How much of a difference does a Newt Resolution advantage make!? Let's Find Out!

next to me here is the Redcat 51 it is a small scope it is light it is easy to use it is the perfect beginner telescope for astrophotographers and it has been wildly popular the current version this is the original version but now it's the Redcat 3 it comes with all sorts of En enhancements like in particular an internal focuser and it costs around $900 so it's definitely not cheap but still because of its ease of use it is is the weapon of choice for many beginners and even the weapon of choice for advanced astrograph when they're going uh to do some remote Imaging I mean some Imaging in remote Dark Places or when their larger telescopes are giving them issues and frustrating them and they need a a reprieve they need something to relax with and then they will turn to those small telescopes I am no exception but what about its larger cousin the Newtonian telescope so this is actually a small Newtonian teles scope uh it has an aperture of 150 mm compared to the aperture of 50 mm from our small refractor and it costs roughly the same price around $950 with its included coma corrector and those small newtonians can cost even less the one that I have in the background there uh as part of this dual telescope was I think $450 when I bought it although I did have to do a lot of upgrades to it and I have documented my journey if you're interested so newtonians have the potential of being cheaper than small refractors but how much better are they and so for today we are going to make those telescopes fight against one another to see like okay they're roughly the same price and to be clear I'm only going to be comparing this one out of my uh dual scope Franken scope here so only one of those telescopes will be pitted against the uh Red Cat here so the red cat 51 with its 50 mm or 51 mm aperture and 250 mm focal length for a focal ratio of f 4.9 against this small neonian with its aperture of 150 M millim its focal length of uh 580 millim for a focal ratio of f3.8 oh and by the way I'm qu the lazy geek welcome back to the channel and if you're new and if you like this kind of video you can like the video also subscribe it really helps the channel out so on the face of it the Newtonian has the Advantage it has more aperture it has a faster focal ratio which is linked to more aperture and it achieves that by having more focal length meaning that it can zoom into objects more but how much of an advantage is it so what I decided to do is to point both of the telescopes on the same night at the same time on a small Target that has a lot of detail so we could compare the resolution of both of them and uh I chose the target of M51 the whirpool Galaxy it's also very interesting because just as I Was preparing this video by taking the data I saw that lcao so Luke from the lucao channel released a video where he compared his very large SCT to his very large refractor and so Luke already did the same exercise for big telescopes I'm doing the same exercise for small telescopes now I want to compare mostly the resolution of those uh telescopes obviously in terms of SNR uh again this one will have the big advantage and I want to have like somewhat comparable field of views before I crop into the M51 Galaxy and so I chose to use the ASI uh what is it 585 MC Pro sensor here that has a tiny sensor with relatively small pixels of 2.9 micrometers I really like the sensor because it allows you to kind of dig into the details while sacrificing a little bit of per pixel signal to noise ratio and for this one I chose the SI 2600 MC dual which is an apsc size sensor with larger 3.76 micrometer size pixels as I recall but with those set setups we actually achieve roughly the same field of view except that uh this red cat in theory has 2.39 arccs resolution per pixel and this one here has 1.39 I think arccs or 34 arccs per pixel so there is a difference between the two of one arcc per pixel how bad could that be we're about to find out so what I did is I set up those telescopes to image on M51 on the same night it was one of the very rare clear nights that I had uh in recent me memory it's been horrible weather here in Tokyo and we are now entering the rainy season so yeah not great but in the end I let them SP basically spend the whole night on the same Target and at the end of it I noticed that the red cat had captured 20 minutes more data than the Newtonian and this is likely due to the synchronized dithering that the Newtonian had to do with its uh brother uh from the Dual scope setup but that's something else which means that I got I believe only because there was a lot of clouds and stuff only around 165 minutes of Imaging with this one and around uh 185 minutes of Imaging time with that one so they're very close I also made sure that uh we I guided both via an Offa guider so I have a small Offa guiding camera here and the of course the ZW ASI 2600 MC dual has a a guiding chip an Offa off AIS guid uh chip integrated so that we had the best possible guiding The Guiding figures during the night were roughly 0.45 to 0.5 arcc RMS uh for the uh refractor although it got significantly worse in the morning when clouds really started to roll in and M51 was much much closer to the Horizon as expected and similarly here I got roughly 0.7 arccs uh guiding throughout the night except that it became uh significantly worse again in the early morning but I kept the frames we're going to compare the two both of course are taken with a simple luminance filter so that is as much as an Apples to Apples comparison that we are making but to figure out the rest of it we need to get inside and look at the results because I have already taken the exposures stacked them drizzled them I'll get to that that in a moment and we are ready to compare them so follow me inside for that oh before you do so again make sure to subscribe to the channel if you're new and which case welcome to the channel like the video that simple click makes the a whole amount of difference so thank you so much for doing that and also leave a comment down below to tell me like how much of a difference do you expect between the two do you expect a small difference are a very large difference and the uh amount of difference whether it's towards the very small side or the very large side might surprise you so be ready for that oh and while you're at it if you want to support the channel more directly and you're planning on buying anything from like aena Astro or High Point scientific or first light optic or even anything absolutely anything from Amazon if you do so after clicking the links that I have down in the description it helps me out at no cost to you and of course I have all of the links to the equipment used for this comparison down in the video description and finally if you want to even support me more directly you can join the channel as a paid patreon member it makes a huge amount of difference and same thing you can join the channel as a member of the channel that's the join button next to the Subscribe button and my patreon supporters and YouTube members you make the channel possible you know it I say it every time and I cannot thank you enough and we are inside and we're ready to look at the results so obviously I'm looking at the Stacked images and both have been drizzled because I dithered every 5 minutes and all of my exposures were 60 seconds long and therefore I was able to drizzle for doubling the resolution well to some extent uh of the image while stacking in pix in sight and we'll be able to see the results now I also noticed something while I was stacking I noticed that there were uh star trails in the center of my frame so where M51 is located for my Newtonian telescope whereas in one of the corners the stars were perfect sharp and I assume it's because my Newtonian uh the cation was bad and I had spent so much time the day before aligning my Franken scope so I assume while I was doing that the cation went bad and I didn't fix it so the Newtonian here is at a disadvantage and yet we all know like from experience that uh the Newtonian should perform better than the refractor the question is only by how much because you know 150 m m aperture versus 51 mm aperture like duh what are you even doing this test for it's to see the difference and what this simple one Arc uh per pixel difference makes and just to give you a quick overview of how it would look like this is on M51 we have in yellow the Newtonian field of view with the apsc size sensor and in red we have the refractor field of view with a much smaller sensor with smaller pixels of the 585 so all of this makes sense very similar field of views uh what is going to be different of course is the resolution we have 1.34 arccs per pixel for the Newtonian which is what I have now with a do limit basically the maximum Optical resolution of the telescope of a lower 0.77 Arc seconds uh so it is indeed like our resolution is within the do limit as it is higher than the do Do's limit so that makes sense now let's look at the same uh result with the uh Redcat 51 here we can see that our resolution is 2.39 arccs per pixel so like this one arcc difference and the doll's limit is still 2.27 arccs uh for the Optics just a smaller aperture means that the maximum resolution that you can grasp that you can reach for is limited uh more than with a much larger aperture like the Newtonian still our resolution is above the Dos limits so we shouldn't be hitting that and if anything is going to be our an issue is the seeing but at those scales the seeing shouldn't be that much of a of a problem either plus the drizzling kind of helps with this kind of stuff so let's look without further Ado into pix Insight here is the result can you guess which one is the refractor which one is the Newtonian uh and yeah it's kind of very obvious at least to me uh Just for information those images they're the final Stacks with a dynamic crop to Center on the Galaxy we've removed the background with grabert and done a spectr photometric color calibration to have decent colors and then a screen transfer function to just be able to see what's in there that's it we didn't do anything more and what can we see knowing that the Newtonian was somewhat poorly culated and the refractor had 20 minutes more exposure time throughout the night uh yeah the refractor on the left the Newtonian on the right it's not even a comparison right it's even looking from afar the Newtonian has noticeably more details I mean duh it makes sense right but still I did not expect the difference to be that large come on look at those two images completely completely different and uh we can zoom in but before I zoom in I'm also going to zoom out the whole size uh there's like this weird mle uh pattern for the uh Red Cat and I don't think this has to do with the signal to noise ratio although the red cat has a lower signal to noise ratio due to its much lower focal ratio so that's something to keep in mind but also the sensor uh when I used it at too high a gain uh during that night so that's due to the sensor but still uh there there is noticeable especially if we look like in the in the tail here as well as in the the tail of the Galaxy uh there there is a noticeable signal to noise ratio difference between the two the Newtonian has an advantage and and when I zoom in the Newtonian has an advantage in the resolution as well because this is with the Galaxy zoomed in and I mean I don't even have to comment right it's night and day between the two and this is far far more than I expected in terms of the difference expected the difference obviously but the the the question was how much and the answer is apparently a lot and I'm really surprised actually by this result it's very very interesting now of course we need to check with blur exterminator to see if we can try and enhance those results here see how much is going to be enhanced per image and what the end results are so let's do it and now I've applied blur exterminator only on the refractor image on the left this is the uh before and this is the after obviously a huge difference but even then the refractor can't really hold a candle to the Newtonian there are some uh streaks here like that link features together like there's this weird little square here where we can see it's something very separate on the Newtonian the Newtonian very simply was able to resolve things much more than the refractor and yeah it's something to think about when you're buying your telescope refractors they're very convenient but yeah they do have their limitations and reflectors like this Newtonian here they require colation a victim of poor cation here and it requires some knowledge and sa Warfare and cleaning the mirrors that kind of stuff more work but then for the same price definitely the results at least on small targets show a big difference let's try to apply blur exterminator to the Newtonian image on the right as well and here we go this is the result and we have the uh before and after and again like the there's a lot of detail that is are available within M51 despite M51 not being the best Target for a small Newtonian let alone a small refractor and the Newtonian again comes out on top like very handily and this is just with uh less than three hours of data from Tokyo which overall I think it's pretty impressive so what are your thoughts on this like obviously we expected a difference and I'm surprised that the difference is so large are you surprised as well let us know down in the comments and I'd also like you to leave a like on the video subscribe to the channel in which case welcome and of course you can like subscribe the video Etc but that's basically it for today so uh thank you so much for watching don't forget whenever you can to look up at the stars and I'll see you next time

Channel: Cuiv, The Lazy Geek

Views: 19,286

Keywords: astrophotography, redcat, redcat 51, best telescope for beginner, best astrophotography telescope, CarbonStar 150, Best refractor, Best Newtonian, refractor vs newtonian, astrobackyard, nebula photos

Id: _7BIqiYRRbs

Length: 15min 12sec (912 seconds)

Published: Tue Jun 11 2024