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Doc

Was that F15 refractor at SGL5?

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I've not heard any reports on that F15 Refractor someone was bringing along, cannot remember who.

Did it turn up?

Was it any good?

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Mick it was Nick H who bought it over and it was minus a dew shield. I never had chance to look through it but I think Andrew* did and he reported that the collimation was out. I imagine that Nick might give an overview sometime.

By the way we all missed you and hope to see you at SGL6 if not before.

Regards

Mark

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What a shame couldn't anyone sort the collimation out.

It's such a shame I'm not very well at the moment and the missus has wrapped me up in cotton wool, but I'm defintely going to SGL6.

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We tried the F/15 briefly on my CG5 mount with it's tripod extension. We observed the crescent moon and Saturn and compared the views (not in a particularly in depth way) with those through my Vixen ED102SS (F/6.5). My feeling was that the views were very similar although someone else felt the Vixen's contrast on a lunar rille was a little better. When we star tested on Regulus the diffraction rings showed significant displacement on one side showing that the F/15 was out of collimation. There was also a faint flare of violet CA visible. We did not attempt to collimate the scope so were possibly not seeing it at it's best. For reference the eyepieces used were Nagler T6's - a 9mm in the F/15 and a 3.5mm in the Vixen F/6.5 to give broadly comparable magnification.

If anyone else who had a look though the scope on that night would like to share their impressions, please do :D

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Hi Mick

I was the guy who thought the contrast was better in the Vixen.

The F15 was well out of collimation and I am sure this was a factor.

Cheers

Ian

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I was the guy who thought the contrast was better in the Vixen.

I also noticed it. I also think with good collimation this wouldn't have been so obvious.

On the moon I found the view slightly steadier through the f/15 compared with the Vixen, but there wasn't much in it. It was like the seeing was 3/5 rather than 2.5/5. On balance, I don't think this small increase in steadiness justified the huge size difference between the two scopes. The Vixen was on a short tripod with an Ambermile mount, but the f/15 was on a fully extended and raised CG-5 (which is still under-mounted!). These are the extremes of portability.

Nick assures me the collimation was spot on the night before. I'm pretty certain the scope hadn't been mishandled in between, so I think it's a poor lens cell that puts an f/15 light path significantly off in under 24 hours....

Andrew

Edited by Andrew*

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Now thats surprised me, for a scope that isn't cheap I would expect perfect collimation, or at least be able to hold it for 24 hours. My little Tal 100r is 6 years old and has never needed collimation.

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Hi,

I have a Skylight F/15 and can personally vouch for its excellent optical quality. I'm not the only one who thinks this way either. Ian Ransom has also given it the thumbs up in independent tests. If there was a collimation issue with the scope, then all fair tests are null and void. I'm very surprised that no one could remedy the problem in situ. It's a fairly simple matter to remedy with an allen key.

Neil.

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Neil,

You are right: the optical comparison is not fair if one of the telescopes is properly collimated and the other not. The point is: the telescope proved itself to be inferior in the lens cell department.

I was attending a star party under some of the best skies in England. Amateurs went there to enjoy the night sky and the company, not to waste precious sky time attempting to save the reputation of a poorly constructed telescope. I do not have the expertise to collimate a refractor, and those who do, did not wish to waste their time on it.

Any refractor lens cell should hold perfect collimation over one day under ordinary circumstances. A quality lens cell is just as important as the lens itself.

I would like to add that the finder is pants! It is just a standard Opticron brass model, with decidedly poor optical quality.

Andrew

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Now now Andrew,

That was uncalled for. I wouldn't say bad things (although I could) about your scopes in such a disrespectful way.

Neil.

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Neil,

Apologies if I caused offence. I didn't mean any disrespect. I should justify the point about "wasting time in collimating". I didn't mean it's a waste of time, I just meant that in the circumstances, the attendees were more interested in having a nice time, rather than fiddle about with collimating the scope.

I am not "saying bad things about your scope", I am merely sharing my experiences of a particular model, as was asked for.

Andrew

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The fact is Andrew and Neil if I spent £1500 on a refractor I would expect a first class lens cell that only needs collimating if it received a very heavy knock. With normal unpacking, packing and transport duties a refractor should stay collimated.

Edited by Doc

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The Skylight F15 is mine…& I make them. A post of mine a couple of months ago was deleted by moderators, so I will try not to cross the line, and hopefully this one will stay.

From the very beginning I have been very clear that this scope is not a mass produced clone, each one is unique…up to and including the collimateable cell, which leaves final control up to the user. I am also 100% sure that once collimated correctly, the cell is perfectly capable of holding collimation.

The F15 you used had been tested previously over some weeks by more than one person, and no problems with collimation were reported. I picked it up last Saturday from the previous user, who I found had used it with one of the grub screws completely loose. So, I collimated again from scratch using a Cheshire, then gave it to Nick shortly afterwards. However, I was unable to star test, so I gave it to Nick telling him it would probably need a tweak under the sky. I was pleased to hear that Nick enjoyed the first night with it, and adjustment wasn’t immediately required. However, it would seem that the second night, it did require collimation tweaking. Perhaps the 3 screws weren’t seated 100%, and temperature variations from day to night caused the cell to shift slightly, or it could have taken an unnoticed knock (always a risk with a scope this long). I don’t know…I wasn’t there.

People who used the scope on the second night viewed through what is stated to be an out of alignment scope, but nobody knew how (or didn’t bother), to spend 15 minutes to adjust it...that's absolutely fine, but it was your choice. The fact remains that because of this failure to prepare it fully, the refractor itself was blamed (even by someone that I understand wasn’t even there).

Thank you to Nick H. for taking the scope along for you to try, and I’m sorry to see that the rest of you couldn’t see it at its’ finest. But not bothering to collimate the cell is not a design fault.

I’d like to also state that I did not request that my telescope be brought to your party, it was Nick’s idea (and it was a thoughtful one). With honesty, because of knee jerk reactions and bandwagon jumping like this, if I felt the need to have my reputation saved, SGL would not be on my list.

Thank you for your time.

Richard (Skylight)

Edited by canuck

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Richard is right, it was my idea and one I thought would hopefully let as many people as possible try out a scope... I bring all my kit to star parties for that purpose (solar rigs etc) to let others have a play as well..

To me the night previous (and images and people looking could vouch for this) the views of Saturn and the Moon were terrific, so maybe something did happen between nights...not sure... I too think it unfair to compare if it was out of collimation. I have reported my findings to Richard at Skylight in a fair and accurate manner and have also reported ALL comments made to me about it to him in the same way. Just a professional way to approach things.

I didn't like the finder, but my gripe was that it was almost impossible to find things with it in use. The lack of a brass dewshield was IMHO something which would let it down visually, but Richard has been fair in accepting these and all other points I have made to him, with no questions asked. That, as someone who reviews products as well, is all I could really hope for..

Richard ;literally dropped it off with me at my office in Chiswick and had warned me it MAY be out of alignment, and mentioned the screw issue...as I didn't see it first night, I thought it must have been okay

Others will be trying it soon, and I hope that any collimation issues are resolved prior to any formal test reports. The review in AN I think was accurate, as having looked through it myself, I did like the possibilities for planetary use... I am not a huge fan of long focal length refractors perse, but am glad I got to try it out, and also to bring it down to SGL.

I hope this thread keeps formal and professional...all I wanted was to try out something which grabbed me at Astrofest and let others try it. I gave it to Andrew, someone I had only met the day previous, and I trust his judgement also. If it was out of collimation, then it was out..and I hope that future reviews will see it perfectly aligned

Now...where is Steve Collingwood when you need him?

Edited by NickH

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Having read a lot about the scope, I for one was glad to have a chance to look at and, briefly, through the Skylight F15. I guess we could have spent some time collimating the scope but it was a) an expensive piece of kit, :D not mine and c) getting dark rapidly so I feel that taking it carefully off the mount and returning it to Nick was the best option in the circumstances. I'd be pleased to have a chance to have a look through the scope again sometime when it's collimated.

Thanks for bringing it to SGL5 Nick and Richard.

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Hi,

I'm very surprised that no one could remedy the problem in situ. It's a fairly simple matter to remedy with an allen key.

Neil.

Yes, I'm very surprised as well.

A f/15 scope with a Cheshire is so easy. The first time I did one, I took it really slow, so as not to mess it up, and that took all of 5 minutes.

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Yes, I'm very surprised as well.

A f/15 scope with a Cheshire is so easy. The first time I did one, I took it really slow, so as not to mess it up, and that took all of 5 minutes.

The problem I'd have would be doing it without permission on someone elses (quite expensive) scope.....:D

Edited by GazOC

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I wasnt even there and I'd be worried about messing with a £1,500 telescope that didn't belong to me. Come to think of it I'd be woorried about messing with a £1,500 telescope that DID belong to me.

Actually I am rather interested in the Skylight scope and none of this puts me off really. Its just good to know if my tax rebate ever comes in I will know what to ask Richard to change such as the finder.

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The problem I'd have would be doing it without permission on someone elses (quite expensive) scope.....:D

My thoughts exactly at the time Gaz :)

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I was always under the impression that one of the advantages of a refractor is that they dont need collimating, did I get that wrong? :D:icon_scratch::)

Im curious as to how it would be done, would be keen to see pics of the mechanism for adjusting the lens cell. Just out of curiosity as I say.

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I think Richard's assessment on the screw/loose cell could be accurate..lots of people ad a look first night and nobody said anything about it being out of collimation.

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It seemed ok on the first night on Venus moon and Saturn...

Peter...

It looked superficially OK on the Moon and Saturn on the 2nd night as well. The miscollimation only showed itself when I looked at Regulus. The diffraction rings were clearly displaced to one side of the ariey disk, very similar to the lower of these star test pictures (the in focus ones):

http://www.spacealberta.com/equipment/refractor/startest.jpg

My understanding is that long focal ratio scopes were reasonably tolerant of some mis-collimation so it may not have had a major impact on views of the moon and Saturn although it would have reduced sharpness and contrast slightly I guess.

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We had intended a 'group test' of refracters at SGL-5 but the Tal 125R Apolar APO didn't arrive and Richard's Skylight F15 wasn't at its best so we didn't proceed. Hopefully we will be able to arrange something for the Salisbury Star Party in August.

HTH,

Steve :D

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