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astrnmrtom

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Everything posted by astrnmrtom

  1. No, what you read is not possible. Laser pointer can be attached to the side of a telescope tube to be used as a way to roughly aim a telescope, or to point out where in the sky the telescope is pointing to people standing nearby. There's no way a laser can be used to "find" a deep sky object. Even professional observatories don't use them this way. I can see mounting and aligning a laser pointer to your camera mount to aid in aiming to an object in the sky as long as you know where it is. I've never heard of anyone using them this way. Alignment is critical to point using a lens of any focal length and you wouldn't want the laser shining during your exposure. What kind of astrophotography are you interested in doing? A good way to get started is to do widefield sky images using a wide lens. Keep exposures under 20-30 seconds to minimize elongated stars caused by the Earth's rotation. Attached is my image of the winter Milky Way and Orion setting in the West. a6000 12mm f/2.8 lens, 30 exposure iso 4000. The middle "Star" in Orion's sword is a famous deep sky object - M42, the Great Orion Nebula. In my image you can see its larger than other stars. You'd need a long lens and a tracking mount to get a good image of it.
  2. I know this post is a few month's old now but I'll offer some info. Light pollution filters have been around for quite a while in the astronomy community - since the late 1970s(?) Most imaging was done through a telescope so they were sized for that purpose. It's only somewhat recently that there's been a big surge in widefield and telephoto astrophotography which is why you are seeing them for cameras now. I owns several type and have used them visually through a telescope for 30 years. I'm finding I rarely use them anymore because they are much less effective. I have not used them for astrophotography though. As for effectiveness? They are getting less and less effective as the world switches to LED lighting. A lot of the light pollution used to be from mercury vapor or sodium lighting which emitted light at a handful of specific wavelengths. By making a filter that blocked those specific wavelengths but let other through, you could increase contrast by reducing skyglow. Unfortunately LEDs emit a much wider spectrum so are almost impossible to filter out because you end up blocking the light of the object you are imaging too. This article should be helpful: https://www.bhphotovideo.com/explora/photography/hands-on-review/9-light-pollution-filters-tested-do-they-really-work Now, a lot of light pollution is dealt with in post processing. If you want to dabble in astrophotography, I suggest joining a forum for that specific topic. https://www.cloudynights.com/forum/74-astrophotography-and-sketching/ Hope this helps. Tom
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