x210 or x190, does it make a difference? EP help please

[Bart]

Hello All,

Big dilema, I'm looking for a planetary EP. I'd like to get the highest mag, that I could actually use here in Ireland. I have narrowed it down to 3 EPs for my F5 250mm FL1250mm Dob (wingings its way!)

Explore Scientific 6.7mm 82 degree AFOV giving x186 ~€110

Meade 5000 6.5mm 60 degree AFOV giving me x192 ~€70

TMB Type II Planetary 6mm 58 degree AFOV giving me x208 ~ €46

Should conditions allow me to go to high x190s reasonably often or is > x200 here a waste of money?

As usual, any comments or suggestions very welcome, thanks.

[Capricorn]

Ireland isn't actually known for it's cloud free climate however I have no idea if once it has rained then you could have a clear atmosphere for a while. That is only something you can answer.

For simple safety I would pick the Explore Scientific. Safety being that having the least magnification it should be the one to potentially least fail to supply a good view.

If you bought the TMB and it was little use then you don't have an eyepiece for high magnification.

You could then get the TMB later (it is the least expensive) if the magnification from the Explore Scientific proved to be easily within the capabilities of the scope.

From the costs you could get get 2 TMB's for one Explore Scientific. However until you know the performance of either it is a bit of a gamble.

[Crunchard]

I can't comment too much on the ES 6.7 nor the Meade, but I do have a TMB 6mm Planetary and I have a 250PX dob.

I've used the TMB a few times now and it was very good on Saturn a couple of months back, and it was very average seeing (not really dark at all). For the price I think it is a cracking little EP.

I'm sure others with way more experience than my few months will offer up more advice.

[cotterless45]

Better spend the £ on a 21mm Hyperion and enjoy deepsky objects.

f5 is going to be harsh on lenses, at those sort of magnifications, no sooner are you in focus than you'll hve to start tracking. That's assuming that you have good seeing conditions.

Big dobs basically catch a bucket full of light from faint objects.

Just a few times a year planets drift by, just to have a peek, just a basic 6mm would give you a good view.

For dso s the most magnification you'll need is from a 12mm eyepiece.

Spend as much as you can on a decent collimation tool and change the primary mirror springs for stronger ones; Bob's knobs.

This'll save you a load of hassle.

plenty more advice on the dob usesrs group.

[dweller25]

I'm in Lancashire so not too far from you and use a 8" F/6 Dob at x200 (6mm eyepiece) and x240 (5mm eyepiece) regularly.

I have used the same scope on Mars at x390 a couple of years ago when Mars was very high and we had excellent seeing.

You will find that any eyepiece giving up to to x250 will be used frequently in your scope.

Here are two very recent drawings done at x200 .....

[Mr Spock]

I have an eyepiece which gives x181 and I find at that it's hiding detail beyond what my eye can see. Only when I get up to x261 do things open out.

[cgarry]

I have often read on this forum that you cannot use more than x200 magnification in the UK. I suspect this is generally just people repeating what they have read on the forum rather their direct experience and so the myth propagates.

With my C9.25 I mostly use a 10mm EP for planetary observing (x235 magnification) and on a few special nights when the seeing is excellent I use an 8mm EP (x294 magnification). On the rare nights that the seeing forces me to drop below x200 magnification, I simply do not bother with planetary observing and go for DSOs instead.

Cheers,

Chris

[Pete Presland]

i have a 3.5mmm Hyperion which will get hardly any use,but you never know when a really clear night might happen and it only takes a minute to try the eyepiece.

that said i certainly would not have made it one of my first eyepieces to buy,more one to buy funds permitting

[John]

I tend to subscribe to the view that planetary viewing really gets more interesting a rewarding over 200x but you do have to be guided by what the seeing conditions during any particular session will allow. I'd rather have a smaller but crisper and more contrasty view than a larger but slightly mushy one.

It's good to have something in the "toolbox" for when conditions allow the magnification to be pushed so I have options in the 6mm - 3.7mm range for that purpose. Some get more use than others of course

[brantuk]

I've found that 180x to 250x is the range I get most use of in the east mids. Much over that is rare - but then my schedule stops me taking advantage of really clear nights a lot of the time.

I think circa 200x is a guide really so newbies don't think they can go straight out and get 600x mag every night as some scopes tend to state in their specifications.

[cgarry]

I think circa 200x is a guide really so newbies don't think they can go straight out and get 600x mag every night as some scopes tend to state in their specifications.

In the first post in this thread it appears that Bart has incorrectly been led to believe that x200 is a strict limit and it is probably not worth going above it.

I agree that x200 it is a good guide to prevent beginners from buying expensive EPs which would give unrealistic magnifications, but it far too often incorrectly stated on this forum that x200 is a strict limit in the UK. I actually think that x180 to x250 is a much better guide, indicating that the maximum magnification varies with seeing conditions rather than being fixed.

Cheers,

Chris

[brantuk]

Absolutely Chris - couldn't agree more - it's nuts to think 200x is a strict limit - hope Bart is still reading

[Bart]

Sure am, thats put my mind at rest. Informative as always. Thanks again to all folks who chipped in. Looks like I might have to buy two of them!! My wife will love that!

Thanks

Bart