Rendering true colour in rose photography

I have sought to conquer the problem of incorrect colour rendition in rose photography for quite a while now. I realize that a key factor is the size and quality of the CMOS sensor. However, even after buying a digital SLR of reasonable quality (A Nikon D90) I am still not satisfied with how it interprets various shades of blue, red and pink. I'm not the only one whose photos do not do justice to roses, and I can forgive an el cheapo camera for coming up short. My Fuji and Canon point and shoots each rendered either blue or red well, but not both. My colour perception is very good, and I'm probably more fussy than many others, but it drives me crazy to shoot one of my treasures, only to find the photo falls short of my expectation.

Now the D90 should be quite capable of doing a good job of photographing colours correctly. So the fault probably lies with the operator rather than the camera. I have 4 lenses - Nikon 18-200 1:3.5-5.6, Nikon 35 1.8, Sigma 18-50 2.8 and Sigma 105 2.8. I tend to rely on automatic settings, however, am reasonably confident with program as well as aperture and shutter preferred. I am familiar with the various functions available on my camera and where to find them.

Any hints and tips would be much appreciated.

There are many factors, Lili, that affect colour rendition in digital photographs from CMOS quality/size/resolution to lighting, white balance, and even lens type. I notice you have a Sigma 105mm lens... is that the 105mm f2.8 1:1 macro? Sigma lense are well known for giving images a yellow cast. I've seen it described as 'Sigma Yellow' I know my Sigma 105mm macro gives things a yellow cast, even when I do a custom white balance, necessitating colour correction in photoshop in post-processing.

Digital SLR or not.. digital cameras (and most film camera for that matter too), and not very good at rendering colours like reds in full sunlight. I try to photograph my roses in the shade and set my white balance to one of the preset levels describing shade or overcast conditions. Regardless of which lens I use this gives a consistently better result than shooting in the sun. A custom white balance helps enormously when shooting in the shade as well so it pays to have a white balance card in your kit (I made my own in photoshop and have a black one, a 50% grey one and a white card). It also helps to slightly underexpose your shots. This helps in shooting in lower light levels as well.

All that being said... digital cameras are still going to struggle with some colours or combinations of colours. I don't think there are any photos I put anywhere whose colours levels or colours I haven't adjusted in photoshop. I'm a semi-pro photographer and am able to minimise the amount of tweaking that needs to be done to reduce my workflow but I still need to make slight alterations to most photos and as you say, purples, reds, blues are some of the hardest to capture against a green backdrop (by themselves they usually reproduce faithfully, but when combined with other colours like green (which by chance are at opposite ends of the colour spectrum) it seems to cause trouble.

So a typical rose photoshoot for me would go like this:

* I'll use either my Sigma 105mm f2.8 macro (for Canon) or my Tamron 24-135mm f3.5-5.6 macro zoom (for Canon). I might use my 50mm f2.8 prime but not very often. The bokeh you get with the Sigma 105mm macro is delicously smooth which means it's my most common weapon of choice.

* I'll wait until later afternoon when the sun has gone down but there is still plenty of light to enable shooting at 1/60th of a second or higher at 100ISO using mid-range f-stops (f-5.6-10) for better DOF.

* I'll shoot the WB card and set the camera to custom white balance and switch to either full manual or Av. I rarely use Tv or any of the automatic settings. Years of shooting film has given me a dislike of automatic modes.

* Shoot the flowers so there are no competiting light sources like back-lighting. You want the diffused light from the late afternoon sun to be striking the flower from the front to eliminate the shadows and high contrast situations.

* Slightly under expose the images.

* I post process all my images in photoshop where I will adjust levels and colours if necesary to ensure a faithful reproduction of colour. Some people will frown about digital darkroom techniques but it is no different to all the burning and dodging that we use to do with film back in the day. If you don't have photoshop there are a few free ones online that you can download and often there is bundled software that comes with the camera that can also do these kinds of adjustments.

* If the shoot is REALLY important I will even take my reflecting umbrella out and mount it to my external flash and put the flash trigger on the camera's hot-shoe and and set up studio-like lights using the constant colour-temp of the flash to iluminate the flower(s). I've only had to do this three times though.

Post some photos and show us how you go and publish the camera's settings with them. It will be fun to see how close we can get without too much tweaking.

Simon, Very useful tips.

Thanks Simon
I thought white balance settings, type of light and exposure were likely to be the key factors.

I've played around with underexposure trying to capture a particularly lush purple of a lasiandra, which had come up closer to sky blue than true purple blue. I've also tried it with a very dark blue double aquilegia that again became too light. I suspected that the auto setting had compensated for perceived darkness by over exposing. The actual quality of light that I'm working with may be at fault, and your explanation gives me plenty to think about.

I'm not so confident on the subject of white balance, but have tried using a blank white sheet to set my custom white balance with reds. It helped in a different context, photographing a handcrafted box with a rich red lining. I'll have to give a proper white balance experiment a go.

Many things I have tried have been instinctive rather than being based on expertise with my camera, and perhaps I may be a little more lazy than I should be. The afternoon light is definitely an easy one to try as we have long sunshine hours here and good light almost all the time.

I have the full Photoshop and Elements , though I am by no means expert in their use. I have to say that I hadn't noticed a colour cast as such, more likely a 'flattening' of colour ranges particularly the reds.

For example, Mr Lincoln and Oklahoma will photograph almost the same, yet my Oklahoma is a noticeably darker tone than Mr. L. So it is just a shade on a fairly wide continuum of reds, but enough to disappoint me. I have Josephine Bruce, Europeana and La Passionata in a row and this should be a good trio to test out reds.

I'm seeking to do a proper database of my individual roses, and will take all this on board to see if those delicate differences in shading can be captured properly.

Thanks again Simon

You might also think about spot metering so the camera is less likely to average out the exposure of the image and instead base the exposure on the point that you are trying to expose for.

I know what you mean about blues appearing white/light in photos and this can be fixed, somewhat by using spot metering to expose for the blue instead of including the surrounding green in the algorithm. You might find you need to lighten the background if you do that because then you are faced with exactly the same problem as you were before... but in reverse. I will do up a photoshop tutorial on how to even out dynamic range in these images to achieve a more balanced effect... actually I'll do up two tutorials to show the two different ways I do it. I'm not sure which photoshop you are using but the techniques should be easily adapted in any of the later versions. I'm using CS5 extended so any screen shots I include will be from it.

Thank you so much Simon. I look forward to the tutorials, and I'm sure I'm not the only one who is in need of such assistance.