Hypocalymma robustum [Swan River Myrtle]

[LookCloser]

Hourston, M. (2022)  Hypocalymma  robustum (Endl.) Lindl. (Myrtaceae) Swan River Myrtle. Flowers photographed in ultraviolet and visible light. LINK

 

Location: Banksia woodland, Perth metropolitan, Western Australia

Date: 21 August 2022

Australian endemic wildflower in natural vegetation

 

Synonyms: Leptospermum robustum

 

Comment:  Small shrub covered clusters of sessile pink blossoms in late winter to early spring.

Endemic to Southwestern Australia.  Very common in natural bushland throughout its range, including remnant pockets in suburban areas.

 

Reference:

Hypocalymma robustum : Swan River Myrtle | Atlas of Living Australia (ala.org.au)

 

 

Visible Light:  Olympus EM1ii, Olympus 12-40m pro f2.8 [24mm, F7, 1/250", ISO 200, ] Flash lit.

 

 

Ultraviolet Light: Olympus EM5i Full-spectrum modified, Rodenstock Ysaron 75mm f4.5, macro helicoid adapter, Kolari UV bandpass lens filter [F5, 1/5", ISO 1000, 7 focal stacked images]  Natural sunlight.

 

 

Visible Light: Olympus EM1ii Olympus 12-40m pro f2.8 [24mm, F7, 1/60", ISO 200, ] Flash lit.

 

 

Ultraviolet Light: Olympus EM5i Full-spectrum modified, Rodenstock Ysaron 75mm f4.5, macro helicoid adapter, Kolari UV bandpass lens filter [F5, 1/2", ISO 1000, 5 focal stacked images]  Natural sunlight.

 

Published [22/08/2022]

Updated [22/08/2022]

 

 

 

[colinbm]

Pretty in pink & pretty in UV too.

[LookCloser]

Thanks Colin

[Andy Perrin]

These are nice!

[Andrea B.]

Thank you for this lovely contribution to the Botanical Section. 

[Andy Perrin]

I noticed that your UV pics seem less focused (even at the sharpest locations) than the visible light. That may be due to your lens, but don't forget you can stop down further in UV than in visible light, not sure if that would help. If it's caused by motion blur, though, forget I said anything!

[LookCloser]

You're right Andy, the visible light images are far sharper than the UV.  The comparison is really apples and oranges.
 

The UV camera is a 10 year-old Oly em5Mk1 body with a 16mp sensor and a vintage lens, taken with natural light only. Focal stacked.

The VIS camera is an Oly em1mk2 (newer and higher series), with a 20mp sensor and a very nice pro series lens. Image taken with flash and macro diffuser. non-focal stacked

 

So in terms of gear there are differences in resolution, lens sharpness, in-camera engine, motion blur, lighting and post processing. 

I also have a lot more experience with the VIS light system than the UV, so I am yet to wring the best out of it.  That will require time and practice on my part.

 

For comparison, in this Beach Evening primrose entry I shot both VIS and UV with the same camera / lens combination, only swapping out the filter.  You can see the image clarity is not so different between the two.

 

In short, I would be highly surprised if the images were comparable in this post. I still have some work to do before my proficiency is same in UV as it is in VIS!

[Andy Perrin]

Yeah, I can see why the visible would be better, given the camera and lens resolution differences especially, but I still think just stopping down the lens in UV will give you a significant boost, assuming you can get the flower to hold still! I like F/11 to F/16 even in UV. We can really milk the whole lower diffraction limit thing, and even vintage lenses look better stopped down if it’s not diffracting. 

[LookCloser]

Excellent advice Andy, thank you.  I'll have to find a non-windy day and see if I can get the flowers to hold still for me. 

The other down-side of the older camera body is that it has poor high ISO performance.  It introduces significant noise as soon as you move from base ISO.

 

I do have a flash with the fresnel removed, which puts out a decent bit of UV.  I also have a Convoy S2+ that I used in this image.   I might have another go at augmenting the natural light a bit.
I just don't like the harsh contrast you get from an undiffused flash   I have looked through the pages here for a UV-friendly flash diffusion system but that's still on the to-do list.  I'm thinking a reflector may be the way to go.

[Andy Perrin]

This may help steady flowers!

https://www.tripodhead.com/products/plamp-main.cfm