting doesn't adequately substitute for having the right lens. Is any part of that incorrect?

OhLook wrote in post #15734388
Any subject that small, I have to crop severely. I'm using only the center of the frame most of the time. That's all I can do until I get a real macro lens.

Original photo, no PP except reducing the total size:

What about the eggs being in the center makes it unnerving?

Extreme cropping and enlargement is always going to exaggerate any fault in the original. No lens will take unlimited cropping.

Preeb wrote in post #15739945
Extreme cropping and enlargement is always going to exaggerate any fault in the original. No lens will take unlimited cropping.

Right. I'd like to know how to bring more pixels to bear on a 1-mm object. Do people combine macro and zoom? (But with zoom you have to get farther back, which negates the enlarging effect.) I asked about supplementary lenses in the G-series area of this board. No answers yet.

OhLook wrote in post #15742007
Right. I'd like to know how to bring more pixels to bear on a 1-mm object. Do people combine macro and zoom? (But with zoom you have to get farther back, which negates the enlarging effect.) I asked about supplementary lenses in the G-series area of this board. No answers yet.

Extension tubes is the best answer I can offer.

Preeb wrote in post #15743117
Extension tubes is the best answer I can offer.

I think those are for the kind of camera that has a removable lens, but thanks.

Some members have answered in the G-series thread now.

As noted add on closeup lenses are noted for CA. Genrally it is much more difficult to correct for aberrations for a lens that has a wide focus range, this is why macro lenses tend to be twice the size and half the max aperture of a similer focal length standard lens.