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TV Radian 14mm question


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I might be able to get a good deal on a Radian 14mm, which would will a gap in my solar set-up (now I jump from 24 to 12mm, so a 14-15mm and 20mm would be nice). I was considering getting an XW 14 or  Delos 14, but the former did not get a very good review by Alan, and I have qualms about the focus position for the Delos. I find my Delos 8 focuses at a very different position from either the XWs, XF, and even Nagler 12T4. This is not much of a problem in my white-light set-up, or night-time planetary work, but in the little LS35 it is a pain, because the helical focuser does not have much range. I seem to remember the 12T4 was not too different from my former Radian 10 in terms of focus position, and the XF8.5 and Radians were also not too far apart (but only in the C8, because I got the LS35 after selling the Radians). Does anybody know how far the focal positions of the Radian 14 and 12T4 are apart?

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Michael,

The XW 14mm is not a bad eyepiece and TS do still have one but it is not as good as the 14mm Delos, but that is only me talking, who ever said i know what I am on about.  I nearly bought a 14mm Radian myself after trying one some time back, they are a very underated range of eyepieces in my books, I think it is only that the 60 degree FOV and Delos coming on the market that they have lost their appeal a little. In my opinion for around 100 quid they are the best secondhand buy there is.

I don't know about the focal position but I agree the Delso and XW are way apart, if Radians are parfocal then I can easily check it for you against my 12mm Nagler, the 4mm R and 3mm R are and I think the 5mm is too.

Just a thought do you use the 12mm as a 2inch or 1.25, the focus will be different.

Alan

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Michael,

I have not tried any of the eyepieces you have mentioned other than the Delos and I have found it to be a lovely eyepiece :laugh: I am finding the more I use them the better and easier they get to use, I do believe the Delos are absolutely perfect for me :smiley:

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Michael,

The XW 14mm is not a bad eyepiece and TS do still have one but it is not as good as the 14mm Delos, but that is only me talking, who ever said i know what I am on about.  I nearly bought a 14mm Radian myself after trying one some time back, they are a very underated range of eyepieces in my books, I think it is only that the 60 degree FOV and Delos coming on the market that they have lost their appeal a little. In my opinion for around 100 quid they are the best secondhand buy there is.

I don't know about the focal position but I agree the Delso and XW are way apart, if Radians are parfocal then I can easily check it for you against my 12mm Nagler, the 4mm R and 3mm R are and I think the 5mm is too.

Just a thought do you use the 12mm as a 2inch or 1.25, the focus will be different.

Alan

Thanks for the quick response. I use the 12T4 as a 1.25" in the LS35 and in the Herschel wedge, and as a 2" in the C8. I found this table from TV

http://www.televue.com/engine/TV3b_page.asp?id=214

but sadly data on the Radian 14 are missing. It does look like the Radian 3 (only one still listed) and Delos 8 focus at the same position. According to the table, the Delos 14 focuses 0.48" (!) further inwards, which might mean it is closer to the XW14 in focal position (which should be parfocal with the XW10). In that case the Radian might not be the best choice.

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Michael

 

Somewhere I saw a table of all the Radian and other TV eyepieces saying what was parfocal, maybe it was some time back and now you have taken that from the site earlier. I would be happy to try the Radians I have against the 12mm Nagler in the 1.25 sleeve.

Alan

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Michael

Somewhere I saw a table of all the Radian and other TV eyepieces saying what was parfocal, maybe it was some time back and now you have taken that from the site earlier. I would be happy to try the Radians I have against the 12mm Nagler in the 1.25 sleeve.

Alan

Just a comparison with an XW would help. That is my main concern. I read from their table that the Delos 12 and 14mm are 0.48" apart in focal position, if the value in the F-column is anything to go by. In your comparison of the XW14 vs the Delos 14, were they far apart in terms of focal position?

The odd thing is that the 12T4 is apparently further away in terms of effective position of the field stop (the column F value) than the Delos 8, which is counter to my experience (may have to do with the 2" sleeve)

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Sadly, I have sold it on so I am only going on memory and I only had the 14mm Delos and that in the focuser on that test session some months back. I don't remember them being massively different but I am guessing a little.

The other XW I have the 5mm is a good way from the 4.5mm Delos and the 6mm Delos, .48 of an inch could seem about right with that comparison but I don't remember the 14mm being so far apart. If you recall before I finished the work on the review the buyer turned up and took it away, I also had the 13mm Ethos in the mix which is clouding my judgement a little as well. I am not being very helpful am I.

Alan

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I'm a Radian fan, the 14mm and 8mm are my medium and high power with my 10" Dob (86x and 150x).   The 27 Pan is my low power, 44x.

The Radians are all parfocal 'B', same as the Delos range, apart from the 14mm and 17.3mm.   Does that help ?

I find that TVs parfocal 'B' needs more out focus than many other make of EPs like Vixen.  The 27P needs even more out focus than the Radians.

Regards, Ed.

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TV's par focal "B" point is the same as the 1.25" TV plossls from 32mm down and the T6 Naglers I believe. From what I understand of the way TV expresses the focal plane in their eyepiece data, it looks to me like the 17.3 and 14mm Delos have a focal point just under half an inch inside (in terms of focuser travel) the other Delos eyepieces and around 1/8th of an inch further out than the 31mm Nagler.

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So Michael, as Ed very kindly confirmed all the Radians are Parfocal so I could match it against any of my three and the 12mm Nagler.

Rik,

I hope when I reviewed the 14mm XW that is how it came across, a little FC, read some of the other reviews from over the pond and it sounds a whole lot worse.

Jumping on the back of what John has said may indicate that my memory was not as bad as I thought, there was not a lot of difference.

Alan

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So Michael, as Ed very kindly confirmed all the Radians are Parfocal so I could match it against any of my three and the 12mm Nagler.

Rik,

I hope when I reviewed the 14mm XW that is how it came across, a little FC, read some of the other reviews from over the pond and it sounds a whole lot worse.

Jumping on the back of what John has said may indicate that my memory was not as bad as I thought, there was not a lot of difference.

Alan

Alan I like your reviews because you say what you see :) I'm sorry I can't add anything to the discussion re the Radian because that is one TV design I haven't tried. I thought about getting a 5mm Radian but I suspect I won't like the very slight warm colour tone. We all have things that bother us and colour tone bothers me.

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Rik,

I think we will be able to help Michael out between all of us. On the colour aspect of Radians, a few years ago I had to do a very extensive eye test, part of which was colour perception, I got the best marks out of the whole factory, over 500 were tested, I made one mistake. Two nights ago I spent about 2 hours 20 mins with the 3mm 4mm & 5mm Radians and the 3.5mm and 4.5mm Delos, looking at the Moon, I could not see a great deal between them and I was really looking for it. Whether this is something that is more obvious to some than others I really am not sure, but that's my take on it for what it's worth.

Michael sorry for going off topic.

Alan

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Michael,

Next time out I will put the 12mm and one of the radians in a scope and let you know how much difference there is by PM, I will also put the 14mm Delos in there as well, at the moment the clouds have taken over, for how long, who knows..

I will use the APO it has mm markings on the focuser.

Alan

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Michael,

I have the 18,14,12,10 and 5mm radians, They do all indeed focus at the same point, or within a tiny fraction of a nudge. So Alan's test will tell you for sure. The 14mm Rad is a cracker btw, and as Alan has said, the colour cast stuff is all blather to my eyes too.

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I'm a Radian fan, the 14mm and 8mm are my medium and high power with my 10" Dob (86x and 150x).   The 27 Pan is my low power, 44x.

The Radians are all parfocal 'B', same as the Delos range, apart from the 14mm and 17.3mm.   Does that help ?

I find that TVs parfocal 'B' needs more out focus than many other make of EPs like Vixen.  The 27P needs even more out focus than the Radians.

Regards, Ed.

That is very handy to know. I think that settles it: it is as far out of the rest of the range of EPs I use as the Delos 8mm (also "B") the XW14 and teh Delos 14 both seem better. I will save up for one of those rather than buy a temporary stop-gap.

Thanks everyone for all the feedback!

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