Protecting Digital Camera (Canon Powershot SX 50 HS) against Sun burn in.

[Skybuck Flying]

Hello,

I would like to point my Canon Powershot SX 50 HS towards the sky to take
pictures continously.

However I am worried that the Sun will eventually shine into the lens and
then burn the sensor inside the camera (like a magnifieing glass).

Is there anything that can be done to prevent that from happening ? While
still maintaining some kind of reasonable image quality ?

At least during day would be nice... and evening/night would be a bonus

I think some kind of ring could be attached to the camera
(Kiwifotos LA-58SX50 Lens Adapter Ring )

but what else would I need ? Some kind of filter ???

Bye,
Skybuck.

 

[mike]

Hello,

I would like to point my Canon Powershot SX 50 HS towards the sky to
take pictures continously.

However I am worried that the Sun will eventually shine into the lens
and then burn the sensor inside the camera (like a magnifieing glass).

Is there anything that can be done to prevent that from happening ?
While still maintaining some kind of reasonable image quality ?

At least during day would be nice... and evening/night would be a bonus

I think some kind of ring could be attached to the camera
(Kiwifotos LA-58SX50 Lens Adapter Ring )

but what else would I need ? Some kind of filter ???

Bye,
Skybuck.

Build yourself a sun tracker and instruct the camera to point
elsewhere. Or just cover the lens when the sun approaches
the "burn angle".

 

[Jasen Betts]

If you point the lens straight up, the solar zenith (sun height) will
never be higher than 90 degrees minus your latitude. For example, in
my area, at latitude 36 degrees, the maximum elevation will be 90-36 =
54 degrees.

that's only correct twice a year.

the annual max is 113.5 - lattitude

 

[Martin Brown]

If you point the lens straight up, the solar zenith (sun height) will
never be higher than 90 degrees minus your latitude. For example, in
my area, at latitude 36 degrees, the maximum elevation will be 90-36 =
54 degrees.

Actually no. That is only true at the equinoxes. The altitude of the sun
at transit varies with the time of year from the nominal equinox
altitude by +/- 23.5 degrees which is the angle between the Earths
orbital motion and its axis of rotation. So for your latitude of 36
degrees the range is 90-36+23.5 = 76.5 summer and -23.5 = 20.5 winter.

At my latitude of 54.5N the sun gets to only 59 degrees in summer and a
pathetic 12 degrees in winter. This makes solar power unattractive!

The definition of the tropics is the region of the Earth where at some
time of year the sun will be directly overhead at transit.

<http://www.usa.canon.com/cusa/consumer/products/cameras/digital_cameras/powershot_sx50_hs>
24mm widest angle (35mm equivalent) lens. That yields a viewing angle
of about 73.7 degree. The lowest solar elevation where the sun can
illuminate the sensor directly will be 90 degrees min 1/2 of the 73.7
degree viewing angle:
90 - 73.7/2 = 53 degrees.

Therefore, if you point the camera straight up, open the lens to the
widest 24mm FL, ignore the 0.5 degree width of the sun, and live at
latitude 36 or higher, the sun will never shine directly onto the
sensor. However, 1 degree is not a good safety factor, and you should
install a lens hood on the camera.


Canon cameras can be hacked. (I have several):
<http://chdk.wikia.com/wiki/CHDK>
Write or find a program that retracts the lens when the iris is fully
closed and/or the sensor detects too much light.

Silicon CCDs are fairly robust but continuous sun on one will eventually
bleach the dyes in the Bayer mask.

No. The sun has risen and fallen daily and quite reliably for
millions of years. Other than biblical accounts of the sun going into
overtime for a few hours during a battle (Joshua 10:13), there is no
known method of preventing the sun from trashing yet another of your
electronic devices. I suggest that you purchase an extended warranty.

However, if your voodoo or magic incantations fail to stop the sun,
you could also just install a dark filter on the lens.

The standard for this is Baader solar film - photographic grade.
http://www.telescopehouse.com/acatalog/Baader_Astro_Solar_Film_A4.html

Depends what you are trying to do. Stopping the lens down to a largish
pinhole should be good enough to avoid damage to a CCD.

The dynamic range of the CMOS sensor is not sufficient to maintain
quality at high light levels. You'll need a dark filter to photograph
the sun or any manner of super bright light. A fully closed iris is
probably insufficient.


I wouldn't worry much about the night. Your camera is likely to have
been stolen by then.

Plenty of people run whole sky cameras but tend to live in very dark
areas. They seem to survive daytime OK despite having fast lenses and
180 degree field of view. DIY all sky cameras are gaining popularity:

http://stargazerslounge.com/topic/121275-diy-all-sky-cam/

A couple of new serious amateur ones have been launched fairly recently
although details online are surprisingly scant. Try it with a
sacrificial webcam and see if it does what you want.

 

[josephkk]

that's only correct twice a year.

the annual max is 113.5 - lattitude

It is also correct at two longitudes all year 'round. Plus how much to
'add' to 90 degrees varies by longitude.

?-)