Eschscholzia californica and Citrus x limon

[Bill De Jager]

Here are a couple of flowers I photographed today in the back yard. First is the California poppy (Eschscholzia californica) the state flower of California. I tried photographing it earlier this year using older pre-AI Nikkor lenses (45/2.8 GN and 55/3.5) and the Baader Venus filter but had no luck. I could not find the flowers at all in the very dim image live view presented, even when the flowers were in full sun. This was very puzzling.

 

Well, today I tried my UV-Nikkor 105mm on one of these flowers. Again I could not find it even though the lens was pointing right at it, but when I looked more carefully I could faintly see a very dark outline with a sharp boundary. Ah-ha! This flower, such a bright orange in visible light, is very nearly black in near-UV. Some exploratory efforts and false starts eventually led to the following:

 

 

Equipment: Nikon D5100, broad-spectrum converted, UV-Nikkor 105mm, Baader Venus filter. Aperture was f/8; I'm not sure what the shutter speed was but I think it was 4 seconds. The flower was in shade.

 

Next, I photographed a lemon (Citrus x limon) flower with the same equipment but with more attractive results. I believe the exposure was shorter. Focus was on the tips of the anthers so the petals are less sharp.

 

 

My introduction was posted today in the introductions forum.

 

Bill

[nfoto]

It may come as a surprise at first that many flowers are UV dark or even UV black.

 

I took the liberty to try to colour-balance your Citrus shot. Ideally this of course should be done either in-camera (feasible with a Panasonic) or in the post-processing work flow (if you shoot RAW and/or use a camera without the ability to do native colour balance for UV). Done directly on a jpg without further information is a hit-and-miss, though.

 

Anyway with these caveats your Citrus should look similar to this;

 

[Andrea B.]

Bill, it takes awhile to get the conversion working well for a given camera/lens.

 

For the D5100-broadband and UV-Nikkor, make an in-camera WB against a generic neighborhood scene with NO filter attached. This will give a WB that is less saturated and thus easier to work with for determining whether you have a good UV exposure. The red channel will still blow out some in UV shots.

 

Set the D5100 Picture Contol to Neutral[4,0,0,0,0] for UV photos. UV shots tend to have wide dynamic range and are very contrasty. You certainly don't want extra saturation or contrast when shooting. Both those can be easily boosted in an editor but they are more difficult to reduce.

 

Set ISO to 400. You might need to go to ISO 800 if shooting in the shade.

 

Initially set the in-camera Active D-Lighting to Off, but remember that setting it to Low or Normal is very useful for dark UV shots such as your Cali Poppy above.

 

It appears like you have a bit of light leak in the bottom of the first photo. Remember to close your viewfinder for a 4" shot to avoid this.

 

Hope all this helps!

**********

 

 

Bjørn, Photo Ninja will do fairly well even on a Jpg. Your rebalance is too dark, so the proximal dark petal patch is not well seen. All that magenta in the original foliage should go to gray, but in PN it takes a full desaturation of green/cyan (due to blowout) to accomplish this. As well as some serious slider work with the Highlights slider.

[nfoto]

Aw - just did a quick'dirty curve adjustment in PS - no PhotoNinja. Agree what there probably is more than meets the eye on the original.

 

My point was to entice Bill to explore the beneath-the-surface world of UV.

 

A final point is noting that not all foliage will be UV neutral gray/dark. So it is best to balance against known standard(s), say a neutral PTFE disk.

[Andrea B.]

Bjørn, have you ever experimented much with UV conversions in ACR? Or tried ACR recently?

I have not played with ACR for some time now. I used to think it produced some unusual artifacts in UV conversions - perhaps because it could not handle such "unbalanced" R,G and B channels produced in a UV foto. But it has changed a lot since then, so might be better now.

[nfoto]

I don't use ACR at all so wouldn't know.

[Bill De Jager]

Thanks for all the help, Bjørn and Andrea!

 

I actually did 'color-balance' the shots from RAW in Photoshop Elements, but only to get what I considered a more pleasing effect (less red) than the originals. I also played with exposure, contrast, etc. to try to improve the appearance. I have only barely started keeping the color in my UV photos; previously I've desaturated them. The shots were both made at ISO 800 in the shade.

 

The light leak was due to my incomplete application of an improvised shade. Earlier shots has a terrible flare on the top third (which went away on just one shot) that I could not figure out until I remembered to shade the eyepiece. The shot with no (actually less) flare was the clue I needed- I had been leaning far over the camera on that one.

 

I definitely intend to learn how to achieve your standardized white balance as I would like to post formally in time. For all shots I'll at least want to start off with a better in-camera white balance, whatever I later decide to do with the results.

 

So is it a fair assumption that lenses which produce a redder UV-only result out of the camera are letting in light that's farther into the UV spectrum? Some of my old lenses give very purple results with the Baader Venus, the 45/2.8 gives more reddish results, and the UV-Nikkor (which we know has a broad transmission range) also gives reddish results.

[nfoto]

Bill: the assumption about "redness" as an indicator of UV response is in line with measurements, but is not very accurate. The very least one should obtain a standard colour balance first before drawing conclusions. This is easy with a Panasonic. Less UV-responsive lenses tend show cold and/or magenta tones while the "good" ones show warm greys, yellows or greens.

 

Some cameras, for example Nikon D3200, produce heavily oversaturated reds straight off the camera and these mask any UV differences. The camera has to be set to b/w to show UV features in the finder. PhotoNinja put the "false" colours right though.

[Andrea B.]

I'll play around with ACR today and see if it is of any use for conversion of UV stuff. "-)

 

Bill, try everything and experiment like crazy at first!! You will soon sort out how best to shoot with your UV gear.

(BTW, don't shoot UV in the shade.)

 

If you like, you can get a D5100 UV NEF file to me and I'll play with it in ACR/PSE, Photo Ninja, Capture NX2, View NX2 and Iridient Developer to see what works best.

 

For large raw files, a dropbox area is needed to pass a NEF to someone else. We have used Hightail (formerly You Send It) in the past for this. You can set up a free Lite account there: https://www.hightail.com/litesignup?s=1000684&cid=ppc-1000684&opword=hightail~29008886834&gclid=CLTQs_KUjLkCFZKk4AodfwIAVg

[Bill De Jager]

Thanks again, Bjørn and Andrea. Unfortunately, I'll be working a lot of overtime the next few weeks so I probably won't get too much fun stuff accomplished other than relaxing when I can. However, you have both given me a lot of information I can refer back to later.