Techniques to photograph red flowers.

<p>Was wondering what techniques people were using to photograph red flowers with dslr's.<br>

I find the Red channel to clip when using a grey card, or exposing off a neutral subject in the same light.<br>

I will then expose again to save the red channel by adjusting my exposure.<br>

This tends to underexpose surrounding leaves, etc, etc, even though the red channel is not not clipped and retains detail.<br>

Apart from digital manipulation (such as masking, luminance, etc), is there anyway to tame the red channel without sacrificing the rest of the image at capture stage? I.e, filters or the like?</p>

<p>I understand that the problem with clipping the red channel is real, however if a red flower clips the red channel, then a white object would also clip the red channel with the same exposure and white balance.</p>

<p>Using raw format might help, since it is possible the in-camera processing might take a red channel that was not clipped at the sensor and clip it in the jpeg.</p>

<p>And yes, in theory you could add a filter to reduce transmission of wavelengths longer than red and then alter the white balance. This would require what sounds like an unusual filter, would not work for white flowers, and risks clipping green or blue instead, so I do not recommend it.</p>

<p>Yep, using nikon nef (raw) on a d700. You would think that a white object would also clip the red channel, but it's not the case. It seems like there is a sensitivity to red primary colours.</p>

<p>Blown-out reds are a widespread problem with digital cameras.This is not just a matter of overall luminance, as Joe suggests. it is a problem specific to one color channel. I believe it is because the range of red that the sensor responds to is wider than that perceived by us humans. Whatever the technical reason, you can see this very clearly if you set your camera lcd to display histograms for all three color channels separately as well as the overall luminance histogram. It is very common to have clipping in the red channel when the overall luminance histogram and the histograms for the other two channels all look fine. I do a lot of flower photography, and I have this problem often.</p>

<p>Yes, you should shoot raw if you are having this problem (you should anyway), and if you shoot raw, you can probably recover detail if the clipping in the red is relatively minor. However, in my experience, if you just meter without respect to color channels, it is often the case that intensely red flowers will be far too far gone for recovery in processing RAW files.</p>

<p>The only solution I know of, short of using a filter to cut down reds, is monitor the histograms of all three channels in situations where this may be a problem, and underexpose enough to bring the red channel down enough to that it is not clipping or is just barely clipping. This will of course increase noise in the rest of the image, if it becomes dark enough, but you can clean that up later. And you can easily adjust the exposure in other areas of the shot in postprocessing.</p>

<p>I work in the same way, regardless of the colour of the flower before me: raw format, white balance set to daylight. Red has given trouble sometimes, but then there are so many more flowers that are not red...<br>

http://www.shotindia.com/searchresults.aspx?photo=3903&phname=Mukul</p>

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<p>This is not just a matter of overall luminance, as Joe suggests.</p>

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<p>I did not say anything about overall luminance. What I said was that white objects can reflect as much or more red light (as seen by the camera sensor) as red objects.</p>

<p>Also, I misspoke above, it should have been "reduce transmission of wavelengths shorter than red".</p>

<p>If the red channel is actually clipping at the sensor, you just need to reduce the exposure. However, it seems more likely that post processing is taking an unclipped red channel and clipping the red in the final output. I don't suppose you could post a raw file somewhere so that I could see if red is really clipped?</p>

<p> </p>

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<p>However, in my experience, if you just meter without respect to color channels, it is often the case that intensely red flowers will be far too far gone for recovery in processing RAW files.</p>

 

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<p>I've never experienced what you've described exposing so my camera's LCD histogram preview highlight peak is pulled about 1/4 to 1/5 away from the right, sometimes more. Since ACR, my Raw converter of choice, applies a .50 base exposure adjustment the histogram will show the highlight peak very near the right and sometimes clipping.</p>

<p>From my experience the problem mainly arises in how the default Raw converter's settings renders the preview which can show VERY non-smooth transitions of color giving the perception colors have blown. Believe me, there's detail in that blob of glowing color.</p>

<p>It takes some work to coax the detail editing which I suggest you work at 100% zoom view. Usually the first fix is setting proper looking color temp, next is to choose a camera profile that noticeably reduces the color blobs. Nikons and Canons have so many camera styles and profiles it shouldn't be too hard to find one that fixes most of it. And from my experience with my own camera, a custom profile didn't work. I used the original ACR profile that everyone complained of giving yellow/orange reds. Your camera may be different.</p>

<p>If that doesn't work you'll have to adjust Saturation and Luminance of suspect colors and micro tweak rose petal highlights using curves. See below a sample of what I've had to work with shooting a red rose in noon day direct sunlight using AWB. Setting to Daylight would've given the same orange/red WB but at least the rest of the pics taken of the same subject would be easier to fix. </p><div></div>

<p>These are the before and after histograms in ACR 4.6. The LCD histogram showed the highlight peak for the blue sky pulled back. ACR shows its base exposure adjustment almost go to clipping on this highlight.</p><div></div>