Help required Orion Optics UK VX12

[guillaume320]

The thing is: If I have 2 Ethoses, let's say 13 and 21 mm, getting the Powermate 2X will yield an 10.5 and a 6.5. This would cost me about 4 times less than buying the 10 and 6 mm Ethos!

I've read in another thread with regards to Powermate and Paracorr combination some people claim it's not necessary to combine both. Meaning you wouldn't use the Paracorr if the Powermate is being used... Will this really yield acceptable results? Bear in mind we are talking about an f4 scope...

 

Once again many thanks for all your (valued) inputs
G

[John]

At F/4 I feel it's simply not sensible to invest in well corrected wide field eyepieces unless you use a good coma corrector.

 

[Commanderfish]

Well yes you need a Coma Corrector where you are not using a powermate/barlow, but with a x2 Barlow your focal length and therefore focal ratio are twice as long - yours becomes an F8 - so that's why some people say you probably don't need a Coma Corrector when using the Barlow.  

Unfortunately I haven't been using barlows until now (just about to start using one with a binoviewer) so I can't say for sure whether this works in practice - the theory makes sense though.

[Commanderfish]

I would also say with this scope you should try the Televue Nagler 31mm Type 5  OR the Explore Scientific 30mm 82 degree (which is basically a very good copy of the Televue 31mm).  They give the widest field you can get with a sensible exit pupil at F4.  With the Paracorr in, the exit pupil is 6.7mm which is at the reasonable maximum of what you can use.  

The Televue 41mm Panoptic gives a slightly wider field still, but the exit pupil is a bit too big and the sky tends to looks a little bit too grey.

The Ethos 21mm is of course a really lovely eyepiece, many people's favourite.  But for max field in an F4 dob I use the Explore Scientific 30mm 82 degree.  Instead of the Ethos 21 you can get the Explore Scientific 20mm 100 degree, again this is a very good Chinese copy of the Ethos 21mm.  I have one of each.  The ES 20mm 100 degree gets used in my ST80 scope which I use as a finder scope on my 16" F4 dob.  Gives a 5 degree field in there...

[Piero]

As far as I understand the coma free zone can be calculated with 0.0007" x f/ratio³ . At F4, this area is rather small, hence a coma corrector is needed. 

By increasing magnification the area is reduced. However, as the magnification is increased, the coma effect increases proportionally too. 

This means that a 21mm Ethos will show similar levels of coma than a 10mm Ethos (or 21mm Ethos + 2" 2x powermate/barlow). 

 

[guillaume320]

I think I will start off with the Paracorr and a single Ethos (probably 13), and with time slowly expand with a 21, 8 (or 6?) and 4.7.  Not sure in which order yet.  I probably skip the Powermate as the whole setup (PM+PC+E) would be a bit too 'awkward' from the looks of it...

Am I correct in assuming the Ethos 13 is the best 'all rounder' of the bunch?

[rl]

The WO / Nirvana 28mm with a paracorr is  a superb alternative in an OO 12" F/4...it's my most used widefield setup. 6mm exit pupil is about as good as it gets combined with *50 and 1.6 degrees TFOV. Throw in a UHC filter and you're all set for the veil....

[Piero]

58 minutes ago, guillaume320 said:

I think I will start off with the Paracorr and a single Ethos (probably 13), and with time slowly expand with a 21, 8 (or 6?) and 4.7.  Not sure in which order yet.  I probably skip the Powermate as the whole setup (PM+PC+E) would be a bit too 'awkward' from the looks of it...

Am I correct in assuming the Ethos 13 is the best 'all rounder' of the bunch?

In my opinion, Yes and No.. The Ethos 13mm is a very good eyepiece, no doubt.

However, the question should be will the Ethos 13mm be used a lot with my telescope?

Your telescope is F4 and focal length 1200mm. The TV parcorr will increase the focal length by a factor of 1.15x. This means that your telescope becomes F4.6 (f.l. 1380mm). The Ethos 13mm will give you 106.2x and an exit pupil of 2.8mm. To me at least, that exit pupil is in no one's land territory because it is not a sufficient low power eyepiece for extended nebulae and it is not a middle power for studying a target. I would prefer to have a dedicated low power eyepiece and then zoom in sufficiently when the target of interest is found. This is not a fault of the Ethos 13mm; it's the combination of a 13mm eyepiece with your F4.6 . 

If I had a F4.6, I would like something like this: 

- a low power eyepiece with exit pupil within the range 4-5mm or eyepiece focal lengths of 18.4mm - 23mm.

- a medium power eyepiece with exit pupil around 1.7-2.2mm or eyepiece focal lengths within 7.8mm - 10.1mm.

- for high power eyepieces you also need to consider your local seeing conditions. Most locations support a maximum magnification within the range 160x - 250x. As your telescope has a focal length of 1380mm, the equivalent eyepieces will have focal lengths within the range  8.6mm - 5.5mm.

If you want Ethos, I would get 21mm, 8mm, and 6mm with your telescope. For saving some money (but not quality), I would get Lunt 20 HDC, Pentax XW 7mm, Pentax XW 5mm. 

Said this, I'd advise to buy gradually after having clear ideas about tastes, interests, and after spending some time with your current equipment. 

 

Some time ago I wrote this mini guide. Hope it helps.  

 

[guillaume320]

That's extremely interesting Piero!  I'm leaning towards the Ethos 8 as a starting point now...  

[John]

2 hours ago, guillaume320 said:

That's extremely interesting Piero!  I'm leaning towards the Ethos 8 as a starting point now...  

Although, on paper, 13mm is a very useful focal length, I find that my 8mm Ethos gets more use than my 13mm in my 12" dob. Even though the 8mm is producing 199x magnification, you still see half a degree of sky which is great for many galaxies, globular clusters and planetary nebulae. The views of M13 and M92 through this eyepiece and my 12" dob on a dark night are simply amazing

It's also my favourite eyepiece for delving into the heart of the Orion Nebula to see the fainter Trapezium stars E & F.

[guillaume320]

5 hours ago, John said:

Even though the 8mm is producing 199x magnification

Hi John,

Sorry to ask, but I thought the 1200mm, with Paracorr corrected to 1380mm and an 8mm eyepiece would yield a magnification of 172? How do you end up with 199?  You are using the same scope, right?

G

[Moonshane]

John's scope is f5.3 = 1600mm

[guillaume320]

24 minutes ago, Moonshane said:

John's scope is f5.3 = 1600mm

That makes more sense... Sorry for the confusion

[scarp15]

Another contender at 1380mm F/L as an effective all rounder would be for a 10mm Ethos, so provide 138X. 8mm yielding 173x will be very purposeful as stated. Its hard to settle on just one.

[John]

On 13/07/2017 at 07:33, Moonshane said:

John's scope is f5.3 = 1600mm

Yep - well 1590mm according to the engraving on the mirror.

Sorry for the late reply - I was away for a few days.

You might want to consider the Lunt 100 degree eyepieces on account of this thread:

 

[guillaume320]

Digging up my old thread...

Yesterday I happend to read this .

I hope those are isolated cases? Or is those 'standard' issues with OO?

G

[John]

17 minutes ago, guillaume320 said:

Digging up my old thread...

Yesterday I happend to read this .

I hope those are isolated cases? Or is those 'standard' issues with OO?

G

If they were standard issues I doubt anyone here would be recommending Orion Optics scopes

There are quite a few owners of them here and many are experienced observers. My OO star tests very well but it was bought used so I guess any issues from new would have been sorted by previous owners.

There will occasionally be the odd rogue scope / mirror that slips though though, with all brands.

[Stu]

45 minutes ago, guillaume320 said:

Digging up my old thread...

Yesterday I happend to read this .

I hope those are isolated cases? Or is those 'standard' issues with OO?

G

For me there are too many reports both public and those which remain private of issues with OO kit. This is a premium brand charging a lot more than the Chinese manufacturers and they should have QA in place to avoid these problems. They pride themselves on optical quality, so whilst I can forgive some of the mechanical issues, astigmatism in mirrors and poorly put together cells is not on. Combined with their legendary attitude to customer service, if you have a problem then it can be difficult to resolve pleasantly.

I think I've had 6 OO scopes now so I'm clearly a glutton for punishment! The only new one I bought was an OMC200 which always had a problem with collimation. I took it back to them personally (about a 6 hour round trip) and was basically fobbed off with a tweak of the secondary. Eventually, not long before I sold it, I was brave enough to open it up and found that the primary was unseated because it had not been held in place properly. I reseated it and then all was well but I should not have had those problems and wasted a number of years not getting the best performance out of it.

VX10L, VX12L f6, VX12L and 2 x OMC140 have basically been fine optically as far as I could tell and the latest OO focusers seem very nice.

If I were you I would just make sure you check the scope out thoroughly when you receive it and push back hard if there are any optical or mechanical problems.

If I was going for a larger mirror these days (which I am not currently!) I would probably opt for a Nichol or one of the premium US brands like Zambutto but it would go in a truss dob.

One thing I don't understand it that, I believe, the testing is done prior to coating. If there is a problem with the coating process, how is that picked up or is the Zygo done afterwards?

[guillaume320]

Thanks for the reassuring words John.

Stu, I understand the 'issues' don't seem to be as isolated as I would have hoped... Anyway, the order is in, the money is paid, so I can only pray for a smooth ride now

G

[John]

I think Stu is right - check the scope out thoroughly when it arrives and be firm with Orion Optics if there are any issues that you are not happy with.

I've owned 2 of their newtonians and both have been good but they were both bought used.

[scarp15]

It will be interesting, as no doubt you will, to gain feedback when you do eventually get to receive and assess condition, performance of your new scope. It should not be about 'dodging bullets' where a premier optical, scope building company is concerned, though as stated there are accounts declared on-line or private that address recurring concerns and issues. Mostly though I would think particularly standard order scopes arrive as expected. I have two, the larger VX14 is second hand, the 8L purchased new. Optically, mechanically they are both very good, focuser on 8L is a bit misaligned and might need a collimation tweak. For reassuring confidence or otherwise, transparency on these matters is a positive and inclusive for informing future potential purchasers.   

[Stu]

2 hours ago, guillaume320 said:

Thanks for the reassuring words John.

Stu, I understand the 'issues' don't seem to be as isolated as I would have hoped... Anyway, the order is in, the money is paid, so I can only pray for a smooth ride now

G

I genuinely hope you have a good experience Guillaume, please do let us know when you get the scope.

[ollypenrice]

On 12/07/2017 at 16:05, John said:

At F/4 I feel it's simply not sensible to invest in well corrected wide field eyepieces unless you use a good coma corrector.

 

It's very rare indeed that I disagree with John  but this time I do, though based on experience of only one scope. We have a 20 inch F4.1 with 'satisfactory' but not great primary mirror. We've never used a coma corrector in it and some pretty serious visual observers have used it and confirmed my own feeling not to bother. By default we use only only two EPs in this scope, with an occasional third in the form of a 10mm TV Radian. The two main EPs are very wide field ones, a 13 Ethos and a 26 Nagler. They work like a charm. While not perfect, the edge of field is way better than that seen on more budget EPs like good quality Plossls. I feel that these great widefields clean up the view very well.

However, as I say, this view is based on a sample of just one!

Olly

[andyrawlins]

On ‎19‎/‎06‎/‎2017 at 13:24, Moonshane said:

I cannot access the FLO site at work but there's a bargain to be had here :

http://www.365astronomy.com/Baader-2-NT-Steeltrack-Crayford-Focuser-for-Newtonian-Telescopes-bf-30mm.html?gclid=COeun5_zydQCFUq37Qodg7YOgA 

Hello Moonshane - well spotted, this looks like a bargain.  This is the non diamond, original version and half the price of the current model.  Can anyone comment on whether this is worthwhile?  Until I saw this I was thinking of getting one of these http://www.rothervalleyoptics.co.uk/skywatcher-dual-speed-2-low-profile-crayford-focuser-for-newtonian-reflectors.html   which appears to be what OO fit to their entry level scopes these days.  My 8" has a rather nasty rack and pinion so I'd like to upgrade but, as an occasional viewer/DSLR imager, not spend a fortune.

Thanks in advance

[Moonshane]

I believe from my own experience of both that this Baader is far superior to the skywatcher. I know someone ordered one of these and two had an issue requiring adjustment. Personally I'd just adjust it but I think they successfully  exchanged. Just be aware of this in case 365  have not adjusted the issue on the remainder.  I am sure they would