Wednesday, May 30, 2018

Jewels Underfoot XI: Marina del Rey black sand

One day I was walking along the beach, just being there. I ended up going south of the Venice Pier, all the way to the Marina del Rey entrance channel. Can't go farther south from here without a boat.

I noticed a patch of darker sand up at the high tide cusp.Taking a closer look I saw that it was black, unlike anything I've seen here. My first thought was that it was polluted sand dredged from the channel, which idea a lifeguard corroborated. As I thought about it, though, this didn't make much sense. I picked up a handful and washed it in the ocean. Nothing happened. It didn't feel oily, it didn't float, it didn't dissolve. I found a cup and took some home for a closer look.

Later on I went back for more. About halfway back home from that trip I began to feel the weight. This stuff is more dense than the common sand. I did some research.

Magnetite forms in swamps. Ballona Creek used to be a swamp. How this small patch of magnetite ended up here I don't know.

When I took some macro photos I got a surprise. Most of it is black and fine, but there are other characteristic grains mixed in, such as garnet. What a fascinating sculpture could be made with this sand.

This sequence of photos zooms in step by step. The first one is the full frame scaled to the blog dimensions. These first three were shot as an experiment on a cloudy day using manual white balance from a grey card.. 
Click on any image to see it full size.



The image below has been cropped to about half the original frame, then scaled to the blog to get in closer.



This image is at maximum size, cropped to actual pixels. The area is about 15mm wide.



This maximum magnification image was shot earlier under sunlight with a diffuser.



Not being all that happy with the photos taken under cloudy light, I took some more today. The day was clear, just a high white haze, so I used a diffuser to cut down the specular highlights. The original is 6720 pixels wide; I cropped that to 3360 and then scaled to 1536 and used unsharp mask.


Friday, May 18, 2018

Jewels Underfoot X: Dunhuang, China

A co-worker went to tour parts of China, and took a camel ride near Dunhuang on the Silk Road. He brought back a sample of sand for me.

It's beautiful sand, and tricky to get the color balance. The new GIMP 2.10 makes some of this easier, so I made a new edit on one of the photos. These were photos I took before I had better control of the photography itself.

The Unsharp Mask took in GIMP 2.10 is also better. Easier to use, I can see the effect, and does a better job os sharpening with fewer artifacts. This image is the best I know how to do... right now. Click on it to get a bigger version.



I wasn't all that happy with the color balance in the Dunhuang sand. It's very sensitive to variations in light and nothing looked right. So, I did a manual white balance from a grey card and got color I liked better.

Then Blogger threw a wrench into the works. With the camera pointed straight down, it doesn't really know which way is up so it makes a guess. Some images are properly horizontal, others are rotated 90 degrees, and some are rotated 270. GIMP asks me what I want, and brings the image in horizontally. I do the edits. Upload to Blogger and it goes by the original EXIF data, which makes the lighting strange to my eye.

I tried various ways to get the image horizontal. The only one that worked was to open the image with Digital Photo Pro, rotate, export as TIFF, edit that in the GIMP to do color balance. Yes, it comes out horizontal as I want, but yeow. What a hassle. There must be a better way.

The image below is of the manual white balance one, but it's a quick edit to see if the concept works. I  overdid the contrast adjustment. I also notice a color shift between the thumbnail below and the enlarged view; the latter goes pretty strongly green-blue. Sigh. This works better in Second Life slide shows, where what I import is what I see on the display.


Thursday, May 3, 2018

Jewels Underfoot IX: Hawai'i Mauna Kea Beach

This sand is from Mauna Kea Beach on the big island.






Jewels Underfoot VIII: Hawai'i Hapuna Beach

Here's another new look at Hawai'i sand. This is from Hapuna Beach, at Kohala on the northwest coast of the big island.

Photographs taken with a 100mm macro lens on a full-frame digital SLR camera at closest focusing distance. Sand is on a white porcelain platter under a diffuser, with the camera looking straight down.

Sand from Hawai'i Hapuna Beach. Click to enlarge.

Sand form Hapuna Beach. Click to enlarge. For some reason, Blogger wants to show this vertically. It should be horizontal, upper end to the right.

Sand from Hapuna Beach, Hawai'i. Maximum magnification, 1:1 pixel view. Should be horizontal with upper end to the right.

Jewels Underfoot VII: Hawai'i Punalu'u Beach

I recently gained access to three more samples of sand from Hawai'i (the big island). This sample is black sand from Punalu'u Beach, on the southeast coast. It's fascinatingly different from the black sand I've seen elsewhere.

I'm guessing this sand is older, due to the polish and the lack of olivine. In direct sunlight it sparkles brightly. All images here were taken using a diffuser to cut back on specular highlights. 100MM macro lens on full frame digital SLR, mirror lock-up, self-timer. The sand is on a white porcelain platter.


Punalu'u Beach sand. Click to enlarge.


Punalu'u Beach sand, closer view. Click to enlarge.


Punalu'u Beach sand, maximum magnification, actual pixels. Click for full size.