I am so skeptical of this story but I want it to be true so badly.
If I shine a laser through, does it really focus on the sighted spot? Does the coating on the telescope not filter IR? I thought most did maybe not. Could I shine a flashlight through and illuminate the room? How is that not the same?
1. Optics are symmetric, so it will shine on the spot with the same total power, which might not be noticable.
2. Maybe! Cheap ones might not even have a coating.
3. You can do this! See (1) for how much brightness you can expect.
If it worked, it’s due to televisions having a relatively low activation threshold for user comfort, so you don’t have to aim the remote accurately, or often at all! Often secondary or even tertiary (or more) IR reflections will trigger television functions. For a quick sample, try aiming your remote at the opposite wall and seeing if the tv turns on. I don’t doubt this story, but I also believe it would have worked merely by pointing the remote at the TV, telescope or no.
> For a quick sample, try aiming your remote at the opposite wall and seeing if the tv turns on.
But first make sure it isn't radio controlled. The remotes at my old house were all assigned a cable box and you could control that box with its remote from anywhere in the house.
> > For a quick sample, try aiming your remote at the opposite wall and seeing if the tv turns on.
> But first make sure it isn't radio controlled.
Based on my experience, this isn't actually a problem for people interested in trying it with their TV as RF remotes included with STBs, streaming sticks, etc., still have IR transmitters built in to control the TV.
Specifically, the actual device (e.g. cable box) is controlled with RF signals (often bluetooth) but the power and volume buttons are often controlled via IR because those are functions of the TV and most TVs have IR receivers. TV power/volume can also be conttolled via HDMI-CEC in theory, but in practice I've run into compatibility issues more often than not that way whereas doing it over IR just works.
For #2 - Assuming it's not a spotting scope or similar, filtering IR wouldn't have much benefit. An IR filter might even hurt for the typical star gazing type usage, depending on the equipment used. Cameras for looking at things in the night sky often explicitly lack IR filters (often at massively increased cost) to increase sensitivity to any available light.
Very much this. Any IR filtering on a telescope would not be a very favored option. There is so much interesting stuff to see in the IR range. To your point about lack of IR filters, there are places that offer a service to have the IR filter removed from your DSLR. You can just add an IR filter to your lens to have it back to "normal".
This seems incorrect. Everywhere I look I hear effectively:
> All refractive optics require IR filters.
The reason seems to be it prevents "bloating" of bright points of light - eg stars, and increases contrast in the visible range by cutting off UV and IR (which CCDs are apparently sensitive to), so it is in fact desirable to have IR filtered out.
Possibly desirable for optimal image quality, sure, but taking pictures is not the only use for a telescope. Many things just require knowing how much light is present, and how that changes over time. Occultations are one such case which I have familiarity with. Objects are often so faint that every little bit of light is essential to improve SNR - https://occultations.org/
IR filters are generally pretty effective too, so just having one anywhere will do the trick unless you're dealing with a lot of light. Cameras which would be undesirably sensitive to IR would usually have the filter built in, basically right on top of the sensor. No need for added coatings on the telescope itself.
remotes are not lasers, since a laser would only worked if you point at the small ir receiver with high accuracy. Instead remotes are regular IR which is allowed to scatter.
I used to have a TV-B-Gone universal remote with only one button - OFF (oh hey it is still a thing https://www.tvbgone.com/). It was glorious, I used it in airports back when they had TVs all over the place, in hotel bars, in airport shuttles. It came with a booklet warning you about dangers of using it in a crowded sports bar during large sporting events...
1: Get the other house's TV sighted in the eyepiece.
2: Move your eye out of the way and hold the remote control up to the eyepiece.
3: ...
4: Move back and observe the confusion.