In a blogpost from 2017 on this website, there is a photo of the Orion Nebula (taken with 8" telescope and captured on DSLR). The brightest stars in this image have trails of light shooting out, 4 of them, at right angles. I don't know what these are called so I'm calling them "artifacts." (But what is the name for this?). What causes this? Is it considered a negative or a desired effect? Is it controllable? In some photos they appear and in others, they do not (e.g., there is another image later in that same blog post where some stars are really big and bright but this effect is not present). I think they enhance the image, give it a sort of grandeur and impact. But in reality, this is not what the star looks like, it's a single point of light. So... how do you feel about this when it appears in an image, is it desirable and is it controllable?

Dalia and Antoine, I have a question about your excellent book, "The Messier Catalog Workbook." Under the discussion of the globular cluster M13, you stated that this is a great target for "beginner-grade DSLR cameras." Can you please explain what your definition of "beginner-grade" camera is? I have a Canon EOS Rebel T1i which dates back to 2009, it was given to me for free and has been collecting dust for years (not literally). I suspect it's not a great camera but I recently thought it might be good enough to get started with astrophotography, so I am going to try to use it. But I wonder if this camera falls into this category of beginner-grade? Thanks!

I have an old Canon EOS Rebel T1i which I plan to use for my first attempts at capturing images. I have heard that there are some advantages to removing the IR filter when used for astrophotography, but it's not clear if it should be replaced with something else. Anybody out there ever done this?

I am new to astrophotography and am just starting to learn some things about it and it's been fun. I don't really have a specific question here, just an observation to share about something I saw recently. I have been watching some YouTube videos concerning the image processing procedures. I was rather amazed when I saw a video today which showed a single image being "stretched" by post-processing software. The original, raw image showed only a few stars against a black background -- and it was pretty boring. Then... the operator performed the stretching and, incredibly, the background filled in with a huge amount of fine details! I suppose it would be called gas and dust. This was really amazing to see something evolve out of nothing, because the original image was nothing great to look at. And the image was captured using (I think) a simple DSLR with a basic 50mm lens, there was not a lot of magnification with a big scope on a specific target, like a nebula. This fine background detail was visible throughout the entire frame, as I recall. I just thought that was quite remarkable because I expected to see a few more discrete stars visible in the photo after processing -- but the detail that emerged was really amazing! I never would have guessed that there was this hidden content in the raw photo. It makes me wonder what any image captured by randomly pointing a camera up at the sky might reveal, because apparently you can't see any detail with the naked eye and you have no idea what's really there without a lot of exposure time. It also makes me think that I'd probably be disappointed with basic astronomy real-time viewing thru a telescope if it can't pick up the hidden details that are revealed by astrophotography. Anybody else have this experience?

If anyone has used this free image processing software and also others, I'm curious to know how it compares, especially in terms of performance but any other feedback is appreciated. Is there something lacking in this program that makes paying for something else worth the expense? I guess as a beginner I will start with this free program but I am wondering what I might be sacrificing to save $$. Thanks for any advice!

I am new to astrophotography but want to learn about it and get started. I just bought Dalia and Antoine's book "The Messier Catalog Workbook" and am enjoying this content, I highly recommend it. Great work on that, Dalia and Antonine! Not knowing much at this point but planning ahead to when I start buying equipment, I am wondering about how easy or difficult it is to locate deep-sky objects in a telescope. I understand that some scopes are equipped with a "go-to" target-finding system (or it can be added, I guess) which allows you to enter the coordinates of the target and the mount moves to that location automatically. But I would like to know how difficult it is to find targets when using a telescope without this technology?

I'm a complete beginner in astrophotography but I've been doing some research into it because it seems like a really cool hobby! There's something I haven't seen explained anywhere yet about the image collection process, in the scenario where a fixed mount (not tracking) is in use and many exposures are taken to be stacked (and other processing steps, of course). If I were to center my target in the camera field of view and begin taking exposures, how do I know WHEN to stop to adjust the camera, to re-center the image, before taking more exposures? I am assuming that the stacking software is lining up the individual images in order to combine them, but is it able to work with images where a small target is located in a wide range of places in the camera frame, or must I re-center the target area more frequently in the camera frame so that there is not much difference between individual images? Thanks for any input!