New to Dobs: Questions please experts? :)

[kirkster501]

Hi all,

I have never used a dob before but I am very interested for visual - particularly the 250PX Truss Tube. On the other hand I am new to Dobs so thinking maybe go for the 200 first and a Telrad and see how I get on with them. Thoughts guys please?

My question is how do these things stay collimated when they have to be collapsed down all the time? Mine will be kept in the garage covered up.

Will these scopes work well with my TV Nagler EP's? With the stock focuser? Will I need to upgrade the focuser?

Since I am selling my CPC1100 for a C9.25 for Planetary and some DSO AP but still want my visual fix should I go for a 12 inch truss Dob instead? is it MUCH bigger? Whats the FOV like on a Dob?

Sorry for so many questions !!!

Kind regards, Steve

[NGC 1502]

Choice between 8" and 10" comes down to cost & weight. Most of these are 1200mm focal length, so tubes are the same length, the 10" is a bit fatter & heavier. Not a huge difference in what can be seen between these but of course the 10" will have the edge. I suppose that's your call but if you could get to a retailer with a showroom that could help the decision.

Don't know how these scopes hold collimation when collapsed and then extended, I've heard conflicting opinions. I'd guess maybe a tweak may be needed.

The Nagler eyepiece is about as good as it gets with reflectors. I'm happy with stock focusers myself, most work well, but some folk are not happy and upgrade.

Many would say that a 12" Dob is the max for them, but again a trip to a retailer could help. Of course, at star parties you will see Dobs up to 20" plus, so much depends on what individuals find acceptable for lugging around.

Field of view with any scope can be found by dividing magnification into apparent field - Example, 1200 mm scope, 31mm Nagler, mag = 1200/31 = 39x, FOV = 82/39 = 2.1 degrees actual sky seen.

Regards, Ed.

[Dunkster]

Selling the CPC?!?

[kirkster501]

Selling the CPC?!?

Yep. Its a lovely piece of kit. Make no mistake. I love it. And if I had a obsy where I could mount it permanently I would keep it without question on a wedge. But its too much moneys worth sitting not doing much for visual only. Also, I hate to say it, I am kind of bored just pressing buttons and gotoing with visual. I like the thrill of finding stuff as well with a star atlas. I have also got into AP. So getting a C9.25 OTA to mount on my NEQ6 to compliment my ED80 refractor and also looking at getting a large Dob for visual - probably a 250 and a telrad to start with. The sale of the CPC funds all of this.

[estwing]

you want something you can wheel up and down

[Dunkster]

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Yep. Its a lovely piece of kit. Make no mistake. I love it. And if I had a obsy where I could mount it permanently I would keep it without question on a wedge. But its too much moneys worth sitting not doing much for visual only. Also, I hate to say it, I am kind of bored just pressing buttons and gotoing with visual. I like the thrill of finding stuff as well with a star atlas. I have also got into AP. So getting a C9.25 OTA to mount on my NEQ6 to compliment my ED80 refractor and also looking at getting a large Dob for visual - probably a 250 and a telrad to start with. The sale of the CPC funds all of this.

Best of luck with the sale at least the CPC has trained you for lugging a big heavy scope

[kirkster501]

Best of luck with the sale at least the CPC has trained you for lugging a big heavy scope

Thanks. Sold it today to a chap who is going to mount it on a wedge in an obsy. He will love it. I envy him !!!

[Moonshane]

Hi all,

I have never used a dob before but I am very interested for visual - particularly the 250PX Truss Tube. On the other hand I am new to Dobs so thinking maybe go for the 200 first and a Telrad and see how I get on with them. Thoughts guys please?

My question is how do these things stay collimated when they have to be collapsed down all the time? Mine will be kept in the garage covered up. Collimation is part of owning a newtonian, especially a large one. it's really very easy after a week or two. you won't even think about it as an issue. I check collimation on all my newts every time I use them. usually the primary needs a tiny tweak, that's all.

Will these scopes work well with my TV Nagler EP's?As churchill (the dog) would say "oooooooh, yesh" With the stock focuser? yes of course but I prefer a dual speed with a fast newt in particular.Will I need to upgrade the focuser?

Since I am selling my CPC1100 for a C9.25 for Planetary and some DSO AP but still want my visual fix should I go for a 12 inch truss Dob instead? is it MUCH bigger? Whats the FOV like on a Dob? the FOV will depend on the focal length but is likely to be more in a 12" dob than any SCT above 6". in a 12" f4 your 35mm Panoptic (which might result in too large an exit pupil with an f4/5 scope) would provide a true field of 1200/35 = 34 and then 68 / 34 = 2 degrees of field. in an f5 12" it would be 1.6 degrees.

Should you get a dob - I refer you again to my canine insurance selling friend.

Sorry for so many questions !!!

Kind regards, Steve