Eyepieces needed for planetary viewing

[butser]

My wife is just starting out in astronomy, and we are currently looking at the equipment needed for visual use only. We think a Skywatcher Explorer 200 P-DS on an HEQ5 mount is the right setup, but are now stuck on what size eyepieces to go for. She would like to be able to see some detail on the moon and major planets, so what do we go for to achieve that ... 4mm, 8mm ? In other words, assuming good seeing conditions, what magnification is needed to see some detail on Jupiter, Mars and Saturn?

We are currently looking at Baader eyepieces, as they seem a good balance of price and quality, and would be grateful for any views on their suitability, as well as any other recommendations for good medium-priced eyepieces of less than £100.

[alan potts]

Firtsly different amounts of magnification are required on different planets for ideal viewing. Jupiter with show nice detail from X100 or there abouts but you don't really need to go above X180-200 with this planet, you can but there is no real need in my opinion. The Moon can be viewed with almost any amount of power and still show detail up to the scopes upper limit.

Saturn is an object that can handle a little more mag, X240 or in this area but at this point, you ,except under excellent seeing conditions run into turbulance caused by the atmostphere. Mars also need a good deal of power because it is small when put against the other two.

I would like to know the focal length of your scope before I consider eyepieces, No doubt some members will know it without even looking it up, if it is a fast scope, that is one with a shorter focal lengh ratio to mirror apperture, then this becomes more demanding on eyepieces. The cheaper ones on the market will not show the stars at the edge as sharp points of light, in fact even some of the more expensive ones fall short on this point.

Alan

[PDW]

I have some Baader Hyperions - good quality, wide field of view and not super expensive. There are accesory fine tuning rings of two sizes that alter the focal length - the thinner ring or the thicker ring or add them both and you have a total of four achievable focal lengths. They can go into a 1.25" or 2" fitting. I am happy with mine.

[Carbon Brush]

Baader Hyperions are very good all rounders. I have used them and got on well. Just in budget new and £65/70ish used.

For a bit more money you can get the zoom version. I recently bought one but the weather has meant it has not been fully tried out.

Results so far are very encouraging. Image quality is excellent. The benefit for planetary viewing is you can easily turn the magnification up/down to find the best results for how the sky is looking at the time. The only downside is that the FOV is narrower than a fixed Hyperion. For DSOs this is noticeable, but for planets not an issue.

There is a 2.25x Baader barlow available. I bought one with the zoom as there was a package deal on at FLO. The barlow is very good and I have not found any degradation in image quality from using it. Can't say the same for the low cost barlows.

The EQ5 mount with a 200P (or PDS) is fine for visual work. But is on the limit if you start on photos and HEQ5 is more suitable.

My SW200P has taken approx 285x viewing Mars, once. This was using a 3.5mm Hyperion. Generally though the sky limits the magnification rather than the scope.

Hope this helps, David.

[butser]

Many thanks for the speedy responses. The focal length of the 200P-DS is 1000mm, which makes it an F5 focal ratio. What is concerning me is that if we need a magnification of 200 plus , which it appears ideally we should go for, then we would need an eyepiece of 4mm for that, and one so small would present problems. If that is so then maybe we should be looking for a telescope with a larger focal length so that we can use larger eyepieces e.g. 6 or 8mm.

[Qualia]

assuming good seeing conditions, what magnification is needed to see some detail on Jupiter, Mars and Saturn?

There's already been a whole load of good advice offered, so I hope I'm not going to repeat what has already been said. When it comes to planetary viewing, I've noticed that even a slight change in the EP's focal length can make a significant difference to what can be tweaked from the given object. From this realisation I have a little run of EPs which include in terms of magnification:

• f/10: 200x, 166x, 142x, 133x, 111x, 100x, 83x.
  
• f/5: 250x, 208x, 178x, 166x, 138x, 125x, 104x.
  

For Lunar work, depending on the night, every single EP offers up something to see and be amazed by. I love the low power EPs to frame the Moon, the Mid-range ones (in this list above) to frame craters and seas and mountain ranges and I love the high-power EPs to spy subtle features.

For Jupiter - looking through my journal - I find the most used EPs since last July have been those which have offered a range between 140x to about 180x.

For Saturn - looking through my journal for last year because this year I haven't begun viewing - I find that I was mainly working between 140x to 200x. I'm sure I can go higher and will try out for practice this Spring season.

Mars - according to my journal for last year - was tricky and I figure one really needs excellent seeing conditions to tweak any kind of significant detail from the tiny red-orangey orb. The way I look at is that Jupiter is in general about 3x the size of Mars and to see Jupiter nicely is, say, at around 150x which means that for me to get a 'similar' view of Mars I need 450x. Well, I'm just not going to get that kind of viewing quality here in Spain. So, I figure a compromise is needed, say around 250x which still means seeing conditions will have to be very, very good.

Other than that, in general, try to view the given object as close to the zenith as possible and bear in mind that as a general rule of thumb the brightness of an object will decline as you up the magnification. If I up the mag twofold, say, I'm reducing the image brightness by a factor of four. If I keep on doing this eventually details just disappear.

On the other hand, increasing the mag does make detail more apparent, so, as you can appreciate, we're now at a trade-off: will increasing magnification gain more detail even though I'm making the object fainter?

I've found that playing around with this trade-off - dependent on the evening's seeing (I've found that LP doesn't really affect planets) - does make a difference. Even as little as 1mm increase or decrease in the mag - about 10% to 15% difference of magnification - can be quite surprising which is the main reason why I have quite a run of high-mag EPs.

For planetary work I love using Orthos and in particular those that used to be made by Baader - the BGOs (no longer in production). By all accounts, brushing field of view to one side, the quality of image in these BGOs is about as good as it gets. Baader also have a Classic range now on sale which by all accounts is almost as good as the older BGO types. There's also a tasty range of Hutechs which look just like the older BGOs and I imagine offer up a similar quality of image.

Final thought, if you can, try to sit with your given object for a peaceful twenty or thirty minutes or so on each of your observation sessions and often what happens is that they'll be moments of great clarity and seeing. Also by practicing this attentive sitting, you come to notice more and more detail from the given object as the weeks go by.

I hope this helped a little

[butser]

I'm really grateful for all the advice given. Clearly there have to be compromises and trade-offs, and as this is our first venture into astronomy the 200P-DS with some Baader Hyperion eyepieces seems a reasonable route to go down. I think we'll go for eyepieces of 5 - 20 mm to start with to give us x50 up to x200, and then take it from there as we get a better feel for the equipment and more observing experience.

[John]

Hyperions are nice eyepieces but don't do so well in scopes faster than around F/6. Stars in the outer parts of the field of view will look increasingly distorted towards the edges of the field. I just don't think they are worth £98 for use in fast scopes.

For observing the planets I'd suggest the William Optics SPL 6mm (less expensive than a Hyperion too) or the Baader Classic Orthoscopic 6mm (less expensive again but optically up with the best).

Sorry if that confuses things

[alan potts]

I would tend to agree with John here Hyperions and F5 I feel are not such a good mixture. It is better to buy something you are happy with even if for now you can only afford the one. Look at the second hand market, Astro Buy and Sell have some good buys on the site and most are from known astronomers, many from this site. Check the history behind sellers, the vast majority are honourable people but there are a few sharks.

I would try for something around 6mm if planets are what you are most interested in. I have a 1000mmm scope and know a 6mm will give pleasing results, the WO SPL is also a very good eyepiece but I have only ever looked though one for a few minutes. They only come in 3 sizes, 3mm, 6mm and 12.5 I believe., FLO sell these so you should not have any problem getting one. You could also consider the longer one and a Barlow this would give you 2 focal lenghts.

There is also a 6.7mm UWA eyepiece from Meade that would do you very well but this is one for the secondhand market as they are no longer made by them

There are many more on the market but sadly with a large ticket price.

Hope this is some use.

Alan.

[cotterless45]

For the money Bst Explorers are hard to beat . From the same source there's also an excellent flat field 8 mm whch performs well at in fast scopes.

For planetary and lunar work I find that a 1200mm f6 ota {SW 150pl } gives lovely contrast and excellent views with a 5 mm Bst,

Nick.

[Iddy]

as a small side note : the 200PDS comes with a 2" 28mm eyepiece, so make sure you dont order one of those

[andrew63]

I hope you don't mind me putting a bit of a spanner in the works - but just a few things to consider if not already pondered on.

Firstly have you had a chance to see one in the flesh? Often people are surprised just how large telescopes and equatorial mounts are when delivered. Although not too large this is a serious bit of kit to move about - and what else have you considered? - there are several more portable options available. This site and others are littered with stories of equipment left hardly used and sometimes other setups could be more suitable depending on circumstances.

Perhaps you could get the opportunity to go to a local astronomy club and when they have an observing session get to see some different telescopes. Just some food for thoughts as starting out can be a big investment!

I also would not consider hyperions - certainly not in the type of equipment you are thinking about and eyepieces such as the celestron x-cel lx will perform much better around the edges of the field of view. Hyperions would be fine if used in a F8 to F10 telescope.

Sorry for sounding a bit negative, but whatever your wife choses i hope you enjoy the new telescope!

andrew

[ronin]

As Andrew has said have a look at the scope and mount when it arrives, they always sound small but are not. I bought an HEQ5 took one long look at it and eventually bought an EQ5 (as well) the EQ5 is less scary. However the HEQ5 is all the mount you will need and is better suited to a 200P then an EQ5 is - all my scopes are smaller then a 200 so I am fine with the EQ5.

Eyepieces: To me there are about 2 options in the budget range = Celestron X-Cels or BST's.

BST's come in 5, 8, 12, 15, 18, 25

X-Cels come in 2.3, 5, 7, 9, 12. 18, 25

For 200x then either range, however the X-Cels have the 7 and 9 which I think would give better choices then the single 8mm in the BST range.

So I would suggest looking at the X-Cels and perhaps the 7mm first, or if you get just one eyepiece with the scope then the 9mm just for the slightly wider viewing. If you know anyone with either the X-Cels or the BST's then see if you can try one. Simply the difference is minimal, if there is any, and ultimately the BST's cost £20 less.

For above 200x then neither really supply anything, pretty sure that the 2.3mm would be too much for just about anything. Seems an odd size to build but if someione here has one and can comment that would be useful. Now if there were such a thing as a 4mm X-Cel then that would be useful.

Will say that the only object that really seems to need greater then 200x is usually Mars. Viewing Mars tends to be as much luck as equipment. Having read 2 passes worth of Mars posts here it may be 80% luck and 20% equipment.

[butser]

Taking the views I am getting, and having done a bit more scouting around SGL forums, I take the point about Baader Hyperions not being the right eyepieces for a fast scope such as the 200P-DS. Martin of FLO has very kindly agreed to replace the Hyperions with X-Cel LXs, and my wife has gone with 5, 9 & 18mm ... the 5mm when the seeing's really good. Together with the 28mm I think these will give her the spread of magifications she's looking for.

[Qualia]

You're going to really love the X-Cels LXs, Buster. They're sharp across the image and you can adjust eye-relief just as you need it. It's probably very much a subjective thing, but I prefer LXs over the Hyperions and have found that both in the f/5 and f/10, they're just of a different class of quality. Only warning - don't unscrew them! I messed my lovely 18mm by doing just that

[rwilkey]

You're going to really love the X-Cels LXs, Buster. They're sharp across the image and you can adjust eye-relief just as you need it. It's probably very much a subjective thing, but I prefer LXs over the Hyperions and have found that both in the f/5 and f/10, they're just of a different class of quality. Only warning - don't unscrew them! I messed my lovely 18mm by doing just that

Good call, like John above, I agree that the Baader Hyperions are a bit soft on fast scopes. Also, in my opinion, ep's from 7mm (142x) to 32mm (31x) are best suited to the 200P from my experience.

[Stargazer_00]

Taking the views I am getting, and having done a bit more scouting around SGL forums, I take the point about Baader Hyperions not being the right eyepieces for a fast scope such as the 200P-DS. Martin of FLO has very kindly agreed to replace the Hyperions with X-Cel LXs, and my wife has gone with 5, 9 & 18mm ... the 5mm when the seeing's really good. Together with the 28mm I think these will give her the spread of magifications she's looking for.

Hi,

It may be too late but if you intend to buy a 2x barlow then buying a 9 and an 18 isnt totally wise. you'd be better off with a 18 and a 12 to get 9 and 6 from a barlow.

[butser]

Thanks for the warning about unscrewing the X-Cels!

On the question of size raised by andrew63, we spent a lot of time looking at portability, as we will need to take it out in the car to find some skies darker than in our back garden. We looked at quite a lot of telescope videos on YouTube to see how people were able to handle their telescopes, and took into account comments on size/weight made on this forum. The view we came to was that 8" is about the maximum you can consider taking out in the car; we did think about lightening the load by going for an EQ5, but then we thought that would compromise the stability needed to get into photography, if that is something my wife feels like trying. So, yes, we understand the setup is a fair lump of kit, but if we go out to star parties or to somewhere other than the garden, we thought we would manage that by breaking it down to tripod, mount and scope. We're going to practice assembly and dissassembly ... first in the house in the light, and then in the dark with a red light on, because otherwise I can imagine our first experience could be disappointing to say the least.