Sunday, May 22, 2022

Difference Between 8 Inch Newtonian ( Dobsonian) And 8 Inch Schmidt-Cassegrain Telescopes

In this video i will compare two 8-inch 20 centimeter telescopes and one of them is a neotronian to the right and the other one is a schmidt cassie green to the left and newtonian is a skywatcher 200p and the schmidt castlegrain is a meat lx 200 .

8 inch classic the skull watcher 200p newtonian has a diameter of 200 millimeter for the mirror and focal length of 1000 so the f ratio which is the f divided by d creates the .

Focal ratio of 5. the schmidt casa grain has a diameter of 203.2 millimeter and focal length is 2000 almost f 10 a focal ratio of 10. both of them are now looking at the moon .

And let's see how the view looks like through each first through the 8 inch skywatcher newtonian this is the view to the scrub watching newtonian as you can see the field of view is about uh yeah four times or three times three and a half times the size of the full moon .

Full moon is around and the diameter of the moon is around one half a degree sorry half a degree and that makes the image wheats from one corner which you can see to the right to the other corner around one and a half .

Degree to two degrees and so it's quite wide field for the viewing so that was the view to the skull watcher 200p and the same eyepiece 28 millimeter now let's see .

To the 28 millimeter under schmidt casey green let's see the view what is immediately you notice is that the image is uh bigger it has a narrower field of view so finding the object without the .

Use of a finder scope is almost very difficult or impossible probably the narrow field of view can be a problem but it's perfect for planetary bodies like the moon and other planets as you can see you can see more details here so .

Another difference between the newtonian and the schmidt catherine is that the position of the eyepiece as the targets uh is in different parts of the sky will change so you have to bring it down or up and that means you have to change your sitting position also either sit or .

Rise so it's it's not very easy in that sense it's better to be able to have something which is a stationary and it stays the same and that is what we have with the schmidt cassegrain the position of the eyepiece more or less stays the same because it's just .

Pivoting on this axis up and down slightly not much you can just sit the same height and look at the most of the object so it's easier another difference is that the size of .

The newtonian when this is the same for the topsonia is about twice the size of a schmidt cassegrain of similar size and that makes the schmidt caster again quite compact although it has a bigger focal length .

That's two thousand millimeter two meter focal length it has that one has one meter for equivalence but because it has several reflections back and forth the tube is more compact so the size is the difference another difference another difference between them is that .

The price for this bought second hand so if you buy secondhand at least one thousand pounds around one thousand five hundred dollars that's one second and about around 200 pounds which makes it around 300 and that's a difference so the price .

Difference is about five times this one is more expensive than that so with 300 you can buy this 1 500 for this transport of this is easier than that also it's more compact takes less of space when you want to store it in the home that's the consideration or in the car .

If you want to take it to somewhere dark side for observation and of course you can use a focal reducer with this focal reducer is a reverse of a power load when you attach it it actually increases uh or decreases yeah increases the decreases the firm f ratio so practically focal reduces for .

Celestron omit six point zero point six street and we'll make the field of view wider so that makes it practically like that from a wide field telescope if you use it on this this is the reverse of a barlow practically instead of magnifying it just reduces magnification you will be able to .

Find bigger targets in the sky like most of the difficult deepest objects you must know that galaxies and the star clusters and everything else are quite huge although they are so far from us compared to moon and the planets the huge andromeda galaxies in the outer sky is almost four degrees that makes it .

Eight times the size of the moon in our sky so practically a huge object even though that's two million light years away so you have all this uh available with this when you use a focal reducer of course the field of view again you need a bigger field of view if you want to use the .

See something the whole width of the uh and dramatic galaxy pinnacles will do it better another consideration for when you want to consider buying this is that that one doesn't have any electronics it's cheaper it doesn't break this one has electronics they easily .

Break or they become obsolete and in this case the capacitors of this were the classic emit lx200 emc the capacitors easily burst after a while so you have to replace them or just use it as ultrasound without in electronics so they're they're prone to .

Being outdated obsolete or breakdown that one is just mechanical nothing there and then the rest of it is optical optical tube and there is no danger of that another thing that may confuse you is that as you have seen in the video i presented you the image .

In this one compared to this one is reversed this reverses the image compared to the normal viewing that one even swaps sweeps that image to the mirror part of it so practically you will see even another image which is not the same as what you can see with your normal eye .

And is a reverse it's very interesting thing when you look at the moon from these two through these two objects you have to use different maps for this if you want to be comfortable finding objects and the names of the targets one of the things that you can .

Do with both of them is astrophotography with this one you can do you know digiscoping hold your mobile camera mobile phone and take a few seconds or a few minutes depending on the video or photo uh of uh .

Celestial object including planetary objects with this one you can guide it so most of the speed can be guided unless they're broken so when you can guide the telescope practically you can take up to 10-15 minutes of the guided astrophotography .

Unfortunately you will have some field rotation because this is moving in ultrasound it's moving like this a little bit like this a little like this a little bit like this it's not a equatorial that follows in a curve it has to follow the curve in steps like that .

So and this causes field rotation when you have field rotation your image at the center looks centered around it objectively look appearing as if they have rotated it's like as if the you're looking at the polaris and the stars around it but with the video and other things you .

Can just take short videos and just add them stack them with the software that will be you will be able to do that with the um vocal redo so you can have a wider field of view and just do whatever you want to do planetary you don't have any problem you can just take the pictures or the moon the same .

And i i don't do any processing i can photograph with all of them i do some master photography also of the brightest objects like orion nebula and things like that so this is the moon i'm holding the camera against the eyepiece .

As a skywatcher 28 millimeter 2 inch ips on a skywatch 200p this is a newtonian the same as the f5 focal ratio 5 the same as a score watcher or orion or similar to that dobsonians .

Okay this is with the media schmidt casey green as you can see i showed you during the daylight now we are looking to the night or twilight and you can see the image scale is larger ips is the same just because it has a higher f ratio .

You can see more of the object and less of the sky background that means that is a narrow field of view good for planetary viewing not very good for deeper sky objects but you can use a focal reducer and it's a reverse barlow practically makes .

It suitable for using as a white white filled telescope and i cannot say which of them i prefer they are different in what they do and as you can see i have both of them so you can make your own judgment based on .

That but if i was going to buy the first telescope and i did was not sure but i want to to dedicate more time and resources to this i'll probably go for the skywatch in newtonian then when i see that i'm more interested let me just get the schmidt classification for what .

Uh another difference between a schmidt caster green and the newtonian is that yeah as you can see the corrector plate on the schmidt castle grain easily gets dew on it condensation of moisture .

And that can actually damage the view that you have it eventually will cause you know deterioration of the screen you have to use of course uh either a dew shield or something like a dew heater uh on the other hand uh newtonian mirrors at the end and it takes a while actually to get .

Covered in due so is in that case is better


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