Spot the difference quiz for Stargazer 200P

[the lemming]

Could somebody please tell me the difference between these two telescopes:

Skywatcher Explorer 200P EQ5

Skywatcher Skyliner 200P Dobsonian

Apart from the mounts, price tags and product names, which even I can spot is there any difference in the telescopes alone, and if so do these differences make it a killer decision to chose that particular model over the other?

Cheers

[NickMilner]

/ edit found a link where this is discussed. (Sorry, it's not much!)

[MartinB]

The term dobsonian refers to the mount rather than the scope. It is a very simple but effective and stable alt azimuth mount invented by John Dobson.

You are right that the package with the EQ5 (a german equatorial mount) is effectively the same scope other than the equipment for fixing the scope to the mount.

For low power visual work the dobsonian is easier to use since the eye piece always stays in the same position relative to the scope axis whereas with a GE mount you need to rotate the scope in it's rings for comfortable viewing. The dobsonian doesn't require polar alignment or leveling and is therefore quicker to set up.

The EQ5 normally comes with motors which means the target will stay in the field of view. This is particularly handy at high powers when, without tracking, the target can move quite rapidly across the field of view. At high powers a dobsonian scope needs regular nudging.

The EQ5 can be fitted with goto for rapid target finding and also gives you the flexibility of being able to use it with other scopes, unlike the dob.

If you want to do any imaging you are better off with an EQ5. For observing the general ease of use and simplicity makes a dobsonian a popular choice, also cheap!

[Hypernova]

The main difference, apart from the mount and name, is that the dob has a slightly longer focal ratio, f/5.9 compared to f/5 for the explorer.

This would make it slightly more tolerant on collimation errors and lower quality eyepieces. But because of the increased focal length you would need a longer focal length eyepiece to get a lower magnification view. I think lowest mag you could go without making the exit pupil too big is something like 32mm which would give 37.5x.

[the lemming]

The main difference, apart from the mount and name, is that the dob has a slightly longer focal ratio, f/5.9 compared to f/5 for the explorer.

I noticed this too but to be truthful did not have a scooby what it meant. The specs also have some other things missing form each telescope.

Are these things which are missing from one and not the other Deal Breakers, putting aside the mounts?

Cheers

[Hypernova]

I noticed this too but to be truthful did not have a scooby what it meant. The specs also have some other things missing form each telescope.

Are these things which are missing from one and not the other Deal Breakers, putting aside the mounts?

Cheers

I can't see what you mean by things missing in the specifications. The only differences I can looking at is that dob does not come with the EQ5 and tripod and a 2x barlow, that and the obvious f/ratio differences (the ratio between focal length and mirror diameter).

Other than that the specifications are the same and they come with the same accessories.

[the lemming]

I can't see what you mean by things missing in the specifications. The only differences I can looking at is that dob does not come with the EQ5 and tripod and a 2x barlow, that and the obvious f/ratio differences (the ratio between focal length and mirror diameter).

Is the obvious f/ratio a major difference or, in the grand scheme of things, not a deciding factor in which telescope to choose?

[Hypernova]

There won't be a huge amount of difference in normal use IMO, you will just have be slightly more accurate in collimating the f/5 to get decent views and also be prepared to tweak collimation more often as it doesn't take too much to knock it out of alignment, especially when transporting in the back seat of a car.

The f/5 may show more coma when using poorer quality eyepieces, this is a fact of life when viewing through a newt and I guess it depends on how much coma you are willing to take. The eyepieces that come with the 'scope will do you fine for a quite a while and will give you time to think through any upcoming eyepiece upgrades. Ones like the Meade SWA's, SW Nirvanas/WO UWAN's and TMB planetary eyepieces are good eyepieces that perform well down to f/5 or so and well worth considering, some of them don't come cheap though and I would hold off for a while until you decide what you really want and/or need.

HTH

[michael.h.f.wilkinson]

There won't be a huge amount of difference in normal use IMO, you will just have be slightly more accurate in collimating the f/5 to get decent views and also be prepared to tweak collimation more often as it doesn't take too much to knock it out of alignment, especially when transporting in the back seat of a car.

The f/5 may show more coma when using poorer quality eyepieces, this is a fact of life when viewing through a newt and I guess it depends on how much coma you are willing to take. The eyepieces that come with the 'scope will do you fine for a quite a while and will give you time to think through any upcoming eyepiece upgrades. Ones like the Meade SWA's, SW Nirvanas/WO UWAN's and TMB planetary eyepieces are good eyepieces that perform well down to f/5 or so and well worth considering, some of them don't come cheap though and I would hold off for a while until you decide what you really want and/or need.

HTH

Coma is more related to the objective than the eyepiece: even a top of the line eyepiece as a Nagler will show some coma on such a fast scope, at least at low magnification. Cheap eyepieces show a lot of astigmatism as well. The main issue with the focal ratio is that (should you want to take photos through the telescope) F/5 allows shorter exposure times. More importantly, it keeps the tube shorter, which make the set-up easier to handle. The latter is more of a concern on an EQ mount, which is bulky in itself, than in a Dobson.

In visual use, the slightly longer focal ratio of the Dobson may actually boost the image quality very slightly.

[PeterM]

Is the obvious f/ratio a major difference or, in the grand scheme of things, not a deciding factor in which telescope to choose?

The difference in focal ratio is minor compared to the differences in how the scopes are mounted. If, say, there was a choice of both focal ratios on the same mount I would go for the F5.9 any time based on tolerance to miscollimation but fundamentally here you are looking to choose between the EQ and Dobsonian mount. That's the main choice, everything else is minor detail.