Looking for a WOW-Factor ep

[scott murray]

Hi Everyone,

I'm a new kid on the block-just finished my 10" Dob a couple of months ago. A great, fun project-happy with the result, but looking for 1 or maybe 2 good, high mag, wide FOV ep's, primarily for planetary and nebula viewing. Scope specs are:

• 10", F5.2
• Crayford R&P

My current ep's are all 1.25 Plossls:30,25,20,15,10 and 6.5.
I also have a Celestron 2x Barlow as well as blue, yellow and ND filters.

I'd be really grateful for any suggestions

Regards, Scott

[davidpretorius]

three things

1. do you have a budget in mind $$ per eyepiece. $100, $300 or $500
2. do you have tracking
3. are you getting a good handle on knowing what is a bad seeing night and what is a good seeing night?

There is currently a great thread (
http://www.iceinspace.com.au/forum/showthread.php?t=9022&goto=newpost)

That outlines the top ones.

I ask #3 mainly that even a great ep will not work wonders if the seeing is bad. There are many factors to take into account. So best to get to a viewing night nearby and look for yourself and then ask someone what their interpretation of the seeing is like.

[scott murray]

Thanks David,

1. $300 or so
2. Just bought Argo Navis, haven't fitted it yet
3. No, still a newbie-not sure how to work out if it's a good viewing night or not??

Thanks for the link to ep thread.

[davidpretorius]

http://www.damianpeach.com/pickering.htm

is a great start to get a feel for seeing conditions. Also are the stars twinkling to the naked eye or dead still. Can you see surface detail on jupiter etc. All these are indicators of seeing conditions.

Also I will throw in mirror temps here. Basically, you want to make sure your primary mirror is the same temp as the ambient air temp.

Questions to ask. Does the temp drop sharply and continue to drop from sunset to say 12am like it does for me in tassie. Does it drop from say 25 during the day to 15 at night like say brisbane???

Even though I am effectively blowing refridgerated air over my mirror, it is basically no good for high power stuff until the ambient stops dropping.

As an example. Tonight, took scope out at sunset, temps were around 16 degrees. The ambient is now 5 degrees and dropping down to an expected minimum of 1 degree. When will it get there????

And once it stops and my mirror catches up in roughly 1/2 hr, what will the atmosphere be like???

Last night i got my mirrors cooled nicely to within 1/2 degree of ambient and then looked at jupiter at roughly 250x. No surface detail and on the above scale from damien peach I would say 2-3.

Tonight, jupiter has surface detail and is around 5-6.

Nothing short of experience helps here. Go out look at the stars, check if they are twinkling, goto a planet with your highest power and see i you can start to build up your own gut feelings regarding seeing. The word "seeing" occurs nearly every time when discussing any observation session!

[davidpretorius]

also re tracking, argo navis will help you find stuff, but you will still have to move you telescope manually.

therefore try and go for a wider high power ep. that 7mm or 10mm pentax or lvw vixens etc all are around 60 odd degree wide. At least the object you are viewing will be in the eyepiece longer.

[scott murray]

Yes, temp is similiar to Bris. 25 day to 10 night approx. I usually get my scope out a couple of hours before viewing, so that side of it should be ok.
Might duck out and see if Jupiter is above the trees yet....

[davidpretorius]

cool, he is low at the momoent ie 30 odd degrees, but if you can see detail, then that can only improve up until he is nice and high. At least 60 degrees by 2am.

Ok, your mirrors. they need to cool 15 degrees from 25 to 10. I have found that they can lose 2 to 3 degrees an hour by themselves. So get your self a cheap thermometer and start to take out each night. watch the temps change and then roughly calculate how your mirror is going

[janoskiss (Steve H)]

Originally Posted by scott murray

$300 or so

Vixen LVWs are just a bit over $300. Best deep sky EPs in this price range if you're buying new. Meade UWAs also qualify (under $300) and have a huge FOV but by all reviews they are only so-so and I was also unimpressed with one I tried.

[ving (David)]

i guess the biggest wow factor EP i know would be a televue nagler in is it 31mm? i cant remember the exact size... 80 odd degrees at low power and high contrast!
of course it'd be way out of your price range... and you want something for planets the pentax 10mm (as mentioned already) always gets a good review

[janoskiss (Steve H)]

In a fast Dob, coma kills the 31mm Nagler wow-factor for me. 22mm LVW is the best EP I've seen so far for that type of scope without a coma corrector.

But they are both irrelevant anyway, since Scott is after a "high mag" EP, which means around 12mm and under for the 10" Dob.

[scott murray]

Ta guys. Next newbie question: Is there such a thing as a 12mm or under ep with a wide FOV?

[janoskiss (Steve H)]

Sure there is. Vixen LVW and the cheaper clones (Stratus, Hyperion), Pentax XW, Televue Nagler, Meade UWA, just to name a few.

[scott murray]

Great !! I'll keep an eye out for some of these. Thanx again.

[matt]

Vixen LVWs offer 65 degrees all the way down to the 3.5mm.

The 5mm is a very nice EP, for hig mag viewing in great conditions, while the 22mm is fantastic for wider field viewing.

[scott murray]

Ta matt - on the lookout..

[rmcpb (Rob)]

Scott,

Be careful of getting a really short eyepiece that can only be used on those rare nights of perfect seeing. I would consider getting something about 10mm for your scope which gives you about 130x which is a good workhorse type magnification for the moon and planets. On the good nights combine this with a good barlow and you can get 260x but for most nights you will find that 130x is great.

If you are determined to go higher a 7.5 would be useful on many nights and a 6 on fewer nights and these barlowed are a rare event.

My point is not to go for the highest mag you can theoretically get as you will almost never use it and those eyepieces are the ones you get eventually after your collection contains all the workhorse ones.

[scott murray]

Point taken, Rob. Narrowing the search thanx to you guys. Had an attack of brains and read thru some forum archives too - some great info. Thinking about a Vixen LVW 8 to 13mm or similar. Q: Is there an ideal eye-relief distance, or is it an entirely personal thing (I don't wear glasses)? Is 20mm comfortable?

[janoskiss (Steve H)]

Consider the Chinese clone of the LVW, the Stratus at 1/2 the price. It is almost as good, esp at the focal lengths you are after it is very close: you'd be hard pressed to tell the diff.

[Starkler (Geoff)]

Originally Posted by scott murray

Is there an ideal eye-relief distance, or is it an entirely personal thing (I don't wear glasses)? Is 20mm comfortable?

It is a personal thing with some prefering longer than others.
At longer ER it can become harder to find the right position to place ones eye without suffering blackout. Eyecup design can help here.
At shorter ER it can feel cramped to place ones eye so close to the lens and theres also issues of eyelashes gunging up the eye lens.

For me, i find 15-20mm to be comfortable, with less than 12mm becomming cramped.

[Gargoyle_Steve (Steve)]

Steve can you give any more info about the Stratus eyepieces you mentioned, eg is Stratus a brand name, or model range; is there anyone in Oz that carries them stock, and roughly what kind of dollars are we talking? I have no idea what the LVW's go for.
Thanks!