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nicoscy

Custom refractor built - sharing the experience

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Hi SLG gentlefolk,

About 4 months ago I got into the process of ordering a custom made refractor  - still an ongoing project and I thought I would share the experience with you  :grin: 

Why a custom refractor?

There is a certain kind of pleasure in getting something custom made for you, be it -I don't know - say cufflinks or a refractor. I certainly did not seriously plan to order one but randomness coalesced into a weird coincidence and that is exactly where I am now.

This will be a rather long thread with a little bit posted every day as I am going through a lot of email exchanges (117 emails so far) to gather the pertinent parts and will document the built of a custom built refractor by Moonraker Telescopes UK .

In retrospect, I can only say that it is truly my fault. How did I end up meeting Mark? Mark Turner is the man behind Moonraker Telescopes. The only "contact" I had with Moonraker was through Astrobuysell UK classifieds when once I clicked on the advertising banner link for Moonraker, checked the scopes really quick and said to myself "cracking scopes, not for me, let's move on".

Moving on a few months down the line and specifically mid-July, I had a spare red Moonlite refractor focuser which I listed for sale on Astrobuysell UK classifieds and Mark needed said red focuser for a refractor built. I called him to discuss the focuser and we ended up chatting refractors, refractors and even more refractors.

And that's when I decided I needed a custom refractor and to see how far down the proverbial rabbit hole I would go. Talking to Mark about scopes in general, I realized that I never actually fulfilled this unknown need of mine for something unique, despite trying refractors from 120mm down to 60mm (in 10mm increments), from Achro to ED and APO and never being fully satisfied.

In the end, his insights transformed my initial vision to what I am happily sharing here.   This is truly a labor of love and the sum total of significant effort to bring about this fine instrument, giving ultimate joy of looking through and also looking at the telescope.

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Why a 60mm refractor?

I ascribe to the philosophy that there is not one single scope that can cover all your needs. In my particular situation, there was a place in my telescope herd for a small refractor to use from my light polluted back yard (or building roof) on a variety of double stars, the moon and planets and a few bright M objects.

An easy scope to set up, fairly light, yet built with longevity in life and a scope that would “draw” me to use it very frequently, but also to take occasionally with me to various dark sites as a companion to my Dobsonian, for the occasional trip abroad and for future mating with a Daystar Quark for solar viewing.

Without further ado, the peep show is about to start. Please be gentle as the scope is still in a rough state and polishing and everything else will be done later on.

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Lens cell assembly

A flurry of emails and telephone calls kicked off the design for a 60mm f7 Triplet APO refractor, utilizing the lens assembly from an Altair Astro 60mm APO (a triplet lens assembly using FPL-51 as the main element) in a wonderful custom fully collimatable lens cell fabricated by Mark.

At f7 I am not really worried about distinctions between FPL-51 and FPL-53, although Mark did manage to score for testing a prototype FPL-53 60mm f6 objective. In the end his testing showed the FPL-51 to be the better choice. Mark being in the UK and me being in Cyprus, I took his word on it and we shall see how this little gem will fare under dark skies on arrival.

For those of you who are not aware of this little gem, the Altair Astro 60mm ED APO Triplet is a fine little scope on its own and had I not wanted a custom made telescope, I would have been most happy to have use of this telescope. BBC Sky At Night Magazine has a short review if you don’t mind the extra “homework”:

https://www.altairastro.com/public/reviews/LW60EDT-review-BBCSkyatNight-Feb-2013.pdf

I must admit to being fascinated with how inexpensive good optics have become in the last few years, courtesy of the increased quality and low cost high volume output coming out of Chinese optics manufacturers. The line separating premium small batch run scopes and your run-of-the-mill high quality Chinese manufactured scopes gets more blurred by the day.

Getting back on the subject, we started some great lenses, then the lathe took over and we ended up with a gorgeous lens assembly.

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So, this is the start, the work and the outcome for the lens cell assembly. As it is 7:59 here in Cyprus and I officially start work in one minute, I will continue this thread tomorrow morning...


1



2



3

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He seems to really be on top of things but at times he strikes me as a mad scientist  :icon_confused:!!! One thing I can say for sure is that our telephone conversations are never boring...

Note that Mark is not the only one hard at work. I have been hard at work on the telescope accessories! Tomorrow some NSFW photos of equipment. I hope you all like photos of naked eyepieces  :grin:

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Very interesting project - thanks for posting the details :smiley:

I can see the attraction of a finely made, bespoke ultra portable refractor but I'm wondering why a triplet at F/7, unless you are intending to image with it ?.

Surely an ED doublet at that aperture and focal ratio would be practically colour free, visually ?. Maybe there wasn't a suitable one available ?

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Hi John,

Quick 2 minute break from work then! I have tried refractors of various apertures, Achro, ED and APO. It was expensive to learn, but the lesson was well learned from past refractor purchases. A triplet performs better than a doublet, lens quality being equal in terms of polishing and mating elements.

I wouldn't mind a doublet fluorite but these are not available at the focal length I wanted, therefore a triplet  is the best choice for colour fidelity, clarity and contrast. Also, f7 is a very forgiving focal ratio for eyepieces. But the lens element is not the expensive part of the telescope anyway, it is the built that absorbs most of the budget as the machining is quite extensive.

And finally, you have hit the nail on the head. Imaging is definitely not in my plans now, but in the future, I would be happy to dabble in it. All I would need is a FR/FF to bring down exposure times and get a flat field for a camera and a lightweight GEM and I am set. I am 100% visual but I cannot preclude imaging in the future, so I went for a triplet to "futureproof" this built.

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Thanks for the explanation Nicos :smiley:

I'll look forward to following the project !

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So, picking up where I left off yesterday...

Meanwhile, I was not sitting idly by. I asked Raul at Desert Sky Astro if he had any DSV-M mounts in stock. He replied that he would have some ready in two weeks and I just jumped at the opportunity. The DSV-M mated to my Manfrotto 055 XPROB will be perfect for quick views and trips when I want to travel with light gear and I am glad to say that it is now on the way to me.

For use at home in my backyard, I will use my Manfrotto 475B and Stellarvue M2 head. I am a firm believer in having solid mounts and tripods for scopes as nothing ruins the experience more than an undermounted scope.

Should I feel the need for tracking, I managed to score a great Nexstar 6SE/8SE mount from the Classifieds which should easily carry thisthis little scope.

I then went on a shopping spree on both UK Astrobuysell and CN Classifieds and grabbed 3mm, 4mm and 6mm Radian eyepieces. I then added a 13mm Nagler and a 2" Televue Diagonal and a 2x Barlow element to use on the 13mm Nagler (directly screwing the element onto the filter threads yields a 1.5x barlow effect, turning the eyepiece into a 8.7mm eyepiece) and I also have a 32mm Edmund Scientific RKE eyepiece (yes, those with a field stop slightly larger than a 31mm Nagler) to turn the scope into a monocular when the situation calls for 5.83 degrees TFOV.

The massive 5.83 degrees TFOV is the only reason for the added weight of a 2” diagonal. Thinking forward as well, there is a lovely 40mm 68 degrees AFOV eyepiece on Teleskop Service which would yield 10x, 6.2mm exit pupil and 6.8 degrees TFOV which will probably be my next purchase for this scope.

I have the 8mm, 13mm and 21mm Ethos and the 31mm Nagler, but I think this calls for lighter eyepieces to complement the scope, hence the eyepiece arsenal above. Televue Radian eyepieces provide 60 degrees AFOV and are very comfortable to use. I could have gone the 82, 100 or 110 degree AFOV but it is wholly unnecessary for my purposes and again, keeping weight low is important.  

Parental Advisory: Naked eyepiece photos to follow - not suitable for minors.

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DSC 0397

This is the second time I purchased the Edmunds Scientific as I stupidly parted with it a few months ago. Yes, edge correction suffers but it has great on-axis performance. I actually used it on my long gone AstroTech AT72ED and at f6 it performed pretty well.

Here’s a nice review contrasting this this particular lovely classic eyepiece to the Nagler 31mm. Despite its limitations I like simply because it is in the feathertouch category Vs the Nagler 31mm which belongs in the heavyweights.

As for the Radians, I like my eye relief at high magnifications to be at least 15mm, hence the choice of the Radians. Again, classic eyepieces for a classic refractor built. As for the Nagler 13mm, it is such a versatile eyepiece especially with the barlow combination yielding a large AFOV in a small lightweight package.

I can't resist some more eye candy. Here's the Edmund again in a NSFW pose.

DSC 0398

So, my eyepiece combination yields the following: 

Eyepieces

I do know that the 3mm will not find much use - only for some double stars and for testing the scope, but it will find use on other telescopes in the future.

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Picking up where I left off...

So, every part of the stock telescope is being reworked or new parts are being machined. The stock telescope did not come with a findershoe or finderscope / red dot finder. A 6x30mm finderscope and a RDF will be added to the mix, but first we had to attend to the findershoe and finderscope bracket.

I am sure the majority of you is aware of the standard 6x30 finderscope and bracket:

Not to mention the standard findershoe (which I am). Nothing wrong with them, but again, noting wrong with a bit of Moonrakerising in the process.

A side by side of the standard -let's call it - findershoe and the machined version by Moonraker. One thing I immediately noticed was that the machined custom version had the screws of the standard findershoe. I wanted them shorter but when I asked Mark to chop them a bit he responded that he is machining new custom screws for the findershoe and he just put the stock ones for the purpose of taking photos for me,

A (4 Of 6)

A (3 Of 6)

A (2 Of 6)

A (1 Of 6)

A (6 Of 6)

Again, a high level of attention to little details which make the scope a pleasure to use.

There was a great thread that run its course lately on SGL aptly titled "Have you chosen a scope on looks alone?"    My response there was that no, I haven't, but looks are equally important as the marriage of aesthetics and performance makes any telescope (or any other thing in life) more pleasurable to use.

Tomorrow I will an exploded photo of the built and another showing how all the parts fit together - well, most of the parts anyway, along with some explanations as to the choice of specific dimensions for the scope to come out the way it did...

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As promised, some photos of the actual scope.  So, here’s an exploded view of the telescope, although it is still missing quite a few parts and needs some more machining here and there.

nicos (1 Of 5)

The OTA has a 3.5" diameter  and the dew shield a 4" diameter, looks like a good tight flocked fit, but Mark will include fastening thumbscrew for the dewshield and 2 baffles in the OTA  + 2 baffles in the dew shield with Protostar flocking on every other bit inside the OTA and dew shield.

The view below shows the length of the scope. A bit long at 20 inches but it has a nice balance between focuser, OTA and dew shield length. However, removing the dew shield (as I plan to do for storage) allows for a compact 11 inches.

nicos (5 Of 5)

I plan to get a photography backpack and have the scope + dew shield along with a 2” diagonal, finderscope and RDF in there. I will probably get an oversized backpack and also fit all eyepieces in there along with the obligatory desiccant and thereby just grab the bag and my tripod and walk out of the door for quick observations. 

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A couple of more details:

Dew shield diameter - 4"

OTA diameter - 3.5"

Larger of course than what is required, solely for the purpose of making the scope look proportional and balanced.

More photos and details to come as the built progresses. I am waiting for the focuser to come back from its polishing session.

Question of the day as I am undecided: Polished aluminium or a mixed gold and aluminium colours? Feedback most welcome...

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A couple of more details:

Dew shield diameter - 4"

OTA diameter - 3.5"

Larger of course than what is required, solely for the purpose of making the scope look proportional and balanced.

More photos and details to come as the built progresses. I am waiting for the focuser to come back from its polishing session.

Question of the day as I am undecided: Polished aluminium or a mixed gold and aluminium colours? Feedback most welcome...

Hi Nicos

I think these scopes look pretty gorgeous whatever the finish.  I gather that the polished aluminium is a very practical proposition when it comes to solar viewing/imaging, in terms of reflecting the maximum heat, but to what degree I'm not sure.  Personally, I think Mark's work also looks excellent when there is some contrast between the tube colour (e.g. black, gold), and the highly polished focuser, finder, rings etc.

I saw these scopes at IAS back in June, and was mightily impressed.  Seriously considering a similar project...

Best

Simon 

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Hello Nicos,

I spent 15 minutes talking to Mark at IAS late in the day and his enthusiasm was infectious. Mad professor? Who cares, because he does.

I too am of the opinion that the pride of ownership in an excessively engineered scope is an investment worth making. Sure, a piece of Chinese bent tin can deliver awesome views due to the quality of optics, but they simply don't engender the love that a bespoke scope can. Moonraker turn a great objective into a lifetime keeper and deliver an OTA that can accommodate an even better objective at a later date. Nice.

I've considered getting my ES ED80 triplet Moonrakered, lest I find a nice WO LOMO 80/480 a bit further down the line. God knows, WO alone are a reason for Moonraker to exist!

Russell

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Hi Simon and Russell,

It is certainly an interesting experience to have a custom refractor built as opposed to getting a run of the mill variety scope. Gratification takes longer as such a project takes time, but the trip is certainly fascinating.

As yet still undecided on colour and now I have to also choose the leather trim for the focuser knobs. Feels like going to a car dealership and discussinf leather interior trims!!!

I am actually a hair's breath away from commissioning a new project for a 123mm triplet, but for a more or less normal OTA to be made by Mark. I am more or less close to the ideal for me telescope collection so I want to get the best possible to last me and keep me satisfied for many years to come.

And yes, everybody raves about those LOMO objectives! I would love the opportunity to view side by side through a LOMO and a FPL-53 objective to see what the fuss is about!!!

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So, it is getting even more complicated. Apparently now I have to decide on the leather trim on the focuser knob. My choices below:

Leather

Considering that I want a durable finish to the scope, I think I will go with black powder coating, polished aluminium bits on dewshield, polished aluminium for focuser with a black leather trim.

Aero rings, dovetail and stalk in polished aluminium and finderscope in black.

Recommendations are most welcome at this point as this is the only aspect of the built that has me completely stumped.  I think the looks on the second scope in the link below should look nice.

http://www.moonrakertelescopes.co.uk/

And even though I will do solar viewing with this guy, I won't be spending an inordinate amount of time to worry about the scope heating up and anyway, it's a small sized scope so not too worried about the black colour.

Thoughts?

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Considering that I want a durable finish to the scope, I think I will go with black powder coating, polished aluminium bits on dewshield, polished aluminium for focuser with a black leather trim.

Aero rings, dovetail and stalk in polished aluminium and finderscope in black.

Recommendations are most welcome at this point as this is the only aspect of the built that has me completely stumped.  I think the looks on the second scope in the link below should look nice.

That sounds a stunning colour scheme to me! But then I'm biased - I love the ultimate contrast of the black and polished metal. This is YOUR very special scope, so I'd be concerned about having any influence on your choice of finishes. However, my choice would indeed be to go for black leather on the focuser, to preserve the "black with shiny" effect. Should look absolutely fab!

I can imagine that the build process is a pleasurable experience in itself, and it's kind of you to share it.

Keep enjoying it!

All the best

Simon

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Thanks Simon  :grin:

I still have a few days / a couple of weeks before committing to a final colour scheme but I think this is it, black and aluminium contrasting each other...

Will keep updating as soon as more updates roll in from Mark.

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This is excellent! I am reading with great interest (and a fair whack of envy too!) :)

Keep the info coming

Joe

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OK, so I emailed Mark and "locked" the colour to black with anodised aluminium bits and black leather for the focuser. 

Now waiting for the focuser to come back polished so that the telescope parts can be fitted together....

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