Skip to main content

Getting pictures in focus with a DSLR (digital SLR) in a nutshell.

Higher-end cameras have a number demarcated by the letter "F" that one can set to change the size of the opening (called the iris) that lets light onto the sensor. High numbers make the iris smaller. Optical physics aside, the higher the number, the more of the picture will be in focus and the more light you will need. Likewise, the higher the shutter speed, the more will be frozen in time and the more light you will need as well. So, if you want to capture something that moves fast and have it completely in focus, you need a ton of light, a high F number and a high shutter speed number. Note that a particular lens only supports a particular range of F numbers (called F-stops). You don't have a huge amount of light usually. So you have to find ways to compromise and/or cheat. One way to do this is to use a flash, but that can scare butterflies. Another way is to set the camera to do more processing. This number is demarcated by "ISO". My SLR goes from 200 ISO to 1600 ISO, if I recall correctly. New ones go to 12500! The higher the number, the less light you need, and the more you rely on the camera processor and the quality of the light sensor. Thus to get a nervous butterfly on a cloudy evening, you need to higher-end camera so that you can set the shutter speed, F-stop, and ISO numbers really high, and still get a photo that's not grainy.

Comments

Popular posts from this blog

PowerShell One-Liners

Introduction

PowerShell is Microsoft's shell for their product lines. It's now on version 3.0. If you miss the power of the command line while using Windows on either your laptop or servers, PowerShell provides that power.


Important concepts:
Almost all aspects of the Microsoft ecosystem are objects within an overarching structure. You query and manipulate this structure and its objects with PowerShell. This includes all aspects of SharePoint, Active Directory, and Exchange. Other companies, like VMware (see below) have also written PowerShell modules.This "object nature" means that PowerShell pipes pass objects and properties, not just text. Variables store data-structures of objects. 
One-liners

Note: Unwrap the code lines before you use them.

Get Help

Get the usage of the command "Select-Object":

Get-Help Select-Object

Built-in examples for the command "Select-Object":

Get-Help Select-Object -examples | more

Get the list of all commands and sort it:

Fixing SSH connection problems in EGit in Eclipse

Note: I posted a version of this on Stack Overflow. Errors can occur when there is an underlying SSH authentication issue, like having the wrong public key on the git remote server or if the git remote server changed its SSH host key. Often the an SSH error will appear as: "Invalid remote: origin: Invalid remote: origin"
Eclipse will use the .ssh directory you specify in Preferences -> General -> Network Connections -> SSH2 for its ssh configuration. Set it "{your default user directory}.ssh\" . To fix things, first you need to determine which ssh client you are using for Git. This is stored in the GIT_SSH environmental variable. Right-click on "Computer" (Windows 7), then choose Properties -> Advanced System Settings -> Environment Variables. If GIT_SSH contains a path to plink.exe, you are using the PuTTY stack. To get your public key, open PuTTYgen.exe and then load your private key file (*.ppk). The listed public key should match the pu…

How to fix this ssh error from a Cisco switch: ssh_rsa_verify: RSA modulus too small: 512 < minimum 768 bits

Problemssh user@cisco_switch returns:
ssh_rsa_verify: RSA modulus too small: 512 < minimum 768 bits key_verify failed for server_host_key Solution The modulus of the ssh RSA key pair on the switch is too small. If you have access, generate a new key pair on the switch with a larger modulus.
ProcedureLogin with ssh protocol version 1 (ssh space dash one): ssh -1 user@cisco_switch(On the switch): enable(On the switch): Authenticate to "Privileged Exec Mode" mode on the switch.(On the switch): conf t(On the switch): crypto key generate rsa general-keys modulus 1024(On the switch): Press enter to accept that the current key pair for the switch will be replaced. You now should be able to log into the switch with ssh protocol version 2.