Got my Dob, but where now with eyepieces?

[TimboS]

Hi All,

I'm now the proud owner of a 10" Skywatcher Dobsonian. My first telescope and well, just a *tad* different to the 10x50 binoculars :D

Although, I've only had a chance to look at Saturn and parts of Orion's sword - the weather here in Adelaide has subsequently clouded over with the "promise" of rain. We'll see...

That 1/2 hour or so experience has told me one thing though - I like the supplied 25mm Super Plossl for both it's FOV and eye relief. I can't however see myself wanting to continually use the supplied 10mm Plossl - the eye relief is no where near as comfortable. So, now it's a case of deciding where to go with eyepieces.

First things first though, I have a monster great sodium streetlight right over the back of my house and it bathes almost all of the yard in orange. The strength is such that if any of it makes it's way into the front end of the Dob, the image takes on the good old orange hue and all but blows it out. In short, there is a huge angular slice of the sky where I simply can not point the scope. So, I think I need a light pollution reduction filter. I've looked around a bit and seen a couple of types included the Baader UHC 1.25" "Nebula filter" and Baader OIII 1.25" Narrow Band Filter. I'm wondering though, which would be more use to me? The price tag is $150 give or take $10 or $20 and if it does the job then the price is basically peanuts given the outcome.

Next, eyepieces themselves. I was thinking of following the advice of "one for the planets, one for deep sky", and a Barlow. I have already spied the Vixen NLV20 and NLV6, both in 1.25", and from what I read on this forum these would do the two jobs nicely. BUT, these come in 50 and 45 FOV, and even though they have a nice 20mm eye relief, I was hoping for a wider view. Is that an unrealistic expectation? Of course, add a 2x Barlow to those eyepieces for when viewing is good, etc.

I don't see myself wanting to speed a huge amount on individual eyepieces. The prices I have seen for the above Vixens (about $180 each) is pretty much as far as I would want to go at this time.

So, I now open the floor to any recommendations, opinions, rants and/or raves !

Tim

[TimboS]

Sorry people - looks like I have unintentionally double posted

[Starkler]

Hi Timbo, what you need is a tube extension at the front of your scope to shield it from light coming in on directions other than what your pointing at.
Some people incorrectly refer to them as a "dew shield".
No filter will help what you have described.



Pretty much yes. As the saying goes you can have any TWO of the following........ wide field..... well corrected field....... low price.

[TimboS]

Thankyou Starkler.

I suspected the equivalent of a "lens hood" would be needed. I'm sure I can make something up for the purpose.

As for the eyepieces, I also suspected that I will be limited in what I can reasonably expect for the budget. I see however that some eyepieces can go up to all but $1000 and given that price, might it be possible to get 2.5 out of three ;)

Tim

[JethroB76]

Good but not premium widefield EPs (68 degrees) are Orion Stratus and Baader Hyperions - both basically the same EPs - and clones of the more expensive and seemingly better performed Vixen LVW EPs.

Very good EPs for the outlay, you may not quite get them new for $180 (unless you look overseas) but secondhand you should - you just have to wait for them to come up..they come in 3.5mm, 5mm, 8mm, 13mm, 17mm, 21mm focal lengths and work quite alright at F5 and are very comfortable to use - if only a little heavy/bulky

[Jay-qu]

I purchased 40 and 25mm william optics SWAN's - they have 72 degrees FOV and only cost about $180 new. They are a good quality EP but at your faster focal ratio of F5 I would be worried about a bit image quality towards the edge of the field - but you are going to get some amount of this with just about all wide angle EP .

[Paddy]

Hi Tim,

Good eyepieces make a great difference and are worth investing in. However, I would recommend playing with what you've got for a while til you get a better idea of what your viewing preferences are. Its also worth going to some star parties to have a look through various eyepieces so you can work out what you like by way of field of view and eye relief. If you take some time, you'll be able to work out a small number of good eps to meet all your needs. And they are worth investing a bit more in - if you make the right choices, you'll have them for life and they'll wlrk out cheap on a per view basis.

Just my thoughts.

[Strider]

Hey Tim,

I am in a fairly similar position to you.
I have had my 12" truss skywatcher dob. for a couple of weeks and have enjoyed some nice views of Saturn with four of its moon's and the Orion Nebula.
I am thinking along the lines of Paddy's advice. That is to get as much viewing in over the next couple of months or so with the supplied ep's and then investing in a good quality ep and 2x barlow.
I am personally leaning towards an 11mm or 13mm Televue Nagler and televue barlow as my first purchase. I know that is more than you want to spend but my way of thinking is make the purchase once and it may save you money down the track.
What's that saying 'quality lasts long after the price is forgotten'.
Anyway they are my thoughts. Hope the skies clear.

cheers Brad.

[mrsnipey]

Get a good zoom eyepiece and a good barlow.
The combinations should just about cover any requirements you have.

[TimboS]

Thanks to all.

I managed about another 1/2 hour last night to have another gander at Saturn (with two moons this time, and everything oh so bright!) and Orion's sword (oh so green). This time I was also looking for specific differences between eyepieces in the way of contrast, edge blur, etc. I can honestly say that I can't see myself using the supplied pieces for a second longer than I have to. Watching Saturn go from one edge to the other of the 10mm Plossl was like watching a smear transition to a nice sharp image then smear right out again, and the field is no where near flat - there's a fair bit of radial distortion. I know, the supplied pieces are just to get you going so I guess there is no surprise there.

I think both FOV and eye relief will dominate my choice of eyepieces. I have looked around a bit further and come across the 68 degree Orion Stratus eyepieces that are claimed to have constant 20mm eye relief across all focal lengths. I also see the Orion brand has various Barlow options and LPR filters, etc.

But now there's three questions in my mind:

1) Do I need an LPR filter for each eyepiece?
2) When is a Barlow not a Barlow? i.e. is all this "baffling" and so forth bit of a marketing gimmick, or really worth it? If I had to pick from the Shorty, Shorty Plus, Ultrascopic and Deluxe, which do I go for and why?
3) Is it best to pick a Barlow from the same manufacturer as your eyepieces for, um, not sure how to say it, but optical uniformity or things along those lines?

Tim

[wavelandscott]

I think you are on the right track with your thinking...get some eyepiece time with what you have and decide what you like/don't like about your current set...better still, if you can get to a viewing night or find some fellow IIS's near you and have a "sharing" night so that you can look through other people's gear before you spend your money that would be great.

In my opinion, once you get to the "top shelf" of eyepieces your own personal preferences will outweigh the "technical" differences...I mean regardless of brand (in this case Pentax and Televue) they will be technically great with outstanding QC/QA...but the "other" things like field of view, eye relief (even size and weight) will tilt you one way or another...

While I am a firm believer in getting a "few" of the best, instead of a whole case of mediocre, the "Top Shelf" is expensive (but not so bad compared to a boat)...you will still want to get each purchase right for you...so try'em before you buy'em...

[wavelandscott]

In my opinion...

#1 - no, one filter (assuming it is the same barrel size as all of your eyepieces 1.25 inch/ 2 inch) can be used on more than one eyepiece...you just thread it on and off. I'm not sure I would recommend an LPR filter...they will "filter" out some of the excess light...but better to spend the money on petrol and get to a darker sight (in my opinion)...If you feel must get a filter, then I would recommend a UHC over an LPR. I have both and get much more use out of the UHC.

#2 - generally speaking, you get what you pay for...if you are a serious observer (or will become one) I suspect that you will notice the difference in the end. A good time to go to a viewing night and try before you buy if possible. An optical chain will only be as good as it's weakest link...

#3 - Not sure there is an advantage really unless you are going to be on the "high end"...an Ethos in a cheap barlow probably isn't a good look (but I have not tried it)

[TimboS]

Thanks Scott, but, for point 2, what would be the order of Barlow quality from the listed types? I presume, even going on just price, that the Deluxe 2x is best of the list.

Also, I presume UHC = ultra high contrast and to avoid constant threading on and off I need one filter per eyepiece. What is the difference between LPR and UHC ?

Further, ignoring price for just a moment:

If I want good eye relief and am willing to accept the standard 52 degree field of view or therabouts, what make and type of EP would be considered the "bees knees" ? (Recall I have a 10" Dob)

Conversely, if I want wide FOV (say 68 deg) and am not too worried about eye relief, what is considered to be "best" make and type ?

[Jay-qu]

Hi Tim,

The difference between an LPR and a UHC is the colour of the light they let through. A UHC will block out most light except for a very small range of colours that come from emmision nebula (like orion), this in effect should make stars, sky etc darker while leaving the nebula just as bright as before - hence increasing contrast. An LPR is similar, but its main purpose is to just block the colour of light that comes comes from sodium street lamps - this doesnt give as good of a contrast improvement.

I own a Lumicon UHC and I can tell you that the improvement is there but dont expect it to work miracles - I would expect that an LPR would do very little. (Caveat - I live in the outer suburbs of melbourne, so perhaps my light pollution is low and thus I dont get as much of an improvement from filters).

When you are paying over $100 for a good filter, I dont think you will mind screwing it in and out a few times! If it really bothers you, sometimes it is possible to screw the filter into a spacer, that can stay in the focuser barrel, then you dont have to do any unscrewing or buy more than one!

[TimboS]

G'Day Jay-qu,

Thanks for the filter feedback. It sounds to me that the effect of an LPR is included in the UHC filter and "then some".

The sodium streetlight out the back of my place is obnoxiously bright and makes averted vision all but impossible. My whole backyard is bathed in orange to the point where the reflection off the Dob tube will destroy night vision in an instant if you accidentally look at the scope (and forget putting your eye up to the scope if you are not going to make a full seal around it!). I suspect that the advice of using some petrol to move further away is going to be very sound, but impractical for viewing every night. After all, I'm sure most people like the idea of just whipping out the back or front and using almost all available time for viewing rather than having some of it chewed up for transport.

I think I need a long hood for the Dob and certainly one or more filters. I would hate to damage any threads on any accessories by constantly screwing filters in and out, so two would be best, or a spacer... As it is I find I am changing eyepieces every couple of minutes to keep changing the FOV etc and that's already a pain as is!

I'll be most interested to hear what people claim the "best" EP to be..

Tim

[Jay-qu]

That is a very unfortunate viewing situation and as others said a filter isnt going to do much in that situation. If you could get to a local park or football ground within 5 mins of your house it would be infinitely better (providing they dont have lights too!)

[astroron]

Hi Tim I don't think it is such a big deal screwing filters, after all I and others have been doing it for years without any mishaps:D
In your light polluted back yard you could build a surround, out of say tarp or hessian or some other material to cut down the light intruding on your space.:(
Filters are no good for galaxies, UHC would be the best filter to use, I often use it in moonlight to some good effect.
Don't let your location spoil your interest in the hobbie, try to use your imagination to make the situation better:)
I know of people who observe from the middle of Chicago and do some reasonable work.:)
When you then go out to a dark sky site you will appreciate your efforts more:)
Last but not least go to an observing night with other observers and get some first hand advice.:thumbsup:

[JethroB76]

IMO
Ultrascopic=Deluxe>Shorty PLus>Shorty
From my experience the ultrascopic is very similar if not the same as the Deluxe performance wise (ie very good IMO) - they have the same baffling.

For UHC filters, given they can cost $100+, most make do with 1 (maybe 2 - of diff. sizes). A 2" filter can normally be attached to the bottom of the 1.25" adaptor in the focuser so can be used easily with multiple 1.25" EPs, or can (obviously) be attached directly to a 2" EP. 2" filters are however normally somewhat more expensive than 1.25" filters.

Another way around the hassle of constantly changing filters is to use a filter slide, which on a reflector would be fitted inside the OTA and when needed you slide the filter in its holder across in front of the focuser drawtube bottom...

[wavelandscott]

Another option (depending on the economics) would be a filter slide or wheel...one filter would work for all eyepieces then...

[wavelandscott]

Can't tell you...I opted for a Televue Powermate

[wavelandscott]

If eye relief is your main criteria and you want the Bees Knees I would suggest that you try the Pentax XW line of eyepieces...good eye relief and approx. 70 degrees field of view...outstanding eyepieces. I have 2 a 7 and 10 mm and they are very good in my dobs. It is hard to fault either one in my opinion.

If you don't need/want that much eye relief, you can maximize FOV with the Televue line either the Naglers or Ethos...but neither will have as much eye relief. Again they are fabulous eyepieces...I have some Naglers and Panoptics and they too are very good in my dobs.

I would highly recommend that you try some of these TVs or Pentax before you buy them. They are both expensive but worth it in my opinion.

[Starkler]

This needs to be reiterated and emphasised!

You will read around general nagler hysteria in some places. What isnt immediately obvious from online research is that every one of them has differing characteristics and trade offs.

Not one of them is perfect in every respect and when you're spending that kind of coin you dont want to get inadvertently stuck with the wrong set of compromises that goes against your likes and viewing comfort.

[dannat]

Tim, if you want reasonably priced ep try looking for a william optics spl, the 3mm is not great but the 6mm & 12mm are good for the price.
I have the 6mm. Fairly sharp views, 20mm er & about 62 deg fov ( bit more than a plossl). You should try before you buy though. Andrews comm have the ep's new i think for $129

In the longer lengths (20-32) i would buy a TV plossl, fov is not great but still excellent value

[wavelandscott]

Great comments and in line with the suggestion I was trying to make...no eyepiece is perfect...get enough eyepiece time to understand your needs/wants, try some and then buy...the right choice for you will not be found on a forum post but decided with your own eye(s) and may be different than other people.

[Greenswale]

I have an 8" F6 Newtonian on a dobsonian base, with 32mm TeleVue, 10mm and 7mm Pentax XW eyepieces. Let me add in that I am >60, and just 18 months into this obsession.

The main reasons for choosing these eyepieces are quality of image, field of view, and eye relief. I considered field of view quite important, to reduce the amount of nudging required to keep an object in view, and eye relief important for comfort and ease of use. I do not like a narrow field of view.

The TeleVue does not match the Pentaxes with edge of field of view 'sea gulls' being quite obvious. It is a very good eyepiece for getting onto a target and gives acceptable wide field views, and is great value for the price. The future will see a similar focal length, wider field of view, high quality replacement.

Pentaxes are absolutely delightful. To my eyes they are just magic, and it is pretty cool to actually be able to 'look around' in the eyepiece to take in the full view. As I move to higher magnification work, introduction of a high quality barlow or another Pentax will be the go.........!

My brief experience has shown that high end eyepieces are absolutely worth having, but there is the cost issue! It is also worth understanding that one tends to grow into observing, and with the experience gained, good decisions can be made about equipment; and with improving equipment, more discovery and subsequent enjoyment results.


Wren

[TimboS]

All good comments.

Of late my attention has been brought to Siebert eyepieces.

Checking out their website I note some interesting things.

I'm wondering at this time however about a Power Mag Wheel Barlow and one eyepiece rather than simply buying mutiple eyepieces.

My thinking is to buy a single 2" EP, and use the above Barlow to provide medium and high powers, thereby replacing the need for other EP (at this time). Although, of the power wheel options, one is a 2x, 3x and 4x combination, but 4x ?! Wow. Granted, 2" is not necessary for high powers, but I really like my eye relief.

I've checked into price, performance and availability of Vixen LVM versus Hyperions versus Stratus versus Televue, etc. So much to consider !

Does anyone have any feedback on the Siebert power wheel Barlow ?

Thanks,

Tim

[lacad01]

Gday Tim to 2nd what Ron has said - don't give up :)
I live about 6km from Sydney CBD, have lots of glow from various street lights, neighbours with yard lights that should be confined to sports grounds and to top things off, the South/South-Eastern part of my sky is awash from Sydney Airport :sadeyes:
But I've learned to adapt...a beach umbrella here, screen there and it's surprising how much a difference it does make.
Have also learned heaps by joining an astro club and getting first-hand advice at dark site gatherings :thumbsup:

[TimboS]

Wow, it sounds like two things are prevalent in astronomy. First, that alot of people have bad viewing from their house, and secondly, many people give up because of it. Well, at least that's what I am inferring from the advice given so far. Some things however just make your resolve stronger, and this is one of those cases for me. I think that I couldn't be bothered with using tents or domes or the likes - I think I'll just drive away from all that as per advice given a while ago ! Seems logical. And, all the while I've been on this forum, the viewing has been absolutely *nothing* like it was the week leading up to actually buying my scope. Can't help but "see" the irony in that !

It's funny, all the while I am stuck inside because I can't be outside with the scope, I am reading up on what I would buy next.... Seems like an 10" LX90 or 8" LX200, but that'll be a short while away yet since I have to figure out what to do with the eyepieces for my Dob.

The chap that sold me the scope has viewing nights at his place and I think I'll call up to see if I can book in to have a look at some of his Siebert stuff. It seems a little odd however that these EP are claimed to perform really well in comparison to TeleVue gear, but the price is much much less. I read, repeatedly, that as a general rule the more you pay the better the optics, so what about Siebert gear ? Are they really a bargain, or again a case of you get what you pay for meaning Vixen LVW will be much better, etc? Anyone care to comment?