Choosing a Planetary eyepiece

[russ]

Let me have a look round for you. Hold on a sec.

[russ]

Here you go:

1.25" 8mm 58 Degree TMB designed Planetary eyepiece on eBay (end time 28-Apr-11 20:00:39 BST)

£36 + £2.50 p+p

I have the 4mm & 7mm of that series from Alan, pleased as punch. The 7mm was cracking in our 127 Mak when used at SGL6 but the 8mm would have suited better. While the 4mm is awesome in the 150 newt.

[GazofCorra]

Russ - Thanks mate that is awesome

Knowing that you too have a 127 Mak i was wondering if you use a RDF with it? I have a telrad to go on my Dob when it arrives but if i fitted the telrad to the mak i would have trouble using a dew shield due to the size of the telrad .

Gaz

[Adz]

Is that the old model Russ? Mine looks nothing like that. I believe mine is a type II and it has adjustable eye relief.

[johninderby]

There's no real difference between the clones and the TMB branded eyepieces except for the style of the twist up barrel. However I've found that the clones seem to have better and more consistent quality control. The clones came along after the TMB IIs so they could be considered as the newer eyepieces.

BTW a note of warning on the TMB IIs. A big batch of substandard ones have been flogged off on eBay lately so it's buyer beware.

John

[russ]

Russ - Thanks mate that is awesome

Knowing that you too have a 127 Mak i was wondering if you use a RDF with it? I have a telrad to go on my Dob when it arrives but if i fitted the telrad to the mak i would have trouble using a dew shield due to the size of the telrad .

Gaz

Gaz, i use the same MRF i linked too in your other thread. It gives a 0.5deg circle projected onto the screen, which i find is perfect for nailing everything i want in the Mak. After all I won't be doing a Messier marathon with the Mak, so no need for an optical finder.

[russ]

Is that the old model Russ? Mine looks nothing like that. I believe mine is a type II and it has adjustable eye relief.

John has answered this one now. But i have used all versions of TMB Planetary from the earliest genuine Burgess TMB MkI to those linked and i have no complaints at all with the clone.

[GazofCorra]

Gaz, i use the same MRF i linked too in your other thread. It gives a 0.5deg circle projected onto the screen, which i find is perfect for nailing everything i want in the Mak. After all I won't be doing a Messier marathon with the Mak, so no need for an optical finder.

Russ, i only just twigged that the link in the other thread was from you, doh.

So you have it located in the standard finder shoe on the mak?

Being new to all this and having been on a spending spree of late and only had 1 viewing session, i am yet to understand what the mak does best, like you say you will not be doing a messier marathon with the mak, so what is it's role best suited too?

From the beginning i was told that no one scope can do it all, so for DSO's i bought the dob, but it can still be used on planets etc.

The mak i stumbled onto as i am still waiting for my dob to arrive (since 9th March) and wanted to get out a see something, so i was going to sell the mak later on and buy a largish refractor for planetary and lunar viewing, but then people have said keep the mak as it is very good, but good at what i am not sure.

[Adz]

Well it has a long focal length for the size and portability. I also believe it gets better contrast to refractors and is great for webcam imaging of planets. Don't hold me to all of that though

[russ]

The Mak is best suited to planets, moon and double stars. But that said, from the SGL6 star party, we had some cracking views of fainter DSO's. It had no problem with the Leo Triplet, a really nice view. And also picked up M95/96 with ease. So it will do the deepsky as well from a dark sky.

[russ]

Well it has a long focal length for the size and portability. I also believe it gets better contrast to refractors and is great for webcam imaging of planets. Don't hold me to all of that though

Slow focal ratio means it is very easy going on cheap widefield eyepieces. It holds collimation incredibly well. And the view, once cooled (cool down time not bad on the 127), will give some expensive scopes a nasty shock. It's a classic scope for good reason.

[GazofCorra]

Nice one, now i see why the standard finder scope is not needed as well as a RDF, as most DSO's are a space hunt and only through a magnified finder scope can you be certain you are in the right spot (unless you keep peeping through the scope and panning around)

I am happy i now know the purpose of my mak, So like any scope it has targets that it excels at viewing and can be used on most other targets with limited results.

[Httetal]

Great thread - glad I stumbled across it, as I've decided it's time to think about some more eps than just the 2 plossls that came with my dob. One for deep sapce (maybe a 2" long focal length and wide angle) and one higher power for planets - and with a baby on the way I don't want to spend much - the TMB planetaries seem perfect for the later (planets not bables), only thing - what size would best suit a 150 Dob??

[Adz]

Hi Henry,

Seems like you are in a similar situation I was a couple of weeks back. Since then I have invested in a tmb planetary 6mm for close work and a televue 32mm plossl for my wide stuff. I grabbed them for under 100 quid which wouldn't break your limited budget if thats what it stretches too? The TMB is fantastic value for money with the wide field considering the magnification. The 32mm is great quality, but perhaps taking full advantage of a 2" focuser would be more idea for you. Skywatcher 2" panaviews come to mind.

HTH

[Httetal]

Cheers for the advice Adam,

yeah, about 100 quid is the limit. Think I'll take the plunge on the TMB, I was thinking the 6mm would be about right. Still need to do more research on the DSO ep though.

[Adz]

Shame you are so far away, I am always up for letting people use my kit.

From the research on here, at 79 quid the panaview is a real beauty. Especially as the distortion towards the edge of fov is minimal in a slower focal ratio scope. It will probably be my next ep, as an exploration into whether 2" fittings are worth it.

[great_bear]

The other night i tried using my televue x2 barlow with the 13mm nagler on saturn and it was slightly blurry with no conrast, maybe the conditions were not that good, but i want to try 1 or 2 high power EP's to see how they compare.

And the finalists are:

1. William Optics SPL 6mm (55 deg fov & 20mm eye relief) £70

2. TMB Planetary 6mm (58 deg fov & 15mm eye relief) £55

3. Celestron X-Cel ED 8mm (55 deg fov & 20mm eye relief) £60.

None of the eyepieces suggested are going to be any better than your Nagler + TV Barlow.

[John]

None of the eyepieces suggested are going to be any better than your Nagler + TV Barlow.

I agree 100%

It will be the conditions or collimation, rather than the eyepiece / barlow combination that's blurring the images.

[swamp thing]

I agree 100%

It will be the conditions or collimation, rather than the eyepiece / barlow combination that's blurring the images.

Ditto

[Moonshane]

I agree and suspect it's magnification. I can rarely use 230x (assuming you were using the Mak with effectively a 6.5mm eyepiece) on Saturn due to seeing conditions. Double stars and moon yep, but not often planets.

[GazofCorra]

Guys i am not saying that my nagler and TV x2 barlow are at fault here as i was viewing at 230x and the conditions were fair, so not only am i magnifying the image of Saturn but also the turbulent atmosphere too.

But i want some short focal length dedicated planetary EP's for using with my Mak and my reflector, from what i have read using a x2 barlow practically doubles the focal ratio of the scope as well as doubling the power of the EP, so my Mak which is f12 will be more like f24 when using a barlow, that is why quite a few people recommend using a barlow for high power work on fast scopes up to f6 as it not only doubles the power of the EP but it practically doubles the focal ratio too, so a f5 dob theoretically becomes a f10. And everyone knows that the other advantage of using a barlow is the eye relief of the EP being used is maintained allowing for more comfortable viewing.

I will be using my X2 barlow with my 13mm nagler on my f6 dob, which will give me 184x which is as high as i want to go using a manually operated dob.

BTW - As John stated it will be the collimation or the conditions blurring the image and i assume it was the conditions, but how can you tell if a mak needs collimating and doesn't it have to be done by a trained technician?

[great_bear]

i want some short focal length dedicated planetary EP's for using with my Mak and my reflector, from what i have read using a x2 barlow practically doubles the focal ratio of the scope as well as doubling the power of the EPns blurring the image

It doesn't practically double the focal ratio of the scope - it literally doubles the focal ratio of the scope - but it doesn't double the power of the eyepiece as well as changing the focal ratio - nor is it responsible for blurring the image more than a short focal-length eyepiece would.

- and here's the catch - all of the eyepieces you mentioned, work by having a built-in Barlow anyway*

how can you tell if a mak needs collimating

Observe a bright star slightly out-of-focus at an exit pupil of about 0.5mm. It should sit nicely within concentric rings of light.

doesn't it have to be done by a trained technician?

Depends on the Mak. My Sky-Watcher Skymax 180 and Skymax 102 can be collimated by anyone with a set of Allen keys

*a built-in Barlow, strictly speaking, is called a Smyth lens.

[GazofCorra]

GB - You quoted me as saying "i want some short focal length dedicated planetary EP's for using with my Mak and my reflector, from what i have read using a x2 barlow practically doubles the focal ratio of the scope as well as doubling the power of the EPns blurring the image"

but i did not mention the words "blurring the image" in my post so that bit has not come from me.

Thanks for the other info though.

[great_bear]

i did not mention the words "blurring the image" in my post so that bit has not come from me.

It came from the bit when you said "conditions blurring the image" - which got accidentally concatenated during my editing - sorry!

It's a difficult task trying to multi-quote a message sometimes!

[John]

I'd suspect viewing conditions before collimation to be honest. The seeing we get in the UK can bring the best collimated scope and the finest eyepieces to their knees all too often I'm afraid