11 replies to this topic

[Andrea B.]

Blum, A.G. (2020) Penstemon jamesii Benth. (Plantaginaceae) James' Penstemon. Flowers photographed in ultraviolet, visible and infrared light. http://www.ultraviol...ve-beardtongue/

El Dorado of Santa Fe, Santa Fe County, New Mexico, USA
23 May 2020
Wildflower

Synonyms:

• Penstemon brevibarbatus Crosswhite
  
• Penstemon jamesii subsp. typicus Keck
  
• Penstemon jamesii var. jamesii Benth.

Other Common Names:

• James' Beardtongue

Comment:
Found growing on steep, dry, roadside dirt bank. All flowers grow on one side of the stem. The visible striping on the interior and exterior of the flower throat are much less prominent in UV light. The visible yellow beard on the staminode is also not remarkable in UV light.

Reference:
SEINet Arizona - New Mexico Chapter (accessed 27 May 2020) Penstemon jamesii Benth.

Equipment [Nikon D610-broadband + Nikon 105mm f/4.5 UV-Nikkor]
unless otherwise noted


Visible Light [f/11 for 1/320" @ ISO-100 with Micro-Nikkor 60/2.8G AF-S on D850]
Penstemon are very drought tolerant.



Visible Light [f/16 for 1/4" @ ISO-100 with Onboard Flash and Baader UVIR-Block Filter]



Ultraviolet Light [f/8 for 1/30" @ ISO-400 with SB-14 UV-modified Flash and BaaderU UV-Pass Filter]



Infrared Light [f/16 for 1/13" @ ISO-400 with Onboard Flash and Schott RG780 IR-Pass Filter]

[colinbm]

This flower is so delicate with those lovely pascal colours in Vis & IR & so bold in UV.
Lovely pictures Andrea.

[Andrea B.]

Thank you, Col. Somtimes it is nice to photograph a flower indoors without all the wind and dust.

I was going to climb a bit further up the bank to try to gather some seeds from the plant shown in the 1st photo
(if any seeds remained in the pods), but the dirt gave way and I went sliding downhill instead.
The plant I took the photographed cutting from did not have any pods yet.

[Andy Perrin]

Was this taken under indoor/“lab” conditions? How was the white background obtained?

[Andrea B.]

Yes, the photos were made indoors under my kitchen skylights with illumination boosted by flashes. The background is a 5x5" Spectralon square. I could not photograph these flowers in situ because of the Santa Fe winds that day.

Aside: This might as well be Oklahoma where the "winds come sweeping down the plains". Winds die down in late afternoon and early evening. Early morning seems also to be wind free. But in late afternoon and early morning there is much less UV. And so it goes.

After converting the file, the Spectralon background in the first two photos was brightened a bit in Capture NX because it was some distance from the flowers and and thus not uniformly illuminated. The photos were cropped to omit the Spectralon's black framing and all details outside the square.

Also my Spectralon square has seen a few years of use and shows some scratches. It also *very* easily attracts dust and fibers. I carry a small paint brush to try to keep it clean. If I use Spectralon as a background, I always need to use a clone-out tool on the photo. Lots of work.

The only other edits were the usual adjustment of black & white points, application of white balance and colour profiles and some added detail enhancement brushed into key areas of the flowers to bring out interesting features like the hairy "beard" and the fuzzy surface of the flower tube and unopened buds. (And we need to resharpen a resized photo before posting it online.)

The IR file required some cloning out of sensor dust bunnies which always show up much more in IR.

[Andrea B.]

This is what the file looked like before crop and adjustments. I think it was underexposed, but the conversion turned out OK.

[Andy Perrin]

I almost wonder whether using virgin PTFE might be better than spectralon for that application (backgrounds) because it would overexpose so you wouldn't see the dust?

[Stefano]

I think overexposing something if you use a WB (if you shoot UV and IR basically) is not optimal since it will not appear white, but yellow or blue (in my case yellow). Maybe it is better to use a neutral gray background?

[Andrea B.]

Depends on what camera you are using. You can push exposures of the white background in Nikon DSLRs (sometimes up to 2 or 3) stops without getting those highlight discolorations in the converter - particularly when using either Photo Ninja or a Nikon converter. So what Andy suggests is possible. But I probably would continue to brighten a Spectralon or PTFE background in a converter because it is quite easy to select a white background and brighten it or change its color.

(Nikon DSLRs are said to have a lot of "headroom" which makes "exposing to the right" feasible. I'm sure some other cameras have this feature but I'm only familiar with mine.)

Added: I also wanted to say that it is somewhat easy to overexpose Spectralon too. I confess to doing this rather regularly making the photo unusable for white balance.

[Cadmium]

Andrea, Those are really excellent photos!

[Bill De Jager]

Cadmium, on 29 May 2020 - 19:35, said:

Andrea, Those are really excellent photos!

Agreed! I love penstemons and fortunately we have a large number of penstemon species in the western U.S.

[Andrea B.]

Thank you, Cadmium and Bill.

I have some other types growing in my new garden and also on the property. Might be tough to identify some of them as there are so many! I particularly love the red ones we have.