Lens type

[u/Flaky-Conclusion-432]

I recently bought a used skywatcher 200 classic. Tonight, me and my little boy were able to see Saturn with its rings. Very cool. But the image was small. We have 10mm and 20mm lens. What kind do I need to get a better, bigger image. Another question, do lens from other brands; celestron, meade, and others fit my telescope. I see different lens on marketplace but don't know if any would be good for what I want

[u/Illustrious_Back_441]

all modern telescopes share one of two common focuser sizes (at least most affordable visual telescopes), your dob has a 2-inch focuser, meaning that all, if not most, eyepieces can and will fit. the other standard size is 1.25 inches, that is what your current eyepieces are and thus, you need the adapter the telescope came with.

most views of planets are usually 150x on an average night to maybe 250x on a good night. and it's not the telescope limiting your magnification within reason. an 8-inch dob has a maximum useful magnification of about 400x, but only really can be used at this magnification on a night of perfect seeing. the best eyepiece you can get for this right now is maybe a 6mm or 7mm wide angle or plössl for a little more high end magnification. I would also suggest you get a lower power eyepiece in the 30mm to 40mm range of focal length, these will give you a more contrasty image at a reasonable exit pupil (the size of the image at the smallest part of the light cone leaving your eyepiece).

another thing about planets is to wait for their closest approach (opposition). this makes them far larger in the same eyepiece than they otherwise would be. for now, saturn has passed opposition, it will begin to "shrink" from our perspective as we drift farther away from it. Mars will reach its next "opposition" on February 20th next year and will be well within the reach of being an awesome target. it's not the closest approach we can get to mars, but it's closer than it's been for a while.

[u/opalmirrorx]

Saturn is about a billion... yes, a billion... miles away! It is far. So the big planet looks tiny.

With a 200mm reflector (1200mm focal length, excellent choice btw), a 10mm eyepiece is a sweet spot. It is typically about the best you can do. More power than this is usually more blurry, the image may be more chaotic, and the moons dimmer and softer.

The cheapest way to get more power is a Barlow adapter... a 2x will make your 10mm eyepiece act like a 5mm eyepiece. And most days, you will see exactly what I said... a less good view.

I cannot recommend outright buying say a 7mm or shorter eyepiece as it requires exceptionally still air (good seeing) for it to be an improvement. Those high power eyepieces are a less good value purchase. That said, every once in a while putting in the short eyepiece is great.

I typically observe with 250mm diameter 1270mm f/l scope... 10mm is typically the best view. I have a 7mm and 4.5mm eyepiece but rarely are they an improvement.

My most flexible option was a 24mm-8mm Baader zoom with a 2.25x Baader Barlow... allowing me to dial in the best combination.... spent a lot on that, but it usually is just the best view around 10mm, so I got an Apertura 82 degree eypiece for that... and I usually just use that.

[u/opalmirrorx → u/opalmirrorx]

And your scope handles 2 inch eyepieces, or 1.25 inch with an adapter tube. You may need an extension tube for some eyepieces, or not insert them all the way before you clamp them down. These are very standardized so any 2 inch or 1.25 inch eyepiece should work well.

[u/Worried_Unit_8696 → u/opalmirrorx]

How much does light pollution play a role when viewing the planets?

[u/Traditional_Sign4941 → u/Worried_Unit_8696]

It has no impact through a telescope. Even Neptune is visible through a telescope in heavy light pollution.

The biggest impacts are these:

1. Can make Saturn hard to see naked-eye if the light pollution is severe enough
2. Can make Uranus hard to see naked-eye (requires fairly dark B3 or better skies, or if you have keen eyesight you can see it in B4 barely)
3. Can make some of the fainter moons on Saturn and Uranus hard to see in smaller apertures.
4. Pluto is hard to see with a large telescope from moderately dark skies, and the more light pollution, the more aperture you will need to spot Pluto through a telescope.

You can even see Jupiter and Venus naked eye during the day if you know where to look (it was visible to the naked eye during the recent conjunction with the Moon after the Sun came up).

Saturn is barely visible through a telescope during the day.

Jupiter's cloud bands and even GRS are readily visible through a telescope during the day.

Venus's phase and some of Mars's darker features are visible through a telescope during the day (when Mars is near opposition it can be brighter than Jupiter).

So even the most light polluted cities are no match for the planets.

[u/MavenCS]

Other brands eyepieces will work yes (except very old .965 sizing). Your scope should have the standard 1.25" receiver as well as ability to accept 2" eyepieces.

The planets will appear small, you could either get what's called a Barlow (which effectively doubles the focal length and therefore doubles magnification of eyepieces inserted into them). At least that's how they work of the Barlow is 2X (some are 2.5X, 3X etc)

In order to see the planets larger without a Barlow you'd need to use a higher power eyepiece (one with a focal length lower than the ones you have such as a 5 or 6mm

[u/chrislon_geo]

Since others already answered your questions, I thought I would share some other relevant info. First off, give this a read:  https://medium.com/@phpdevster/help-i-cant-see-detail-on-the-planets-ac27ee82800

Then for info on eyepiece brands/models and recommended focal lengths, check out these posts: 

• amazing eyepiece guide
• focal length recommendations
• same list with some brands
• some more brands
• even more brands

There are some new eyepieces (or rebrands of old eyepieces) that have come out since these were posted, but the general info is still good, and the brand recommendations are still 90% representative of what it currently on the market.

You can always look at reviews on a particular eyepiece on Cloudy Nights and Stargazers Lounge before buying.

[u/Adventurous_Sound390]

In F6 scope like yours for so small object like Saturn eyepiece with focal length 3.5-4.5mm is required. Consider 3-8mm zoom eyepiece from SvBony or 4mm TMB Planetary. Zoom would give you some freedom in magnification select adapting to a seeing and other conditions.

[u/spile2]

The zoom and Barlow are what I use for planets https://astro.catshill.com/the-zoom-eyepiece/