Which telescope to choose?

[Andreiiorg]

HI! I want to purchase a telescope and right now I m thinking to choose between:

https://www.astroshop.ro/telescoape/omegon-telescop-dobson-advanced-n-203-1200/p,48730#tab_bar_1_select

https://telescop-expert.ro/dobson-skywatcher-skyliner-150-1200-classic_100101

What is your opinion?

[Clarkey]

Personally if it was me I would go for the greater aperture. The Omegon will collect much more light than the skywatcher given they are both the same focal length. I don't know much about the quality of Omegon kit, but as a dobsonian there is not much to go wrong and the mirrors are probably made in the same factory anyway.

I am not a visual observer - so you might be better waiting for someone more knowledgeable to give their opinion.

[Peter_D]

Just looked, the Omegon comes with a Red Dot Finder, the Skywatcher with a 6x30 Finder scope. It's a detail just to think about (no problem replacing either).

[Orange Smartie]

All other things being equal, the larger aperture (tube size) will give the better view - about 70-80% more light grasp and better resolution.

I have not heard of Omegon, so I'm not sure about the build quality. 

Couple of other things to consider - the larger telescope will be heavier, and might require a little more storage space.  You'll probably also want to budget a little more for a couple of better eyepieces - the ones supplied will most likely not be very good.

[Carbon Brush]

Welcome to SGL.

@Orange Smartie has touched on the questions that haven't been considered. Unless you have looked at this for yourself.

In general a 150/200 mirror dob is a good first scope. Note the 'in general'.

If you weight 50Kg, have a bad back, need to carry the scope down 3 flights of stairs, etc, a large scope is not a good choice.
If you have to negotiate storage space in a tiny cupboard, similar comments apply.
If you have to deal with a lot of light pollution, there are other scopes that will be a better choice.

The best scope is always the one that gets used the most.
I have a 300mm mirror scope on dob mount. On the face of it a much better scope.
But at 35Kg total for the tube and mount, moving and set up need thinking about.........
I also have an 80mm refractor that can sit on almost any tripod/mount.
Moving this is easy. Tube in one hand and mount/tripod in the other.

If you tell us a little about your viewing circumstances and what you hope to see, the advice offered will be much better.

Enjoy the journey,

David.

[Andreiiorg]

10 hours ago, Carbon Brush said:

Welcome to SGL.

@Orange Smartie has touched on the questions that haven't been considered. Unless you have looked at this for yourself.

In general a 150/200 mirror dob is a good first scope. Note the 'in general'.

If you weight 50Kg, have a bad back, need to carry the scope down 3 flights of stairs, etc, a large scope is not a good choice.
If you have to negotiate storage space in a tiny cupboard, similar comments apply.
If you have to deal with a lot of light pollution, there are other scopes that will be a better choice.

The best scope is always the one that gets used the most.
I have a 300mm mirror scope on dob mount. On the face of it a much better scope.
But at 35Kg total for the tube and mount, moving and set up need thinking about.........
I also have an 80mm refractor that can sit on almost any tripod/mount.
Moving this is easy. Tube in one hand and mount/tripod in the other.

If you tell us a little about your viewing circumstances and what you hope to see, the advice offered will be much better.

Enjoy the journey,

David.

Thank you all for your time and energy! This scope isn t going to be moved too much, only in and out of my house, and storage is not a problem. I don t live in a town with much air pollution. Being my first telescope I want to see pretty everything, from planets to nebulas and other deepsky objects. I hope it helps.

Clear skies!

[ONIKKINEN]

11 hours ago, Orange Smartie said:

I have not heard of Omegon, so I'm not sure about the build quality. 

Omegon is the Astroshop.eu variety of nameless chinese products. Carbon copies with many sharpstar, astro essentials, svbony, TS etc products. I have a few omegon eyepieces and they are pretty good for the price, so i believe you get what you pay for.

[Ricochet]

13 hours ago, Andreiiorg said:

Being my first telescope I want to see pretty everything, from planets to nebulas and other deepsky objects.

If you want to see deep sky objects then aperture is king and this pushes you towards the 8" over the 6". There are three "standard" dobsonians generally available, the 6" f8, 8" f6 and 10" f5. All three of these have the same focal length, so they are the same height, and have approximately the same size rocker box so they all take up the same amount of space in storage (assuming stored vertically in one piece), all can be transported with the OTA across the back seats of a car with the rocker box in the boot, and all are best used with an adjustable height observing seat. As you increase in size, there is an increase in cost, but also an increase in weight. If you store your dob in a shed or similar location and only have to carry it over flat ground then the 6" is a 1 part carry, the 8" might be a 1 part carry depending on your stature (it is for me) and the 10" should definitely be carried in two parts. I am sure people will respond that they can lift their 10" in one piece, and I know if I had gone for a 10" I would be tempted to too, but you really shouldn't. If you will need to carry the telescope up and down stairs then all of them become two part carries and fitting decent handles to the OTA should be looked at. The smaller and lighter the telescope is, the more likely you are to use it and this isn't taken into account often enough.

With regards to the view through the telescope, when viewing planets, resolution and optimum magnification scale with aperture (diameter of the mirror) so the 8" is a bit better than the 6". However, the 6" being f8 over the 8"'s f6 means that it has a proportionally smaller secondary so there is less diffraction from the secondary and this will mask the difference between the apertures so in practice you would probably find that the difference in planetary performance is not that great.

However, when it comes to deep sky objects we are interested in the light gathering capacity of the telescope, which scales with the square of the aperture. In this case, going for the larger telescope will allow you to see dimmer stars that are invisible in the smaller telescope and it will also allow you to view extended objects at a higher magnification with the same image brightness, which makes them easier to see. In this case what you really want to do is go for the biggest aperture that you can easily get out/put away as this will be the scope that you get the most use out of. For me the 8" fits the bill perfectly. If it looks like it might be clear that evening I can get it out to cool on the off chance as it is no hassle to put it away again if it clouds over. Similarly, if it is unexpectedly clear and there is a half an hour window to observe in I can get the telescope out and be observing within a couple of minutes.

[Mikeshuerto]

Hi, iI dont know if you've already purchased your Dob, but I'd thought I'd give you my 10 cents as a beginner. .About 18 months ago, I bought my first scope used on UK buy-and-sell. It was a Skywatcher 14 inch GOTO Dobson. I am so glad I got a GOTO. This has allowed me to combine visual with some fairly serious astrophotography. After struggling through the usual beginner errors, like blowing the Alt control board, and not collimating correctly,  I have the scope completely wired-up remotely to my PC  with a remote-focuser, camera and even a de-rerotator. I can livestack and plate-solves via Sharpcap, which makes it perfect for EAA. I was able to snap a pretty good live-stack of Comet Leonard, by just putting in its RA-Dec coordinates.  Here's some of my better shots: https://www.astrobin.com/users/MikeHuerto/

The alternative, you have is to just start with the non- GOTO version, and if/when you are tempted to do attach a camera and dabble in astrophotography you can buy an eq platform. There are several on the market (eg Geotek or Triangulim).  This guy has done wonders with an 8" and  12" manual Dob and the Geotek https://stargazerslounge.com/profile/68662-tiago-ferreira/

Hope this helps!

Clear skies

Mike

Edited December 8, 2021 by Mikeshuerto