Reasonable EP's for new refractor

[tonyjh2]

I have acquired a 115mm f7 triplet, with a 2" diagonal (it will also take 1.25" EP's) and am interested to hear what makes of EP are considered to be reasonabe, i.e. good value that don't break the bank. I am starting all over again with EP's and with a f7 scope being a little less forgiving with EP's than my previous f10 SCT, I don't want to rush in and make an expensive mistake.

I have up to £150 to spend and I would hope to get at least 3 EP's (high, medium, low) for this amount. I wear glasses, so I suppose ones with longer eye relief might be useful. Any other commented, gratefully accepted.

[Capricorn]

BST Explorers, £41 each.

5mm, 8mm, 12mm, 15mm, 18mm, 25mm.

Would guess all will be good in a 115mm triplet at f/7.

Depends what magnifications you are contemplating.

Say 8mm and 25mm for 100x and 32x, not sure about a third, suppose it is either 5mm for 160x or 12mm for 67x.

[damnut]

Hi Tonyjh2,

Firstly what a lovely scope, secondly the bst explorers are great for the cost. I thought it was the other way round?? the faster the scope the more demanding it is of the ep's?? worth checking. For your triplet it is wrth looking for some second hand hyperions and a good barlow if not looking at new BSTs. I have bst's and hyperions and they are great. You will also see good comments on the Hyperion zoom which would give you some more flexibility.

Good luck on your search and check out the buy & sell.

Cheers

[Damo636]

Hi Tony

Lovely scope. The TS Planetary HR are also very good at £49 a pop. Eyepieces @ Modern Astronomy

[newman]

I thought it was the other way round?? the faster the scope the more demanding it is of the ep's?? worth checking.

Cheers

Yes, that is correct. It's also what the op said - he used to have an f10 scope which he replaced with an f7. That is a faster scope, so it will tolerate cheap ep's less.

I'd like to point out that an f7, while faster than f10, still isn't too bad. It's more of a medium speed than a fast scope. It's certainly not an f5 dob.. So you won't have to break the bank on premium eyepiece offerings that work well with the fastest of scopes. I haven't tried this combo myself but I imagine Baader Hyperions ought to work well with your scope. I'm also a big fan of Orthos for high power work, if you haven't tried one on a refractor you owe it to yourself

At any rate, when planning the ep collection you'd do well to write down several options, then list magnifications you get with them them (with barlow if you get one too) as well as calculate true fields the eyepieces will provide (AFOV/magnification in your scope). That way you can make sure you're not buying redundant eyepieces.

[John]

....I'd like to point out that an f7, while faster than f10, still isn't too bad. It's more of a medium speed than a fast scope. It's certainly not an f5 dob......

Thats a good point - my F/7.5 ED120 refractor is my slowest scope - it's relatively easy on eyepieces compared to my F/4.8 newtonian

For your £50 per eyepiece budget BST Explorers are probably a good bet, especially as you need decent eye relief. If you could find a few more £'s you could get some Celestron X-Cell LS's which are getting great reviews right now.

[rwilkey]

I would say the BST Explorers are a great choice, no problem at f/7, and the eye relief is good for spectacle wearers. Extremely good performance for the price, you won't regret it IMO.

[ronin]

f/7 is faster then f/10 but most start experiencing eyepiece problems with f/5 scopes, if they get any.

At f/7 it will be long enough that most reasonable budget eyepieces are fine. BST's are good, TMB II's should be good, both around the £40 mark.

Think we tend to consider a scope as "fast" at the f/5 mark, but worth being aware of potential concerns at f/6. Unless the eyepiece is a real budget model I would not expect much concern at f/7 and slower.

Probably most eyepieces are OK but a fast scope can produce a curved image for the eyepiece and it is this I suspect that budget eyepieces have the problem with. Hence the use of a filed flattener to remove the curvature of the scope image.

[tonyjh2]

Thanks to all of you for your informed replies. Think I'm going to opt for a couple of BST Explorers. Was tempted by the Hyperion Zoom, but was just that more expensive than my budget.

[damnut]

Hi Tonyjh2,

A good choice, you will be impressed with them as they come out of their new boxes, they handle very well.

Good Luck