saturn same size in 200p as 150p

[chemtom24]

hi all,

I was kinda dissapointed that saturn wasnt that much bigger in my newly gained sw 200p than in the sw 150p.

I know both these scopes are fast at F/5 but I still expected a larger image than I got.

Am I hoping for too much? Can anyone name a few reasonably good planetary scopes which I can get hold of cheaply?

[Ags]

The image should have been 33% wider... that's quite a substantial improvement, especially as the 8 inch shows the larger image at a higher resolution.

With an 8 inch aperture, your current scope is already very good at planets. Short of getting a massive 10 or 12 inch scope, I'm not sure what you can do. These would also only show a small incrementaql improvement over yuor 8 inch.

[chemtom24]

so a slower 150 wouldnt give me a bigger image than the fast 200?

[Bazzaar]

Well you shouldn't have been disappointed because all the figures are available before you buy to work out that you would only have got 33% more magnification from the 200p.

The 200p IS a decent planetary scope, and you have the eyepieces to get the best out of it.

Wait until Jupiter is more conveniently placed and see what you think then.

Regards

Barry

[John]

Which eyepiece(s) were you using ?

It's the eyepiece coupled with the focal length of the scope that gives the image size, not the aperture.

The 200P has a focal length of 1000mm and the 150P is 750mm. A 10mm eyepiece used with the 200P would give the same magnification as a 7.5mm with the 150P.

[chemtom24]

i know that ep's give the mag but i was under the impression that a bigger primary mirror would give a larger view of said objects? or am i confusing that with a longer focal length - in which case i shall ask again - is a slower 150 better for planets than a fast 200?

[Bazzaar]

Slow/fast are terms used for photographic purposes, focal length determine image size, generally larger mirrors have longer focal length but its not safe to assume that. So your question "is a slower 150 better for planets than a fast 200?" is not answerable.

[John]

The bigger primary mirror will show more detail but the image size is determined by the focal length of the scope divided by the focal length of the eyepiece. So a 150PL with a focal length of 1200mm (F/8) will give more magnification than the 200P will a focal length of 1000mm, assuming the same eyepiece is used. The 2OOP's image will contain more detail though.

[noakesy]

i have a 200p and when i put in x2 barlow with 15mm the pic is very good

[Ags]

To answer your question, no. The longer focal length just results in the same EP giving a higher magnification. So in the slower scope you could just use a shorter FL eyepiece to get the same effect.

I think the only real issue is that a slower scope will have fewer aberation like spherical aberatino and coma, and would need less collimation.

[chemtom24]

maybe im being fussy and its the seeing which isnt allowing me to push the scope

thanks for all repleis

[John]

The 200P should be able to deliver nice images of Saturn at around 200x - that would need a 5mm eyepiece. Pushing above that does not generally deliver better images (ie: more features resolved) unless the observing conditions are really good.

[todd8137]

buy a cheap spc880 from morgans flash it to spc900 spec,then down load WcRmac flash again to "specail factory setting the webcam in the ep on the 200p use sharpcap to capture your avi zoom to 150% with sharpcap its about the size of a 50pence piece on the screen with cassini div and storm bands on saturn just the other night nere i have a sw300p it can zoom to about 400% with the rack and pinion focus may be a prob i have a crayford and its ok i have had other planets this way but the dob base makes tracking i prob but still at 30 fps its not a prob

clear skies always

pat

[spaceboy]

hi all,

I was kinda dissapointed that saturn wasnt that much bigger in my newly gained sw 200p than in the sw 150p.

I know both these scopes are fast at F/5 but I still expected a larger image than I got.

Am I hoping for too much? Can anyone name a few reasonably good planetary scopes which I can get hold of cheaply?

You will have to forgive me but I find it mind blowing that I can see the rings of Saturn the cloud bands and the cassini division given that all I am seeing if the light reflecting from the planet 1.2 billion km away. 1.2 billion km and I can see it with my own eyes. I can appreciate your concerns that you have shelled out on an upgrade only to feel you have wasted your money but the reality is all the planets are a REAL long way away and there is only so much an affordable scope can do. If you want to see drastic improvements in size you are going to have to look into getting a re-mortgage. TBH I don't see any real improvement between my 8" & 10" on planets but the subtle improvements on those faint and fuzzes makes lugging that larger tube around worth it.

[stev74]

maybe im being fussy and its the seeing which isnt allowing me to push the scope

Don't be too disappointed it's not the best time of year for observing. I've had some great planetary views with my 200P, on a good night stunning views with my 5mm TMB (x200). Most nights my 6mm Ortho (x166) is used for planets although they look slightly smaller they will be better resolved.

I'm a great believer in the more time you spend at the eyepiece the more detail you will be able to tease out of an object. I find some basic sketching can help concentrate the mind and gain you some extra detail.

Also the more time you spend observing the more experience you will have of the viewing conditions - seeing, transparency, atmospheric condition etc.

Take your time and enjoy the views, you have a great scope.

[chemtom24]

spaceboy - dnt get me wrong, i too am in awe of the universe and the distances involved, but every now and then my greedy mind wants an instant wow factor and the scope was 2nd hand got it pretty cheap

steve - yes the more you look the more you see! im still getting used to the seeing conditions i think, and being able to tell if i have good or bad seeing isnt too easy - i keep blaming my scope or the ep or the collimation but theni rememeber that seeing might eb bad and that is most liekly why im not getting the views i want. i picked up cllimation opretty quickly so its not that and i have the scope and ep's for good views so i guess its the seeing.