10 - 13 mm or barlow? 2"

[gooseholla]

Hello,

For viewing deep sky objects I use a 20mm T5 Nagler and a 26mm Panaview. I also have a 15mm 2" eyepiece for getting in closer. These provide me with 75x, 58x and 100x magnification. However, I'm considering something in the 10 - 13mm range to up my magnification for looking at galaxies on a clear night.
 

Would a barlow or a new eyepiece be better? Sky's the Limit have this for £42 http://www.ebay.co.uk/itm/Skys-Limit-2-2X-ED-Barlow-Lens-1-25-adapter-/380835033316?pt=UK_Telescope_Adapters&hash=item58ab8970e4.

This would give me 150x and 115x.

A 2" eyepiece of good quality is going to be double that I suspect. Although I am welcome to suggestions! Or should I get a 1.25" version, of say a BST 12mm at £50, giving 125x? I could house it permanently in a 2" adapter... 

Any suggestions welcome!

Thanks

John

[alan potts]

If galaxies is what you like I would go for another eyepiece as putting extra glass in the line will reduce light through put a little. I would go for something like the 11mm TV Plossl, excellent sharpness and quality all round and very good light transmission.

Oh, and they don't cost a mint for a Televue.

Alan.

[Dude_with_the_tube]

+1 on Alans post.You dont want extra glass in between.

What eye piece to purchase or what brand,thats up to you to decide depending on your budget.

[swamp thing]

Hi

I Powermate my 20mm T5 Nagler most observing session it works extremely well Barlowed on galaxies.

I don't feel the light transmission is effected in any way using Naglers for galaxy hunting myself or I'd use plossls. The extra glass makes no difference IMO.

The extra elements with a Barlow won't make a blind bit of difference either.

Edit: I'm actually a bit surprised that observers using nine element ethos eyepieces are worrying about number of glass elements with a T5 Nagler and Barlow..,,,,,that would be eight ekements

How's your ethos eyepieces on galaxies guys.......rubbish I shouldn't wonder. It must be pitch black in them

[gooseholla]

Well, I am drawn to a barlow, as it will give me more options for less than £50. But, part of me wants to buy a new eyepiece! I think I may try some old 1.25" plossls against their respective 2" pieces with large glass elements and see if there is much of a difference light wise.

[rwilkey]

Hi John, I would suggest the 12mm BST StarGuider would be better, in my opinion, or the 11mm TV Plossl as Alan suggests above.  At this range I have the 11mm ES82 Series and very pleased with it.

[Dude_with_the_tube]

a BST Starguider better then barlowed T5 Nagler? i would love to see that.

[alan potts]

Dude,

I am sure not better but without doubt cheaper.

I am going to leave it a while until we have a water shortage then I am going to put money where my mouth is and get a couple of TV Plossl's, maybe the shorter ones.

Alan.

[bingevader]

I don't think you'll be disappointed with either option. Alan's suggestion of the 11mm TV plossl is an excellent one however. I have one and it's a very fine ep indeed. I haven't tried it with the 2" adapter, but do use my 14mm ep with an adapter and that works very well for the hassle free change overs when I'm out dso hunting with the 2" EPs.

[bingevader]

Btw, the tv plossls are even better value 2nd hand if you're prepared to wait.

[animaal]

I haven't seen much difference in quality between good high-power eyepiece and a good low-power eyepiece with a good barlow.

However, I don't like fiddling with the barlow (and its extra weight) when I'm moving between magnifications.

[gooseholla]

Well on Saturday I drove down to Telescope House. Picked up a 2" 2x Barlow from Revelation and must say I am impressed. On my 15mm 80 degree and 20mm Nagler T5 it did a great job. Only the very edge is soft and everything else was razor sharp and good views. Was nice to see Mars and Saturn in 80 degree views so clearly and detailed. Not bad for £32.

Only down side is, it is quite large and unbalances the scope! Will have to hang something off the back when it is in use.

John

[swamp thing]

That 20mm Nagler Barlows real nice doesn't it

Enjoy

[AlexB67]

Hi

I Powermate my 20mm T5 Nagler most observing session it works extremely well Barlowed on galaxies.

I don't feel the light transmission is effected in any way using Naglers for galaxy hunting myself or I'd use plossls. The extra glass makes no difference IMO.

The extra elements with a Barlow won't make a blind bit of difference either.

Edit: I'm actually a bit surprised that observers using nine element ethos eyepieces are worrying about number of glass elements with a T5 Nagler and Barlow..,,,,,that would be eight ekements

How's your ethos eyepieces on galaxies guys.......rubbish I shouldn't wonder. It must be pitch black in them

I notice a difference in brightness with a 2x barlow and a decent pentax 10.5 to give approx the same mag, compared to a 5mm BGO alone with just 4 elements.  Now granted my barlow is a cheap as they come 2 element, I've never tried a powermate,  but I recently also noticed that  on certain objects even a BST starguider 8mm  is slightly "brighter" ( or a bit more contrast, hard to separate to the eye) than an 8mm Radian with more vibrant colours on stars as well.  On deep sky I noticed these differences too on planetary nebulae, globs, quite subtle, but detectable.  On the whole  admittedly more so on the brighter more obvious objects, and quite easy to detect on planets as well after a while of testing recently.  It did become somewhat  harder to tell when there is not much brightness to work with on some galaxies in some cases. I am speculating that is more because the eye can't, or perhaps I should say my eyes can't detect such subtle changes to be certain.

Perhaps if you have a big scope and good dark skies where you get better apparent surface brightness to work with it becomes less important ? but if you observe under somewhat light polluted skies as I often do where I did these tests  most of the time from home, I can't say I agree, because even amongst eyepieces I can notice some differences in terms of seeing contrast and/or perceived brightness, not to mind adding my barlow.

[AlexB67]

Forgot to add,the sketch attached is consistent with some of the differences I am seeing in different eyepiece barlow combos  ( though different objects, but it gives a very good idea of what I experience in practice ) I Got it from one of those reviews one time on CN but don't recall the link but demonstrates the point perfectly. Probably somewhat more pronounced than what I see but anyway, to give a rough idea.

[John]

Interesting pics Alex. I've read of the Radian's slight lack in light throughput compared to some other eyepieces although slight is the word I think (ie: 89% v's 94% for example). The TV Plossls seem, on the other hand, to have about the highest levels of light transmission of any eyepieces - I've seen figures of around 97%.

Personally I feel that the Baader Classic Orthos in the 10mm and 18mm focal length are some of the best for this that I've used. The 18mm even seemed better in throughput terms than the much admired 18mm Baader Genuine Ortho, to my eyes. For <£50 a throw worth having in an eyepiece box for the keen DSO hunter perhaps ?

For planetary and lunar use though the issue is less critical and the Radian's shine (excuse the play on words) at that 

[AlexB67]

I do love the 6mm Radian in particular on Jupiter John, that being said and I am beginning to find the Radian line does have some weaknesses  in that area of throughput/contrast ( just my opinion and to my eyes ) but it only became clearer until recently when I compared it the 8mm BST to be more sure of that.

Talking of planets, on Saturn for example the perceived contrast I see is also a small bit less pronounced, as you say subtle, but for sure I can see it, the difference in colour for example between the equatorial zone as you look towards the poles seem that little bit more muted to me, and stands out that bit out more  to me in a BST as well as a pentax where it is that little bit more vibrant and obvious. 

On planetary nebulae that have blueish tint it is also quite noticeable. I suspect  because the lower transmission in the Radians occurs in the blue to green region where it is about 88% in some tables, and it goes as low as 85% depending which table focal length you look at, but it is also where the eye is quite sensitive.  I suspect it is just the progress that has been made over the years perhaps with newer eyepieces to some degree I guess, coatings and so on ? .  The Radians are getting on a bit now.

Don't get me wrong, not meant to be  bash of any kind in every other respect I do really like them. but I really wasn't expecting these results to be that visible in terms of contrast and transmission situations , I am going purely what my eyes are telling me, quite a few observers will agree on this point, some say it is perhaps  a bit of nonsense to get hung up on. I guess each to their own, but with my findings so far I would pick orthos/pentaxes over radians with what I am seeing in most situations so far. That BST if you forget about optical correction and some other things can happily compete with the radian on Axis (again to my eyes anyway), so that makes the Radian a little bit less special to me in some ways.

I can't vouch for the more expenive updated models like Delos and so on to compare. I expect they are better in that area with updated coatings. That 14m Delos is still  on my shopping list

I will be vey interested in hearing your view on the SLV when your review is ready,for example how it compares to an ortho, you already said it was very good, but also the Radians if you can compare in the same focal length and see what you make of it.

[gooseholla]

I agree a Barlow does reduce some of the light. For example, my TMB Planetary II 6mm is slightly brighter than my 15mm barlowed up to give 7.5mm. However, in terms of best views, the Nagler T5 20mm barlowed gave the best views of Mars tonight. 6mm was bright, but contrast seemed to be lacking, which was there at 7.5mm (250x compared to 200x).

The real test is going to be on galaxies using the Panaview 26mm barlowed, or Nagler T5 barlowed. But, at the moment, I am certainly happy with the setup I chose. Was considered another eyepiece, but barlow is more flexible.

[swamp thing]

I agree a Barlow does reduce some of the light..

I don't.

Next they'll be saying the actual thickness of the lens elements effects the light transmission. So if your plossl has 6mm of glass to let light go through and mine has 4mm..............

Like I said originally if it made that much difference I'd be using plossls....I don't.