And while we're at it, does anyone know how to get the periwinkle color come out right? No matter what I try, that color always comes out more purple than it should, for me.

The standard response to that is, do your picture taking on a cloudy day or at dusk.

The most successful answer is, use a post imaging program that allows you to 'tweak' the color on the image to how it really looks to you, with the flower next to the monitor.

Cheating? Well, yeah, but it works!

steve, a picture with the metadata would help. Hard to suggest what to try when we don't know what equipment you have, the camera settings or the conditions you took them under.

How are you metering the light? Being more of a dark colour if you are letting the camera meter off the flower you may very well be over exposing causing the colours to wash out.

As CC suggested try taking the picture either at dawn or dusk. Manually set your exposure (or try different exposure compensation settings) and use a diffused or bounced flash. You will need to experiment with the angle and strength.

SCG

I forget the technical details, but it has to do with the interaction between blue coloration in flowers and the ultraviolet in sunlight. Film had the same issues. Your camera does not respond to these effects the same way that your eyes and brain do.

Taking pictures in shade (or dawn or dusk) will result in a blue that is truer to the actual color. If you experiment enough with degrees of shade and light angles, you should be able to capture a photo that looks like your plant, without retouching in photoshop.

Thanks for the suggestions. I tried photographing Taboo both outdoors early in the morning in soft indirect light and also indoors under artificial light. I set a custom white balance and tried various different exposures. I now have to wait for another bud to open to try again. By the way, the photo on the Swan Island site doesn't seem like a very accurate representation either. I found one on Dave's Garden that seems closer. (Image #166449)

Perhaps one problem with trying to capture iridescence is that what you are trying to capture is a color that shifts when viewed from different angles. Obviously a photograph can only capture one fixed angle so perhaps it is just not possible to capture such subtlety in a fixed image.

Looks like a good reason to buy a couple soft boxes and a couple more flashes!!

This subject has been discussed on dahlia sites for very many years. Part of the problem that is never mentioned is that computer monitors need to be calibrated also. The deep purple color does not appear on a computer screen easily. We have two digital machines, the digital camera and the computer and monitor that must be in total sync.

I have taken some better purple flower pictures with the sunlight coming from behind the bloom and shining through some of the outer florets. Carefully focus on the center of the bloom and set the camera to show the center clearly and even though the light coming through the florets may be
over exposed, the center of the bloom will have accurate color. Easier said than done. I suppose one step further would be to reflect some light onto the center of the bloom also.