Random Photos

[Point Conception]

A few preliminary images using crossed polarizers:

View attachment 323975
Caffeine crystals ('psychedelic spaghetti') at 16x

View attachment 323976
Potassium permanganate (also 16x)

View attachment 323977
No

The colors arise because nearly all crystals are birefringent, the total phase difference between ordinary and extraordinary rays ('retardation') is what is visualized as color.

View attachment 323979
Starch grains@ 10X.

View attachment 323980
Tree bark @ 8x

View attachment 323981
Bone (compact, cross section) @ 8x

View attachment 323982
Hair (human, scalp section) @ 4X.

Hello, How exactly is the ' total phase difference between ordinary and extraordinary rays visualized as color? Would that be from constructive/destructive interference?

 

[Point Conception]

The South West Wind and Cappuccino effect

 

[DennisN]

A few preliminary images using crossed polarizers:

Very cool photos!

Potassium permanganate (also 16x)

Amazing colors!

medium-format film is not a road I am ready to travel down

Hehe, it's another rabbit hole...

I've actually got two medium-format lenses in my collection. They were so cool that I couldn't resist them on an online auction, and I got them quite cheap. They are the oldest lenses I have. But I can't use them since I haven't found any adapter for them. Maybe I'll try building one myself someday, we'll see.

Here they are:

Carl Zeiss Jena Tessar 105mm f/3.5 (from the 1950s) (mount: Pentacon Six)
(note the 15 bladed aperture (!), quite cool)

Here beside my camera:

Carl Zeiss Jena Tessar 150mm f/4.5

 

[Andy Resnick]

Hello, How exactly is the ' total phase difference between ordinary and extraordinary rays visualized as color? Would that be from constructive/destructive interference?

Oh sure... ask me to explain something I just learned about :)

(Optical) Minerology is a "delightful" blend of ray and wave optics, the main conclusion of which is the "Michel-Lévy interference color chart" (a good online explanation: https://www.mccrone.com/mm/the-michel-levy-interference-color-chart/). My reference is an excellent book I inherited from my doctoral advisor- lots of diagrams- which is currently in my office. So I don't want to mangle an explanation right now. I'll provide a better explanation shortly.

 

[BillTre]

Here's a striking picture:

NatureSMS https://www.facebook.com/naturesms0/photos

 

[Andy Resnick]

Hello, How exactly is the ' total phase difference between ordinary and extraordinary rays visualized as color? Would that be from constructive/destructive interference?

My reference book is "Introduction to the methods of optical crystallography" by Bloss. A viewable PDF version is here: https://archive.org/details/B-001-002-290/page/n111/mode/2up so I'm not going to try and summarize what is an excellent presentation of this subject beginning on page 101.

 

[DennisN]

A fish in an aquarium, somewhat in focus, at least :

Using Google picture search I think it is a "Naso vlamingii".
@BillTre would maybe know if that is correct or not.

 

[BillTre]

It could be that. There are a lot of fish.
Was it in a public aquarium? Its kind of large for the normal range of hobbyist sizes of aquaria.

 

[DennisN]

Was it in a public aquarium?

Yes. It's in a nearby shopping mall. I'd say the dimensions of the aquarium is ca 5 m x 1.5 m x 1.5 m (width, height, depth) and it's built into a wall.

 

[BillTre]

That's big, which is appropriate to that size of fish.

 

[pinball1970]

Here's a striking picture:
View attachment 324047

NatureSMS https://www.facebook.com/naturesms0/photos

Wow! That is a genuine image? No touch up?

 

[BillTre]

Wow! That is a genuine image? No touch up?

?

 

[berkeman]

?

Well, you have to admit that the combination of crazy cloud formation, lightning and a rainbow seems a bit implausible, but it could possibly be genuine. That's what he's asking about...

EDIT -- Or maybe no lightning, it's hard to tell...

 

[pinball1970]

?

It is possible to manipulate images, colour, contrast... throw in a vortex etc. These crazy kids can do a lot with images these days.

Your image looked so beautiful and spectacular I had to ask.

 

[pinball1970]

I think it might be too dangerous to have him in the cockpit when flying. He would probably freak out.

If it is your daughters dog it would not freak out. A regular dog would but I do not think your daughters dog would.

 

[BillTre]

Well, you have to admit that the combination of crazy cloud formation, lightning and a rainbow seems a bit implausible, but it could possibly be genuine. That's what he's asking about...

EDIT -- Or maybe no lightning, it's hard to tell...

I would only say check out the link. It may provide some answers, but I wouldn't count on it.

 

[Andy Resnick]

Sodium Iodide again: "psychadelic tic-tacs":

Two conoscopic views through a transparency sheet, showing biaxial structure: the first through crossed linear polarizers, the second obtained by replacing the illuminating polarizer with a circular polarizer (commonly available as polarizers for camera lenses)

The circular polarizer suppresses the isogyres, leaving only the isochromes. Finally, a very tiny guest showed up, ready for his closeup (reflected DIC method):

 

[nsaspook]

Net fishing Smelt on the Sandy River, Oregon.

 

[Tom.G]

Here's a striking picture:
View attachment 324047

NatureSMS https://www.facebook.com/naturesms0/photos

I vote a composite of either 2 or 3 images and maybe some manual touch-up.
Based on:
1. Apparent Solar position seems incompatible between lower and upper mushroom clouds. Sun position of lower mushroom and low clouds on the right seem 90° to the right, while upper cloud deck seems roughly 120° to the right (with the camera at 0°).

2. The multicolor features are not compatible with either Sun position. Rainbows are about 138° from the Sun.
2A. The multicolor could be reflections/refractions from ice crystals (think Sun Dogs) but, the intensity of the illuminate would have to be several times that of the Sun.

3. The Blue area to the upper right of the multicolor feature has sharp edges at the top and sides with neat 90° corners.

4. The shadows cast by the ground cover do not seem compatible between the left and the right of the road. The shadows to the right reach to the left and away from the camera. The shadows on the left point parallel to the road towards the camera.

(Whew! Photo Forensics is time-consuming.)

Cheers,
Tom

p.s. still an impressive image though

 

[DennisN]

Something unusual this time, at least for me... a couple of black and white photos.

A nice place at the canal:

A cool tree in the park:

Another place at the canal:

All three are stitched from multiple photos taken with Canon nFD 28mm f/2.8.
I also used an orange (or maybe red, I don't remember) filter, which increases contrast when shooting black and white (another trick I learned from somewhere). It helps for instance to get more details in skies.

In fact, yellow, orange and red filters all do this for black and white photography; yellow does it somewhat and orange or red do it more.

 

[nsaspook]

 

[dlgoff]

If it is your daughters dog it would not freak out. A regular dog would but I do not think your daughters dog would.

It's her dog. But I wouldn't want her to take that chance.

 

[pinball1970]

It's her dog. But I wouldn't want her to take that chance.

I know. Tongue in cheek.

 

[Point Conception]

One kg shrimp being steamed. About $8.Radioactive Orange

 

[jtbell]

We don't need to go to the Masters golf tournament (a couple hours drive from here) to see azaleas. We can just look out our window.

 

[Andy Resnick]

The photos I took using the transparency sheet came out so well, I wondered what would happen if I used a 2-ply version, with relative orientations of 45 or 90 degrees between the sheets:

here's 45 degrees:

and 90 degrees:

Then, just to play around, I replaced the illumination polarizer with a 'varicolor' filter (red-blue, by Cokin). It's hard to describe the optical effect of the varicolor filter, it has a polarizer and the color switches from blue-red as the filter is rotated: https://www.focuscamera.com/cokin-a171-varicolor-red-blue-filter.html

Using the varicolor filter as my illuminating polarizer, I get results like this:

it's very weird. Fun to play with!

 

[DennisN]

A selection of marvellous photos of animals here:

Soaring, leaping, swooping … a world of wildlife by the world’s top photographers (The Guardian, 4 Apr 2023)

My three favorites (but all of the photos were great):

Spotted torrent-frog by Lucas Bustamante

Ricord’s rock iguana by Tamara Blazquez Haik

Iberian lynx by Antonio Liebana

 

[Point Conception]

 

[Point Conception]

A group of Thai girls , 2000's

 

[DennisN]

A red and yellow tulip in front of a grave (taken in May 2022):

(Lens used: Helios 44M7)