Largest mm for SkyWatcher 200p

[Kebabologist]

Hi, Very new to this so I have a quick question about lenses -

I have a 2.5mm UWA / Super 10mm & 25mm but I'm looking for some thing with a bigger view. So the question is what is the largest mm i can use on a Skywatcher 200p ? .

[John]

Hi,

By "bigger" do you mean to make objects look larger, ie: more magnification or to see a wider view, ie: a broader expense of sky ?

Also, is your scope the 200P on the equatorial mount or is it the dobsonian one ?. One has a focal length of 1000mm and the other 1200mm.

[Kebabologist]

Hi John

I have the EQ5 Mount (1000mm) and I would like to see a broader expanse of sky as I have reached the x400 max with the 2.5mm lens

[brantuk]

400x with a 2.5mm eyepiece is very high magnification and you'll get a very narrow field of view. I've comfortably used a 35mm eyepiece in my 200P and had very wide fields of view at only 28.5x magnification. So if it's wide fields you're after then a lower magnification is required and longer eyepiece focal length. I'd suggest something in the 28mm or more wide angle range.

[emadmoussa]

If you mean field of view, then the 100-deg eyepieces. There's the 9mm 120-deg, but it's about £1000. 

[Kebabologist]

Thanks for the info guys

Wide fields of view with a 35mm sound good,

Emad - £1000 for an EP ! my wife would have a shallow grave dug before it arrived in the post.

Again thanks for the direction 

[Cornelius Varley]

The lowest useful magnification, according to this site http://astronomia.co.uk/index.php/sky-watcher-explorer-200pds-eq5-telescope.html . is 20x which would require a 50mm eyepiece. 40mm would be more practical.

[emadmoussa]

Thanks for the info guys

Wide fields of view with a 35mm sound good,

Emad - £1000 for an EP ! my wife would have a shallow grave dug before it arrived in the post.

Again thanks for the direction 

I personally  use Explore Scientific 100-deg eyepieces and they're absolutely brilliant. They cost between £200-£400...still expensive, isn't it?

[Kebabologist]

Its not a cheep hobby at all. The wife does not know how much I have spent nor will she. Addictive

[Bart]

Shallow grave!! I'd be shoved into a skip

Barry

[AlexB67]

The lowest useful magnification, according to this site http://astronomia.co.uk/index.php/sky-watcher-explorer-200pds-eq5-telescope.html . is 20x which would require a 50mm eyepiece. 40mm would be more practical.

Unless I got the wrong scope data,  I am not sure how they come to that figure ( something to do with AP where I am clueless) , but for visual 20x would be a 50mm eyepiece that would give an exit pupil of 10mm, not useable since you would start seeing the secondary, plus wasting a lot of aperture.  To keep the exit pupil below 7mm at least gives 33x, this would be an eyepiece of 35mm.

Depending on where you are observing from, especially under less good skies I would say this not the best choice. Without knowing your pupil dilation but for a healthy person 30 - 45 years old or so, 7mm exit pupil  is probably okay in most cases to use and look through, though perhaps not be best for contrast in a  lot of cases.

The 30mm ES 100 would not be a bad choice ?, keeps the exit pupil down to 6mm and a whopping 3 degrees or so,  a nice of expanse of sky if that is what you are after.

[John]

I agree with Alex. 30mm - 35mm would be a sensible max for an F/5 scope. The size of the field of view you can get that is well corrected will now depend on your budget !

I use a Nagler 31mm but the 30mm ES 82 degree or the Meade 30mm 82 degree can be bought for a lot less and show very nearly as much sky.

[AlexB67]

If it were down to me personally since the scope is f/5 and without a coma corrector I would actually get a decent 82 degree eyepiece 30mm or so for such a scope. It would still show plenty enough sky for my liking, and the performance across the FOV should stay reasonably decent in terms of star sharpness  across the FOV, in a well corrected eyepiece.  The 100 degree version will begin to suffer from coma at f/5 ( To the OP, this means stars begin to degrade in sharpness the further towards the edges you look in eyepiece, and the stars begin to look more like comets the closer to the edge you look, the wider angle the eyepiece is, the worse this effect will get) 

There again I am a little bit comallergic, ( is that a word  ) some may be fine with that.

[russ.will]

The 30mm ES 100 would not be a bad choice ?, keeps the exit pupil down to 6mm and a whopping 3 degrees or so,  a nice of expanse of sky if that is what you are after.

Blimey! I've seen a few ridiculous "Buy an Ethos" answers to "What £50 planetary EP should I buy?" answers in my time, but that recommendation is about as profligate with the fiscal provision of a fellow member as I've ever seen! 

Russell

[russ.will]

Hi, Very new to this so I have a quick question about lenses -

I have a 2.5mm UWA / Super 10mm & 25mm but I'm looking for some thing with a bigger view. So the question is what is the largest mm i can use on a Skywatcher 200p ? .

Joking aside, the recommendations for a 30mm (give or take) EP are spot on, but do also bear in mind that with increasing EP focal length, comes a brighter background sky and a lot more weight to balance. A lot more in the case of the latter when you start moving from SWA to UWA EPs. You may also be surprized at how much more sky you fit in by simply going from the 50deg FOV of the SW 25mm Plossl/MA and jumping up to a 68 or 70deg SWA. Have a play with the occulars on Stellarium to see what I mean.

As such, I found I was reaching for the ES82 30mm less and less and the MV 28mm SWA more. It makes a 32mm SW Panaview look a bit sick in VFM terms.

Russell

[AlexB67]

Blimey! I've seen a few ridiculous "Buy an Ethos" answers to "What £50 planetary EP should I buy?" answers in my time, but that recommendation is about as profligate with the fiscal provision of a fellow member as I've ever seen! 

Russell

Coming to think of it I did not intend that eyepiece in the 3 inch format at all, big misfire, I had a few of those today already

[triton1]

I use a maxi 28mm 2 inch and have had some great view and at 95 euros the missus didn't moan,well not to much

[AlexB67]

I use a maxi 28mm 2 inch and have had some great view and at 95 euros the missus didn't moan,well not to much

It is a very nice eyepiece I think, I have one myself, the missus bought it for me for Xmas, pretty much the same as the ES version in a different case, bar the purging,  coatings AFAIK, and and believed to be a Meade clone, or something that never became a Meade, or so are the speculations/rumours IIRC   . Whatever the case, it's cheaper than both and I ain't complaining about the views for a nice sub 100 pound 2 inch eyepiece. It would work well in the f/5 SW 200 scope. 

[Reeny]

I use a maxi 28mm 2 inch and have had some great view and at 95 euros the missus didn't moan,well not to much

The Explore Scientific web prices appear to be all over the place at the moment.

They had everything listed at 5% or 10% lower than normal earlier tonight.

It's all back to normal now.

If there was a special offer on for the Easter holidays - it's gone now.

[triton1]

How,s this one!4.3 inches

[Merlin]

As a guide, the lowest useful magnification is four times the aperture in inches ( 4D ). For a 8-inch ( 200mm ) Newtonian the lowest mag is: 4 X 8=32X.

I have a 32mm TeleVue Plossl which fits the bill very nicely for my 8-incher.

[rwilkey]

I agree with others, 30-35mm is the maximum you would want to consider on low power.  My choice has been the ES82 Series 30mm and it really packs a punch for around £200 (from the States)

[alan potts]

Like Robin, I had the Meade 30mm UWA which is the same glass with possible coating difference and the ExSc has gas, I sometimes wonder why I bought the 31mm Nagler, not that I can find much wrong with it but there is not much wrong with the Meade and I guess the ExSc either.

Alan

[jabberwocky]

I used to have the 30mm ES82* for my 1200mm focal length 200p, great ep but totally put in the shade by my 13mm ethos which was just brilliant, if I ever get back into stargazing the first thing I will buy after a new scope will be a 13 mm ethos. At that focal length it rarely left the ep holder

[bingevader]

Even on some of the larger DSOs? Double Cluster? Andromeda Galaxy?

And what about the other end? 92x isn't much on Jupiter, Saturn or the moon! But, I know, it's horses for courses and each to their own!

Anyway, cheap and cheerful, if a little soft around the edges, the PanaView 32mm is great.