First flight, CHDK settings?

edited October 2013 in General
Hi so i flew my first real KAP rig today. It was fun and a few selected images: http://rotand.dk/pics/KAPing/index.html

I learned a lot about handling the kite and found things to improve. Like not pointing the camera so much down, fix the rig so the auto rotate is effective, get more line, remember to double check that the camera is taking images (doh!), etc

However I was hoping the I could get some suggestions for camera settings. Many of the images were (motion)blurred. I should probably set the shutter-speed down. I bought a second hand canon SX230hs for KAPing with CHDK, and its been a while since i used a camera where i could adjust anything manually. The plethora of options are quite confusing. Do you have a 'fail-safe' suggestion for camera settings for at gloomy Scandinavian autumn day?

Comments

  • edited October 2013
    Looking good.

    Recommended camera settings: set the shutter speed as fast as you can. I see you shot with 1/1000 second. Should be adequate. Go faster if you can.

    Second - shoot video to see how stable your KAP rig is. Make adjustments if you see lots of motion.

    As for more info on CHDK - see long details here.

    WW
  • edited October 2013
    Thank you.

    I will try to adjust the shutter speed, there is a setting TV that fixes the shutter-peed and auto adjusts everything else. I will of course need to field test it, unfortunately there was not enough wind to day.

    The video option sounds like an interesting experiment that also may yield some interesting footage.

    The link looks interesting and informative.
  • Instead of setting Tv it might be better to use P and Custom Auto ISO setting from CHDK, set User Factor to 5, IS factor to 2, and minimal shutter speed to a sensible value (something from 1/500 to 1/1000 makes most sense. Also set your preferred ISO ranges (for auto and auto-hi, see at what ISO levels image noise is still acceptable for you). Then don't forget not to disable Autoiso Override. And finally set ISO to auto (or auto-hi if photographing in lower light conditions) in your normal (non-CHDK) menu.

    In normal Tv mode you'd have fixed shutter speed, only ISO and ND filter (unless you disable ND filter in CHDK) would vary. If theres too little light for your preset exposure at max auto ISO setting (for 1/1000 it's pretty likely) then you'd get underexposet shot.

    In P mode with Custom Auto ISO you'd have fixed speed if there is enough light, but if light is too low even for the highest ISO then shutter will be slowed down. Sometimes even 1/30s shots are sharp (if kite line is almost slack while wind is steady) while taking that photo at 1/1000s exposure would yield a black frame (photo underexposed by 5 so called stops would be pitch black except images of bright lightsources and their specular reflections - anyway, it'd be unusable 99.99% of time).

    rgds
    \Seb
  • Hi - I suspect the reason for the motion blur is because your rig is moving about a lot - certainly seems so from the photos where the horizon is tilted quite a bit.

    How are you suspending the rig - pendulum or picavet? And how far below the kite are you fixing it to the kite line?
  • I would second sebaska's suggestion to use the CHDK Custom Auto ISO. It will adjust ISO as needed within the range you set in order to keep the shutter speed fast, but will lower the shutter speed if that's needed to get a picture. So it's more flexible than Tv.

    However, it does not deal with aperture, so it foregoes using aperture adjustment to help keep the shutter fast. I'm currently working with one of the CHDK gurus who volunteered to write a lua script for CHDK that will use everything available to keep the shutter speed at your target setting - ISO, aperture, and ND filter - and will work on iris cameras, ND filter cameras, and those with both. Basically, it is a script specifically written for KAP. Hopefully it will be available in the next week or so for testing by those interested. I'll post in a new thread when it's ready.
  • @wayback: Awesome! Keep us posted, eagerly waiting for that script! :) Going to need the fast-as-possible shooting now, when the daylight begins to be scarce. I think next week it's already so that the sun is up only during the time I'm at work, how sucky is that. It leaves only weekends left...
  • edited October 2013
    Thank you for the input.

    The auto-iso settings and using P -mode sounds like a good choice I'll see if i can figure it out.

    @wayback the script sounds great.

    @heharkon yes daylight is scarce. To add insult to injury the local weather forecast is rain all next week.
  • Oh i almost forgot.

    @dave: I am using a picavet, made from ikea door stoppers : http://www.ikea.com/us/en/catalog/products/10098949/ and i have a small rig ala http://www.brooxes.com/newsite/bbkk/KITS.html, hoBEAK. But with a gear and dc-motor for rotation. The rig were attached when the kite were up and flying, so something ala 10-15 meters from the kite.

    There were gust of wind and movement with the kite, but way to many images were blurred. Further the images with more sky, aka when rig were dangling, we almost all better. So in retrospect it must be the shutter speed. And the suggestions above for fixing shuttespeed / setting a wished minium with auto-iso ought to be a good solution.
  • edited October 2013
    Michael Layefsky and others have long used the following SDM methods that give correctly exposed images at 8x normal shutter speed :-

    http://arch.ced.berkeley.edu/kap/discuss/index.php?p=/discussion/4705/sharpness-revisited-for-chdk-users#Item_14

    The second method allows you to set maximum ISO.
    This has been used on stratospheric balloon flights.
    It does what you want the CHDK script to do.

    My own tests suggest that with these small sensor cameras and with a subject essentially at infinity (which optically can be less than two metres at wide-angle !) stopping-down the aperture is undesirable.

    It reduces sharpness and forces a lower shutter speed.

    Bear in mind that f4 on these cameras is typically equivalent to f22 on a 35mm camera as far as depth-of-field (that you do not need) is concerned.

    The SDM strategy is to force the ND filter out and set aperture to maximum.
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