I really like your approach when it comes to explaining field of view and image scale. Your use of mathematical formulas and performing calculations made these concepts so much easier to grasp even for us long time astrophotographers. Keep up the amazing work!
Thank you!!! I've only just recently started astrophotography as a hobby. Some of the things people say in forums about sensor pixel size seemed wrong to me. I just didn't know how to prove it without just doing AB comparisons of photos using different sensors on my own... and to be frank, it's going to take me a few years before I have both the skill and equipment to prove what I wanted to prove... but here you are casually explaining the math which confirms what I suspected! And not only that, because of your explanation now I understand WHY they say what they say about pixel size (and why what they say has some merit, even if it's not quite true)! I can't tell you how excited I am to have seen this.
Fantastic basic knowledge video, this helped me out a lot! I would love to see a video where you do some planning for shoots and explain your choice of gear options for optimum results, to fully grasp these concepts.
Hi Lusa (is spelling ok?), thanks for the helpful video! Much appreciate the time and work to produce it. You gave me lots to think about. Beautiful Cygnus wall photo! I like your processing on it. Subscribed today. CS!
You have the best and most concise explanations of the theories are facts one needs to know in order to make all these decisions. I don’t think anybody else explains it like this probably cause they don’t think people are gonna look at math anyway I loved it. keep doing great work
great explanation. Therefore as an astrophotographer, it is good to have lots of varying FL scopes and different cameras with varying sensor sizes. love the 185mm APO in the background.
I have another related question for you. I've been trying to use the information in this video to figure out what the maximum field of view of the telescope might be. In other words, what is the maximum sensor size that can be productively used? It would seem to be a function of the focal length and the diameter of the aperture, similar to the pair of triangles you showed for the FoV of the sensor/telescope pair. As I try to work it out, though, it appears you only get full light at the center of the field and as you move off center you get gradually less light until your view is pointing in the direction of the edge of the aperture. (Is this the origin of vignetting?) It seems that somewhere in here is a way to calculate absolute maximum FoV, and how to calculate maximum useful FoV. Any thoughts on this you can add to help me out here?
This is not so simple as a single formula because you don’t just have to consider the illuminated circle but also the fully corrected field of view. You may have a large circle but if the stars look horrible it’s not very useful. Both of these will depend on the corrector/flattener etc used in addition to the focal ratio. Your best bet is to check for the “fully illuminated circle” and “corrected circle” on the manufacturers website and that would be your sensor diagonal. Also take the corrected circle with a grain of salt as they tend to be a little optimistic 😊
Yet another question for you. Do you have similar calculations for eyepieces? For example, consider the Tele Vue 31mm Nagler with an 82° apparent field of view and an f/10 Celestron C11 with a focal length of 2800mm (and a diameter of 280mm). The magnification would be 2800 / 31 = 90x. Is there an easy way to use that to compute what my actual field of view would be?
BTW, I've seen the formula that divides the apparent field of view of the eyepiece by the magnification, which seems intuitive, but it can't be quite right. If the magnification is less than 1, this formula could result in impossible fields of view.
If you want to get a close estimate on magnification, you can calculate your FOV in degrees with your scope/camera and then calculate what eyepiece with your scope gives the closest angular FOV, then use that for the magnification. For example, my 8" RC and Uranus-C camera has a 0.39° x 0.22° FOV, and my 10mm Plossl gives me a 0.32° FOV with the same scope, and that would be about 160x magnification.
Having thought about it this is not really a feasible solution as depending on the build of the eyepiece the FOV is different even with the same magnification. Think “low cost” regular eyepieces vs fancy ultra wide angle ones!
@@the_space_koala That's why I used "my Plossl" as an example. My 10mm Celestron Luminos would not work for the reasons you stated, but my Celestron 10mm Plossl does.
OK, a question here. It seems the one detail you didn't go into is the brightness per pixel, but that's probably covered in another video. I'm not sure how to approach this, but I have heard that for bright, planetary objects you want small pixels, but for deep space objects (DSOs) you want large pixels. The reasoning is that larger pixels work as larger buckets to capture the fainter light, while brighter objects can get by adequately with smaller buckets. But if two sensors have the same area, the sensor with the larger pixels will have lower resolution, yes? This also touches on image noise, that I don't fully understand but which appears to be different for CCD and CMOS cameras. So it seems we need a video like your "Are Fast Telescopes Really Better?" presentation, but this time for cameras. Do you already have one of those? Is that something you might want to do? Thanks!
Everything you wrote is correct. There is two videos in the pipeline that are related to these topics (one on SNR and one on drizzling). In the “fast telescopes” video I suggested 2x2 drizzling to use the same sensor and get higher resolution but you would get exactly the same result if the pixels were 1/4 the size (1/2 the size on each side)
That was a really interesting explanation. I've just studied a uni module in astronomy (it was really hard...) and your explanations were brilliant, thanks. I've subscribed, best wishes.
Excellent presentation of astro optical basics... And, there's nothing wrong with your video editing. I have to ask: What's your day job? You're really good at this!
Excellent content! I am sure you and others are aware of this and it's off topic but it's also important to keep in mind how important SNR is in astrophotography, even if your aperture is large enough and you have a long focal length (= slower f number) with small pixels and great atmosphere but not so dark skies, yes the resolution will be great but the SNR will be much worse than if you have a fast telescope with big pixels under extremely dark skies, that type of high SNR images can be so stunning that as long as the resolution is OK one may almost loose interest in the quest for more resolution. Despite the old CCD cameras being outperformed on paper by the new Sony cmos sensors the large 9um pixels pulled in a LOT of signal, one of the reasons these cameras still produce great images.
@@Jcorban08on a cmos binning and resampling results in the same image - there’s no true binning like on a CCD therefore I prefer to do it in post because then I still have the choice to do it or not 😊
@@the_space_koala choosing to 2x2 bin in post gives you more options :) Is it fair to say that it results in 2x improvement in SNR? Are not the 8300 mono chips still available? Perhaps that will be covered more in the future SNR video. Thanks!
@@the_space_koala oh I just thought of an interesting comparison review: 2x2 binning on CCD camera vs 2x2 binning post with cmos camera. If I only had a CCD to lend you 😂
I have to admit, your focused and clear explanations in your videos far exceed some of the more mainstream channels that I follow. I enjoyed the video on the colour representation of images. My gf thinks I just watch your videos because you’re smoking hot though 😆
@@the_space_koala Well, I can assure you that for a layman such as my self and I’m sure many others, these are not such simple concepts. You definitely have a way of making the concepts much easier to grasp! Thanks once again, I hope your channel eventually reaches the masses in the hobby!
You say there's no straightforward answer when someone asks about the magnification factor in astro-imaging. I'd go even further and say the question doesn't even make sense. Magnification compared to what? At least with visual observation, it's clear what we're talking about: your eye sees an object 100x bigger through the telescope, so it's a 100x magnification, _compared to what you'd see with the naked eye._ But in astrophotography (as in any form of photography) there is no baseline, so nothing to compare against.
I fully agree. I just said "it's not the right question to ask" but I could've easily just said flat out that it doesn't make sense because you're right!! Thank you
I think your neglect of seeing except for the throw away comment and focus on dawes limit is misleading. Aperture ha much less to do with resolution than seeing in normal circumstances. There are many good reasons to like larger aperture but dawes limit mostly comes up in Lucky imaging. Large aperture can have worse resolution than small apertures in bad seeing conditions.
Keep in mind we were looking at tiny apertures here. Even the “large” one in the example was only 150mm. Besides the resolution is still not going to be better with the small aperture, you can just maximize it while on the larger scope you can’t. The seeing is what it is regardless of the instrument used. I see a forever growing trend of throwing microscopic pixels on small apochromats (ehm Vespera Pro and other smart scopes) and convincing people this is all they need. I do see the importance you’re pointing out through and I’m planning a whole separate video more focused on resolution taking into account more factors.
Constructive criticism to help make your videos even better: There seems to be numerous distracting edits when the image on the screen jumps. Try to eliminate the need for these edits.
@@the_space_koala oohh sugar!!?? I'm so sorry, I thought he/she was being mean to you about the animation!!?? I'm so sorry! I'll remove the comment immediately!!🤦♂
![Lp. Сердце Вселенной #60 РОЖДЕНИЕ ЛОЛОЛОШКИ [Финал] • Майнкрафт](http://i.ytimg.com/vi/YoR0pAV9FVQ/mqdefault.jpg)
Thanks for being clear and concise. It's very refreshing.
thank you for saying that, I'm glad!
Great presentation and very clearly articulated.
8:27 subtlety throwing shade ... nice
thank you for saying that!
I really like your approach when it comes to explaining field of view and image scale. Your use of mathematical formulas and performing calculations made these concepts so much easier to grasp even for us long time astrophotographers. Keep up the amazing work!
@@5729ariel thank you so much! I’m glad you appreciate it
very clearly explained with great examples regarding the calculation!
thanks I'm glad you found it easy to follow!
Much-needed content. Thanks on behalf of the astrophotography community for creating it. It turned out to be very informative! 😊
Thanks so much for saying that!
Once again you have made simple a topic that others make unnecessarily complicated. Thank you!
Thanks for saying that I’m happy you think so
Thank you!!! I've only just recently started astrophotography as a hobby. Some of the things people say in forums about sensor pixel size seemed wrong to me. I just didn't know how to prove it without just doing AB comparisons of photos using different sensors on my own... and to be frank, it's going to take me a few years before I have both the skill and equipment to prove what I wanted to prove... but here you are casually explaining the math which confirms what I suspected! And not only that, because of your explanation now I understand WHY they say what they say about pixel size (and why what they say has some merit, even if it's not quite true)! I can't tell you how excited I am to have seen this.
I’m so glad you appreciate it, these concepts are not easy to explain
Fantastic basic knowledge video, this helped me out a lot!
I would love to see a video where you do some planning for shoots and explain your choice of gear options for optimum results, to fully grasp these concepts.
That’s a great idea! Thanks
Excellent video!‼👍👍👍
thanks, glad you liked it!
Hi Lusa (is spelling ok?), thanks for the helpful video! Much appreciate the time and work to produce it. You gave me lots to think about.
Beautiful Cygnus wall photo! I like your processing on it. Subscribed today. CS!
Thank you so much! It’s spelled Luca ☺️ glad you find it useful
very clear explanation. thankyou !
You have the best and most concise explanations of the theories are facts one needs to know in order to make all these decisions. I don’t think anybody else explains it like this probably cause they don’t think people are gonna look at math anyway I loved it. keep doing great work
thank you! In fact I am even doubting most people look at the math but I am so happy some people do!
great explanation. Therefore as an astrophotographer, it is good to have lots of varying FL scopes and different cameras with varying sensor sizes. love the 185mm APO in the background.
I fully agree! I think the largest scope + largest sensor you can use for a given FOV is the best choice :)
thank you for shanring ! very good video about telescopes
Thanks for being here!
I’m a visual hobbyist. Your video provided TMI which I began to appreciate the further you went.
thank you! TMI is my middle name
Well, that was a thorough and detailed video! Sub earned.
thank you for being here!
Really good explanation for a question I get a lot from friends and family. Ace video once again! Thanks!
Thank you I’m so glad it’s useful
I have another related question for you. I've been trying to use the information in this video to figure out what the maximum field of view of the telescope might be. In other words, what is the maximum sensor size that can be productively used? It would seem to be a function of the focal length and the diameter of the aperture, similar to the pair of triangles you showed for the FoV of the sensor/telescope pair. As I try to work it out, though, it appears you only get full light at the center of the field and as you move off center you get gradually less light until your view is pointing in the direction of the edge of the aperture. (Is this the origin of vignetting?) It seems that somewhere in here is a way to calculate absolute maximum FoV, and how to calculate maximum useful FoV. Any thoughts on this you can add to help me out here?
This is not so simple as a single formula because you don’t just have to consider the illuminated circle but also the fully corrected field of view. You may have a large circle but if the stars look horrible it’s not very useful. Both of these will depend on the corrector/flattener etc used in addition to the focal ratio. Your best bet is to check for the “fully illuminated circle” and “corrected circle” on the manufacturers website and that would be your sensor diagonal. Also take the corrected circle with a grain of salt as they tend to be a little optimistic 😊
Yet another question for you. Do you have similar calculations for eyepieces? For example, consider the Tele Vue 31mm Nagler with an 82° apparent field of view and an f/10 Celestron C11 with a focal length of 2800mm (and a diameter of 280mm). The magnification would be 2800 / 31 = 90x. Is there an easy way to use that to compute what my actual field of view would be?
BTW, I've seen the formula that divides the apparent field of view of the eyepiece by the magnification, which seems intuitive, but it can't be quite right. If the magnification is less than 1, this formula could result in impossible fields of view.
Excellent explanations. 🔭👀
thank you Thomas! glad you find it good
Very helpful, thank you!
If you want to get a close estimate on magnification, you can calculate your FOV in degrees with your scope/camera and then calculate what eyepiece with your scope gives the closest angular FOV, then use that for the magnification. For example, my 8" RC and Uranus-C camera has a 0.39° x 0.22° FOV, and my 10mm Plossl gives me a 0.32° FOV with the same scope, and that would be about 160x magnification.
That’s a good idea!
Having thought about it this is not really a feasible solution as depending on the build of the eyepiece the FOV is different even with the same magnification. Think “low cost” regular eyepieces vs fancy ultra wide angle ones!
@@the_space_koala That's why I used "my Plossl" as an example. My 10mm Celestron Luminos would not work for the reasons you stated, but my Celestron 10mm Plossl does.
It is simply wrong.
OK, a question here. It seems the one detail you didn't go into is the brightness per pixel, but that's probably covered in another video. I'm not sure how to approach this, but I have heard that for bright, planetary objects you want small pixels, but for deep space objects (DSOs) you want large pixels. The reasoning is that larger pixels work as larger buckets to capture the fainter light, while brighter objects can get by adequately with smaller buckets. But if two sensors have the same area, the sensor with the larger pixels will have lower resolution, yes? This also touches on image noise, that I don't fully understand but which appears to be different for CCD and CMOS cameras. So it seems we need a video like your "Are Fast Telescopes Really Better?" presentation, but this time for cameras. Do you already have one of those? Is that something you might want to do? Thanks!
Everything you wrote is correct. There is two videos in the pipeline that are related to these topics (one on SNR and one on drizzling). In the “fast telescopes” video I suggested 2x2 drizzling to use the same sensor and get higher resolution but you would get exactly the same result if the pixels were 1/4 the size (1/2 the size on each side)
Very good explanation, I always get asked this and all I can say is lots when using an eyepiece but when using a camera it's like a camera lens
Everyone using phone cameras that say 1x, 2x etc definitely doesn’t help!
@@the_space_koala Exactly!
That was a really interesting explanation. I've just studied a uni module in astronomy (it was really hard...) and your explanations were brilliant, thanks. I've subscribed, best wishes.
Thanks for being here! I wish I’d had the opportunity to study astronomy!
Excellent presentation of astro optical basics... And, there's nothing wrong with your video editing.
I have to ask: What's your day job? You're really good at this!
thank you for that! I work in IT :)
Excellent content! I am sure you and others are aware of this and it's off topic but it's also important to keep in mind how important SNR is in astrophotography, even if your aperture is large enough and you have a long focal length (= slower f number) with small pixels and great atmosphere but not so dark skies, yes the resolution will be great but the SNR will be much worse than if you have a fast telescope with big pixels under extremely dark skies, that type of high SNR images can be so stunning that as long as the resolution is OK one may almost loose interest in the quest for more resolution.
Despite the old CCD cameras being outperformed on paper by the new Sony cmos sensors the large 9um pixels pulled in a LOT of signal, one of the reasons these cameras still produce great images.
I plan on making a video on SNR! I usually end up resampling my large CMOS but I truly wish I had a CCD I could actually bin!!
@@the_space_koala could 2x2 binning with your cmos camera be a good option?
@@Jcorban08on a cmos binning and resampling results in the same image - there’s no true binning like on a CCD therefore I prefer to do it in post because then I still have the choice to do it or not 😊
@@the_space_koala choosing to 2x2 bin in post gives you more options :) Is it fair to say that it results in 2x improvement in SNR? Are not the 8300 mono chips still available? Perhaps that will be covered more in the future SNR video. Thanks!
@@the_space_koala oh I just thought of an interesting comparison review: 2x2 binning on CCD camera vs 2x2 binning post with cmos camera. If I only had a CCD to lend you 😂
Great video. Subbed...👍
thanks for being here Allan!
I have to admit, your focused and clear explanations in your videos far exceed some of the more mainstream channels that I follow. I enjoyed the video on the colour representation of images. My gf thinks I just watch your videos because you’re smoking hot though 😆
I'm glad you find the videos helpful! There is not enough in-depth content on these basic concepts out there
@@the_space_koala Well, I can assure you that for a layman such as my self and I’m sure many others, these are not such simple concepts. You definitely have a way of making the concepts much easier to grasp! Thanks once again, I hope your channel eventually reaches the masses in the hobby!
You say there's no straightforward answer when someone asks about the magnification factor in astro-imaging. I'd go even further and say the question doesn't even make sense. Magnification compared to what? At least with visual observation, it's clear what we're talking about: your eye sees an object 100x bigger through the telescope, so it's a 100x magnification, _compared to what you'd see with the naked eye._ But in astrophotography (as in any form of photography) there is no baseline, so nothing to compare against.
I fully agree. I just said "it's not the right question to ask" but I could've easily just said flat out that it doesn't make sense because you're right!! Thank you
@@the_space_koala No, thank you. The more people we get out there explaining and demystifying astronomy, the better for the hobby.
I think your neglect of seeing except for the throw away comment and focus on dawes limit is misleading. Aperture ha much less to do with resolution than seeing in normal circumstances. There are many good reasons to like larger aperture but dawes limit mostly comes up in Lucky imaging. Large aperture can have worse resolution than small apertures in bad seeing conditions.
Keep in mind we were looking at tiny apertures here. Even the “large” one in the example was only 150mm. Besides the resolution is still not going to be better with the small aperture, you can just maximize it while on the larger scope you can’t. The seeing is what it is regardless of the instrument used. I see a forever growing trend of throwing microscopic pixels on small apochromats (ehm Vespera Pro and other smart scopes) and convincing people this is all they need. I do see the importance you’re pointing out through and I’m planning a whole separate video more focused on resolution taking into account more factors.
I love my galaxy blaster 60 500x !
Constructive criticism to help make your videos even better: There seems to be numerous distracting edits when the image on the screen jumps. Try to eliminate the need for these edits.
Thank you, you’re right! I cut out every “umm” and pause but I should practice speaking better 😁
I don’t mind the cuts at all. I appreciate you cutting out um’s though.😅
Loved the eyepiece in the garbage animation.
Pahahaha
@@wesleydonnelly2141I thought he meant the one with the literal garbage at 0:54 😁
@@the_space_koala oohh sugar!!?? I'm so sorry, I thought he/she was being mean to you about the animation!!?? I'm so sorry! I'll remove the comment immediately!!🤦♂
@@wesleydonnelly2141 haha no worries
@@the_space_koala Thank You!🙏👍x