Which is Best ?

[valvenus]

I am thinking of upgrading my scope soon I own a skywatcher dobsonian 150p and was thinking maybe going for the 200p next but would there be a great deal of difference to what im able to view now or should I hold out for a 250p ?

[emadmoussa]

If you can handle the 250p, then 4" increase in aperture will make a very noticeable difference. However, a 200P be will still give 46% - I think - increase in light collection, which is the difference between an invisible object in the 150p and very faint in 200P. I think you'll notice also increase in contrast on planets and the moon.

From what I can remember there's 4-5 Kg difference between the 250P and the 200P. Having said that, the 250" will be more easier to handle on a Dobsonian mount rather than an Equatorial.

[ronin]

The easy answer is simply that it will collect nearly twice the light, 1.77%, so should present more.

Equally I have read that unless the light grasp is at least doubled then you may not really appreciate it.

The next point is waht exactly do you intend to look at and expect to see more with?

M31 will be a bit brighter, but you cannot I suspect see all of it in one go anyway.

M42 will be brighter, but is it really dim at present.

M45, same as M42.

A few of the more prominent galaxies should be improved.

If however you look at the Virgo galaxy cluster then youi will see more "galaxies" but they are small dots in the 150 and you will get more dots in a 200. That Virgo galaxy that is a dot in the 150 will still be a dot in the 200. You will have more dots that is all.

I would go as far to say that you will see 95% of things in a 150 that you would see in a 200, could be talked into suggesting 98%.

The additional diameter will make a difference on things like faint nebula, Rosetta, N American, Pelican etc. Equally a dark sky will do the same.

Another often overlooked aspect is that the 150 is I suspect easy to take out and use, the 200 is a bit bigger, the 250 bigger still. If you ended up not using the 250 then you would actually see more in 42mm binoculars. You would not be the first person to get a big scope then ehd up not using it.

[RobAro]

I have both the 150P and a 200P. What ronin says is right, for visual the 200P gathers more light and once your eyes are properly adjusted you can pick up more detail with the bigger diameter.

Size and weight are an issue in terms of mobility and also payload your mount can take. I wouldn't use anything less than an EQ6 for a 250P or a 200P if configured for imaging.

If you do go for the 200P I would suggest that getting a Skywatcher 0.9x Coma Corrector and a Skywatcher ED Deluxe 2x 2" Barlow Lens are worthwhile accessories.

[Laurie61]

The 8" dob is a useful upgrade over the 6", at f6 it is also a bit kinder on eyepieces and collimation. The 10" would show significantly more, although it is f 4.7 so you are moving into coma corrector territory. I find it's easier to compare different size scopes using similar exit pupil sizes. The view through two different size scopes, with eyepieces giving the same size exit pupil, will have the same brightness image but different magnifications. A 150 mm scope will have a 1 mm exit pupil (e.p) at 150 x mag the 200 mm scope will have the same 1 mm e.p and image brightness but at 200 x mag, the 250 mm scope will be up at 250 x mag with an eyepiece giving a 1 mm e.p. So by going from a 6" scope to a 10" scope you can see the same target at an extra 100 x mag at the same brightness. I have found this a bit easer to visualise than the extra resolution benefits.          

[Beulah]

The 8" and 10" dobs win hands down in terms of portability.

From my experience, switching from the 150p (6") to the 200p (8") seems a huge jump compared to 200 p (8") to 250p (10")

For example: under a dark sky, the Orion nebula starts to show a lot more detail in the 8" than the 6". The Hercules globular cluster (M13) can be resolved to the core in an 8" and distinguished from galaxies.

I really think that for portability, ease of setting up, collimating and cool-down, the 8" (200p) hits the sweet spot.

In my opinion, if any more increase in aperture is needed, go up in 4 inch increments after the 200p.

[todd8137]

To notice the difference go for the the big boy if you can carry it about

Pat

[Luke]

I think a 6 to 8 inch is a worthwhile upgrade but I would recommend to jump straight to 10 if size and weight are fine.

I've viewed with 4, 6, 8, 10, 12 and 16 inch scopes and a 10 inch for me is a really nice balance between light gathering power and weight.   I mainly observe with a 10 inch dob now and I find mine easy to move, light enough that I don't need much encouragement to pop the dob outside   The 16 inch I need to do a warm up before moving it!   Perhaps I should stick wheelbarrow handles on it!

[Beulah]

  The 16 inch I need to do a warm up before moving it!   Perhaps I should stick wheelbarrow handles on it!

It's doable, providing you can cart it about on wheels and make sure there are no steps on your journey to the garden... 

[valvenus]

Thanks everyone glad the weight was mentioned  something I never thought of so im guessing the 10 inch would be to heavy to carry in and out by myself ?

[Mr Spock]

With the 10" it's not so much weight as bulk. The tube is really big - much bigger than it looks in pics. I moved to my current scope because the 10" tube I had was too big for me to carry, though I do have a bad back.

The 8" is the same length (fl 1200mm), but is a little easier to handle. It would be a good idea to see one close up before deciding.

[Beulah]

Yes, the 10 and 12 inch is in the bruised shins category, the 14 and 16 inch is getting on for slipped disks....

[JulianFR]

I have a 200mm SW and have found it pretty easy to move (one piece at a time). Then recently I fell down with aperture fever and bought the 300 Flextube, which I can manage but is REALLY heavy. I imagine a 250 would be significantly heavy as well.

So I know it's obvious really but if weight is an issue the 200 would probably suit you better.

[Charic]

The jump to 250P would be the most significant jump in size, weight, cost and ability.

The 200P  weighs 21Kg assembled( 9Kg and 12Kg) For me that's easy enough to lift in one and transport to outside.

The 250P probably takes up the same amount of surface area and space, although the OTA is wider.

Both can be moved by separating the two components of base and OTA.

The two main considerations you should look at are the cost and ability.

If you can afford it, go for it. Secondly that 10" aperture will produce results you only dream of now with the 150P.

The 150P gives 459x the light gathering power of the unaided eye, the 200P offers 816x and the 250P has 1275x.

Aperture is king for deep space observations.

[swamp thing]

I think the 10" is your best upgrade unless you hold out for a 12"

[AlexB67]

4 -5 inch upgrades or often recommended as a good upgrade. If you can handle the scope weight wise and transport it if you do that already that is also worth considering. I find a 10 inch scope easy to handle and carry around the garden. If you are of normal health, good back, and you carry a couple of concrete blocks around the garden it is fine as a reference of weight. 

As Laurie said, easier to visualise in terms of image size and brightness, given those factors you'll get an appreciable step, of course many faint fuzzies wlll still be faint, like galaxies, but you will get a very good step in planetary detail. Other targets like planetary nebula for example will become a lot easier to see. clusters will be richer, globular cluster will be resolved to the core, and so on. 

In any case both are great scopes, but in terms of feeling you bought a good upgrade/step the 10 inch would perhaps be worth while holding out for if you can afford it in a couple of months down the line. I went from 5 to 10 inch and glad I did. I don't feel I need anything bigger for a good while for time to come, there is now so much more new stuff to see in that upgrade and an improvement on the whole that will serve me for a loooong time to come 

The other thing to be  aware of is the f ratio, the 8 inch is somewhat friendlier on eyepieces, but still, even with the 10 inch medium range eyepieces in that 50 - 70 pounds are perfectly useable, you can always upgrade them over time, and for less than a 100 pounds you can till get some excellent optics in eyepieces if your prepared to accept  a narrow FOV  and don't wear glasses you don't have to break the bank buying new . 

[Orange Haze]

For my two pennies worth, I just upgraded to the 10" solid tube Dob and was a little concerned over its size and weight before it arrived. However, I have found the set up very easy to move in and out of the home. Of course I move the base first, which has a handle conveniently located on the front to help out. Then I move the tube and while the tube is large, once you find a way to hold it comfortably, the weight is not an issue at all, it is hollow after all.

I'm hardly a weight lifter, but I've been surprised to find how portable the 10" is and wish I'd got one sooner!

One other thing...... it's awesome!!

[AndyWB]

I seem to remember being told that the 200p and 250px had the same base, so that should weigh the same. The OTA of the 250px is, as mentioned, not too heavy - certainly lighter than the base - but it is bulky. I'm fairly big, so it's not a problem, but if I was 5'0" it could be. I do move it in two parts.