Buying a dobsonian: 8 inch or ten inch?

[timetraveler3]

I am just getting started with this amazing hobby. I have not even purchased a scope yet. I have done a lot of research and have decided a dobsonian scope is best, lots of good viewing for the money. I have read other forums but I can not decide whether to get an 8 inch or ten inch scope. At first I assumed the ten inch would  be best but after reading several articles I am thinking 8 is fine, since I am a beginner. The price difference is minimal so all of you out there I would love to hear your opinions and experiences with both.

Thank!

[jetstream]

I just purchased a 10" and am happy with it.This size is at the limit for portability,for me anyway.I'm just north of you here-depending on where you are in Minnesota,there are some very dark skies available.The 8" f6? would be easier on eyepieces I think and easier to carry for sure.Have fun with your decision!

[Luke]

My vote would be a 10 inch solid tube dob, so long as the size and weight /portability are not a problem for you. Be sure to check out the size, or you may be in for a shock, these are big beasties!

John posted a lovely pic and weight info in this thread:

http://stargazerslounge.com/topic/172790-dobsonian-size-comparison/

I have a 10 inch dob and find it to be close to a perfect blend between ease of carrying out into the garden and light gathering power. I previously had a 12 inch Skywatcher solid tube dob (no longer sold) and that was a superb scope but I find the 10 almost effortless for me to move while the 12 always felt like a bit of a heft (though well worth it for good nights). As the 10 is so quick and easy to move, I found I used it a lot and would pop it outside to cool down even if the forecast did not look good.

It might possibly be a scope you would keep for a very long time, even if you added a larger dob later on. I have a 16 inch for the best long nights but use the 10 more often as it's such a breeze to set up and use and is already a very powerful telescope.

The only downsides I can think to a large solid tube dob aside from its size (can you e.g. get it in a car or will it be for garden only?) is that it needs a bit of time to cool down to the outside temperature before you can get a steady view at higher magnification. I used to allow about an hour or so before using my 10 at higher power but that was guesswork, I'm not sure what is optimal. Or of course you could store it outside in a shed so that it's already cooled down.

I think one reason why the 8 inch is so popular and suggested to newbies is the price. The 10 is often over budget for a first telescope, especially if you are keeping a bit of money back for an upgraded eyepiece or two.

[Daniel-K]

Ive had a 8-10-16. For a first scope I would get a 10 you'll love it. Hopefully I can get another soon

[swamp thing]

For me a 10" Dob is the perfect balance between aperture and portability.

That said they aren't without draw backs. The 10" commercial scopes tend to be fast. This means they are tough on cheaper eyepieces. Also the weight of a 10" mirror means that adjustments to collimation are needed more often than with an 8" too.

Lastly you will want to upgrade at some point. From a 10" it's gonna be BIG

[Mr Spock]

10" is an ideal size for most targets.

Be aware if at a later date you want to mount a solid tube on an EQ mount a 10" is a heavy tube to lift that high. That's why I sold mine to get an SCT.

[Naemeth]

If the price doesn't bother you then definitely get the 10" dob. It's not that heavy, and as long as you're fine with lifting 15kg then you'll be fine (base is 15kg, OTA is 13kg). The OTA is the same length as the 8" too, just fatter.

[Bart]

I agree with Luke on everything he said. I also have a 10" and 16" and love both. The 16" gets deeper into space and brings out more detail, but the 10" is so easy to use. You can whip it out in minutes. If you're using it on planets, yes it needs about 30-45 mins to cool down but if I'm just going for dso's I pretty much get dug in straight away. I love the 10"

Here's a family photo, the 10" sits on a sack truck to move it around the place

Good luck

PS go for the 10"!!!!!!

Barry

[RikM]

 I would think about the total package (scope + eyepieces) and your own interests. How important are lunar/planetary views compared to deep sky observing? An 8" f/6 is perfectly good for the majority of objects and is kinder to eyepieces. A 10" f/4.7 will give you better views of fainter objects and better resolution on solar system objects (if the sky conditions allow it !) but will need better eyepieces to get the best out of it. 

As a deep sky nut, I have a solid tube 10".

[andyman]

8" or 10" Mmm let me think 10" everytime buddy goldilocks of scopes not to big not to small and gives exellent views

[bish]

If you have the funds then go for the 10", although there's not a huge difference between the two. Sometimes that little extra aperture is the difference between just about making out  faint DSO or not.

Where in Minnesota are you? I spent a few months in Minneapolis many years ago and have followed the Vikings ever since.

[arrayschism]

Transport, storage and focal ratio aside, I'd certainly go for the larger aperture every time. 

[nephilim]

Get a 12" 

[Scott]

get an 8". one day you'll want to upgrade and going up one size isn't going to be very noticable.

If you've got an 8 then the next reasonable upgrade is going to be 12" (still not to dear).

if you've got a 10 then the next upgrade is going to be a 14 or 16 (time to sell one of them lungs)

then again, you might decide to get into ap eventually so all this will be moot

[nephilim]

get an 8". one day you'll want to upgrade and going up one size isn't going to be very noticable.

If you've got an 8 then the next reasonable upgrade is going to be 12" (still not to dear).

if you've got a 10 then the next upgrade is going to be a 14 or 16 (time to sell one of them lungs)

then again, you might decide to get into ap eventually so all this will be moot

Thats why its best to just go straight for a 12.

[brantuk]

If the only thing worrying you is "being a beginer" then the 2" difference isn't going to be any problem at all - go for the largest aperture you're comfortable with handling. The 10" light grab will be better and the only criteria for going smaller would be portability, storage, and lifting ability.

If you go for imaging down the line somewhere - then you'll need a totally different scope to a dob. If you upgrade later on then you can go for a 14" or 16" dob for an appreciable improvement. But a ten inch is a great place to start. Hth

[Charic]

timetraveler3........Hi. based  on your question, and the fact that your home work is up to-date......

. At first I assumed the ten inch would  be best but after reading several articles I am thinking 8 is fine, since I am a beginner. The price difference is minimal so all of you out there I would love to hear your opinions and experiences with both.

Thank!

 

Do you want fine or best?

 

The 10" gathers more light,  FACT  no argument ( under the right conditions)  If your back yard is full of light pollution, then the 10" may be worse for the result, and remember Dobsonian mounted newtonian Telescopes are really purely for observational use. Dont get one if you think an a few Weeks  time you want to photograph something.

 

I`m happy so far with my 8" skyliner. but `Ive yet to see the real end results from a proper dark site. Just not made the effort yet.

 

Most here have suggested the 10".

[timetraveler3]

Thanks so much everyone! This site is so helpful. It seems like the general thought is go for the ten inch. That was my first hunch so that Is what I will do, sounds like most of you have one, and not too big of a deal to haul around.  It seems like one I would not feel I have to upgrade anytime soon. By the way I live in Stillwater, MN about half an hour east of St Paul, on the WI border.

Skies are fairly dark here but surely would venture out to even darker skies with this scope. I plan on ordering a scope in the next couple of months, will have to learn to use it when it is freezing cold!

[jetstream]

Thanks so much everyone! This site is so helpful. It seems like the general thought is go for the ten inch. That was my first hunch so that Is what I will do, sounds like most of you have one, and not too big of a deal to haul around.  It seems like one I would not feel I have to upgrade anytime soon. By the way I live in Stillwater, MN about half an hour east of St Paul, on the WI border.

Skies are fairly dark here but surely would venture out to even darker skies with this scope. I plan on ordering a scope in the next couple of months, will have to learn to use it when it is freezing cold!

Stillwater,Apple River and the Cedar Lake racetrack are all at your figertips!Nice area,should be some nice dark skies just waiting for you to try, http://www.livescience.com/25389-black-marble-zoomable-image.html,http,://cleardarksky.com/csk/prov/Minnesota_charts.html

[neil phillips]

10 is serious,  8 wants to be,  anything higher is luxury

[LukeSkywatcher]

10 is serious,  8 wants to be,  anything higher is luxury

I wouldn't call an 8" scope a "wannabe". Its serious, just not AS serious as 10". I agree that  anything above 10" is a luxury.

[swamp thing]

10 is serious,  8 wants to be,  anything higher is luxury

"Anything higher is a luxury"??? Take it from me anything higher is serious fun

[LukeSkywatcher]

"Anything higher is a luxury"??? Take it from me anything higher is serious fun

If you can handle it.

[Naemeth]

If you can handle it.

"Anything higher is a luxury"??? Take it from me anything higher is serious fun

You're both right. If you have the means to use a scope bigger than 10" then go for it, but I'd always keep my 10" even if I got a 20"+ scope because the 10" is so portable.

Mind you, this is coming from the guy who bought 5 scopes in 19 months (well, 1 scope for 13/14 months, then the next 4 over 5 months ) , of course I wouldn't sell it .

[AlexB67]

A bit late to the thread but my 2 cents. First thing I would say how much is the cost worth. The jump to a 10 from 8 inches is quite appreciable, but that's up to you.  In the end there is no limit to aperture in the sense of it being a luxury IMHO, there is always a faint target that an 8 inch will not show and a 10 inch will, the same as you go up the scale.  To compare a bit:

• cost,  8 inch less than 10 inch.
• 8 little bit lighter, therefore a bit easier to handle.
• great all-round starter scopes  for planets in the case of both I'd say, though the 10 inch will perform that little bit better and is often said to a good middle point for everything. Often with bigger scopes  such as a 12 inch or above, the atmosphere will be the  limiting factor what you can see in planetary detail.
• Usually the 8 inch has a nice focal ratio and is quite forgiving on cheaper eyepieces, the 10 inch a bit less so. For the SW models anyway as often they are sold in the same focal length but smaller aperture for the 8 inch.
• Main point, whilst the 10 inch is only 2 inches more, since light gathering is defined by area, it actually gathers about 45% more light.  This is an appreciable amount if deep sky targets are of interest to you in terms of limiting what you can see when it comes to the fainter targets, but also in general, the deep sky stuff will be that bit more pleasing.

The 8 inch is the most sold beginner DOB for a good reason striking a good price  and performance.  It would be my recommendation starting out today given what I learned so far, but if money is no object and you are pretty certain you'd like the hobby enough then a 10 inch would be worth considering. 

Good luck with whatever you buy, starting out in the hobby I doubt you'd be disappointed with either.