Know How...

May 7th 2015

Know How... 142

Synthetic Diesel, Feedback & How Cameras Work

Film verses Digital cameras, and how they work!
Although the show is no longer in production, you can enjoy episodes from the TWiT Archives.
Category: Help & How To

Synthetic diesel, convert a phone jack into an Ethernet jack, best replacement drive for a NAS, soldering iron upgrade, cradelpoint modem, how cameras work, the Know How FPV250 Quadcopter, and more!


Can I use this for my network?

  • Luke Kolarsky "Hello KH community, I was wondering if i could use this existing phone line (I think it's Cat 5) to convert this phone jack to an Ethernet jack? Any help is appreciated!?"
    1. It "probably" Cat5 or Cat5e. Probably riser rated.
      • Look for labeling on the cable insulation
    2. It's most likely been spliced from room-to-room, outlet-to-outlet.
      • You can't just tape the ends together. You'd want to terminate and couple to make sure you're keeping proper electrical signal.
      • You want to map out the wiring to see how they ran it. It's possible that they've run everything back to a central panel, if that's the case, then you're good to go. If not, you're want to terminate-and-couple or drop a switch at each outlet.

Time for a new drive

  • Geoffrey Auld "I have a Buffalo 500gb Single HDD NAS Box. The Samsung HDD has finally crashed with the click of death and I want to put a WD hard disk in side and was wanting to know which would be best, ie WD Red, Black or Green. Thanks Geoff from Australia. ?"
    • WD Red (~$120 for 3 TB)
      • Run cool, great for NAS, low price per gigabyte, decent speed
      • BUT HORRIBLE for single drive usage
    • WD Green (~$100 for 3TB)
      • Runs cool, reliable
      • Slow
    • WD Black (~$180 for 3TB)
      • FAST.. CRAZY FAST! (7200rpm), 5 year warranty
      • Runs hot, expensive.

I need a new Soldering Station

  • Edie Foy "Time to replace my no longer in biz soldering station. (can't get tips anymore). I can spend $500 for a killer station, I prefer at or under $200. I don't need SMD/SMT. Suggestions thus far are: Hakko, Weller, Metcal, Edsyn?"

Cellular Ethernet

  • Ben Yanke "Does anyone know of a good GSM to Ethernet modem (something I could hook up to my own router, not a WiFi hotspot that creates it's own network). Obviously I could just buy a hotspot and pick it up with an AP acting as a client, and hook that to my router, but that is obviously less than ideal, and less reliable.?"

Traditional, film-based cameras

Oldtimers (Those of us who started with FILM) will remember that there were three ways to control the amount of light that would create your image.

  • ISO (Or ASA, or DIN)
  • Aperture
  • Shutter

These three variables could be changes to change the amount of light you needed to create a proper image, and how much light actually reached your film.

  • ISO
    • Has been called ISO, ASA and DIN: This is the "speed" of the film (Typical values: 100, 200, 400, 800, 1600)
    • The higher the number, the "faster" the film, and the less light it needed to form an image in its emulsion
    • However, as a film becomes faster it:
      • Increases "grain" (the individual particles that capture light clump together)
      • Decreases detail
      • Decreases contrast
    • Those of us who shot with film, knew to always use the slowest film we could get away with.
      • In a pinch, we could shoot slower speed film as if it were higher-speed film, we would just need to adjust our development time to match.
      • It wasn't perfect, but it means that we favored slower films unless we KNEW we were going to be filming in low-light, fast-shutter situations
  • Aperture
    • This was the size of the lens opening through which light passes.
    • The more light that passes through the aperture, the more that can act upon the emulsion on the film.
    • Larger openings made "faster" lenses because they allowed more light to pass through in a given frame
  • We rate the opening in "F-Stops"
    • 1.4 // 2 // 2.8 // 4 // 5.6 // 8 //11 // 16 // 22 // 32
    • Each of these "F-Stops" lets in half as much light as the stop before it.
      • f2 lets in half as much light as f1.4
      • f4 lets in .125 as much light as f1.4
      • f32 lets in half as much light as f22
      • f32 lets in 0.0000038 as much light as f1.4
  • Why do we care?
    • Aperture didn't just change the amount of light that would strike the film, it also changed your depth of field.
    • Depth-of-Field is how much of your shot is in focus.
      • With a small F-Stop, like 1.4, only the things on a very small plane of focus will be in focus on the film
      • With a large F-Stop, like f32, pretty much everything, from the closest to the farthest will be in focus.
  • Shutter
    • The "Shutter" was the mechanism in a camera that would open and close, allowing light to strike the film for a measured amount of time.
    • That measurement was in fractions of a second
      • 1 = 1 second, 1/4 = quarter second, and so forth
      • Anything longer than 1/60th was bound to get you some motion blur * As we increased our shutter duration, we allowed more light into the camera, but we also increased the probability of motion blur
  • ​​Tie it together old man!
    • So we had three ways to control the amount of light that would compose our frame:
    • If we needed MORE light (i.e. low light situation) we could:
      • Use faster film
      • Use a smaller F-Stop
      • Use a longer shutter duration
        • However, this would increase grain, decrease detail/contrast, reduce our depth-of-field, and increase our chance of motion blur.
    • If we needed LESS light (i.e. outdoors) we could:
      • Use slower film
      • Use a larger F-Stop
      • Use a shorter shutter duration
        • However, this would decrease grain, increase detail/contrast, increase DoF, and freeze action on the film.
  • The thing is... all these things persist in the digital age!
    • There's going to be a long segment here about the anaologs to my AG-HMC150 Prosumer Camera
      • ISO = GAIN Control
      • Aperture = Iris Control
      • Shutter = Shutter Control

Quad Feedback


  • Eric Berger "TWIT 122 & 250 FPV: Hi guys. I've been wanting to build a 250 FPV quad, and now that spring is arriving I'd really like to do this and take advantage of the better weather. The FPV 250 kit you recommended looks great, but it's been on back order at Hobby King forever. Can you recommend another kit form anther vendor? Also, did you make specific hardware recommendations for the few items you must still buy/add, like controllers and xmit/receivers?"

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