Biology happens while we shoot

[Andrea B.]

I was sitting happily shooting these little Potentillas. I did not touch them!! Sigh.

 

 

Visible record made at 2016.07.06.14.25.25. No flash was used.

 

 

UV record made at 2016.07.06.14.26.57. Two petals dropped!!

This was 1 minute and 22 seconds later.

Just long enough for me to have switched from a Vis filter to a UV filter and reset the exposure.

I can't tell you how many times this has happened to me while shooting Potentillas.

How does this flower know I'm there shooting it? Perverse little thing!

[rfcurry]

The Potentilla or Cinquefoil operates at the quantum level. Thus, observer effect is common. Had you not been there to observe the flower, the petals would not have dropped. Your observation alone was sufficient to alter the flower's quantum state and thus it lost particles (petals) in changing from waveform to particle form. See https://www.scienced...80227055013.htm

[Andrea B.]

oh LOL !!!!!

 

I suppose I'd rather have Potentillas obeying the laws of particle physics rather than simply being mean to me. "Oh here's that pesky UV photographer again. Let's get her good. Get ready to drop some petals. On my count now.....1,2,3....wheeeeeee!!!" [scads of petals flutter slowly to earth.]

[Bill De Jager]

The petals probably jumped back onto the flowers after you left. ;-)

[Cadmium]

Pardon me mentioning this, but the background of the UV shot is rather noisy, is this the ISO or the camera? Or??

[Andrea B.]

Good question. That's mostly just UV, methinks?

If you open the UV shadows even a little tiny bit, blammo! noise appears.

Or a bit of banding which is also seen in this one (lower left).

 

When the original raw colours are wrenched about during the white balance step,

there can also be a big hit to the smoothness of colour areas.

There is also a hit in the transfer from 14-bit raw to smushed JPG.

 

Also, UV is very easy to underexpose. It is difficult to push the UV exposure for noise avoidance and still maintain control over the highlights. Highlights in UV are not always easily recovered without colour artifacts. I suspect that underexposure was the underlying cause of some of the noise in this photo.

 

However I don't care much about noise. In the olden days that was called "grain". :D

I suppose I could smooth it out, but then the photo might look artificial and too digital.

 

I'll go dig out a raw composite and we can look at how noisy it really was.

[Andrea B.]

Aha! Underexposure is indeed the case for some of the noise in this particular UV photo. The raw composite shows a very dark photo. Not surprising given that I was scrunched down in a "meadow" of tall plants trying photograph these little Potentillas in situ. The UV-flash shortened the exposure, but also created a very dark background. So the flowers are (mostly) properly exposed, but all the rest is underexposed.

 

The raw composite which appears to be quite smooth. Thus the conversion, white balance and shadow push revealed the underlying background noise in the final photo.

 

 

 

A screen shot from Raw Digger. The blue area indicates underexposure. The chart in the upper right shows the underexposure percentages. The underexposure is worst in the Blue channel. This is almost always the case in a UV file. Then when we apply click-white balance we bring up the noisy Blue channel at the expense of the less noisy Red channel - all to the detriment of the final edited photo.

[Cadmium]

Thanks Andrea.

Hmm, D600, ISO 400, seems like that should keep it pretty quiet.

Back in 1972..., in my dark room, grain was not too much on my mind.

Now a days grain is more of an issue for me. We have high resolutions cameras, I like to avoid grain/noise.

Sometimes it seems like sharpening an image can make it look more noisy too.

[Andrea B.]

Hmm, D600, ISO 400, seems like that should keep it pretty quiet.

 

Unless, as mentioned, there is underexposure or one tries to open the shadows up.

[Andy Perrin]

Sometimes it seems like sharpening an image can make it look more noisy too.

That's not an illusion, that's real. The spatial frequencies in an image (we are talking about differences between adjacent pixels here, not colors; this applies even to monochrome images) are directly amplified by sharpening filters. On top of that, when there is a spatial discontinuity, aka an "edge," that will make ringing artifacts. These are directly related to the Gibbs phenomenon:

https://en.wikipedia.org/wiki/Gibbs_phenomenon