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laser_jock99

Cape Newise 8" F6 Reflector

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Took delivery of a Cape Newise 8" F6 reflector today. It's a UK made scope from around 2004 and best described as a catadioptric Newtonian. The front glass plate is a plano window and merely acts as a support for the secondary assembly. There are two lenses in the in system designed to reduce coma, one between the primary and secondary, and another lens in the focusser.

It's a second hand scope and has a few minor marks as might be expected with an 8 year old instrument but I got it fairly cheap on E-bay.

I took the scope into our Optical Clean Room this morning, dismantled it, cleaned all the optics & tube components and then re-assembled.

Just a need a clear night now to do some star tests and start the collimation process. Full review to follow.

Cape Newise 200mm F6 mounted on an NEQ6

Dsir4194.jpg

Dsir4192.jpg

Focuser

Dsir4183.jpg

Tube side view- very short, about 600mm!

Dsir4182.jpg

Edited by laser_jock99

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Nice scope, it will be interesting to see how you get on with it, the focuser looks well made.

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Ahha, excellent.

Was looking through some of my old posts and wondered if you'd picked this up.

Thanks for the pics.

Like Earl says, looking forward to your further posts on this interesting scope.

Cheers,

Andy.

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Focuser looks very well machined. Does it work as well as it looks?

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Fascinating and rarely seen scopes those. I look forward to your reports on it :cheesy:

Will a laser collimator work with it or would you need a cheshire ?.

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I very nearly bought one of these quite a few years ago when they were first advertised. I subsequently heard some bad stories about build quality of the earlier samples but presume that they got sorted out. The spec and design always seemed quite appealing to me so will be interesting to see how you get on

Stu

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I very nearly bought one of these quite a few years ago when they were first advertised. I subsequently heard some bad stories about build quality of the earlier samples but presume that they got sorted out. The spec and design always seemed quite appealing to me so will be interesting to see how you get on

Stu

Yes- I read the report on Cloudy Nights regarding their 'sample' scope. This apears to be one of the later ones with an aluminium tube with orthogonally machined ends. This means (hopefully) everything should be roughyly in place after the strip down and rebuild. Ordered a laser collimator and will be making an artificial 'star' tomorrow to help with collimation, though my initial tests semm to indicate it's not that far out.

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The clear window is interesting, I wonder why more newts don't try this? It would get rid of diffraction spikes but I suppose it's a balance between this and any losses caused by the extra glass and the additional cool down time.

Does the scope have fans fitted? How well do you think it will cool?

Stu

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......Ordered a laser collimator and will be making an artificial 'star' tomorrow to help with collimation, though my initial tests semm to indicate it's not that far out.

I'm interested whether a laser collimator would work with the Capenewise optical design. I'm wondering if the 2 corrector lenses will mess the laser up as it does with the "bird-jones" designs :icon_scratch:

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The clear window is interesting, I wonder why more newts don't try this? It would get rid of diffraction spikes but I suppose it's a balance between this and any losses caused by the extra glass and the additional cool down time.

Does the scope have fans fitted? How well do you think it will cool?

Stu

The optical window adds a lot of cost. An optical flat 250mm diameter with AR/AR coatings and a hole drilled in the middle and a substantial machined cell is going to be expensive compared to thin steel spider vanes.

The cool down time of this type of scope is longer than open Newts. Shouldn't be an issue to me as it will be kept outside in the obsy.

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I'm interested whether a laser collimator would work with the Capenewise optical design. I'm wondering if the 2 corrector lenses will mess the laser up as it does with the "bird-jones" designs :icon_scratch:

The lenses are mechanicaly fixed in place (there's some amount of in-out adjustment on the focusser lens) so I can only assume that the mechanical centration of these optics is factory set in the optimum position. Whether the overall arrangement can be laser collimated remains to be seen?

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Good point about the cost of the optical window. I presume though that it gives the secondary much more stability and probably means it will hold collimation better?

Stu

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Once collimated these will hold collimation like S88t to a blanket-comparable with the russian MakCass . I had awful trouble trying to collimate with a laser and found it was far easier to use a sight tube & cheshire ( PS IIRC Peter told me that the focal plane should be 172mm +/-2mm, ie distance from the centre of the lens in the focuser to the field stop- I made a measure from a length of broom handle and felted the bottom) .

BE wary of the length of the cheshire as it can be oh so easy to let it drop onto the lens !!!

Cool down wasn't too bad I found 45mins to be acceptable, in an obsy it'll be fine.

LJ looks like you were lucky and have the same focuser as mine and judging by the pics you have the optical window coated :) in later versions to save some money the optical windows were left uncoated, but the lens between the primary and secondary were coated instead. The later crayfords that were used felt distinctly flimsy. My focuser had a bit of shift but this was sorted out using some aluminium shim( amazing what you can use a coke can for ! :)

I still maintain that the views thru the Cape are extraordinarily good, bright and with XLNT contrast- indeed I recently bought a long Losmandy dvt specifically so I can start using the Cape again on the NEQ6. I also found LJ ( if you're interested) that it was easy enough to add a SW Accufocuser to the Crayford .

I hope you don't mind but I've included a pic taken thru the Cape with my now long gone QY5

post-792-0-72582300-1339408980_thumb.jpg

PS I think for the money- you'll be very happy. I've resisted selling mine because all the bad publicity in the past kicks up the same old same old stories- people making judgements without having had any experience of them first hand. For you this has meant a reasonably cheap price :)

I have a sneaky feeling I know this scope of yours and it's previous owner, so you ought to have an enjoyable experience ;) My info sources tell me that only about twenty of them actually exist here in the UK !! So it is indeed a rare item.

Edited by beamish

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Oh another thing :) the first time I met Peter at Abergele he collimated the scope inside 5mins using an artificial star on a bench with just a simple sight tube that looked like one of those DIY jobbies from an old film cannister- I felt such an idiot !!

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Sorry LJ, I had previously said that the focal plane distance is 172mm This is wrong it should be 142mm- I would like to feel confident about this figure too but for the life of me I can't find my measure so you may want to get Peter to confirm the correct distance as this is pretty critical when collimating ;)

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Thanks for all that information Karlo- should make things a lot easier. I have made an artificial star using a 250 lumen LED torch and 600um optical fibre so I could try collimating with that.

As you say I think a Cheshire Eyepiece is the way forward. I returned the laser collimater I got off e-bay, the laser wasn't even collinear with the eyepiece tube!

I have tried to contact Peter and see what his advice is.

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Interesting stuff.

Keep us updated.

Hopefully you can get it close to bang on.

Cheers,

Andy.

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No probs :)

I've found my measure and it reads off at 144mm ( including the felted bottom so close to this figure and you should be okay. A bit of tracing paper secured over the top of the focuser (once set to the distance) then move the primary to bring objects into focus on the paper- that should then be your starting point for collimation using the normal tools, as I understand it ;) worked for me:)

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Interesting scope. One reason we do not see many flat window pane front ends to Newts is that it also adds extra weight. This adds to the cost of the mount and tube assembly as well.

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