Skywatchers 200P... Maximum Potential Viewing?

[lighty89]

I've got a 200p dob and was just wondering what the smallest mm eye lens I could use with a 2x Barlow lens?

I struggle with the focusing! I've got one 10mm plosl lens that I bought off someone on here as well!

Also, andromeda never looks very big through it either, how should it look?

Anybody have example images of what I should be able too see through it?

[John]

The Andromeda galaxy needs the lowest power eyepiece you have - it's a very large object. Images don't help because our eyes can't see what CCD's and image processing can pick up. Sketches are a better guide. Unless you are under very dark skies, the central core of the Andromeda galaxy is what you see - it's still nearly as big as a full moon though.

Your maximum power, which you would use on the Moon, planets and double stars, would be somewhere between 180x - 240x depending on the seeing conditions which are the biggest factor determining what we can and can't see.

So eyepieces in the 7mm - 6mm - 5mm focal length are useful. You can get there by using a 2x barlow on 15mm, 12mm or 10mm eyepieces of course. The stock 10mm eyepiece is not good quality though so don't expect much if you use a barlow with that !

Other objects such as nebulae, smaller galaxies, star clusters etc are best viewed with low or medium magnifications, ie: 30x - 80x or so.

[onesmallstep]

Hi

You could use a 6mm plossl with a 2x barlow which would give a magnification of 400, the maximum for the aperture of your scope.

However, things aren't that simple. The rule of thumb is to magnify 2x per mm of aperture so 200mm x2 = 400x magnification. The RoT is based on perfect 'seeing', perfect optics, perfect eyesight, etc. A more realistic magnification from the UK is between 1x and 1.5x per mm or aperture. The skies are rarely clear enough to push magnifications above this ratio without the quality of the image suffering. Also, the magnification required for individual objects will vary from 15x on a full moon or a large object such as M31 up to 200x on planets or to focus down on specific lunar regions.

It might be worth investing in some higher quality eyepieces. Ideally you need one each of low, medium and high power. Used with the barlow lens this will give six magnifications covering all objects. A moon filter would be another usefull accessory.

HTH!

[sunshine185]

Mars,Saturn,Jupiter I have been using around 6mm-9mm lately on these, but the last couple of days it has been so good I think I could have pushed it a little more.

[twotter]

I have used a 6.4mm plossl with a 2x barlow in my 200P dob, two or three times. Far more often I use longer focal length eyepieces to enjoy wider views, though the view of M31 and M45 is still a little tight. I'm saving for a 31mm or 36mm Hyperion

[Solar_observer]

Just brought the scope in from an hours viewing (200p dob) I'm a little confused about this maxvision magnification thingy? Just for curiosity I tried a 5mm bst/x2 celestron Ultima Barlow combo 480x and almost......Just almost it was perfect,I think it was the fact there is high thin cloud and the seeing is average. So 480x is well beyond the spec of this scope,so how was this possible?

Clear skies to you all :-)

[todd8137]

Low power for high contrast views the standard eps are ok but not the best try low power for brighter views

[John]

Just brought the scope in from an hours viewing (200p dob) I'm a little confused about this maxvision magnification thingy? Just for curiosity I tried a 5mm bst/x2 celestron Ultima Barlow combo 480x and almost......Just almost it was perfect,I think it was the fact there is high thin cloud and the seeing is average. So 480x is well beyond the spec of this scope,so how was this possible?

Clear skies to you all :-)

What object were you viewing ?.

My 12" Orion Optics has great optics but I rarely use 400X or more on anything other than the moon or a tight binary star and even then it's not adding any detail to the image, just boosting it a bit.

When I had a 200P dob (which was a great scope) I found 200x or 250x the highest I wanted to go. I did venture to 300x a couple of times but things generally got less in terms of contrast and detail, rather than more.

[Solar_observer]

Sorry it was the moon,it really took me by surprise how good the view was. It wasn't pin sharp detail but it was good enough to spend time at the eyepiece with.

Clear skies to you all :-)

[John]

Sorry it was the moon,it really took me by surprise how good the view was. It wasn't pin sharp detail but it was good enough to spend time at the eyepiece with.

Clear skies to you all :-)

The Moon is great for pushing the power - I've just been up to 530x and it's still quite sharp. Not as sharp as 300x though but fun all the same 

Jupiter doesn't like it though ! 

[Solar_observer]

Really did feel as though I was about to land on the surface :-)

Could only manage 150x on Jupiter tonight,even then the detail wasn't too write home about.

Clear skies to you all :-)

[Daz Type-R]

Yeah general rule of thumb for British skies is about 200x max, potential max power is just that, potential, you have to remember that you are not only magnifying the object you are trying to view, you are also magnifying atmospheric distortions, thin high cloud etc etc....

My personnel choice is not to get an ep higher than 6mm, i could get a 3, 4 or 5mm but they will only be used 2-3 times a year when the atmosphere is absolutely perfect.  

That's just my personnel choice, I'm starting to spend a fair bit on eps and I would actually like to use them, not have them sat in a case.

[Charic]

Just brought the scope in from an hours viewing (200p dob) I'm a little confused about this maxvision magnification thingy? Just for curiosity I tried a 5mm bst/x2 celestron Ultima Barlow combo 480x and almost......Just almost it was perfect,I think it was the fact there is high thin cloud and the seeing is average. So 480x is well beyond the spec of this scope,so how was this possible?

Clear skies to you all :-)

Its all theory, and also dependent on 'Your' seeing conditions and' YOUR' eyes. I was often,"on the Moon" with 375x using a Revelation 2.5xBarlow,  and my 8mm BST ,and swear I could have gone much higher. The detail was just awesome  between  Day & Night  on the Moons mountain ridges. And my recent best views of Jupiter were at 360x using my replacement Barlow,  the 2x Deluxe from Skywatcher (just the lens, not the Barlow tube at 1.5x directly attached the the 5mm EP). I witnessed my first trasnsit of the shadow of Io, the shadow was a perfect black circle, just amazing, then some time later Io appeared (masked by the brightness on Jupiter). This again is 'pushing the limits' of whats supposed to be achieveable. Sometimes its just pot luck as to what we see, other times its down to  perfect conditions between you and the target, which would be different for me at exactly the same time and date, but at the other end of the country.

I know these limits are well below your 480x but  at 360x my view was perfect for me. The next time I get a similar clear view, I'll try with the Barlow tube at 2x.

[ollypenrice]

You can push the magnification on the moon, sometimes, towards 500x but the acid test is to pick a tiny feature and then compare it with a mag of 250 and ask yourself honestly whether you are seeing anything new at the high power. I doubt that you are, you are just getting a buzz out of a feeling of proximity. When you look at Jupiter, which has tiny details, you can see the truth - which is that the ultra high magnification is not in fact better in terms of resolution.

Olly

[Solar_observer]

I will try that method of a high mag on a particular spot and then switch too medium. I certainly was getting a buzz like you said. But I suppose a buzz is not good enough if it's reducing the quality of the image.

Clear skies to you all :-)

[John]

As Olly says, while it's fun to really push the magnification sometimes, after a certain point, which tends to vary with the seeing conditions, the finest details start to get harder to see rather than easier, as the magnification level climbs.

The conditions during the early part of last night were pretty good and my 12" dob seemed to show a pretty sharp image of the moons surface even at 500x. When I wanted to tease some really fine details out though, features that are close to the resolution limit of the scope, I found dropping back to 250x - 300x was required for the clearest and most consistent glimpses of these features.