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How to safely shoot into the Sun
#11
Quote:They might individually have less energy, but there are an awful lot of them. Total energy received is still significant.
 

I suggest having a look at a solar emission spectrum.
#12
According to Wiki: Sunlight at the top of Earth's atmosphere is composed (by total energy) of about 50% infrared light, 40% visible light, and 10% ultraviolet light.

#13
And here is the solar spectrum (from http://www.globalwarmingart.com/wiki/Fil...trum_png):

 

[Image: Solar_Spectrum.png]
#14
BrightColour – I realy like picture #2. Wonderful composition lighting,colours, details. I have look at this picture and enjoy it it a lot. Thanks for sharing.

 

I have some taught about spectrum

  1. sun spectrum before entering atmosphere.
  2. Transfer function of air – it is dependant of time of the day. I assume that you shooting early in the morning or late evening. Not pointing out the camera vertical to sky at 12:00AM and searching the space shuttle. :-)
  3. Transfer function of lens. – not very important, since the most attenuation comes from air
  4. Transfer function of IR and colour filters.
  5. Last but not at least – transfer function of Silicone /sensor/.  Silicon gap is equally high as IR photons. That is why silicone detectors are best in IR spectrum. Just think how good is jour TV IR remote control.
#15
My feeling /not scientific/ is that IR will not damage jour camera but IR will electrically saturate the CMOS/CCD sensor. making strange looking images

#16
Quote:My feeling /not scientific/ is that IR will not damage jour camera but IR will electrically saturate the CMOS/CCD sensor. making strange looking images


Thank you for your input, miro. I remember sometime ago there was a post here which showed that the shutter curtain of a camera was burned out (maybe) by the Sun. So I put up this post to ask for advises for avoidong this to happen.
#17
Quote:I don't think so. The main purpose is to limit the amount of direct sunlight entering through the lens. A telephoto lens has a bigger physical aperture size than a wide-angle lens. So at the same F-stop, you'll let more light enter the system with the telephoto lens - which is the main worry here.


I don't think so. What matters here is the solid angle of the lens to the sensor, not the diameter size of the lens element. At the same F-stop a tele lens has the same solid angle as a wide lens to a point on the sensor. But for a tele lens the light ray will hit the sensor more likely with a straight angle.
#18
Quote:I don't think so. What matters here is the solid angle of the lens to the sensor, not the diameter size of the lens element. At the same F-stop a tele lens has the same solid angle as a wide lens to a point on the sensor. But for a tele lens the light ray will hit the sensor more likely with a straight angle.
 

I don't quite understand what the problem is here. Switch on a strong light bulb, shoot it with a wide-angle, then take your longest tele lens, shoot the light bulb from the same distance using the same f-stop and exposure time (!) and check which one comes out brighter. When aiming at a point light source, the telephoto will let much more light enter the system than a wide-angle, which is why shooting the mid-day sun with a telephoto is dangerous for your eyes. No?
#19
Quote:I don't quite understand what the problem is here. Switch on a strong light bulb, shoot it with a wide-angle, then take your longest tele lens, shoot the light bulb from the same distance using the same f-stop and exposure time (!) and check which one comes out brighter. When aiming at a point light source, the telephoto will let much more light enter the system than a wide-angle, which is why shooting the mid-day sun with a telephoto is dangerous for your eyes. No?


Yes, it is true that at the same F-number and the same exposure time, the sensor collects more energy from the Sun for the tele lens. But the energy spreads over a larger area on the sensor. The energy received per unit area on the sensor is the same, providing that the incident angle of photons are the same.
  


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