Bogdan a suggestion for a future video, if you think it’s interesting: the effective aperture and light gathering capacity of reflector telescope. On the internet forums it’s a highly debated topic but almost no youtuber talks about it. A lot of people do not know that the effective aperture of a reflector is lower than the theoretical one and also that the light gathering capacity of a reflector is lower than in theory because of the central obstruction and low light reflectivity of usually just 88-92% of the mirrors.
Effective aperture is not effected by central obstruction as far as resolution is concerned. Contrast is reduced somewhat as diffraction enters the equation, but the arc second resolution is not reduced by the obstruction. Modern coatings such as UHTC and xlt bring the transmission close to if not equal to refractors. The thicker glass and multiple elements of refractors also reduces light transmission , and the coatings help reduce reflective light loss, but there has never been a free lunch . Refractors offer increased contrast and tighter star images, which makes them appear to perform as well as a slightly larger reflector, but they don't have the same actual resolving power as larger aperture reflectors. Certain targets do look better in refractors, that is true.
Great video! I bought a C5 last year but then got the sv503 102ED after watching your review. I very much agree that the C5’s main drawcard against a quality 4” refractor is portability. My ES twilight mount is perfect for the C5 but showing its limits with the sv503. Another difference is that my sv503 suffers from diffraction spikes whereas the C5 provides pinpoint stars.
Good looking scope. I have a Celestron 6" SCT and a Hyperstar 6 v4. My optical tube is orange and my metal dew shield is black. Really like that black color. Wish mine was black.
I have been using the C5 for astrophotography for a few years. I use it with the ZWO AsiAir, along with a custom made adaptor for the EAF. Both the cameras I use with it (ASI294MC/MM) work great. I use it with the Celestron .63 reducer. I used a william optics cat guide scope mounting for the guide scope. Only thing I have noticed is once in a while it does have some star anomalies on really bright stars that are near the edge of the field of view. But otherwise perfect light weight scope for a quick portable and set up imaging session.
I'm not sure a C5 is a good investment anymore, given that 4" ED Refractors are now approximately the same price, and the C5's performance is equivalent to a 3.75" ED Refractor. The C5 can't compete on Field of View. SCT's win when their price and tube length is less than a comparable refractor, but that begins at the C6-8" range these days.
The closest thing I'd see being around the same aperture / focal length / focal ratio once a 0.63 reducer for the C5 and a flattener for the refractor would be the Askar 103 APO with the 1.0 field flattener. As an all-rounder I'd prefer the Askar, but it would cost around 70% more than the C5 while being significantly larger. I'd definitely consider the C5 just for an entry into being able to shoot more galaxies than the 180 / 270 / 360mm refractor focal lengths I'm currently working with.
@@ishanr8697 - Technically, but it's not a good solution for imaging both in terms of speed and image quality. If I put a 2x barlow in my 360mm refractor, it would image at 720mm, but the focal ratio would be changed from 5.9 to 11.8, which means that to gather the same amount of light, I'd need to shoot four times the exposures (and F5.9 is already not particularly fast).
Bogdan maybe begginers will find intresting a video with your list of favourite astronomical targets in your newtonian and 4inch refractor combo, maybe also eyepiece focal lenghts you use for them
Yes I felt like the same. A c5 is probably not the best investment compared to a 4 inch ed refractor. However considering the cost it's getting interesting. A c5 is usually sitting at around $550, whereas a C6 is 600, which is a much better bargain. I'm not sure why the pricing is like this
I wonder if the C5, perhaps even the non-Edge C8, are not what they once were, when US made under Johnson at Celestron-Pacific in the 1970s? Celestron used to market large apertures to professionals, before branching into the amateur market. However, in the early 1970s, every C5 and C8 manual stated proudly that each Celestron telescope was set-up at their factory to deliver diffraction limited performance, the secondary aspherised,, and the system bought to an optical null. Regardless, the C5 remains attractive as one of the most easily portable scopes.
There is definitely more unit to unit variance in the Chinese versions but the newer coatings can make them brighter than older ones, other than the final years of USA production that had starbright xlt. But even the USA models made for a brief time after the halleys comet craze that had demand so high that both meade and celestron wore out their tooling, put some sub par optics on the market, so it is a good idea to try before you buy a late 80s meade or celeston, c5, c8 and 8" meades being the most popular were where most of the issues show up.
I think size and weight, the C6 is a better investment because down the road if you want more AP use you can get a hyperstar for 300mm @ f2. The C5 is a neat scope but you can get a used C6 for 300-400USD, really can almost get a used C8 but if you want portable I feel like the C6 comes in at a great spot (I own one so maybe I am biased)
What you said is about what I assumed to be the case. The refractor would provide better resolution than the C5 although not as bright. My 90mm Evostar provided better images than my Skywatcher 102 Mak. The resolution for the C5 should equal a refractor of about 85mm aperture.
I bought a C5 XLT when it became unmanageable to carry my larger SCTs around. Its been a great backyard 'It may rain tonight' scope because it's so easy to make a hasty retreat with a 5 inch SCT vs my C14. Its an all-around fantastic scope.
Schmidt-Cassegrains have a huge central obstruction which not only reduce the light gatherig capability but also lower image contrast significantly. This results in smearing the finer details on planets. That's why smaller SCT-s arent good planetary scopes.
@3dfxvoodoocards6 It's not harder to collimate than a Newtonian telescope. It takes a bit to get the hang of it, but after a few tries it's fairly easy. Thumbscrews help make the process easier in the dark. As for the cooling time, I would say it's comparable to the SV503 102ed,.about 15-30 min depending on the ambient temperature.
I’ve been learning collimation for 12 months with a big 16” f/4.5 dob which has been a challenge. In comparison, I’ve collimated the C5 once since getting it 8 months ago and did it by using a star. It felt trivial in comparison to the big dob. So I reckon it’s on the easier end of collimation. Just don’t scratch the corrector plate whilst doing it!
I bought a Celestron Evo 8 and love it. I also just found a perfect 5SE used for $300 and jumped on it as a super EZ, grab-and-go... Very NICE addition. Both are great scopes.
The 127mm Maksutov either Skywatcher or Celestron (same scope) takes a 2" diagonal and as long as I don't use more than a 72 degree fov eyepiece vignetting isn't a problem. The C5 is simply Celestron not putting a 2" back.
Nice video. What is the practical useful maximum magnification of the Sv503 102ED ? Does the image quality of the Sv503 go down over 200x ? 240x or more ? Thank you :)
Any chance you're doing an astrophotography-focused review for the C5? I know there are challenges when it comes to attaching the usual ZWO accoutrements (due to how small the scope is indeed the runt of the Celestron SCT line) but I'm really curious if one can fit the EAF and EFW within the 105mm backfocus with the f6.3 reducer and allowing the camera+filter to be rotated. Plus points if you can slap on an OAG there too haha. Nice work here!
Yes I currently use the C5 paired with the .63 reducer, custom made EAF adaptor. I use it with the ASIAir and the ASI294mc pro. I'm using the Celestron t-adaptor-sc to achieve the proper backspacing. I also use it with the ASI294MM pro with the 5 place zwo EFW. It's really a great light weight scope for astrophotography and gotten a ton of great images with it.
Hey Bogdan, thanks for the great channel. I subbed. 😎 Question for you... I'm a pre-beginner, I haven't bought a telescope yet. I've been watching astronomy/telescope videos on YT for a few months now but still very confused about what hardware I should get. Is it even possible to get a decent sized view of Jupiter or Saturn for under $2000 spent? I mean a big and clear enough view to see details and moon transits? What kind of telescope would get me there? Astrophotography sounds like a money pit, that I don't need, so I'll skip that.
@100amps Thank you! Astrophotography is definitely a money pit, but which hobby isn't really? I do believe that you can put yourself a rig together that satisfies your conditions for under $2k if you don't factor in the cost for a new laptop. A C6 on an Go-To EQ5 mount + a planetary camera like the Svbony SV705 should be capable of showing you a lot of details on Jupiter and Saturn. Keep in mind that at least 50% of a decent picture comes from skill in using your setup and post processing the raw images. It's amazing what a seasoned astronomer can capture with a basic setup.
@100amps For 2k you can get a pretty good setup for visual observations as well. In fact, you only need an 8" or 10" dob for some nice views of Jupiter and Saturn. Keep in mind though that the atmosphere will limit the capabilities of the telescope no matter how much you spend on your setup. For example you won't be able to get close enough to see the moons of Jupiter transiting. Cloud bands, the great red spot and Saturn's rings are however visible.
@@BogdanDamian Thank you very much. No transits is disappointing, but I will survive. I am resisting Dobsonian type because they are so large. Can a Schmidt Cassegrain type perform as well as a Dob? Or something else that is also more compact?
@100amps Sure, an 8" SCT would be great for planetary observations and much easier to transport than a dob. If you get one, then get it on an eq5 mount with a go-to. This will make your life much easier and it will also be ready for astrophotography later on if you should choose to.
@nguoisat134 The skymax should deliver better views thanks to the smaller obstruction caused by the secondary mirror an the better corrected meniscus lens at the front.
@jair_rillo That would be an unfair comparison as a 12" Newtonian telescope is much better in every category. The only aspect where they are similar is build quality. The only advantage of the C5 is its size, but you can't really compare the two.
Damian, help me, I am really confused between buying the skymax 127 or the C5. I am looking for an all-around telescope, solar system and brighter deep sky objects. The doubt are about the coma of the C5 and the ease with which I read that it loses collimation.
@frzguida Hi! The problem is that neither of them is a great at everything. Thanks to the long focal length both are excellent for planetary observations and astrophotography. But the long focal length is also responsible for a narrow FOV, which isn't that good if you want to observe DSOs. This means that you won't see the whole DSO in your eyepiece. But if it has to be one of these two, I would go for the Skymax. It offers better corrected images. Just make sure you get the one with collimation screws at the back.
Do you think an AR refractor 120/600 could be more suitable for solar syatem and dso and could be better choice? I dislike newton and weight is important for me.
@frzguida No, because of the fast f-ratio. F/5 will result in noticeable chromatic aberrations in achromatic refractors. An f/8 or slower refractor will be much better, like a 120/1000.
About the resolution limit: this sounds wrong. If the optics are perfect resolution has to be limited by diameter.Obstruction plays no effect on resolution. So to me either collimation was of or the C5 (at least your copy) has some optical flaws. other parameters like contrast are effected by obstruction like contrast as you said.
Of topic into imaging for a long time Astro few months the useful have cone across mt weights connections need lot of investigation before purchase limits of low power in 1 .4 inch .first purchase power mate televue 2.5 on a mac 127 could adapt to imaging but long wait and hefty a$147 price for t2 connector.The next baader mark 4 zoom the 8 68 degree stop is real sweet spot for my setup for planets .The parfocal eyepieces and adaptability to imaging of baader eyepieces .Has them my fav company switching baader eyepieces minimal re focusing needed .The 32 Plossl think to much as having issues with it edges v messy next purchase 24 baader h interested max low power on 1,4 heard 27 ?
Scts don't deliver less than their aperture of resolution, central obstruction may lessen contrast, but it has nothing to do with resolution. If that was the case all those giant observatory scopes would be wasting their time. And if you were using the 45deg diagonal that came with your scope, then you haven't tested it or compared it yet. That diagonal robs light, contrast, adds diffraction and vignettes anything wider than the 25mm plossl.
Bought exactly this type 2.5 yrs ago... not a good experienjce at all for a reason not even touched upon in this video : it is practically impossible to collimate this thing. Let me clarify : the factory collimation screws are either fully seized or have an insane amount of play when loosened even just a bit. I have a degree in mechanical engineering, and no way these screws are suitable for fine adjustments at all. So went on a search for better screws. I ordered a set of C5 collimation screws from a reputable Celestron supplier : wrong type ! Turns out the two types available in Europe for C5 are not suitable : needs a third type that is not available. Bottom line : I Dumping this on the second hand market
Please stop spreading the myth that you can't use 2" eyepieces on telescopes with baffles less than 2". Light is a cone not a pipe, if the baffle is not obstructed, there is no problem with 2" eyepieces. You need to go down to a 90mm mak before you start to get vignetting. Not only did I experience this for myself, but I sold tons of 2" diagonals and 40mm swans (72deg, max 2 inch field) to owners of 5 and 6 inch maks as well as c5s and c6s. And many of them called in thinking it wouldnt work because of what they read on internet forums. They didnt get returned, because that is a MYTH, not reality. You only have issues when using larger SCTs that have a 3.25 rear cell to 2" step down plate, which obstructs the baffle. Hence a peterson eye opener for meade lx200s equipped with an obstructing microfocuser, or other solutions like an AP visual back for c11/14, or a celestron or meade specific 3.25" rear cell adapter plate for your Jmi, or starlight or whatever brand focuser.
