8mm Radian or something else ??

[AlexB67]

While I saw the radian slowlly crop up in the ethos thread it got me thinking

http://stargazerslounge.com/topic/202181-47mm-ethos/

and I did not want to derial it completely, so thought to ask the question here, more for future reference as much as anything.

At some point I'd be interested in a radian in that sort of 6 - 8 mm range if one turned up second hand,  having said that, I had some slight reservations about them after reading a review here and there, no less one back some time ago by Michael Wilkinson comparing it with  a pentax XF.  When he says something about eyepieces I'd better listen and take it very seriously. It also tallies with a review here

http://www.cloudynights.com/item.php?item_id=1438

admittedly, it is about the 12mm, but feel this is perhaps a common pattern with the Radians, it is not the first time I've heard about it.  The issue that has left me slightly on edge is their deep sky performane.  One of the reasons I'd like something in that range is not for planets, although I think the 6mm Raian would actually be great at 200x for me on bright sources like Jupiter, but when it comes to planetary nebulae and some of the deep sky fainter stuff it seems brightess  is not the best, that is an important point for an 8mm which would interest me for the purpose of deep sky also. 

I have little doubt that in a fast scope the radian would be very good off axis it being a TV and all, but if I were to get a  8mm say, a good sweet spot for some of the PNs,  I think I'd favour the high tranmission  and contrast a much as anything.

Fire away and redeem the Radian

Note: Suggesting a plossl at 8mm or so is not an option with wearing glasses for me, but suggesting anything else is fine. I suppose a budget option would something else narrow FOV too, though I admit that extra 10 degrees is a nice thing, 60 - 70 degrees ideally, good eyerelief and so on. The 8mm BST I have I am very happy with, so it is not a case of  I need it tomorrow type thing.  I should say after a sample of pentax XL 10.5 a Pentax XW 7mm would be a cracker,  I think it would be worth every penny if one turned up, or even save for new if need be. If buying a 7 - 8 mm needs to wait long term to just buy the bigger more costly thing  down the line it is an option I'd be fine with and skip the Radian line altogether.   

[alan potts]

Alex,

I have had 5 Radians and still have 3. 3mm 4mm 5mm 6mm and 10mm. I have only really ever used them as a planetary eyepiece which is what they were aimed at when they were marketed. Fully understanding that not everyone can afford 3-4 eyepieces of the same focal length for different jobs. I do not have the 6mm any longer but it is a superb eyepiece and I would put it up there with the likes of the Delos which I bought to replace it. You can argue until the cows come home about which is best, but for planets, for me the Radian is as good as any. It is only the other week that I thought the 3mm was better than the 3.5mm Delos on Messier 15 through a 115mm APO, the differences between them are very small. I have to say after some work on a similar test with the 4mm Radian and the 4.5mm Delos my findings are not that different.

I remember reading Michaels report and after I was still looking at the Radian 8mm as my favourite, sadly though I didn't get it in the end, being bitten by the Ethos fever bug landed me the 8mm instead from that range. In all honesty for a 100 quid or so S/H they are the best value on the used market and I would but more of them if I had the chance, but solely for planetary viewing where for me they excell.

Alan

[michael.h.f.wilkinson]

While I saw the radian slowlly crop up in the ethos thread it got me thinking

http://stargazerslounge.com/topic/202181-47mm-ethos/

and I did not want to derial it completely, so thought to ask the question here, more for future reference as much as anything.

At some point I'd be interested in a radian in that sort of 6 - 8 mm range if one turned up second hand,  having said that, I had some slight reservations about them after reading a review here and there, no less one back some time ago by Michael Wilkinson comparing it with  a pentax XF.  When he says something about eyepieces I'd better listen and take it very seriously. It also tallies with a review here

http://www.cloudynights.com/item.php?item_id=1438

admittedly, it is about the 12mm, but feel this is perhaps a common pattern with the Radians, it is not the first time I've heard about it.  The issue that has left me slightly on edge is their deep sky performane.  One of the reasons I'd like something in that range is not for planets, although I think the 6mm Raian would actually be great at 200x for me on bright sources like Jupiter, but when it comes to planetary nebulae and some of the deep sky fainter stuff it seems brightess  is not the best, that is an important point for an 8mm which would interest me for the purpose of deep sky also. 

I have little doubt that in a fast scope the radian would be very good off axis it being a TV and all, but if I were to get a  8mm say, a good sweet spot for some of the PNs,  I think I'd favour the high tranmission  and contrast a much as anything.

Fire away and redeem the Radian

Note: Suggesting a plossl at 8mm or so is not an option with wearing glasses for me, but suggesting anything else is fine. I suppose a budget option would something else narrow FOV too, though I admit that extra 10 degrees is a nice thing, 60 - 70 degrees ideally, good eyerelief and so on. The 8mm BST I have I am very happy with, so it is not a case of  I need it tomorrow type thing.  I should say after a sample of pentax XL 10.5 a Pentax XW 7mm would be a cracker,  I think it would be worth every penny if one turned up, or even save for new if need be. If buying a 7 - 8 mm needs to wait long term to just buy the bigger more costly thing  down the line it is an option I'd be fine with and skip the Radian line altogether.   

Deary, me, you make me blush . Maybe I need to qualify my review about the Radian 8 vs XF8.5. There is only a very small difference in performance between the two. Yes it is there, and if you don't mind the slightly lower magnification of the XF8.5, that is the way I would go (as it is cheaper), unless you can get a good deal on a Radian 8mm second-hand.  The Radian is excellent, but the XF is just ahead by a gnat's whisker. The Delos is better still, mainly due to its bigger FOV and smidgen more contrast, but the cost is really a lot higher.

[alan potts]

I think that sort of sums up my views on them, I have never seen a Pentax 8.5mm but know Michael had one, Delos are tad better but if the FOV is not an issue save the money, even secondhand they are double.

Alan. 

[John]

Just because one eyepiece performs very slightly better than another in one or two areas under some targets / conditions does not then render the 2nd one in any way a poor product. The 10mm Baader Classic Ortho has been ranked above the Delos, the Ethos and the XW by a noted observer on deep sky objects but I don't notice anyone feeling that thats the end of the line those 3 much more expensive eyepiece lines 

Radian's and Pentax XF's are great eyepieces although the latters range is limited to just 2 focal lengths. From the reports I've read on these lines (many of them !) I reckon the XF's might be a tad better if DSO's are your thing and the Radian's major on lunar and planetary viewing but thats probably splitting hairs too !

[AlexB67]

Thank you folks so far. I can see one way of going, 6mm Radian mainly for planets.  Pentax XF 8.5 for some more of the deep sky.  Do some nuclear fusion on this option and turn it into a 7mm Pentax XW is also an option . 

Plenty time to ponder anyway and build up more experience in the mean time. In the longer term I am sort of thinking how to complete my line up for the foreseeable future perhaps, but that is a sort of different topic. Mid range 14mm Delos or pentax XW 14 when I come tp upgrade my BST 15mm.  Again no rush, the BST 15mm is very good already. 20 mm, well I got a Maxvision, I think that would be a long way down the line to worry upgrading that,  I find it that good, 28mm Maxvision incoming soon, if not for Xmas from the missus I'll get it next month. 

BTW Not to worry, I appreciate that differences are quite marginal at this level and not in any way feel such eyepieces spank each other in different areas, but when I look at this level margins are not be ignored at the same time.

[AlexB67]

A 6mm and an 8mm Delos  , how could I forget, options options options ... 

[Stu]

Just because one eyepiece performs very slightly better than another in one or two areas under some targets / conditions does not then render the 2nd one in any way a poor product. The 10mm Baader Classic Ortho has been ranked above the Delos, the Ethos and the XW by a noted observer on deep sky objects but I don't notice anyone feeling that thats the end of the line those 3 much more expensive eyepiece lines

Radian's and Pentax XF's are great eyepieces although the latters range is limited to just 2 focal lengths. From the reports I've read on these lines (many of them !) I reckon the XF's might be a tad better if DSO's are your thing and the Radian's major on lunar and planetary viewing but thats probably splitting hairs too !

I totally agree with this John. Having read a number of threads on CN, I was thinking that the a Radian was not worth bothering with, but having tried them I think they are great eyepieces. There is a tendency to focus on very small differences as if they are major, but I doubt there are many (any?) things you could see in a Delos that you couldn't see in an equivalent Radian. The colour caste has never bothered me, but then I am not that sensitive to colour in my night vision anyway. The radians give lovely crisp images with good eye relief, in a nice package so I am a fan.

Stu

[Stu]

I totally agree with this John. Having read a number of threads on CN, I was thinking that the a Radian was not worth bothering with, but having tried them I think they are great eyepieces. There is a tendency to focus on very small differences as if they are major, but I doubt there are many (any?) things you could see in a Delos that you couldn't see in an equivalent Radian. The colour caste has never bothered me, but then I am not that sensitive to colour in my night vision anyway. The radians give lovely crisp images with good eye relief, in a nice package so I am a fan.

Stu

Meant also to add that I am sure the US based observers and others with better skies are able to see differences which are not visible to us except on very rare occasions.

Stu

[Naemeth]

I totally agree with this John. Having read a number of threads on CN, I was thinking that the a Radian was not worth bothering with, but having tried them I think they are great eyepieces. There is a tendency to focus on very small differences as if they are major, but I doubt there are many (any?) things you could see in a Delos that you couldn't see in an equivalent Radian. The colour caste has never bothered me, but then I am not that sensitive to colour in my night vision anyway. The radians give lovely crisp images with good eye relief, in a nice package so I am a fan.

Stu

I felt the same when I compared my Vixen LV7mm and my TeleVue 8mm plossl. An observer would be happy with either, it's only in using them side to side that you notice one is slightly ahead of the other.

Personally, go with whatever your budget will stretch to, the XF or 2nd hand Radian if it's around £100 (per eyepiece), the Delos / XWs if it's around £250 (per eyepiece).

[michael.h.f.wilkinson]

I am not sure my skies are any better than UK skies, but the Radian is underrated in many reports. I also sometimes wonder about the following: when you get a new EP, it is in pristine condition. You then compare this to an EP which you have had for a while, and might have the odd speck of dust (please DON'T rush off and clean your kit!!). When looking at the tiny differences, it might be that odd speck of dust that makes a difference. There is also the psychological tendency to want your shiny new piece of kit to perform better. This is a key problem with EP evaluation: it is never a blind comparison. You know what EP you are looking through.

I would not worry too much: all the EPs you list are cracking good ones, all will give great views. If you can get a Radian second-hand cheaply (and there are quite a few deals to be had), you won't lose (much) money if you decide to go towards the XW or Delos EPs.

[alan potts]

Stu,

I know it is only a very small part of the country but if you go anywhere near LA you would be lucky to see the stars.  Is there any evidence to suggest that their skies are better than we have. I have been out on the Moors a few times when the sky state was nothing short of excellent.

Alan

[jetstream]

I think the tester on CN was in Switzerland @ about 1100 meters-interesting to note that he heard that EP's function well to -5c.....I wonder what happens at -25'c?The Radian was/is phased out ot TV's line,there must be a reason-not to say they are not a good eyepiece,I've never seen one.Contrast and image brightness is what I'm after...I would sure like to compare an XW to everything

[alan potts]

Doing just that now with the XW 7mm and the Nagler 7mm.  All good things come to those who wait.

Alan

[jetstream]

Doing just that now with the XW 7mm and the Nagler 7mm.  All good things come to those who wait.

Alan

Can we throw an Ethos in the mix too?I'm thinking those Pentax XW's are really good,optically, with 20mm ER and twist up eyecups-for the cold.I have heard something about field curvature in FL above 10mm with the XW's-any thoughts anyone?

[michael.h.f.wilkinson]

I think the tester on CN was in Switzerland @ about 1100 meters-interesting to note that he heard that EP's function well to -5c.....I wonder what happens at -25'c?The Radian was/is phased out ot TV's line,there must be a reason-not to say they are not a good eyepiece,I've never seen one.Contrast and image brightness is what I'm after...I would sure like to compare an XW to everything

I think the Radian was phased out purely because the Delos came in. Aimed at the same audience: those that do not feel the need for 82 or 100 deg, but do want more eye relief, they would be competing in the same marketplace. One could say they were phased out in the same way the Nagler Type 1 and Type 2 were phased out. Some called the Radians "Nagler Type 3" (which never was).

Doing just that now with the XW 7mm and the Nagler 7mm.  All good things come to those who wait.

Alan

The XW7 is a cracking EP, I have no doubt it will hold its own against a Nagler, or even the mighty Ethos (except of course in terms of AFOV).

[alan potts]

I think in real terms it is asking a bit much to make a effective study of a XW which are of cousre 70 degree FOV and an Ethos, even though I do have the 8mm and the 6mm. To be honest it is difficult to even work with the Nagler at 82 degrees. They are of course the same 7mm and whilst they not be absolutely exact 7mm they really look like different magnifications with the field difference, plays tricks with your eyes.

I have been using a 6mm Delos as well in the mix as a sort of referee. I have had 3 nights of clear for 20 minutes and then clouds so it is slow at the moment but I am getting there, it will give me something to do now I can't build.

Alan

[Stu]

Stu,

I know it is only a very small part of the country but if you go anywhere near LA you would be lucky to see the stars. Is there any evidence to suggest that their skies are better than we have. I have been out on the Moors a few times when the sky state was nothing short of excellent.

Alan

Well I definitely agree about LA, but if you are in the middle of the US, potentially at altitude with a very dry atmosphere then I'm sure you get a clarity we can only dream of.

Stu

[Moonshane]

I think the tester on CN was in Switzerland @ about 1100 meters-interesting to note that he heard that EP's function well to -5c.....I wonder what happens at -25'c?The Radian was/is phased out ot TV's line,there must be a reason-not to say they are not a good eyepiece,I've never seen one.Contrast and image brightness is what I'm after...I would sure like to compare an XW to everything

I tend to agree that we are talking tiny differences and any eyepiece of this standard is going to give great images. forgive my cynicism but like any company looking to stay in business, I feel that surely manufacturers must create new and exciting products for us all to slobber after. whilst I don't doubt they provide a little more this or a little more that they will not provide anything substantially improved upon what precedes them. it's just baby steps.

seeing, transparency, collimation, observer experience and optical quality of the scope have a bigger impact than eyepiece design / quality after all.

don't get me wrong, I like my TVs as much as the next man but differences are small evenbetween them and the cheapest eyepieces. fear not, the Radian is an excellent eyepiece in every way possible.

[John]

I also sometimes wonder about the following: when you get a new EP, it is in pristine condition. You then compare this to an EP which you have had for a while, and might have the odd speck of dust (please DON'T rush off and clean your kit!!). When looking at the tiny differences, it might be that odd speck of dust that makes a difference. There is also the psychological tendency to want your shiny new piece of kit to perform better. This is a key problem with EP evaluation: it is never a blind comparison. You know what EP you are looking through.

I think there is a lot of truth in this, especially the last line

Dare I also add that there can be a certain amount "peer pressure" on forums which also influences how we select and perceive things ? 

[AlexB67]

Seems I've initiated some interesting discussion and food for thought.  I've not really cosidered ethos territory for the simple reason price, I do have my limits being a relatively poor man.  I am more than delighted with what I've managed to collect so far recently, but prepared to go the extra mile and wait for the good things in time

Another reason for no ethos. In a f4.7 Dob I really do find  pushing beyond that 70 degrees I'd want a coma corrector, and it is not as if I'd crave that large FOV anyway.  No doubt I'l have looked through a few by the time I'll spend the bigger cash at one of the regular events here around Bristol, had some kind offers already some time ago.

As I am gaining more experience I am also becoming a bit more sharp eyed in terms of what I can see in eyepieces compared to when I started, and without a CC I have sort of coma limit I feel I'd be happy with.

With a lot left to learn still, It is not as if trying to understand all the various aberations is an easy thing. What causes what and making sens of it all is a interesting hobby in its own right . Again and again I have the experience, I thought I grasped such and such, but than I grasp some more of it. gettig the pentax XL was ( and still is)  another good experience that made me really think about some of that stuff again, but in a good way.

Call me I was a sad person learning about optics, but at one stage I went as far as generating the attached spot diagrams of point sources (not actually hard to do in a great tool like mathematica).  Doing this really helped me at various stages in identifying issues in an eyepiece. Apart from them being interesting pieces of art ( A density plot would look nicer ) It has enhanced my understading of the various issues you can get in eyepieces.  

Yes yes ... I know say it,  you are a sad peron Alex, or if not, just enjoy the kind of abberations you could see and I have seen

[jetstream]

I think in real terms it is asking a bit much to make a effective study of a XW which are of cousre 70 degree FOV and an Ethos, even though I do have the 8mm and the 6mm. To be honest it is difficult to even work with the Nagler at 82 degrees. They are of course the same 7mm and whilst they not be absolutely exact 7mm they really look like different magnifications with the field difference, plays tricks with your eyes.

I have been using a 6mm Delos as well in the mix as a sort of referee. I have had 3 nights of clear for 20 minutes and then clouds so it is slow at the moment but I am getting there, it will give me something to do now I can't build.

Alan

I was just wondering about image brightness,contrast on DSO-I've found this difference shows up immediately under dark skies and good conditions.M42 is a good test for a quick look and my latest "test" is the Flame nebula,unfiltered.While I do like the 100deg apparent field this is not the main deciding factor for me.I think that eyepiece design is all about tricking our eyes/brain!

[Caldwell14]

I have owned a number of Radians and still use a 6mm as my primary planetary eyepiece, cracking eyepiece, you can pick em up for 90 quid second-hand, pure quality.

[AlexB67]

I have owned a number of Radians and still use a 6mm as my primary planetary eyepiece, cracking eyepiece, you can pick em up for 90 quid second-hand, pure quality.

If one turns up for 90 the urge to resist not to get one would be very hard.  I think the 6mm would make a great eyepiece in my collection and I would not hesitate if one did turn up. You have to be fast though and strike, I've seen radians go her and there, but seems asking price is more often something like 110  - 125.  Still worth it IMO, but not seen any for < 100 or so since I started keeping an eye on them in that sort of focal length.

If you do you are welcome to give me a bell any time

[Luke]

I'm in the "Radians are underrated" camp.

I use mostly Delos now and feel that they perform a bit better for me than type 6 Naglers and the Radians. In fact I was a bit surprised by how much more detail I could see with the Delos on the  targets I have tried. The differences on those targets were obvious to me, I did not have to look hard. However, who knows how things would be in a different scope, under different conditions, or on other targets...

But these days, I'm thinking along the lines:

Suppose I was looking through a 10 inch dob and thought my Delos beat the Nagler. Well I reckon using a 12 inch dob and the Nagler would beat the 10 inch dob and the Delos comfortably. When I look through my 10 inch dob, I don't worry that the view would be better in a 12. I just love the view.

So I reckon if I had not directly compared the Nagler and Delos, the smile I had looking at the targets would have been similar with either eyepiece.

I think I am saying, there was a noticable difference, while at the same time, there wasn't a noticeable difference.

One of my favourite eyepieces these days is my little 9mm TS HR Planetary. It gives me lovely sharp views through my hydrogen alpha solar scope, and cost roughly a quarter the price of the Radian. I like its compact size and weight, ideal for use on the mini giro I often use, making balance a bit simpler.