Fun with my digital camera

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#8
This will all depend on the lens you use. If you use a "classic" 50mm lens, it will pass IR perfectly. If you use a modern zoom lens that requires elements that produce reduce dispersion, they do not pass IR nearly as well. This is practical experience. I successfully rehearsed a shot using a zoom lens with on a CCD body, then took the same shot with a 50mm prime lens on a 35mm body and it was overloaded by IR.
 
#10
Circlotron said:
Why do red leds often look blurry in photos when the rest of the subject looks ok?
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Don't know, but I recently took some pictures and the red LED
turned out not only blurry but also purple! I understand
that purple LEDs are the latest hype, but I got it for the price
of a red LED in those pictures. 🙂
 
#11
Circlotron said:
Why do red leds often look blurry in photos when the rest of the subject looks ok?
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Red LED's can look out of focus because they probably are. In typical lenses, red, green, and blue focus at different points. The correct focal points wind up off the image plane, either in front of or behind. Apochromatic lenses correct for this, but are are both rare and expensive. In typical photos, the effect isn't real noticable, but since LED's tend to emit at fairly specific wavelengths, the effect is more pronounced.

It would be interesting to photograph red, green, and blue LED's in a single picture. I think the green should be in the best focus.

Cheers,

bg
 
#12
beerguy0 said:


Red LED's can look out of focus because they probably are. In typical lenses, red, green, and blue focus at different points. The correct focal points wind up off the image plane, either in front of or behind. Apochromatic lenses correct for this, but are are both rare and expensive. In typical photos, the effect isn't real noticable, but since LED's tend to emit at fairly specific wavelengths, the effect is more pronounced.

It would be interesting to photograph red, green, and blue LED's in a single picture. I think the green should be in the best focus.

Cheers,

bg
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Sounds like I should make such an experiment with my
Nikon SLR instead of my cheap digital. It ought to perform
much better if what you say is true.
 
#13
Christer said:


Sounds like I should make such an experiment with my
Nikon SLR instead of my cheap digital. It ought to perform
much better if what you say is true.
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beerguy0 is absolutely correct on apo lenses. They are prized because of their ability to focus all three colors on a narrow(er) plane. your ED nikkors will also do that.
 
#14
in the spring when the fesh green leaves are bursting out.

dave
 

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#19
dhaen said:
How about some IR photo's of working equipment (especially class A) 😎
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I'm not sure that IR film is sensitive that far down, spectrum wise. The IR that film captures is just below red light. Heat is much further down the EM spectrum. What you really want is a thermal imager. I use thermal imagers at work to check component temperatures, like switching FETS, RF coils, etc. You could try it, but I don't think you're going to get what you expect.

Cheers,

bg
 
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