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Me in UV (again), and some flowers

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#1 Stefano

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Posted 26 March 2021 - 22:05

Some photos taken a couple of days ago. Nothing special, I just wanted to share.

Camera: full-spectrum Canon EOS M
Lens: Soligor 35 mm f/3.5
Filter: ZWB2 (2 mm) + Chinese BG39 (2 mm)

f/3.5, ISO 800, 1/4 s exposure
Attached Image: IMG_1652.JPG

My skin is a bit purple. Below the same image but in BGR version, increased saturation and I corrected the overexposes areas replacing the color with white, tolerance 10, all done in IrfanView:
Attached Image: IMG_1652 1.jpg

I always like how houses come out in UV. I like them when they are purple, and also in this red version. There are some houses around with that red color, so they almost look "normal".

Daisies at f/3.5. Although this aperture is not so wide, it does produce a nice shallow depth of field. I may try the Helios f/2 lens one day, it isn't as UV-capable as the Soligor but has a wider aperture. The problem being dust is always waiting to jump on the sensor.

f/3.5, ISO 100, 4 s exposure
Attached Image: IMG_1622.JPG

f/22, ISO 100, 120.2 s exposure. Those flowers are all-yellow in visible light, but the UV-dark center is visible, it appears different. I am sure this flowers are already present in the botanical section somewhere.
Attached Image: IMG_1617.JPG

f/22, ISO 100, 420.3 s exposure. Photo taken on a sunny day, but in the shade. The wind ruined it a bit, but still came out nice.
Attached Image: IMG_1602.JPG

ISO 25600, 1/30 s exposure. I don't know the aperture, but it probably wasn't wide open.
Attached Image: IMG_1595.JPG

And finally, not a flower, but an old ball chewed by our dog. It moved a bit during the long exposure.
f/22, ISO 100, 150.2 s exposure.
Attached Image: IMG_1620.JPG

#2 Bernard Foot

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Posted 26 March 2021 - 22:39

You're getting some good flower images now, Stefano!
Bernard Foot

#3 Andy Perrin

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Posted 26 March 2021 - 22:46

Nice! The improvements to the camera quality are significant. Did you light your portrait that way on purpose? If it wasn’t an artistic choice, I recommend having the sun illuminating your face a little more directly.

#4 Stefano

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Posted 26 March 2021 - 22:51

View PostBernard Foot, on 26 March 2021 - 22:39, said:

You're getting some good flower images now, Stefano!
Thanks. This camera is capable of longer exposures and has lower noise. Also, I can completely control the lens.

#5 Stefano

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Posted 26 March 2021 - 22:51

View PostAndy Perrin, on 26 March 2021 - 22:46, said:

Nice! The improvements to the camera quality are significant. Did you light your portrait that way on purpose? If it wasn’t an artistic choice, I recommend having the sun illuminating your face a little more directly.
Thanks again. It was a practical choice, since the camera was mounted on a tripod resting on a window sill.

Edited by Stefano, 26 March 2021 - 22:52.


#6 nfoto

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Posted 26 March 2021 - 22:53

The flower "looking all yellow in visible" is lesser Celandine Ranunculus ficaria.

#7 Stefano

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Posted 26 March 2021 - 23:02

Thanks Birna.

#8 OlDoinyo

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Posted 27 March 2021 - 18:30

Interesting strongly negative "soap-bubble" background bokeh in the one portrait. This is what the Trioplan lenses are allegedly famous for, but this is not one of those. I wonder if the foreground bokeh is similar.

#9 Stefano

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Posted 27 March 2021 - 19:29

View PostOlDoinyo, on 27 March 2021 - 18:30, said:

Interesting strongly negative "soap-bubble" background bokeh in the one portrait. This is what the Trioplan lenses are allegedly famous for, but this is not one of those. I wonder if the foreground bokeh is similar.
I can test this later and post the results.

#10 Andrea B.

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Posted 27 March 2021 - 22:50

The dog-chewed ball is too funny!
All is lookin' good. Nice to see you using a better cam & lens. :grin: :cool:

Those long exposures are long.
Try f/8 with ISO-800 maybe??
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#11 Stefano

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Posted 27 March 2021 - 22:58

Sometimes I shoot at ISO 6400-25600, at f/3.5, so that my shutter speed is very fast, even in the shade. But I like to do the opposite sometimes too. The Soligor is good at f/3.5, but is much sharper at f/22. Plus, the low noise at ISO 100 makes the image better.

#12 Andy Perrin

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Posted 28 March 2021 - 00:41

F/22 should be getting diffraction losses even in UV. I usually go with F/11-F/16 in UV.

More generally, it’s usually not a good idea to operate any instrument close to the end of its range, because if the people who made it could have gone one marking further, they would have done it, so the last mark is where compromises have become intolerable to the designers.

Edited by Andy Perrin, 28 March 2021 - 00:44.


#13 Stefano

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Posted 28 March 2021 - 01:16

That explains why lenses are the sharpest in medium apertures (in visible light at least, the range they were designed for), like f/8 or f/11. F/22 surely diffracts in visible light, you sometimes start losing sharpness at f/16, but in UV you can go a little further. In "deep" UV, like at 340 nm or at the edge of UVB I would probably start losing sharpness at f/32, if the lens had that aperture. F/11 is definitely the narrowest I can go in IR, probably already too tight.

#14 Andy Perrin

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Posted 28 March 2021 - 03:16

Honestly I think F/22 is too far in UVA. I used it a lot at the beginning when I first started playing with UV, but the supposed lack of diffraction in UV is only good for about one more stop unless you go out to UVB — but you need all the light you can get there. I mean, it does also depend on the resolution of your sensor and the lens quality. If the lens is the limiting factor that might explain any continued improvement past F/16.

Edited by Andy Perrin, 28 March 2021 - 04:19.


#15 UlfW

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Posted 28 March 2021 - 06:01

IMHO the only reason for stopping down with these photos is to gain DOF.
Unfortunately then you need to run at a higher ISO-setting and/or get very long exposure times.
That gives more noise of different kinds and increased risk for motion blur even if you use a tripod as the motif can move over time, if it is organic and alive like a plant.

I would experiment with series of different aperture settings and also do that with different focal distances/magnifications.
There are some good DOF-calculators where you can set the circle of acceptable confusion to match the pixel density of the sensor.

Edited by UlfW, 28 March 2021 - 06:04.

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#16 Cadmium

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Posted 28 March 2021 - 06:37

Spefano, From the top, I tend to like the 3rd, and the 5th the most. :-)