Chen Gao | 髙谌

Songs

热河路 - 李志

程璧 - 我想和你虛度時光 在没有你的时间做遍所有事，不如和你一起甚么也不做，也说不准哪一样才是浪费.

Vlog

Hiking 100 Miles Alone in Alaska - Kraig Adams

日本极地风光 X Nikon Z7II - Links TV

洛克之路 - 在远方的阿伦AaronLiu

Movies

山河故人 - 贾樟柯 "每个人只能陪你走一段路, 迟早是要分开的 ..."

Star trails

I went stargazing on 12/22/2020 and got my first star trail photo. Here I write down the settings. We need to make sure there is enough light. Since we are shooting stars at night, we have to use higher ISO and longer exposure time. A tripod is a must. My settings:

• Turn off vibration reduction
• Turn off long exposure NR
• Turn off high ISO NR
• Use the maximum aperture, f/2.8
• Use wide angle, 24mm
• Use the 500 rule to determine the exposure time. Take the number 500 and then divided it by the focal length of the lens. That will give you the longest exposure before stars start to trail or blur. 500 / 24 = 20.83 seconds
• Start with ISO2500, and then adjust

Here are the steps I took to shoot a star trail photo.

1. Focus the Lens. It's hard for the camera to autofocus the star at night. So we need to focus the lens manually (MF mode). Find the brightest star. Start with focusing at infinity (∞) and turn back slightly until the start looks like a bright and dense point. If you don't do it right, the star will look like a ring. Try a test shot, zoom-in and inspect.
2. Save the images in RAW format.
3. Shoot with manual mode. Then you can manually set the aperture (f/2.8) and exposure time (10s). Start with ISO2500 and adjust it until the image is correctly exposed.
4. Since we need to stack multiple photos, we need to enable interval timer shooting. The interval needs to be longer than the exposure time (I use x+5seconds as an interval). So how many photos we need to take? This number correlates to the percentage of the composition that is taken up by the night sky. If the photo contains half sky and half foreground, then your stars would have to move across half of your photo to produce star trails across the entire sky.
5. Finally, import the photos to Adobe Lightroom and make some edits, e.g., white balancing. Then use Photoshop to stack them.

Here is my first attempt at a star trail photo. In the top right is the Polaris.

Chen's Rubik's Cube - Cheatsheet

Today I grabbed my Rubik's cube, and realized I forgot how to do those fancy patterns. So I made this cheatsheet, in case I forget again...

大中小:

• 大: U2 L2 F2 U' B2 D R F' R F' R F' D' B2 U'
• 小: F2 (L' U' L U' L' U2 L) (R U R' U R U2 R') F2

Tilt-Shift Lens

I always want a tilt-shift lens, especially for the tiny-world effect. Thus, I decide to learn the concepts behind this specialty lens, and then buy myself this expensive toy. Hope Google won't cancel my summer intern, cuz this is a really really expensive toy ...

The first function is called tilt. You can tilt your lens to change the shape of the depth of the field. We know the plan of focus is in parallel with the camera's image sensor. The depth between the plan of focus and the camera's image sensor is constant. However, tilting the lens will change the position of the plane of focus. As a result, you can have more or fewer subjects in focus.

Say you want to take a photo of a book from a higher level. So your camera is facing down. Typically the bottom of the book will be in focus, if we have a shallow depth of field. The top of the book will fall out of focus. What if we want to put the whole book in focus?

We can tilt the lens down so that the plan of focus is in parallel with the book. Boom! The whole book is in focus.

If we tilt to the opposite of the right direction, then here comes the tiny-world effect. This is called reverse tilt-shift (反向移轴).

The second function is called shift. You can shift your lens to have extra field of view without distortion.

Say you want to take a photo of a skyscraper. In order to have the top of the skyscraper in the field of view, you need to face up. It will look like the skyscraper is falling backward, caused by distortion.

To eliminate the distortion artifact, you have two options:

1. Grow a pair of wings and fly in the air to take the photo.
2. Shift your lens up.

Well, your choice :)

Useful Github commands

Recently I am collaborating on a project, and we need to take care of the version control.

I actually never fully understand how those Github commands work. Thus, I'll take this opportunity and learn from scratch.

There is no better choice than this guy to learn from. Actually, he is always my go-to person.

If working along, I can simply do git add, git commit and git push. Done. But working together means I need somebody else to do code review for me. Thus, I need to the following:

1. Create a branch on master.
• git checkout -b [branch-name]
2. Commit and submit all my changes.
• git add -A
• git commit -m ['message']
• git push -u origin [branch-name]
3. Go to Github webpage and make the pull request.
4. You collaborator will review and approve the code.
5. At this point, the pull request has been merged to master. And we can delete all the redundant branches.
• git checkout master
• git pull
• git branch -d [branch-name] (delete local branch)
• git push -u origin :[branch-name] (delete remote branch, online branch)
6. One last thing, what if I kept working on this branch after making the pull request? Master doesn't have my latest changes. We need to rebase to the latest master. (might be incorrect. Avoid this for now.)
• git checkout [branch-name]
• git rebase master
• git push -f

Hello World!

Hey there! Glad you find my blog. I hide it intentionally so I can record my thoughts, useful stuff, or just rant.