Another eyepiece thread

[Chif]

Hey guys,

I've had my 10" dob now for two nights and I've never been so amazed! Instead of dreading night time (means its closer to another day at work ;)) I can't wait for it!

Anyway, I've been reading up on eye pieces, how to calculate magnification etc. I'd just like to find out if I'm on the right track.
Am I right in saying that the higher focal length eye prices are good for deep space, and the lower for planets?

On the subject of purchasing new pieces, I'd really prefer to only have a max of 4 eye pieces or ill end up spending all night changing them around haha.
At the moment I've got a 25mm plossl, 10mm plossl and a 12.5mm unknown brand (but is marked with an H).

I imagine my next step would be a 2x Barlow and probably something 4mm and under?


Any suggestions on what I should purchase/ read up on, I'd really appreciate it.

Thanks for spending your time on a rather long thread,

Andrew

[mental4astro]

Hi Andrew,

I'm glad to read about the thrill the 10" dobbie is giving you!

You are right with how the eyepiece can be used. But also by upping the magnification on some deep sky objects, the increase in magnification will also increase contrast and allow fainter detail in the DSO to be made out. This is very handy with galaxies and planetary nebulae.

Which eyepieces to get next? I'll suggest a nice 2" 30mm like the GSO SuperView, and the 1.25" GSO 15mm SuperView. These are inexpensive and offer fantastic value for money. The outperform eyepieces more than twice their price in a fast Newtonian like yours. I say this from experience with these EPs, and they remain in my kit.

You don't need a Barlow lens. While today's barlow's are head and shoulders better than what was available, really they get in the way when the high power EPs available today are excellent. The best high power EPs for the Lear amount of $$$ are the TMB Planetary Type II range. A 9mm and maybe the 6mm will be fantastic in your scope. These EPs are far superior to the plossls you currently have and you don't need to rest your eyeball on the eyelens to look into them.

Again, I've also got the two EPs, and I've been able to compare them with EPs five times their price and they out perform these.

But before you lay any money down, try to get to an Astro club or other star party, take your scope along, and ask to try out a few of the other attendees EPs to see how better quality EPs perform in your scope. You be making the best informed choice for yourself.

Mental.

[Chif]

Thanks for the great advice alex, i'll look into going along to an event so i can have a squiz at what others are using. :) . I'll also keep an eye out for the pieces you've mentioned. Cheers

[mental4astro]

Andrew, you'll find the GSO Superviews at Andrews Communications. Look under the GSO heading in this link"

Andrews Communications (http://andrewscom.com.au/site-section-10.htm)

The best price for a new TMB Planetary I've seen is here in Oz too. The two I've mentioned are available:

VIT Optics Australia (http://vtioptics.com.au/)

The TMB's do occasionally also show up in the classifieds section.

There are much more expensive eyepieces, and better quality (though it is hard to beat the TMB's for their image quality) and wider field of view, but these will perform exceptionally well for you. They also retain their value very well when you want to sell them on.

[brian nordstrom]

:thumbsup: I second that on the GSO super views , I got one for a friend a while ago , the 15mm from Andrews and was amaized at the quality and views for the price , these are that good :D , I nearly told my mate it hadn't arrived , it was that good ,, nah ;) , but yes as Mental says ... these are very , very good for the price , feel solid with views to match .
Brian .

[cmknight]

Andrew,
That "H" usually means 'Huygens'. A very simple eyepiece which is prone to narrow field and CA. You might want to think about swapping it out for a Plossl.

Chris

[Wavytone]

Hi Andrew,

For new ones on a budget you could look at www.andrewscom.com.au.
Alternatively secondhand ones, the 'for sale' areas on: www.astromart.com or www.cloudynights.com are worth watching.

Huygens (H) or Ramsden (R) eyepieces should be avoided, both are very antiquated designs and virtually anything else will be better.
Konig/Erfle - stay clear of these, too;
Kellner - very old design, OK for 25mm but a Plossl is better;
Edmund RKE are all fine, 8 - 28mm;
Vixen LV, NLV or LVW eyepieces are all fine; the only difficulty is finding these - people rarely part with them - these have very long eye relief and are very comfortable to use;
Plossl, esp 15mm or longer focal lengths,
"Symmetric' is another name for a Plossl eyepiece (see above)
Orthoscopic (often labelled 'Or') are fine, esp for short focal lengths though very little eye relief;
Anything from TMB, Pentax or Televue - all excellent premium eyepieces.

[wavelandscott]

Andrew,

My advice will run a little counter to the other opinions expressed so far in this thread. I suggest that you use what you have for a while and then make sure that you attend a viewing night or two with folks in your area and try out their eyepieces before you spend any of your money on any eyepiece.

Eyepiece preference is often time personal and an eyepiece that I might claim is great to you might actually perform rather average. Generally speaking with all things optical you "get what you pay for"...no doubt there are some good value eyepeices (and other gear) available but you may find that your eyepiece tastes may not be satisfied with the "value" brands.

Alternatively you may find that you can not "see" the difference and the "value" brands are fine.

My observation is that as people get more viewing experience they tend to migrate towards premium eyepieces.

Think of it like wine appreciation...when you are just starting out ""2 Buck Chuck" and "Boxed Wine" fit the bill but as your taste buds "mature" you start branching out into more expensive wine for special occassions and then before you know it top shelf all of the time.

With eyepices some folks like to incremently upgrade and this has them buying and selling lots of eyepieces (or keeping them) as their seeing skills "matures"...others save their pennies and then lash out on the best.

Either strategy is valid and it just depends on you but I would still get a few more nights of veiwing under my belt before I bought any new eyepeices. Once you understand what you like to look (double stars, DSO, planets) some fo the recommended choices become more clear.

No need to be in a rush...well cared for eyepieces will last a lifetime.

Enjoy!

[barx1963]

I will second what Scott said. Don't rush into it! The plossl EPs that came with your scope, especially the 25mm are not too bad. You will use the 25mm 95% of the time you will find and it will give pretty OK views.
There are 100's if not 1000's of objects you can find with a 10" that will look just fine in a 25mm EP.
Remember, power is not always your friend, the more you magnify, the harder it is to focus and you also magnify any poor seeing.

Malcolm

[Varangian]

That 25mm plossl is actually a good eyepiece. But I know how you're feeling, you've got the 10" Dob and now you want to maximise:D Go hard and buy whatever you can afford, the TMBs and the GSOs will put you on the right path without breaking the bank, go on, you know you want to...

[Chif]

Thanks so much for all the advice guys. It looks like some good brands have been thrown out there. I still have to wait a little bit before the missus will let me buy anything more :(, so i'll keep reading and keeping my eyes peeled in the classifieds section of the site :)

Oh also, I'm just wondering, when putting the eye pieces in the scope am I meant to push them in as far as they will go or do I just go half way (the way I have been doing at the moment, it seems to focus better that way). Just wanna make sure I'm doing it right haha.

[brian nordstrom]

:thumbsup: All the way in mate . like any good male fitting :lol: .
Brian.

[Chif]

Haha, thanks Brian :). Although with it all the way in I can't seem to focus as well. Can you think of any reason why that might be?

I'm just having a look at the moon for the first proper time. Easily the most amazing thing I've ever seen :D

[Varangian]

Probably don't have enough rack out with your focuser (back travel) a 1.25" extension tube will fix that. It just goes into the focuser and then the eyepiece slots into that. A GSO brand (either the 35mm or 50mm) can be had for $29. Thus extension tube takes the eyepiece further away from the secondary mirror to allow you to achieve focus. Check Andrews Communications website. Sounds like this is what your problem is, unless your horribly uncollimated but I bypasssed that as your scope should have come close to collimation. Cheers

[Varangian]

Sorry I didn't want to comment and thought I'd just ignore it but I reckon that's a pretty inappropriate comment to read.

[Chif]

ahh ok. I'll have a look and see if I can pick one up. Although i've got a funny feeling i've already got one of those attached. I'll have a look in the manual and have a play tomorrow when it's light. I did buy it second hand, so there could be a chance it's out of collimation :shrug: I'll investigate in the morn. Thanks a bunch :)

[cmknight]

Chif, where did you get your dob from? Is it a home-made one, or a manufactured scope? If it's home-made, the maker may not have done his math right, and placed the focuser a bit to close to the primary, or the primary is in the wrong type of cell. If it's manufactured, it may be too high up in the cell (collimation screws pushed in all the way, pushing the mirror forward). The main collimation cell, where the mirror is, actually "floats" in the mirror cell (the part attached to the tube walls). Collimation screws are typically about 3/4" long, so your mirror may actually be too far forward.

Of course, without actually seeing your scope, this is all just guesswork on my part. Can you post a pic of your scope?

[Chif]

Hey, it's a manufactured one (Saxon). It may have been my fault fiddling around with it when I set up. I'll post some pics now :)

*Edit*

Here are some pics. Could it be the silver piece of the focuser is not in far enough or is too far out? When I loosen its screw and move it, it moves the focusing wheel, although when I move the focusing wheel, it doesn't seem to slide this? Is that normal?

http://imageshack.us/a/img19/4136/scope1.jpg
http://imageshack.us/a/img836/8155/scope2d.jpg
http://imageshack.us/a/img822/1075/scope3.jpg
http://imageshack.us/a/img402/1215/scope4a.jpg

[barx1963]

Systematic approach works best to solve issues like this. Are you able to achieve focus with the eyepiece not fully inserted? If so collimation is not the issue. If it was so badly collimated that stars couldn't focus, that problem would persist right through the focus range.

Malcolm

[Chif]

Thanks Malcolm, that's good to know. If no one can tell just by looking at my pictures, I'll have a play around tonight and see what happens :)

Another edit (sorry to spam so much), I may have solved the problem, I don't think the focus wheel was moving the silver piece properly (sorry bout the terminology) , now there's a lot more movement during focus. I'll give it a try tonight and see what happens.

[Rob_K]

Well said Scott! I'd hasten to add that you might find you never need to "upgrade" and a lifetime can be spent getting amazing views out of simple plossls. The wine analogy is a good one - for some people the nuances are blindingly clear while for others (like me) it all tastes like plonk. Same with eyepieces, it is an acquired taste. For all that people rave on about the differences, I can't really see much myself, despite having looked through a wide variety of 'hand-grenades' at star parties etc. It's a one-percenter. Bar the very cheapest eyepieces (Huygens etc), all modern eyepieces from plossls up have pretty good optics. If you live in that one-percent the differences are real and huge. If you don't want to engage with the deep-pocketed, this-beats-that set you don't have to. Astronomy's about getting out there and seeing stuff, not gear. But people are strange creatures that need to complicate it and develop a complex structure & ritual around something so pure and simple.

Good luck anyway! :thumbsup:

Cheers -

[Wavytone]

Agreed - go try a few at a star party and stick to what you feel works for you, in YOUR scope.

There are too many variables and there is no such thing as a "best" eyepiece that holds true for all scopes and/or observers.

[cmknight]

I have to wait another month, apparently, but at that time I'll have some OEM Meade 5000 SWA's for sale.

[cmknight]

Yeah, Chif, that silver thumb-screw is to add tension to the main drawtube for when you have a heavy eyepiece or a camera attached. Once you've reached focus, you tighten it and the focuser shouldn't move.

[Chif]

ahhh that makes sense now. I think that might have been my issue. I'm not in a rush to buy anything either, so a month is no worries :)