UV of Salt for Andy

[dabateman]

Andy wanted to see what salt looks like in UV. I used my Raspberry Pi HQ monochrome bare sensor with the KSS 60mm Macro lens at F/4 for the images.

 

On the left is Sea salt, on the right is Iodized salt.

 

Here is 2700K white LED with the Wratten 47, 58 and 29 (Blue, green, red) filters so you can make it color. Although I might have moved it during the captures.

 

 

 

Here are the UV images using 2 Germicidal bulbs. I shot this quickly using auto exposure, so some are dark like the 302nm image.

 

 

 

 

 

 

 

 

[Andy Perrin]

Thanks! I was interested in salt compared to other things, like sugar. It's reputed not to change much, so it makes a good control...

[dabateman]

I can try that next. 

This was good to get running again.  I first made a 35mm quartz lens for this, as I wanted wide field of view. The crop factor is 5.8x, the 60mm is like a 350mm lens.  But the center performance sucked, so ended up using the kss 60mm macro lens anyway. 

I also got the newest software installed on my pi from Gordon999.

https://github.com/Gordon999/RPiCamGUI

Its much faster than what I was previously using, but can only capture jpg or dng, not both at the same time. 

It supports a remote release now using Gpio 12. But when I connected my stackshot controller to it for bracketing,  I killed the port. Stackshot must use too high a voltage for triggering. So I will have to use the time-lapse feature for bracketing in the future or figure out what resistors I need to wire into the release. 

[Andrea B.]

That Raspberry 𝝿 has got to be a huge amount of fun to play with !!

 

Can you replace the blown port?

[dabateman]

I am not sure. It may heal after a couple of on off cycles. Or I may have to tell it to do something different with Gpio 12. There are a lot more pins to work with:

I have switched the release code to Gpio 24 as a quick fix. 

 

worst case scenario I just buy a new Raspberry pi 4B or new pi 5 board and plug the MaxMax monochrome HQ camera into that. My software is on a micro SD card. So transferring to a new board is easy. 

the new pi 5 boards support 2 cameras,  so easier to look at various wavelengths or have a full spectrum color and full spectrum monochrome at the same time. 

Gordon999 software can switch cameras. 

I have a Pi5 board,  but haven't played with it.  I gave it to my son to learn how to code.

[colinbm]

Good to see these salt photo in the different wavelengths.
There are some black grains, any idea what they are ?

[ulf]

AFAIK the GPIO port pins on the Rasberry PI boards are not well protected and connected fairly straight into the processor.
It is rather common that they are destroyed.
It would be tricky to repair and cheaper to get a new board if the used port pin for trigger could not be changed by some coding.

[ulf]

Here we see a similar problem as we had with old flashes with high voltages on their trigger pole frying any modern camera's electronics.

 

The input voltage range of a PI is just up to 3.3V 

Old digital logic used 5V instead.

https://www.futurelearn.com/info/courses/robotics-with-raspberry-pi/0/steps/75878#:~:text=A GPIO pin that is,will be read as low.

 

[Stefano]

RGB stack (visible light):

 

Pure salt is transparent in UVC: https://www.edmundoptics.com/f/sodium-chloride-nacl-windows/14170/

 

Since your camera is monochrome, why some of your images have a color cast?

[dabateman]

Since it seem the max settings for auto exposure are ISO 400 and 1/17 shutter speed.  So they range in under exposure. 

I should use manual exposure next time. That should be better. 

Also I think Gordon or Raspberry pi people may have placed in the a color matrix in jpg mode. So also better to record in raw.

[Andy Perrin]

Why, in Stefano's visible tricolor, is the Blue written in yellow(?) and the the Green written in blue(?)? (Subject to my known issues with color ID!)

[photoni]

16 minutes ago, Andy Perrin said:

Why, in Stefano's visible tricolor, is the Blue written in yellow(?) and the the Green written in blue(?)? (Subject to my known issues with color ID!)

they are CMY complementary colors

[Stefano]

Exactly. The writings are dark, so they take away color. You take green from white and get magenta, etc.

[Andy Perrin]

I see. Brain fart.