Everything You Need to Know About Telescope & Camera Optics
In this deep-dive astrophotography video, I walk through how a telescope actually works - not just the optics, but the entire imaging system. We’ll explore how focal length, apertu...
The Space Koala Astrophotography by Luca Bartek
Amazing content!
A topic i am still struggling. Nicely explained, Luca!
all i can say is WOW!!! the production on this video let alone its content should make most videographers run and hide. grade super a+ all day long
I was trying to understand why a longer focal length gives a smaller FOV, but adjusting the aperture didn't change the FOV. This video explained it perfectly! Thanks!
I'm glad this cleared it up!
Being a total novice I really learn an amazing amount of very relevant information from watching your videos, inspiring me to likely make the move forwards, and upwards, from the fool proof Seestar S30 to building my own smart scope very much based on your video on that same subject. One thing that I am still very much in doubt about though is what camera to go for. In you video you suggest the ZWO ASI 585MC AIR and while it is a fantastic way to simplify the setup at a very affordable price I am beginning to realise that the fairly small sensor might be something that I will regret, and I wonder if I would be better off scraping some more money together and wait until I can afford the ZWO ASI 2600MC AIR, or might that be a bit overkill for a novice wanting to move upwards from the smallest and cheapest smart telescope on the current market? As for telescope I am considering the Askar V APO you use in your setup, but I am also considering the Askar 80 PHQ, which would save me some money that I could then spend on the more expensive camera. Some advice would be very much appreciated 😊
the larger sensor of the 2600 will definitely give you a lot of options for larger objects and by all means is a superior sensor to the 585 in my opinion. I just went with the recommendation for the 585 as it is much more affordable - and consider that all the other parts would still need to be bought :D I have never tried the PHQ so I cannot say how good it is. I have had a great experience with my FRA - it is available in 4 different sizes. And you still get the option of the reducer so you can shoot at 2 different focal lengths still.
@the_space_koala Thank you so much for taking the time to reply. To me it is very much the case of the more I learn the more I realise how little I know, so taking the step from a $400 Seestar S30 to something in the area of $5,000+ can be a little daunting. I think, after having used several different combinations on online simulators, that the 2600 sensor size suits my goals much better than the 585 but yes, it is also almost three times the price. I will have a look at the FRA models you mentioned and start looking around for early Christmas sales too 😆 Thanks again for your reply and not least your fantastic channel.
I would like to point out what would happen in the "Critically Sampled" example at around minute 19 if you were to move the everything 1/2 pixel width to the right or left. You'd get a uniformly grey bar. In general, the rule of thumb is to sample about 3.5 pixels across the black->white transition. This way even with shifting left/right you still can see the transition.
you're perfectly right, the illustration I did is incorrect - it is not in line with the verbal explanation I provided. This was already pointed out by someone a few weeks ago as well, but sadly I do not have a way of updating the video
Thanks!
Thanks to you!
19:40 the Nyquist Limit is demonstrated wrongly. the sample frequency has to be twice the highest spacial frequency. in the example both are the same. if you would shift the sensor pixels half of their size to left or right, each pixel would 'see' half of the light pattern and half of the dark pattern, thus all pixel would measure a mid-gray. so it shows exactly a violation of Nyquist.
Thank you for your comment, you're right - the Nyquist limit demonstration is wrong and the sampling frequency should be twice the Nyquist frequency and therefore the illustration is not accurate. Though we didn't enter the math here and I believe the wording I used in the presentation - saying the limit happens at the frequency for which you have just enough pixels to capture the variability of the signal without losing information - is correct.
ti sei dimenticata di dire il colore delle stelle che non siano verdi o turchesi
Can’t imagine the work it took to go from pedagogic vision to this video. Brilliant. You have several gifts. One is to imagine the perspective of the viewer and figure out what might be puzzling them. This is actually a somewhat rare ability. Second is your ability to create illustrations that have precisely the right level of detail. And third is to explain it all with lucidity and precision in an engaging way. And this is all the more impressive if, as might be the case (?), English is not your first language. People who want to make technical videos on any topic should watch this video and learn how it’s done. Bravo Koala!
thanks for the kind words Seth :)
This is so educational, I've been looking for something theoretical like this and this is perfect. Just this one video gave me idea how other content from this channel would be, super subscribed 🔭
thank you so much for the kind words, I'm glad you found this useful!
Congrats, Luca, excellent tutorial. Btw, this could enlighten many (non astronomer) photographers, who often get things wrong, starting by ignoring the lens diameter of their cameras.
oh yes, definitely, nobody outside of astrophotography actually cares about that, I fear even most astrophotographers don't..
Thanks for your hard work educating us, I wish those equipment were available in my country
Thank you, Luca for this wonderful review. I am perplexed at the concept of “parallel approximation.“ While distant light from massive, complex structures eventually funnels into our little objective lenses, the rays from stars that are 100,000 light-years apart from each other cannot be truly parallel. (The diagrams showing light entering a refractor seem to support this concept). It was helpful to simplify by showing the light passing straight through the center of the objective lens, but there also must be a tremendous and complex story associated with all of the “almost parallel” light rays being refracted through every surface of the objective lens (and beyond). Thank you again for this remarkable video (as well as all of your others) and looking forward to your next lecture on this topic.
hey - the parallel approximation doesn't refer to ALL the light entering the lens (we could have a lens that shows like 180 degrees of the sky!) but the light beams coming from a single star only! If you go back to the "sphere" of light that we are intercepting, in reality, the specific ray hitting one edge of the mirror is not truly parallel to the one hitting the opposite edge. if it's easier to imagine in 2D - we take a pizza (a circle is a good 2D analog for a sphere) and we take a slice that is so EXTREMELY narrow, it no longer looks like a triangular pizza slice but just a straight strip. I hope this makes sense. The parallel approximation here was necessary to introduce the concept of calculating field of view because that's the only way the simple trigonometry will work
@the_space_koala Thank you; yes, this makes sense. It’s just astonishing to me that we can resolve so much detail within this extremely narrow field of view. Scott
Well explained tutorial. Thank you.
I have an f4, 200mm Newtonian, the perfect rig, however it was damaged in shipping and will not collimate. Warning to where you purchase your gear, Allstar telescopes out of Edmonton Canada are terrible, just saying. Great video kid.
Ouch, so sorry to hear! That sounds unacceptable. If it cannot be collimated that sounds like an inherent issue of the optics, not necessarily damage from the shipping though
I really enjoy understanding the physics behind the gear, even if the math baffles me. You explained it at the perfect level of technical detail. Please do more of these. Thank you.
Thank you for saying that I’m glad it’s appreciated
That’s a really good explanation! Greetings from Ukraine 🇺🇦
Love the graphics and perfect explanations!
Great video explaining the physics and optical concepts… some minor physical hick-ups. Otherwise GREAT! Thank you!