Anyone have or had a good look at an 8ins cape newise with carbon tube

[Ajohn]

I've been doing a bit of research on these and some have had serious problems. These seem to be down to gluing some of the optics in place with epoxy. Best of intentions as this fixes collimation but unfortunately temperature changes etc cause stresses and also severely astigmatic images. Some models are "user serviceable" others aren't due to the glue. Any one know if the carbon fiber tube version can be completely dismantled?

As a company they seem to have completely disappeared. Anyone know where they are these days or even better how they can be contacted?

John

[Lee]

My understanding is that they went bust last year.

Greenwitch used to sell their OTAs you could try them.

http://www.green-witch.com/

Lee.

[SteveL]

Greenwitch no longer stock them, Cape Newise did go bust. The scopes werent really all that reliable to be honest, a lot of "return to base" fixes required on brand new out of the box OTAs...

[Whippy]

Peter Wise who owned the company is selling his 400mm example here: http://www.astrobuysell.com/uk/propview.php?view=19233 . I believe Karlo (Beamish) has an 8" model does he not?

Peter wise has gone on to form Zerochromat: http://www.zerochromat.com/ . So I guess anything Cape Newise related has gone down the toilet.

Tony..

[Ajohn]

I had the impression this was the case - neat idea with possible problems but very poorly implemented. The scope uses 2 refractive correctors one down from the 2ndry and the other after the 2ndry in the focuser housing. Collimation nightmare but not impossible. The catch is that the refractive elements will have to centered and squared to each other, the light path being bent by the 2ndry. All squared up to the main mirror in the usual way.

This is what happened when the scope went to the US

http://www.cloudynights.com/documents/capenewise.pdf

Oddly Dixons used to do a 4ins newtonian that was much the same arrangement but no glue in silly places so it could be adjusted. I bought one a long time ago to leave kicking about in the caravan. After aligning everything as well as I could the focuser had to be used to carefully "bend" the part of the tube it was mounted on to complete the final alignment.

If anyone knows if the carbon fiber ones are all glues up I would still like to know.

John

[beamish]

Mine's the ally version and there's absolutely nowt wrong with it. "Out of the box returns " is a new one on me, never heard the like on the user's site !

[Kaptain Klevtsov]

Some people thought they were very good when they reviewed them.

http://www.nightskyobserver.com/Photon/Download/Photon_Issue2.pdf

Ade Ashford also liked it when he tested it for S@N magazine, though I can't find a link currently.

Kaptain Klevtsov

[beamish]

Thanks for the link KK.

As for David Knisely's review, in fairness I think one can rest assured that the OTA HAS moved on ! One MIGHT want to read the last two paragraphs !

The scopes werent really all that reliable to be honest...

and is this based on experience using one ? I know I'm only the only forum member to own one BUT surely there must be others who have used one.

[Xlracer]

Attempting to sort out a 12" carbon tube version that had lamentably poor optical performance at the moment.

Mirror had 5 waves of astigmatism when bonded in the cell, relaxed to 1.4 now I have got it out. (All Zygo tests, so dead accurate) The mirror is a high aspect ratio item (thin) and overconstrained with around a dozen areas of silicon rtv bonding it to the cell. The cell is also distorted by the horrendously powerful springs (outer valve springs from a car/van) overly compressed to enable use of cap head bolts, as well as distortion issues due to differntial thermal expansion effects. The carbon tube is also insufficiently rigid.

However I have plans to alleviate most of the detail failings, and it certainly should be improved somewhat.

BTW

Got the mirror out by filling the cell with Nitromors paint stripper (meth chloride) and leaving it standing for a week.

XLRACER

[beetlejuice]

And to think I nearly bought one of these 8" scopes at the thick-end of 1500 quid. All set to buy then a C9.25 came along. They went bust shortly thereafter. Lucky escape. Actually, Newise telescopes still seem to be available through Peter Wise's new company but only in 400 - 1000mm apertures. In otherwords, mega-bucks!

[dph1nm]

When I was last there (about 1 month ago) Rother Valley Optics had an 8" Newise in the showroom. Apparent a superb quality one (they have used it).

NigelM

[Macavity]

One (>8") appeared in a local photographic shop recently. When I asked, they said it was being sold (much reduced) for someone - As having a significant optical problem. It presented a rather SAD spectacle...

I rather wish there was a little more innovation in such things. I sense astro-equipment is rather limited by "tradition"? More power to your elbow, in trying to "fix" it.

[Xlracer]

I have never seen an 8" at close quarters but I expect that the mirror is probably a similar thickness to the 12 " (it could hardly be much thinner) and so relatively much stiffer. The advantages of the smaller diameter in improving stiffness would also apply to the mirror cell and tube, which although carbon is a single skin construction.

The sad 8 " telescope mentioned might well be worth an offer if the price is right as I think if the mirror is freed off and remounted more conventionally it could well make a really nice wide field instrument. The theory looks promising on these telescopes, its the execution and detail design that appears to cause the high occurrence of what is almost certainly an astigmatic optical trains in the reportred poorly performing items. I suspect the problems increase in an non linear manner with increasing diameter.

[beamish]

XLRACER, I'd be keen to see any pics you may have or wish to take regarding any mods to the Cape, as I own an 8" ally tube version.

I have had the whole thing apart except for taking mirror out of the cell.

The glue used in mine re the optical window and the secondary appears to be a silicone based adhesive rather than cement as used in others.

What I will say is that it's a right [removed word] to collimate !

P Wise did pm me to say that the focal plane at infinity should occur with the field stop out at 142+/-2mm.

There's a fair bit of slop in the crayford which hasn't helped so if you have any ideas about sorting that out I'd be keen to hear.

Overall though I have to say it's worth persevering with 'cos when on form the views are superb ! besides who's gonna buy one now ???

Karlo

[Xlracer]

Beamish

Some pictures that illustrate the story so far. The secondary tilts on a flexure whicjh is very clever indeed and saves room, via an adjusting grub screw, but reacts against what looks like a wedge of kitchen laminate strips. I may well change that!

BTW They were not taken at Scarborough in 2009, thats finger trouble on my part in filing the pics properly

[Xlracer]

Final Interferrogram of the mirror in its free state. If you were wondering about the obtuse Scarborough reference, the JPEGS were Scarborough 1, 2 etc

[beamish]

Thanks, a few differences there then by the look of it. My 2ndry holder has the three screws going into a plate behind the actual mirror holder, then in the centre there's a conical shaped recepticle in which sits a 12mm S Steel ball bearing, this is then offered purchase against the front cap by means of a grub screw. Easier with pics but I'm disinclined to take it apart again, soz.

I like the idea of the dew heater hidden in the tube !

Keep up the good work. BTW who did you use for the mirror testing ??

[narrowbandpaul]

thats really quite a bad mirror, even in the free state.

our society has a mirror made in the victorian era. it was repolished at orion optics who also zygo'd the mirror.

it was about 1/4 wave. mind you the mirror is f/10

from those reports I would certainly not buy one.

but good luck to you guys, and kudos for trying to sort there mistakes....

paul

[beetlejuice]

Hmm. That looks a bit ropey, but how was it tested? Improper support can produce poor results.

[beamish]

I do have to say that on the evidence of what I have seen thru my scope it's not in any way in as bad a shape as that.

Whereabouts are you XL, it'd be great to have a scout thru a 12"er

Karlo

[Xlracer]

We have decided to get the mirror re-figured and re-coated as it really is still too astigmatic to be of any use. I have also decided to stiffen the tube up by the use of internal plywood rings and u section alloy channel to create a sort of aeronautical monocoque structure within the carbon fibre tube, will take some pictures of the progress and post them.

XLRACER

[beamish]

Is that a royal "we"

I have to say I am very surprised that P W let this 12" mirror get past if it's so poor, he told me that he bought them in then figured them up to spec himself, and let's face it a 12" Cape was a LOT of money !!!

I hope the stiffening up works, I recently decided to open mine up and flock the inside to try and improve the contrast a bit. Currently looks like it was painted with blackboard paint and appears more dark grey than black. I'll get the self adhesive flocking from Hobbycraft.

Look fwd to the pics XL

Karlo

[chrisrnuttall]

John

I used to own an 8" carbon tube cape newise. They are not all the same as most of the telescopes peter wise sells seem to be 'works in progress', what i mean is that the design changes rapidly. This could be seen as a good thing as he is always improving them, but its only good if you get one of the improved ones.

I can only tell you about my telescope, which i bought second hand. It went back to peter about three times in the three years i had it, once for a new mirror as the original was damaged when i got it, once for an internal dew heater, and once for.....i can't even remember now! Thing is i was constantly taking it apart and trying to sort the performance out. Peter told me it was not one of his latest ones. But that the only differences were a different front end housing to make fitting an aluminium dew shield possible, and a new focusser.

When he went bust i bought a new front end and a new focusser from him. He is a really nice guy and he gave me his mobile number so i could call him if i had any problems - which i did and he had plenty of time for me.

The front window is glued into the cell with silicone (he used to use epoxy but silicone isn't brittle so lasts better) and is not easily removed.

The central obstruction assembly is screwed into the window by its outer ring, it is easily removed if you make a tool to unscrew the ring, there is some silicone used to stop it turning in the glass window too but it doesnt exactly glue it in, you can get it out. It is a good idea to make a jig for re-fitting the central obstruction assembly as it needs to face the focusser pretty well.

Cleaning the secondary mirror is not easy at all, as it cannot be removed from its tube once the little lens has been bonded in the end. I used to clean the secondary mirror and the lens next to it with acetone in a little squirter bottle (PW's idea). The aluminium is anodised and the glues are not affected by acetone either. It works pretty well as acetone will disolve greases and water based marks too.

the main mirror was bonded to a 3mm thick spun steel dish (with a flat base), this was what was used for a mirror cell. There were three small pieces of plastic wedged inbetween the sides of the mirror and the cell wall, not sure why, but in cold conditiond the steel cell contracted and the plastic wedges pinced the mirror badly, creating triangular star images. I removed them and the main mirror was pretty good after that. The whole point is that its a spherical mirror and therefore easy to make to a good level of acuracey. This also has to be cleaned with acetone as you can't wash the whole thing in a sink or it will rust!

The last bit in the train is the focusser which i thought was okay, there is a lens in the bottom of that too, and again it is possible to get to it to clean it, but you have to take the focusser off to do it (or the front window)

So in short, yes you can take it all apart, but every optical element it glued into its holder and cannot be taken out easily.

I think the concept is a nice one, but it suffered from manufacturing techniques and mechanical design flaws. That said my scope did give very good performance once it was sorted out.

You have to get the height and alignment of the central obstruction assembly just right or you get astigmatism.

One of the three different front windows i had was defective and that had astigmatism ground into it.

And of the two focussers, two windows and 1 mirror i ended up with, only one combinations of these was acceptably free of spherical aberation. This telescope taught me everything i know about optical aberations and how to detect and cure them!

I suppose this is why there are so many people who report problems with theirs, and some who say they are great, they are a bit hit and miss!

Don't bother with the internal dew heater, it's just a kendrick band velcro'd to the inside of the tube, and it creates such massive tube currents that you have to stop observing. I bought some nichrome wire and made a heater which fitted the tiny amount of space available around the front end of the tube.

In the end i was pretty happy with my newise but it took three years of messing around with it to get there.

By the way i found that the weights peter claims for the scopes were wrong, mine was several KG heavier than claimed, and the central obstruction also measured closer to 30% than the 25% claimed by the website.

In the end i sold it at quite a loss (especially if you include the amount i spent sorting it out) and i bought an orion SPX 200, which easily outperforms the newise in every single respect, like having a proper mirror cell, a cooling fan, only 2 optical surfaces, just about the same field of view, a smaller central obstruction, a sharper brighter image etc etc. and i will only sell this one when i can semi permanently mount a 10 or 12" version.

By the way I still have a front end, a focusser, the tool and jig i made for the secondry, and the internal dew band if anyone is interested in them.

Oh and a cold, which you can have too

best wishes

chris

[beamish]

Chris hello ! I'm sure we've spoken before on the old newise users forum, I'd seriously appreciate the the secondary tool & jig please and possibly the front end.

I have to admit to having learnt a lot about scopes since owning my 8",my problems did'nt realy start until I had to open it up to clean the mirrors up until then I'd have to say it was a fantastic piece of optical engineering, but yes it is flawed as you say. I'm determined to get this begger up and running again as it should and did and am almost there. The tool would be a great help. Can I pm you my home address and details ?

As for the cold........ had 2x in the last 3wks, think I can give that a miss

Karlo

[beamish]

Just want to say a big thank you to new member Chris for sorting me out with what in future will no doubt prove to be invaluable spare parts. Cheers, nice to meet you and have a chat.

Karlo