It's probably NOT what you think! Clearing EVERYTHING up with Optics Simulation Software!

[@CuivTheLazyGeek]

To try everything Brilliant has to offer-free-for a full 30 days, visit brilliant.org/cuivlazygeek . You’ll also get 20% off an annual premium subscription. My Patreon: www.patreon.com/cuivlazygeek My Merch Store: cuiv.myspreadshop.com/ For any affiliate link purchases, make sure to accept cookies if prompted! Also, browser plugin "Honey" may steal commissions from creators if you interact with it (even just clicking on "OK" to the "No coupons found" message)! Amazon affiliate: amzn.to/49XTx01 Agena affiliate: bit.ly/3Om0hNG High Point Scientific affiliate: bit.ly/3lReu8R First Light Optics affiliate: tinyurl.com/yxd2jkr2 All-Star Telescope affiliate: bit.ly/3SCgVbV Astroshop eu Affiliate: tinyurl.com/2vafkax8

[@christopherleveck6835]

HOOOOOW, NOT HAAAAAR. How. NOT, har...... 👍😎👌

[@woody5109]

Most of these channels are not much more then digital panhandling, yours is an actual learning channel. Great work.

[@CuivTheLazyGeek]

Thanks so much! I do my fair share of reviews as well, but I try to keep as objective and honest as possible when I do this :)

[@corkslagg]

Absolutely. Unfortunately, it’s only a matter of time, as it becomes more accessible and well-marketed, that the hobby of astrophotography goes the way of sound reproduction (i.e. audiophile stuff) full of half truths and folklore. Pretty soon we’re going to hear about people preferring knife edge baffles of carbon fiber to aluminum due to some perceived aesthetic difference.

[@user-br9fx5nl8m]

Bravo! You need to add a few more videos for a series explaining (as others have said) field flatteners, collimation, sensor tilt, aberrations, under/oversampling etc. If you can explain these subjects with equal clarity, the astrophotography community will be greatly enriched. Thank you for your efforts.

[@thomasrider5852]

Of all the astrophotography channels I follow I like how you deep dive into subjects really no one talks about! As always, excellent video Cuiv!

[@CuivTheLazyGeek]

Thank you so much! I'm glad you enjoyed it! The deep dives are a lot of work and get fewer views... but they're such a lot of fun to make as well!

[@ntaylorblanchard]

Great video. I have a degree in Astrophysics and I teach astronomy in an 8th grade Science class. This video is the best explanation of focus I've ever seen.

[@CuivTheLazyGeek]

That's extremely high praise, thank you so much! I hope this video can be useful for education!

[@shilohbridgewater6407]

New Cuiv video? Digging deep into a complex topic? Physics?? Yes, please! 🙌 Thank you for all your hard work bringing us these detailed videos on topics usually not covered, Cuiv. You are truly a gem for the community.💜

[@CuivTheLazyGeek]

I'm so glad you enjoyed it, and thank you so much for your support!!

[@redbird247]

Very nice job, Cuiv. You built the concepts in such a way that by the end of the video, the user has already internalized much of the material at the beginning and can make use of it. Good teaching!

[@CuivTheLazyGeek]

Thank you! I really spent a lot of time building the structure of this video, so I really appreciate it!

[@davewilton6021]

Excellent video! Please do more like this (i.e., on the fundamental science of optics and how things work). There are a lot of astronomy/astrophotography KZbin channels that are all regurgitating the same product reviews/tutorials. It's refreshing and enlightening to see something different.

[@CuivTheLazyGeek]

Check my earlier spot diagram video, and I also have a lot of videos about sampling, SNR, noise in astro cameras, etc.

[@TheCynical0ptimist]

This is great! Maybe in a Part-2 you could get into what influences image circle size. (We have flatteners and reducers which sometimes impact image circle, but no adapters that specifically alter the image circle size, especially to enlarge it. As cameras with integrated guiding chips become more popular that could become a useful mod.)

[@CuivTheLazyGeek]

I'll think about that - it's a complex topic!

[@mtct7878]

Danke!

[@drchrisbartlett]

This was outrageously good content

[@revolting887]

Master class once again Cuiv! Talk about optimal signal to noise!

[@CuivTheLazyGeek]

Trying to keep the knowledge sharing signal high ;) Thanks!

[@GoldenJackalTutorial]

12:20 This is the best explanation to this misconception that I've also noticed many times in many different people. It also beautifully displays why the image you are seeing is actually reversed. Very good video, Cuiv. Hopefully more people will see it

[@CuivTheLazyGeek]

Thank you!! I now see I missed the opportunity to call out that the image was reversed but as you say it is displayed :)

[@ridearocket]

Very informative! Touched a lot of topics in which I understand the outcome of why things are they way they are but then broke them down to a level in which I truly can understand everything behind the scenes. Thanks and always looking forward to more!

[@CuivTheLazyGeek]

Thanks! Glad it was helpful!

[@joshuamuller9705]

Wow, I havn`t even watched to the end of the video and you answered several questions I had since starting with astrophotography :D Thanks a lot

[@CuivTheLazyGeek]

I'm so glad this is helpful! That was the goal!! Thanks for your continued support!

[@clearmore3024]

My first thought was "that was too short!" Proof that it was a good video. Thanks Sensei!

[@CuivTheLazyGeek]

Hahaha that is really high praise!! Thank you so much!! And thank you for your support!

[@lloydlorenz1497]

It WAS too short! More, please!

[@vidholf]

Fantastic video. Thank you, Cuiv!

[@CuivTheLazyGeek]

Glad you enjoyed it!

[@barnaclewatcher4060]

Outstanding explanation made even better with the optics simulator. Thanks, great content.

[@CuivTheLazyGeek]

Thank you, happy you found it helpful!

[@captainfruitbatify]

@10:45 - took me years to figure this one out. I suspect it's the most common misconception of all.

[@CuivTheLazyGeek]

Exactly! I see this one everywhere!

[@revolting887]

excellent explanation Cuiv! 👏

[@CuivTheLazyGeek]

Glad this was useful! Thanks for your feedback and your support!!

[@mtct7878]

Thank you very very much for this video. More of this with pleasure.

[@CuivTheLazyGeek]

Thank you so much and thanks for your support!

[@blueocean9305]

Thanks!

[@CuivTheLazyGeek]

Thank you for your support!!

[@OVSoftLLC]

Another one great educational video. Thanks Cuiv for such useful videos.

[@tommyozzy317]

So what youre saying is i need to double my focal length and upgrade to a full frame? Ill inform the wife immediately lol. Seriously, great video. Wish you will do more common astro misconceptions. Higher gain equals more sensitive camera sensor, that sort of stuff. Many of our fellow astrophotographers, including myself, have much to learn.

[@CuivTheLazyGeek]

Hahaha exactly! Not you have arguments for Christmas spending haha! Good idea on the other misconceptions!

[@renewableteacher]

I had kind of thought as stars as being almost single 'rays' of light from a certain direction, but as you show, there is more of a 'wall' of parallel light rays that hits our lenses and then gets focused to a point. But then this is also kind of confusing, because if it s a wall of light, then why isn't light seen over the whole field of view?

[@CuivTheLazyGeek]

Because that light isn't being focused by a lens! You can think of all those photons being "wasted" unless they make it to a scope or eye lens ;)

[@renewableteacher]

@CuivTheLazyGeek Awesome when you think about it. We are all bathing in star light!

[@paulgatley]

Fantastic video from one of your askar V buyers

[@CuivTheLazyGeek]

Thank you!! How's your Askar V performing for you? :)

[@dineshnaik8494]

Excellent work and presentation.

[@CuivTheLazyGeek]

Thanks, glad you liked it!

[@sianikolaou5440]

Super informative!

[@BruceDumes]

Well done! The use of the modeling software is incredibly illuminating. I would assume that the lens has to do some magic to keep the stars around the edges from getting stretched out because of the angle of the light?

[@gsuhas1]

Great , very nice knowledge sharing

[@astrobondfr]

Crystal clear !!! :) Thank you Cuiv.

[@CuivTheLazyGeek]

Glad it was helpful! As clear as Takahashi lenses on a moonless night! ;)

[@the_astr0bits]

Thank you! This makes so much sense now! Love these deep dives and explanation videos, looking forward to the future topics!

[@TheNewForestObservatory]

Bravo Cuiv - Bravo!!!! I have awaited this one with great anticipation - and you did not disappoint. That was the most complete and detailed explanation I have ever seen - and the diagrams were incredibly useful. Thank you so much. It would be a crime if this video did not go viral - it is an extremely important and very clear explanation as to what's going on 😀 Is there something you could add? Yep - you could spell out there are not more photons entering the low f# scope compared to the high f# scope (even though that is clear from your diagrams).

[@CuivTheLazyGeek]

I really hope this video gets spread - it was a lot of work and a lot of fun!

[@TheNewForestObservatory]

@@CuivTheLazyGeek I have put it on X and KZbin to try and get it moving out there.

[@OldCurmudgeon3DP]

Excellent explanation. Thorough, detailed, "simplistically" presented. Great for the novice & a nice refresher for those of us that already knew most of the content.

[@CuivTheLazyGeek]

Glad this was helpful for both newbies and seasoned veterans!

[@andyrawlins]

Thats a really clear explanation and visualisation of something I sort of knew but didn't fully understand. Now I do :)

[@billblanshan3021]

Excellent video Cuiv!

[@CuivTheLazyGeek]

Thanks Bill! I'm really happy with this one :)

[@sylviedc889]

Many thanks for your educative video on playing with aperture and focal length. It would help if rays from different stars could be shown in different colors. You also could add examples of focused, defocused star images including abberations. By the way could you explain also the different types of abberations ? Anyway I love your educative videos.

[@CuivTheLazyGeek]

True, I thought of different colors (it's possible with this software) but I didn't like the appearance that took... I'll definitely do so next time. A video about star testing would be nice! Thanks for your continued feedback!

[@sylviedc889]

@@CuivTheLazyGeek Just by curiosity mabe you could explain why a Bahtinov mask is usefull and how the image pattern is generated. I don't know if your light rays simulation tool can generate this kind of tracking( I am sorry if you have already done it.)

[@nigelking1536]

Another superb video Cuiv. While I kind of knew this before, you have brought my fuzzy understanding into crystal clear focus!

[@CuivTheLazyGeek]

Glad to be of service!

[@Spaced_Out_Bill]

This is such a helpful video! Thank you so much for helping us understand such a complicated subject in an easy to follow format. Brilliant Cuiv!

[@CuivTheLazyGeek]

You're very welcome, and thank you for your support!

[@ralphguppy]

Excellente présentation!! Quand on comprends les concepts fondamentaux ça roule mieux 😉 Un gros merci!

[@CuivTheLazyGeek]

Merci beaucoup!! Et oui tout a fait d'accord!

[@alfredobeltran611]

Very good summary. Few people does this kind of analysis on social media. It’s more likely to be found in books. Thanks for sharing it.

[@CuivTheLazyGeek]

My pleasure! It was a lot of fun to make!

[@arijeetnath9236]

Great video. I would be really interested in understanding the optics of modern astrographs and how they correct for chromatic aberrations, field flattening, optics of ED glasses. I cannot find any video on KZbin that explains that. If you could make one for explaining how these different lenses are configured, that would be quite interesting. But this was a really informative video. Thank you!

[@declancarey4664]

Masterful explanation Cuiv, up there with your best videos. The wavefront concept was revelatory for me.

[@philipcoombs3544]

Thanks Cuiv! Great idea! Very clear description. Brilliant channel!

[@CuivTheLazyGeek]

Much appreciated!

[@velaknap]

Very good explanations, but could you do a follow-up discussing advantages and disadvantages of different types of telescope eg SC vs Newtonian vs refractor and what they are best suited for.

[@CuivTheLazyGeek]

I do already have some videos on the topic, but I can try a holistic one!

[@italoximenes8755]

Great explanations! It finally gave me a proper physical explanation to effects I had observed but not really fully understood. Thank you so much!

[@CuivTheLazyGeek]

Thanks so much! Glad you found it helpful!

[@yenotiza]

I salute you mr. Lazy Geek. Hands down, this is the best explanation I gave seen on the topic!

[@CuivTheLazyGeek]

Thank you!!

[@ARNFL13]

Great video as always Cuiv. Super helpful (and interesting) with information that isn't very easy to just "learn on your own"

[@CuivTheLazyGeek]

Thanks, I'm glad you found it useful!

[@MichaelLipton-yy1bo]

Wonderful explanations. It would have been nice to add explanation of eye pieces, and of image reversals. I'm looking forward to volume 2! Thanks.

[@canen2031]

Wow! Cuiv, you explained it in just great! Thx :)

[@CuivTheLazyGeek]

Glad it was helpful!

[@ErrorTH]

Great summary! Maybe it's good to mention that focusing primarily on faraway objects simplifies the things by comparing it to a conventional photography situation where light sources are on a significantly different distance from the lens contraty to basically focusing on infinity for astro. As for the good explanation to the whole f-number, focal length, sensor size and depth of field relation there was a nice video on Gerald Undone's channel.

[@CuivTheLazyGeek]

Thanks for the heads up, I'll check out that video! And I actually didn't really want to compare to conventional photography situation because whenever I've used that it tended to confuse people!

[@stefanbalzer611]

That's an excellent video, Cuiv! Many thanks for the great work and the very clear explanations with the simulation software. This illustrates the topic particularly well. I also found the tip about the dew cap interesting. Is there actually a maximum length for these? Is there any way to calculate this? Best regards Stefan from Germany

[@CuivTheLazyGeek]

There is indeed! I don't have the exact formula for it, but it depends on tan(FOV from corner to corner as an arcangle/2), if you search for it it should come up!

[@stefanbalzer611]

@ The length can be calculated: L = (D/2 - d/2) / (tan alpha/2) L = ideal length of the dew cap / lens hood D = diameter of the dew cap in mm d = diameter of the lens in mm alpha = actual field of view of the eyepiece

[@89abojan]

Great video!

[@tonisee2]

A very good video! I really liked those explanations of basic concepts of optics. 👍

[@CuivTheLazyGeek]

Glad you enjoyed it!

[@tonisee2]

@@CuivTheLazyGeek I will suggest your explanation to my students. 😀

[@siegfriednoet]

Very well explained Quiv, great video !

[@simonlaverick9920]

Cuiv, Simply facinating. I had it all wrong until you have explained it - thank you. Darlington UK

[@CuivTheLazyGeek]

I'm so glad this was helpful!

[@davidpearson5574]

Excellent presentation!!!! You passed on in 38 min, knowledge it took me to learn in years!

[@CuivTheLazyGeek]

Thanks for the feedback! Yesss surprisingly there wasn't a good source of definitive "Optics 101" for telescopes, so I just had to make one :)

[@billgolladay2973]

Wonderful content! I'd love to see something about different types of glass used in refractors. What are they? Why are some better/worse? More/less expensive? etc.

[@CuivTheLazyGeek]

Ah that's also an interesting one! But that gets really complex really quickly haha

[@richards3192]

Just to add another comment Cuiv.. Could you possibly do an in depth guide to Newtonian collimation? Including how to align the focus tube, center the secondary spider both axially and centered in the focuser, collimate secondary, allowing for offset if necessary, lasers, barlows etc? I think there's a bunch of people struggle with this. I taught myself from the CN posts but there is a lack of in depth guides on YT..

[@tostativerdk]

Such a useful video! The multiple parallel ray bunches always confused me. Thank you :)

[@CuivTheLazyGeek]

Glad this helped!

[@The_Vinceable]

Merci Cuiv! I think I understood it going in but this was enriching. Great work doing some myth busting here.

[@CuivTheLazyGeek]

Glad this was helpful!

[@galengloetzel1441]

Thank you very much for all interesting and informative videos on your channel, Cuiv!!! You would make a fantastic college professor!😊

[@CuivTheLazyGeek]

That's quite the compliment, haha! Thank you!

[@frankm81m82]

I noticed you didn’t really mention field how field flatteners work. great video!

[@CuivTheLazyGeek]

True, they're actually irrelevant with the ideal optics I pictured, and only come into play with non-ideal optics, far more complex to explain!

[@mighytsirus]

Very clear explanation! You could hold a professor chair on any university :).

[@CuivTheLazyGeek]

I'd say at most high school teacher haha

[@terrizittritsch745]

Nice job explaining things in a way that most can consume it.

[@CuivTheLazyGeek]

Thanks, I tried to make it clear and easy to understand!

[@markdeslauriers6549]

Man...I love your channel. So informative.

[@CuivTheLazyGeek]

Thanks so much :)

[@JimsShed]

Ooooh this was good. I have a 9.25 SCT with a broken corrector plate and have been experimenting with visual observation using a 3d printed spider. With the spider in place, I can collimate and see stars, Jupiter bands, etc, but it has low contrast which I take to be unfocused light. Your demonstration showed this to be a real thing!. Might experiment with a 3d printed aperture mask.

[@backyard-universe]

Hi Cuiv, nice video but I missed something which is very crucial for telescopes and other optical devices (maybe you mentioned it and I didn’t noticed it). The main problem in telescopes is not how to place mirrors and lenses the main challenge is to correct the optical aberrations which all of these optical components introduce to a ideal undisturbed wavefront. At the end of the day the quality of an optics like a telescope is measured by comparing the MTF (mean transfer function) of a wavefront of real optics and the undisturbed diffraction limited MTF. We use software like ZEMAX to optimize the optics especially the correctors in order to optimize the MTF and therefore the optical performance of an optics. Another very crucial point is, especially for a corrector design, to find a design which is as insensitive as possible for tilting or other inaccuracies that can lead to massive problems later in us. To summarize it….optic design is much more complex as you have shown 😅

[@CuivTheLazyGeek]

Oh absolutely! This is Optics 101 made to dispel the most common misconceptions! Without those misconceptions dispelled, it's useless to try and talk about MTF, sensitivity to manufacturing tolerances and inaccuracies (as you mention!). The optical engineer who helped also offered to provide me access to ZEMAX to do a follow up with more details in another video as needed! I made sure to mention that this was using ideal lenses and mirrors to show the overall principles! I need people to learn to walk before they can run!

[@colmbrazel]

Hiya great video thanks...I agree re need for deeper dive re diffraction limited optics, lens aberrations, seeing conditions etc. My collimation efforts are being whacked by unknowns my SCT 11 refuses to give up it's secrets no pins only tiny balls of boiling blobbiness...thanks again

[@jeffreyrice]

Really enjoyed the video. Nice way to start the day.

[@CuivTheLazyGeek]

Glad this was helpful!

[@AsKyOdA]

Thank you mr cuiv. Can you please explain why for DSO imaging with large sensors i need to have precise back focus on my SCT but when imaging planetary with a smaller sensor, back focus is not important and seem to get you same result no matter the length of your optical train is( within reasonable boundaries) - thanks !! 🙏🏼

[@CuivTheLazyGeek]

Back focus requirements come from the nature of the reducer and/or flattener - it has an ideal working distance (related to its own focal length) to provide a well corrected image across a wide field of view. But for a small target at the center of the optical axis (like a planet) you can be very far from the ideal back focus because the center of the FOV will basically always be fine as long as it's in focus!

[@AsKyOdA]

@ thank you 🍺

[@Naztronomy]

Awesome video! And that's a great simulator website. Playing around with it now.

[@CuivTheLazyGeek]

It's so much fun, right?! I couldn't believe there was a website like that available for free!

[@Naztronomy]

@@CuivTheLazyGeek Thanks again for the resource! I ended up using a bit of it in my last video to show difference in light collecting abilities between the S30 and S50. Such a cool tool!

[@jimofmarseille]

Love it ! thanks ! It would be great to have a full Newt callibration video, including positioning the secondary distance from the primary, center with the focuser with simple and cheap tools like a cheshire or calibration cap.

[@CuivTheLazyGeek]

Will look into that as well :)

[@jimofmarseille]

@@CuivTheLazyGeek Great !

[@jimofmarseille]

@@CuivTheLazyGeek And maybe tilt callibration ?

[@andrewleno591]

Best video ever! Fantastic job! Big respect.

[@CuivTheLazyGeek]

Wow, thanks!

[@yoyo.251]

This was a really nice video, I didn't know that using a lens hood can cause vignetting! From now on I will remove the lens hood for my wide angle milky way photography.

[@CuivTheLazyGeek]

Note that usually, lens hoods provided with a lens have the vignetting in mind, and are thus designed to avoid it!

[@ralfg9194]

This is an excellent video. The flaw of schoolbook approaches to geometrical optics is that they only show the image of a central object and are missing what happens with rays coming from decentral objects. This flaw have the most presentations of geometrical optics and with this restriction it is impossible to understand how optical elements work and why an extended object (that is seen under an arc range) is imaged on an area at focal length and not only a point. Often a tree or a human is shown with extent of the lense diameter what causes the misunderstanding that all rays emitted from the tree or the human are frontal rays entering the lense at 0 (or if you want 90) degrees what is utter nonsense. However, well done, excellent work!

[@KevinRudd-w8s]

That is true about many descriptions given in school text books. I think it is just a case of teaching kids to walk before they can run. My qualifications are in electrical and electronic engineering. Basic concepts were covered when I was at high school in the UK but not anywhere near the depth to which they were covered when I attended technical college. For one thing I don't think the teachers have the time to go into things, they have to follow the agreed curriculum, and the school books will obviously follow this as well. The good thing is these days, it is not difficult to access information. Back in the day it was a case of buying text books aimed at people studying for a higher qualification than you were or borrowing one from the library if you wanted to know more than what your grade was being taught. And we do have people like Cuiv who are happy to take the time and trouble to explain things to those of us that are interested.

[@betafoofoo270]

Perhaps because this level would be outwith the school curriculum; certainly covered in undergraduate physics courses though. I agree, excellent video, well done Cuiv.

[@ralfg9194]

@@KevinRudd-w8s My background is electrical engineering, too. My impression concerning geometrical optics is that the "flaws" I described as well apply to university textbooks. Take for exampel the chapter Geometrical Optics in the standard textbook by Eugene Hecht, there are the same sketches that mislead the understanding. However, everything is all right here! Kind regards from Germany!

[@CuivTheLazyGeek]

Thanks so much for this! And I love the little debate underneath about the teaching approaches :) I actually tend to agree with both sides, because I do remember being confused at first as well, and ONLY the full picture really clarified things... I think it's particularly true of students who like to ask questions and really ask WHY about everything!

[@Hilmi12]

You my friend can no longer claim to be lazy if you keep making videos like this. On the other hand I can be lazy because I don't need to explain this to my clients, I just show them your video

[@CuivTheLazyGeek]

Hahaha yeah, I guess that's true! But as you mention I increase overall laziness, so it's still a win! ;)

[@muayaddrdentist2313]

Thank you for that rich information with thearitical estimation I like test every telescope camera combination practically because of the optics design variesion, thank you very much for the preview 😊.

[@CuivTheLazyGeek]

Glad it's helpful!

[@guyjordan8201]

The raytrace diagrams will be a great help to very many people. Good choice of subject.

[@CuivTheLazyGeek]

Glad this was useful!

[@ridetheliger4176]

Awesome, Cuiv, thank you!

[@CuivTheLazyGeek]

Thank you! It was a lot of fun (and work lol) to make!

[@bobbryant4410]

Great video. What software were you using?

[@CuivTheLazyGeek]

Thank you! This is it: phydemo.app/ray-optics/simulator/

[@PeterWillmann-l2s]

Clearly explained. Thank you

[@CuivTheLazyGeek]

You're welcome! Glad it was helpful.

[@richards3192]

Great video Cuiv. Not prompted by Sky Story's ray tracing misunderstandings by any chance? 😂

[@CuivTheLazyGeek]

Shhhhh! Keep quiet! That was part of it, but another part were a lot of questions from my viewers! I do appreciate how Sky Story makes topics approachable and overall he is correct! But yes on some points he does fall for and teach misconceptions... I've studied optics during my master's degree so it's a bit of a painful point for me!

[@richards3192]

@@CuivTheLazyGeek Willdo! You are more polite than me :)

[@mehdiabed6942]

Hi Cuiv ! very nice video

[@CuivTheLazyGeek]

Thank you!

[@astrofromhome]

Thanks a million Cuiv for all the information! My head almost blew up. 😂

[@CuivTheLazyGeek]

Haha I hope you managed to keep your head intact!

[@nicolasmariotti]

Good video overall... but where is the link (and the credit!) to the web app simulation you used?

[@CuivTheLazyGeek]

Thanks! I thought I already had put it in the description, it's added now!

[@nicolasmariotti]

@@CuivTheLazyGeek Glad I could help ;)

[@russellblackadar425]

Great video on a great channel. I've tried explaining this stuff to beginners, with what degree of success I can't say -- but in future I'll just redirect them to this video. One minor quibble at a more advanced level is that, at least for me, your explanation seemed to encourage a common misconception about photons, namely that they fly through space like little bullets each corresponding to a light ray. True, when they hit the sensor they act just like a rain of particles -- no problem with any of that -- but their free motion through space is anything but -- rather, it's wavelike and, in a sense, each photon is spread out over the entire aperture when it enters the telescope. If it were not so, there'd be no Airy pattern, as incoherent photons interfere only with themselves, not other photons. Sorry, I don't have a good suggestion for how to fix that in the presentation -- maybe just a disclaimer that it's tricky to talk about photons, to get the wording right. I've probably gotten some things wrong myself, in this comment.

[@CuivTheLazyGeek]

Thank you! Yeah, on the photons, I know, I know, which is why I mentioned diffraction artifacts were ignored, but I think going further than that would be confusing - and unfortunately KZbin doesn't allow adding anything to a video after it's posted!

[@rossgould4168]

Thanks for your informative tutorial,with dew shields are you saying they need to be shorter or don’t have one at all? I have one on my Celestron edge 800( Astrozap) and is pretty long , thoughts please?

[@Minevi39]

Super vidéo, j’en aurais rêvé quand je débutais et ça reste très intéressant même maintenant ! J’aimerai beaucoup que tu fasses la même chose en montrant ce que font les oculaires la dedans (avec un œil derrière) ! Ça me semble bien plus compliqué à comprendre

[@CuivTheLazyGeek]

En fait c'est très simple! Ton oculaire a une longueur focale, par exemple le classique 26mm. Place le exactement 26mm à droite du point de focus de la lentille principale, et il prendra les light rays et le reparallelise !

[@bezain7663]

Waiting for the second video !!

[@CuivTheLazyGeek]

Errrrrrrr, I'll see what I can do haha!

[@RayosMcQueen]

Thanks for another great video.

[@CuivTheLazyGeek]

Glad this was helpful!

[@peterlaubscher3989]

Thank you - very helpful.

[@CuivTheLazyGeek]

Thanks for the feedback!

[@raphaelcoelho1557]

It looks like this video came from a comment I did about photons balance on a previous video. I don't remember which. Mostly of balance I've seen is based on single or homogeneous photon source. I commented that for real non homogeneous source or boundary conditions the diameter doesn't control the amount of light that the telescope is able to capture because when the number of sources or b.c. changes due to focal distance even if the diameter is the kept constant the amount of light will increase just because more sources emits photos to the lenses. I commented that although it's true we can't just use a wide field lenses and just crop. the problem is resolution and resolution (mathematical concept which stands for capability of representing gradients) will be reduced since the pixels will start to get light from different objects not separating them. That's exactly what shown at the video. Also, a small aperture but with focal ratio like f/1.4 lenses will capture huge amount of light coming from many sources but will direct them to few pixels. That's why a single 5s shot with a 14mm of orion saturates the pixels and clip it on m42 but much longer focal lenses will allow much longer exposures.

[@CuivTheLazyGeek]

I have to admit that wasn't really the source of that video, I'm sorry to say I don't recall that particular comment... But it was spurred by multiple comments on my videos, and by seeing misleading inaccuracies being taught in some other videos! Since I have studied optics as part of my master's degree, I thought this would be a good refresher!

[@ricklaird2218]

super helpful. thank you

[@CuivTheLazyGeek]

My pleasure!

[@RobertRidgley]

I think people may be confused by diagrams of images formed from an extended object that is not at infinity. Those diagrams show the image plane beyond the focal point/length of the lens. They might not understand that the focal plane for an object not at infinity, with non parallel light rays, extends further away from the lens than an object at infinity. Those who have ground, polished, and tested a telescope primary mirror understand the relationship between focal length and radius of curvature. Optics is not intuitively obvious.

[@CuivTheLazyGeek]

Yeah I agree - I intentionally made sure to "skip" those details by limiting myself to point light sources at infinity, and then adding an extended object between them to avoid confusion (while obfuscating some details, true...)!

[@EduardoMonteiro89]

Why do you sound like a pirate when you say "how"? Sounds like "harrr" 😂 Jokes aside, it was a great video! I have been an amateur astronomer for a little more than a year, and I'm really grateful for all the knowledge you guys share with us. It makes this hobby way, way easier. Thank you! 😊

[@larrydoversberger4819]

I think it might be helpful to explain what the image circle size really means. It seems, from your description, that it must just mean the area of the image at the focal point that is actually in focus enough to be useful. Is that correct?

[@CuivTheLazyGeek]

Ah the image circle... depends on the eye of the beholder to some extent. You need to set a threshold in terms of vignetting and in terms of field flatness. Different manufacturers have different criteria and thresholds... With my ideal lenses and no dew shield the image circle is massive (except for the SCT design!) so this representation isn't the best to explain the image circle!

[@larrydoversberger4819]

I guess what I'm trying to understand is, how does the image circle size affect the field of view. If the focal length, aperture and sensor size are the same, if I choose a telescope with a 55 mm image circle, vs. a 44 mm image circle, am I sacrificing some of the field of view since my sensor only covers a smaller proportion of the image circle or would both telescope/sensor combinations produce the same field of view (assuming there is no vignetting or image distortion)?

[@AstroJWA]

If you double the size of the lens, wouldn't you more than quadruple the number of photons?

[@CuivTheLazyGeek]

I said double the surface area of the lens, not double its diameter or radius :)

[@Laurent_BARTHELEMY]

Yannick, tu es un roi de la pedagogie 😊. Est-ce qu'elle cela a été un jour ton activité professionnelle ?

[@CuivTheLazyGeek]

Merci! Non je n'ai jamais ete prof ou equivalent, mais j'adore enseigner tout de meme :)

[@nolho]

Génial. Merci beaucoup 👍🏻

[@CuivTheLazyGeek]

Merci!

[@theHDRflightdeck]

Amazing!

[@CuivTheLazyGeek]

Thanks for the feedback!