What can i expect from by 8" f/6 gso dob ?

[Krishnam kalra]

What should i expect from my 8" f/6 scope . I know that i will not see image like hubble space telescope . I just want to know that if i point my scope towards a planet , say jupiter , then how much detail i will be able to see and at what magnification . Similarly saturn , mars , dso s , etc . 

[Moonshane]

Most bigger planets (Jupiter and Saturn, occasionally Mars) will be the size of a grape held at arms length depending on magnification, subject to seeing. Neptune and Uranus will be pea sized at best.

Google 'astronomical sketches' for an idea of other objects depending on your skies. Most galaxies will be whiffs of faint smoke with a bright centre. Think about what you are seeing rather than the quality of the image.

[michael.h.f.wilkinson]

An 8" scope will show quite a bit of detail on planets, especially Jupiter. Likewise, from a dark site, you should be able to get some nice views of many nebulae (M42 is spectacular). I have managed to spot some 500 galaxies and a wealth of other deep sky objects with my Celestron C8. You 8" Dob should be able to do the same

[PaulM]

I have an 8" f/5 dob

Jupiter - 4 Galilean moons clearly and some banding and the great red spot

Saturn - rings and cassini its division - some of the brighter moons

DSO - depends on your light pollution and the objects - most galaxies are fuzzzy and for me disappointing, globular clusters are great as are certain nebula 

[Ricochet]

I tend to think more in terms of exit pupil than magnification with the following approximations:

Planets: >0.85-1mm (If the atmosphere supports it)

Star Clusters: >1mm

Unfiltered extended DSOs (galaxies, nebulae): >2mm

To calculate the focal lengths of the corresponding eyepieces simply multiply those numbers above by the focal ratio of your telescope (6). Remember, the numbers above are the end of a range and you should not just aim for the highest magnification. The other end of each range will be an exit pupil of 7mm from a dark sky location, 5mm or shorter from a light polluted location.

If you use UHC or OIII filters to view nebulae then the dimness will require a larger exit pupil. For large DSOs you may require a wider field of view to properly frame the object which will require a longer focal length eyepiece.

Personally, I find that for lunar and planetary a binoviewer is best, both for picking out detail and making the image seem to be larger (but that is an optical illusion). Having enough in-focus may be an issue depending on the exact setup of your telescope. A barlow/corrector on the nosepiece of the binoviewer will be needed for a commercial Newtonian.

For DSOs monoviewing is best as they are faint and there is light lost by splitting the image in a binoviewer.

[Mr niall]

With a scope that size light pollution and seeing conditions begin to become the biggest factor in what you can see, but with a scope that size you could happily spend a lifetime viewing and not cover everything.

If you live in a very light polluted area then thing s like faint galaxies will be less amazing but the moon, planets, open and closed clusters and double stars are excellent targets.

[Sunshine]

That scope will provide you with a decades worth of great observing, especially if you can get away from light pollution. You will see beautiful star clusters, nice detail on planets, spectacular lunar vistas and much more, many members here observe with 3 inch refractors which they’ve enjoyed for years, an 8” dob is a great scope.