12" Meade Dob, Parcorr, best eyepieces?

[Nesti]

Hi All,

Advise please.

I have a 12" Meade Dob (FL: 1524mm) and I'm pretty stoked at what it offers. Unfortunately I'm getting greedy (surely that's not a bad thing?! :D ) and I want higher power mag. for some closer peeks of planets, and a cleaner picture (less coma etc).

I don't mid spending the money, however, I hate wasting it. That being said, if anyone can offer some advise on what eye pieces to buy for this scope, which I would (most) benefit from, I would be deeply grateful.

Also (after reading some mags and books on eyepieces) I'm leaning toward a Tele Vue Paracorr and the Nagler style.

I don't suffer from any eye issues ;) and fine movements on the scope is a breeze...is 4mm do-able?

My current eye pieces are
Meade QX Wide 26mm
Meade 5000 Plossl 14 & 9mm
Meade 5000 UWA 6.7mm

Thank you for any help :D

[AstroJunk]

The Tuneable paracorr is a wonderful thing - it improves the image right across the field. Some people say they can't see a difference, but I have never found that to be the case when I pass them mine. If you are fussy about coma, then it's a must.

Other than that, a 2x barlow or 2.5x powermate should complete your collection for the moment. (thats not entirely true - you need a good 35mm).

[mswhin63]

I was loooking at the very same thing, thanks. I was considering taking the step to 2" for wider field, was looking at 2x and 4x Powermate. Still undecided about Barlow.

[AstroJunk]

All barlows are not created equal. I have a 2" 2x Televue BigBarlow which is a fabulous thing. I replaced a 'value' brand, which was not up to the job for me.

You don't often hear anyone complain about powermates either...

[Nesti]

Okay, so I get this right, I whack a Big Barlow (2x) into the 2" focuser, then the Parcorr with whatever eyepiece, and set it to a particular mark determined prior (I read the post on working out the positions and marking the Parcorr for each eyepiece).

I'm guessing the Parcorr is 2" in and out, with the removable 1.25" adapter. So it can handle the 36mm also. Correct?

That's a truck axle setup! :D I may need to bolt a 12volt car battery next to the fan.

BTW, wont that become F5.5 or thereabouts?

Thanks for your help.

[AstroJunk]

You never need to use the barlow and the paracorr together - the barlow will make a coma free f10, so the paracorr will just be an expensive heavy thing in the way.

The paracorr does contain a 10% barlow in it too, but that is to push the focus out a bit so you shouldn't need to modify your scope to use it. (caveat you need about 10-15mm more in-travel to get focus. if your eyepiece is already racked in close to the tube, you may need to make some mods)

You are correct about the adaptor.

When you use a paracorr and a 35mm Panoptic, you will indeed need a truck battery to stop the whole thing toppling over and arms of Thor to pick up your eyepiece case:P

[Nesti]

Jonathan, thanks for all your help. I think I have it clear now.

I'll get a Paracorr, a (Meade UWA) 4.7mm for the planetary viewing, and a Panoptic 35mm for my spacewalk...Would the Tele Vue Nagler Zoom 03-6mm with the Paracorr be too much power and too little field of view? 50deg as opposed to 82-100deg (UWA and Televue Nagler respectively).

The additional travel for the high power should be fine, as my 6.7mm is a long way out in its travel. I have to take a guess for low power travel with both the 35mm and Paracorr, however, as I want the coma correction for planetary viewing, it is my primary concern, so if the low power combo is out I won't be concerned.

[Glenn Dawes]

Hi Nesti,

Personally I'd be very careful about buying a 4mm e.p., even if you are thinking of a Nagler. 2 reasons:

1) the power. In your setup this equates to 381x magnification. You might find you are limited the number of times you find seeing adequate. I run a 9mm nagler in a 16" f/4, which is 200x and I find about 50% of the time I'm not happy with the images (of course when I am, wooo!)

2) Eye relief. I can't comment on the 4mm nagler, but I've seen some short f.l. eps which are not fun to use.

In my opinion if you find your 9mm meade 5000 very good (I love my 16mm), buy a powermate to get the power. Then get a paracorr if you are not happy with the images.

Regards

Glenn

[Nesti]

Hi Glen, thanks for the advice, but I'm a little confused now; can you use a powermate and a Paracorr at the same time?

I would be much happier to just magnify images using the eyepieces I already have, but also want to clean up the image a bit too.

I thought my only option was to use a Paracorr with a higher power eyepiece.

Cheers
Mark

[Satchmo]

HI Nesti

I think you would want to try a barlow first before buying one . They cause a lengthening of the eye releif which some people find hard to handle, and also can be ungainly. Also with low power eyepieces there can be some vignetting at the field stop. I don't think you would benefit much from a Paracor at F5 though you will see some small gains.

As far as high power goes you can't go past the Televue Radians as they have stunning contrast and a 20-mm eye releif. Some people swear by the Pentax eyepieces too. 5mm would be optimal for good seeing giving you a 1mm exit pupil.

The most glaring hole in your collection is the 14mm Plossl and 9mm Plossl. You would benefit from a better eyepiece like Nagler 13mm type 6 for deep Sky ( or even a 2" televue 17mm Nagler Type 4 ) . 9 mm Nagler would be good also or a 10 or 8mm Radian or Badder Hyperion.

Hope this helps.

Mark

[Glenn Dawes]

Hi Mark,

Although I've never used a paracorr, I have always thought this combination was possible. I went away and checked and found this reference on Bintel's site:

Note for Dobsonian/Newtonian Owners
When using Tele Vue’s Paracorr coma corrector, the 2.5x or 5x Powermate™ should be inserted into the Paracorr’s 1-1/4” adapter (i.e., between the Paracorr and the eyepiece). For 2x and 4x 2” Powermates, first insert the Powermate™ into the focuser, then the Paracorr into the Powermate.

Have a look at the 2.5x Powermate in the eyepiece section and click on all product knowledge and go to the bottom.

I would have thought going to a higher power, hence narrowing the field, would make coma less of an issue and eliminate the need for a Paracorr. I suppose it ultimately depends on your optics and what you consider is acceptable.

I hope this helps.

Regards

Glenn

[GrahamL]

Hi mark

In my 12" asside low power .. around 100 x gets the most work
I couldn't imagine you getting a lot of use below a 5 mm eyepiece
I found my 7 mm nagler was pushing it often so let it go .

A 10 mm xw and a decent 2x barlow would give you a fine
combination .. An excellant medium power eyepiece with the option
to ramp up the magnification when seeing allows.

cheers graham

[AstroJunk]

A Rainy day combo....

(Don't try this at home :D)

[mswhin63]

:eyepop: better put disc brakes on my DOB

[toryglen-boy]

TBH i would be surprised if you needed something to counteract coma with a 4mm piece on a 12' dobsonian, coma would be more apparent on low power, wider field views, i would think from about 15-20mm and longer it might be more of an issue.

:)

[Nesti]

LOL - I've seen lighter pieces of metal at the gym ya know!

Most of the weight would be outermost (assumption); wonder what affect it would have on the focuser?!

[Chippy]

That TV Big Barlow looks small in that combo LOL

[astronut]

A generic appraisal for the Siebert Optics is this; I have the Ultra 17mm & 9mm + the Ultra 2x barlow.
I use the optics on my 12" F5 scope.
Star images are pinpoint and sharp to the edge, individually and combined.
Contrast is also excellent.
The other good feature is that the barrels are made of aluminium, making them a lot lighter than comparable e/p's.
If you're after a e/p that looks good from the outside, forget the Siebert they are rather plain looking.
But..........if external beauty doesn't worry you and you're after a very good performing(optically)e/p, then this is for you. :thumbsup:

[TheDecepticon]

I agree. I would've thought that for planetary viewing with high magnification, the highly reduced field of view would have cut the coma out. When viewing planets, why would you want to use a wide field eyepiece, the object will be too small(unless you enjoy that view).
On the other hand, you would want coma correction for viewing wide field deep space objects of the open clusters and nebulae type of objects. Galaxies and globulars will require dark skies and higher mag in general also, so a coma corrector may not help here either.
I recently purchased the Baader MPCC(Multi Purpose Coma Corrector) which I use for imaging and chose it because it DIDN'T increase my magnification on wide field objects. The parracor is overpriced for what it does(my opinion only, based on hours of web searching, not open for discussion) and a Baader MPCC will serve you well for a lower cost.:D

My 2 bobs worth.:P

[Robh]

Is it worth buying the Baader MPCC for visual observations in a low power eyepiece i.e. does it reduce outer perimeter coma noticeable?

Rob

[tnott]

At F5 the use of the Parracorr is not that necessary. Remember, it only corrects coma (comet-shaped stars with tails facing outside of field) not the commonly confused astigmatism (seagulls) seen in cheap widefields at faster focal ratios.

Try a Nagler with and without the coma correcter before buying one. They are not cheap!

You usually won't even see the coma unless you use a really well corrected eyepiece like a Nagler or Pentax. Coma is also usually less obvious at higher powers.

It is also also heavy so can affect balance.

I use a Paracorr in my 22 F3.6 scope but haven't bothered in either my ex-16" or 10" F5 scopes. Threshold for definately using one for me would be F4.5 and faster.


The Type 6 Naglers are really sharp and the wider field is handy when moving the scope manually. Same for the Ethos. Radians are perhaps 0.5% sharper on axis, have a longer eye-relief , but a smaller field.

Ditto about not usually going over 200-250X on most nights.

Maybe get a 13mm Nagler and a good Barlow?

[Screwdriverone]

Hi Mark,

Firstly, because noone has mentioned it, a Pentax XF 8.5mm would suit your scope nicely and only costs $230. Great bang for your buck AND its a quality eyepiece with good eye relief and twist up eyecup. This size EP will give you around 180 magnification on your LB and is not as heavy as most of the combos shown here, not as much FOV as the Nagler's though.

Secondly, because I have an F5 12 inch scope and ALSO have the Pentax XF 8.5mm I can verify its performance on my scope which incidentally, is amazing!

Good place to start.....

Cheers

Chris

[ausastronomer]

Hi,

I don't necessarily agree with some of the advice you have been given. I own a Televue Paracorr, 2 Televue Powermates, a 2" barlow and a 1.25" barlow and to be honest I don't think you need any of those things at the moment. In an F5 Telescope I consider a Paracorr a very marginal piece of equipment. I have one for my 18"/F4.5 Telescope and only use it with 4 eyepieces out of at least 10 that I have. (31mm Nagler, 20mm Pentax XW, 17mm Nagler and 14mm Pentax XW). I don't use the paracorr with any eyepiece in my 10"/F5 telescope or with any eyepiece in my friends 25"/F5 or his 20"/F5.

I think your existing eyepieces are pretty average and not suited to use in a telescope with an F5 focal ratio. Unfortunately the eyepieces supplied when you buy a telescope are usually cheaper ones which don't work well at F5. Telescope dealers will always sell you what they carry in stock. Meade dealers will sell you meade eyepieces. At present Meade don't have any eyepieces that I would want to own and use in an F5 telescope.

I would start from scratch (sell every eyepiece you have)and start building a quality eyepiece collection you can use in any telescope you have now and progress to into the future.

You could consider buying second hand to save some money,

The telescope you have is a good one and will give you a few years of great use before you feel a need to go to something bigger and better.

I would consider building an eyepiece set along the following lines.

Low power = 30mm Pentax XW or 27mm TV Panoptic
Med Power = 16mm Nagler T5 or 13mm Nagler T6
High Power = 10mm, 7mm and 5mm Pentax XW's and a 8.5mm Pentax XF

You could also add a high quality barlow at a later stage if you felt there was a need.

Unfortunately there's quite a few dollars worth of eyepieces listed above and you may want to convert over in stages to suit your budget and any financial constraints.

Cheers,
John B

[wavelandscott]

I'm with John on this...although I tend to use my Parracor all of the time (my preference) I wouldn't encourage you to jump in with one now either because the value is incremental.

Concentrate on getting a good low, medium and high power eyepiece (collecting one at a time) and go from there.

The first one I'd get would be based on the type of viewing that you enjoy doing...

[toryglen-boy]

Hi Rob

Yeah, its worth it. I use it on a 12" dob, and it makes quite a difference with lower power, wide field eye pieces, although the only two points i would make are.

1. its a pain in the niagras to get the spacings right, and getting used to it can be like working out a Chinese logic puzzle.

2. Its best used with really good quality eyepieces, as quite alot of the bad viewing can be caused by defects in eyepiece itself, and not really down to coma. that said, its a handy piece of kit, and with me getting into imaging, and eyeing up a 20" F4 dob, its gonna be an even handier thing to have around.

:)

[Robh]

Duncan,
Thanks for the advice.
Regards, Rob.

[ausastronomer]

Hi Rob,

If you want a coma corrector for visual use only I would forget about the Baader MPC. It's an absolute pain in the niagras to adjust it every time you change eyepieces. The Televue tunable top paracorr is the only way to go for visual astronomy, notwithstanding its significantly higher cost and the fact that it increases the eyepiece focal length by an effective 15%. If you want it for imaging then that is a different matter. The Baader MPC was designed as a photographic tool, the Televue Paracorr as a visual astronomy tool. That all having been said, I think its a marginal thing and subjective to personal preference, with any telescope of F5 or slower.

Cheers,
John B

[Nesti]

To all those who have offered advice,

Thanks for your comments and recommendations; clearly getting the right eyepiece set and accessories is a marriage between experience and gut instinct. One thing I have definitely picked up, is that optical correction devices are no substitute for quality of the primary components. ***note to memory - stop picking expensive hobbies!***


I certainly haven’t wasted my money on my current eyepieces; I’m buying a Dob for my father in law - who’s wanted a telescope since his concentration camp days when he was 6yo :sadeyes: – and since his eyesight is moderate, I might just progressively give him what I’ve got. It looks like the current economic climate is forcing the top-end prices down, so it might be a good time to start.

I think I’ll get a couple of Tele Vue Naglers and look at Pentax next buy.

Thanks once again!

Cheers
Mark
:hi:

[Sentinel]

I agree completely with this. A luxury at f5, a necessity below f5.