Televue 3.5mm Delos and 3mm Radian Pt2

[alan potts]

Televue 3.5mm Delos and 3mm Radian.

Part 2.

I posted a review a few weeks ago and at the time the only planet that was available to me where I was not dropping off to sleep at the scope was Venus. I promised at the time I would report as and when Jupiter was higher in the sky at a reasonable hour, that time is now.

I only used the two scopes for this, both refractors, one very good and the other not so. I have to say I did not see a great deal of commonsense in using one of my favourite scopes, the Mak/Newt 190mm as after seeing the disc of Jupiter at X268 I did not see the point. The observations were taken on 3 different nights and consist of 4 hours 20 minutes of scope time.

70mm ED refractor with carbon fiber tube.

On this scope the 3.5mm Delos gives me X120 and the 3mm  Radian X140 which is at the scopes theoretical maximum magnification. Now bearing in mind the optics on this scope were not made in a fine Russian optical laboratory and were not fit to be pushed above approximately X40 before I performed laser surgery assisted by a mirror with questionable credentials and two tubes of 10 minute epoxy. This seems to have done the trick though probably more by luck than judgement, I do not recommend trying this.

Jupiter.

The Delos gives me x120 on this little scope and my first feeling was, golly that’s not at all bad, when all it said and done this is only 10mm larger than the finder I have on one of my other scopes which is supposed to be high quality but is not. I made the mistake of being seduced by an advertisement with the word Zeiss being used and was sadly smitten. I firmly believe the only things it has in common with the Carl Zeiss C lens design are, it is the same size and made of glass.

Anyway, Jupiter was clearly showing two central equatorial belts and I could also see that something was going on in the centre of the disc that looked like a Moon crossing from one side to the other, I would not say it was extremely distinct but I could make it out none the less. There was no sign of the Great Red Spot but that seems about par for the course for me, I seem to have an uncanny knack of looking at the planet when it is on the other side. This was an eye opener for me as I did not remember being able to see so clearly with such a small aperture, this has wet my appetite for a quality 80mm triplet again, the scope I should have bought in the first place.

Moving up in the power stakes to the 3mm Radian and pushing the scope to levels I would not normally recommend one should. The image was a whole lot better than I thought it was going to be, it lost out a little on contrast to the Delos but this was only because of what was being attempted and nothing to do with the eyepiece itself. I don’t think I would repeat this exercise on Jupiter with this scope, it was much better on the moon which is of course much brighter. I could still make out the transit that was ongoing and see the two broad equatorial belts and possibly a little polar shading, at this point I was going to say, but that was all, for a 70mm scope that really was quite a lot.

I did try the smaller scope on the GRS when it was visible a few days later but i was unable to confirm a sighting, I think it may have been a different story if the air had been dryer. Condition have not been fabulous of late and there is just a little too much quivering in the views offered for me to be sure on such a small telescope.  

115mm APO.

The Delos here is giving X230 which is a fair amount more than I would normally use on Jupiter but the image was sharp enough and I could clearly see the shadow transit and the moon against the surface of the planet, but the optics here are much better than those of the smaller scope. The contrast was not all I would normally have desired either, I find it key to seeing the divisions in belts and other intricate details, but it was still very good on a night where seeing was not all I was used to but the larger apperture was helping no end. The transit was captivating and I watched it until it was over, I found it very interesting that when the moon left the disc of the main planet there appeared to be a dent in the edge of Jupiter, which of course there was not, this was only an optical illusion but one I had not seen before.

Belts were fairly well defined with another set being visible above and below the main ones, there was also a much better polar shading and the whole thing seemed to have a better structure about it. This is not a surprise as the increase in lens size and quality would account for this alone.

A few days later observations showed me the GRS which was a first for some considerable time, it stood out rather well against the disc and appeared to have a soft white/gray edging that was helping the definition. I also had a feeling that from time to time I was just getting a hint of pink from the GRS but could not be totally sure, colour is something I see in my larger scopes but I do not remember seeing it in what is only 4 ½ inch of aperture. About this time the wind, or should I say air current moved and deposited the plume of smoke from my wood burner firmly over the planet, this really messed things up for half an hour and seems to happen too often for my liking, but a cold wife is a dangerous animal. I was back at the scope with a smaller magnification which actually showed me more detail, bringing home to me the danger of over cooking the power, the 3.5mm Delos was on this target was as high as I beleve anyone sould go.

Moving to the 3mm Radian did nothing for the planet what so ever, the GRS was more difficult to see and the belts were nowhere near as clear as beforehand, this is after all well over the scopes recommended maximum magnification at x268, which I have to say was fine on the Moon but not on Jupiter.

I feel here that the power on the larger scope that the 3mm Radian afforded was too much for me on Jupiter, it may well be better on Saturn and Mars, we will have to see later on in the year, this may well be the bellwether to keeping it or selling

Now I have had the opportunity to use the 3mm Radian a number of times on many targets I am not sure I made the right decision buying it in the first place, time will help here, I have the Nagler zoom which would have sufficed for such work. This is of course no reflection on the quality of the eyepiece more on the daft things I do when I have not bought something for a while, there is no doubt it would be better in a smaller focal length scope of high quality, something in the 500-600mm range. The Delos 3.5mm on the other hand was about at far as I would like to go with what I own at the moment, both are without doubt very fine eyepieces, I recall the views of the Moon where stunning and even the gloubar cluster was a treat but maybe this is not best eyepiece for my equipment. I close with a short piece of advice, think very long and hard before spending on very high magnification, I maybe feel did not.

Alan                    

[michael.h.f.wilkinson]

Nice report again. I must say I wonder at the decision not to use the MN190. I use a 7mm XW on Jupiter when seeing is good with my C8, and can get excellent results at 290x. The Delos would give very similar results I would think (the Radian might be a bridge too far). I sometimes wonder what the view would be like using a Radian 3mm in my 80mm F/6, given the pretty decent views I got with a simple 4mm planetary.

[Stu]

Very nice report again Alan.

As you know, I like my small fracs, and often observe Jupiter in either my previous 66mm or now the TV76. It is surprising how well they stand up to magnification, and there certainly is detail to be seen, both GRS and shadows transits have been visible to me a number of times. I generally find that 3.5mm is the max mag I use. My floaters get much worse below this focal length,and it tends not to gain anything, although on Mars it can be useful. I have used a 2.5t6 in the past, again, mainly only of benefit on Mars or for doubles.

I do hanker after a decent quality 80mm triplet at some point in the future :-)

Cheers,

Stu

[michael.h.f.wilkinson]

Very nice report again Alan.

As you know, I like my small fracs, and often observe Jupiter in either my previous 66mm or now the TV76. It is surprising how well they stand up to magnification, and there certainly is detail to be seen, both GRS and shadows transits have been visible to me a number of times. I generally find that 3.5mm is the max mag I use. My floaters get much worse below this focal length,and it tends not to gain anything, although on Mars it can be useful. I have used a 2.5t6 in the past, again, mainly only of benefit on Mars or for doubles.

I do hanker after a decent quality 80mm triplet at some point in the future :-)

Cheers,

Stu

I am not sure the APM 80mm Triplet I have would show much in the way of improvement over your TV76

[Stu]

I am not sure the APM 80mm Triplet I have would show much in the way of improvement over your TV76

I'm not sure either Michael, would be interesting to compare the two side by side. I guess it would show less CA and be a tiny bit brighter but maybe not enough to be noticeable. The doublet does have potential advantages in cooling time, and possibly light transmission over a triplet? As you say, probably not much in it.

Stu

[alan potts]

The APM 80mm was the one I had in mind it comes now for about 900 Euros, not exactly give away but better priced than it once was.

Michael,  I will have a look tonight with the 190mm but after the 3mm Radian in the APO I did not think there was anything to be gained. In view of the fact I can see more at less magnification what is the point of going to X285 albeit with a larger scope. Still it is not something I have done before, as Jupiter was out the way when I got the 3.5mm, so nothing ventured as they say.

As for floater, my eyes must have sunk, I just don't see them with these two, at least not yet.

Alan

[Joves]

Nice post Alan and, as always, has made for a good discussion.

Out of curiosity, what focal length is your 115mm APO? Also, wouldn't the greater aperture of your 190mm go a fair way in allowing for the much greater magnification with the 3mm Radian??

[Joves]

Disregard my first question... I recall you once telling me it's 805mm FL.

[michael.h.f.wilkinson]

Nice post Alan and, as always, has made for a good discussion.

Out of curiosity, what focal length is your 115mm APO? Also, wouldn't the greater aperture of your 190mm go a fair way in allowing for the much greater magnification with the 3mm Radian??

This is really what I meant. I find that the C8 allows me to use WAY higher magnification than the 80mm. On nights where the image in the 80mm degrades above 140x, I can get over 200x with the C8 in most cases.

[RikM]

I was just going to post much the same. On a night where I can get 130x with the Pronto, I could probably go to 240 - 300x in the 10" Dob.

[John]

Very interesting report. The Radian is clearly a very good eyepiece then as the report seems to center mostly on the issues surrounding overpowering the scope, or have I missed something ?.

I think your report also highlights why having a number of high magnification options is good with even .5mm of eyepiece focal length pushing things from good to not good on that occasion.

3mm is not an often used focal length for me either but I'm pleased I have my 3mm Radian anyway. I did actually use it with my 12" dob on the moon the night before last and the seeing conditions were good enough to get crisp views even at 530x. 

[Rustysplit]

Another fine report, Alan. Not a very often used eyepiece with your current scopes maybe, but certainly not a waste of money. On those rare nights where the conditions allow stupid mag, you will remember why you purchased it. As John says above, it is startling some nights that just a tiny increase in power will wreck the views at the ep.

[rowan46]

The other night was the steadiest jupiter i have seen for best part of a year. I would have killed for a 3mm radian I  barlowed a 4.7es but it was just a little much and my barlowed 7mm pentax not quite there 3mm would have been just right. An enjoyable and informative report as usual thankyou.

[alan potts]

As it would happen humidity has fallen through the floor and is down to 34% tonight having been dropping like a stone all day. I have the 190M/N outside now and it is clear as a clanger.

I think the magnification issue is more a personal thing and no one is correct, nore are they wrong.  For me however I would always side with a power that allows my eyes to see the most detail. Johns point about .5mm jumps is very true, if money was no object and there were focal lengths on the market, I would go for .25mm jumps at the very top end, sort of made a case there for the 3.7mm Ethos.

I am expecting very good conditions in the next 3-4 hours, I will be trying for a Sirius result too, I feel left out.

Joves,

Correct 805mm and the M/N is 1000mm, the little scope I was using is 420mm.

Off out into the cold.

Alan

[Stu]

As it would happen humidity has fallen through the floor and is down to 34% tonight having been dropping like a stone all day. I have the 190M/N outside now and it is clear as a clanger.

I think the magnification issue is more a personal thing and no one is correct, nore are they wrong. For me however I would always side with a power that allows my eyes to see the most detail. Johns point about .5mm jumps is very true, if money was no object and there were focal lengths on the market, I would go for .25mm jumps at the very top end, sort of made a case there for the 3.7mm Ethos.

I am expecting very good conditions in the next 3-4 hours, I will be trying for a Sirius result too, I feel left out.

Joves,

Correct 805mm and the M/N is 1000mm, the little scope I was using is 420mm.

Off out into the cold.

Alan

Just regarding the 3.7 SX, to me it seems ideally placed as a high end, but still regularly useable planetary ep. 3.5mm in my scopes is sometimes too much, 4mm not quite enough so it fills the gap wonderfully. That's my excuse anyway :-)

Must try it in the Mak (not!!), would give x1081!!!

Btw, are clangers clear? I thought they were sort of brown woolly things? ;-)

Cheers,

Stu

[Pig]

Excellent report Alan,

I did try the 8mm Delos the other night giving 293 x a little to much on Jupiter. I then put the UHC filter inline, as recommended by an SGL member, and it very surprisingly transformed the view, I was stunned at the size and clarity of what I could see. There was a very slight green tint to the moons but it was hardly noticeable

[Naemeth]

Surprised I missed this. Nice report Alan, as you've already got 420mm I don't see the need in going any shorter FL? If you get a FL any shorter you're entering the world of sub 60mm refractors.

I spent a lot for high power observing, but to me the 3-6mm Nagler Zoom covers it all when conditions are right - being effectively 7 eyepieces and everything in between.

[RT65CB-SWL]

Another excellent report 'From our Correspondent' in BG.

PS...

If BNT - Bulgarian National Television (БНТ - Българска Национална Телевизия) wish to do an equivalent of 'Stargazing Live' Alan P. could do the Brian Cox part & Slavi Trifinov does the Dara O Briain part.

[alan potts]

Philip,

I don't think I am clever enough and Slavi is not funny or fat enough, so a bit of a none-starter. I think though we could do a good rendition of Bill and Ben the flower pot men.

Alan.

[RT65CB-SWL]

Philip, I don't think I am clever enough and Slavi is not funny or fat enough, so a bit of a none-starter. I think though we could do a good rendition of Bill and Ben the flower pot men. Alan.

Worth a try! - I must stay of the Rakia!

[Druid]

Interesting series of reviews Alan. Very useful.

I just ordered a 3mm Radian, feeling I'd like one step up from the x120 a 4.5mm Delos gives in my 4" f5.4 apo and thinking that x180 from the Radian will be more often useful than barlowing up to x240 on the Delos. 

I'll post my impressions once I've had a chance to use it properly.

[Vega26]

Nice comparison. I have read reports about problems with lateral colour in the Radians. Something you have noticed?

[Rustysplit]

I use a range of Radians, and imho, the lateral colour thing is much overated. Maybe there is a very slight warm cast when viewing the moon or other bright objects, but I certainly do not notice it, and for me it looks as good as any ep I have looked through. I guess we all see things in a different way, but I would not get put off by talk of the colour cast. They are fabulous ep's at a reasonable price 2nd hand.

[alan potts]

I have to say I am with you on that one Alan, unless I am missing something it is blown out of all proportions unless this is more noticeable on the 8mm 12mm 14mm and 18mm which I have never owned.

Alan.

[Stu]

Totally agree with this, the radians are great eps and the colour cast issue is totally over stated in my experience. I have two and really like them.

Stu

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