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I thought I'd fork off the discussion from the other thread and gather a list of things that a new or prospective CDK 14 owner should be aware of. Although it's disappointing that Planewave aren't shipping better OTAs or fixing known issues themselves, this will at least let owners take care of these problems before finding out the hard way and having to waste their nights chasing things down, especially if they plan to operate remotely. Planewave has fairly bad warranty terms that require you to shell out and ship everything back to them at your own expense, which is extremely expensive, and then they also bill you for return shipping (for problems that were THEIR fault, after already charging upwards of $16k!). After 2 years, you're completely SOL on warranty (and only 1 year on the coatings). As such, it will probably be on you to deal with things yourself. I'll continue to edit this top post to keep things organized. Would greatly appreciate input from those with experience if they wouldn't mind sharing what they've learned and had to fix or correct. 1) Shroud Obstruction The spandex shroud will block your light path. Planewave has not addressed this issue. Rouz Astro has a spacer kit (https://rouzastro.com/product/cdk-carbon-shroud-spacer/). Some owners claim that even under light winds, the shroud negatively affects performance and it's better to not use it at all. You'll need to either remove it, or find a solution to hold the shroud away from the light path. 2) Pegasus UPB may fry the Delta-T Multiple people have lost Delta-T units that were hooked up to a Pegasus UPB. Both vendors are aware, and neither Planewave nor Pegasus seem to think their component is the problem. Root cause and fix unknown, so don't use this combo. References: https://www.cloudynights.com/topic/819094-planewave-cdk14-first-light-and-testing/?p=12324761 3) Wedge shaped spider vane causes wavy/duplicated diffraction spikes Currently another active thread investigating this. It appears some units were made with a thicker, wedge shaped vane different from the others. No known fix yet. Reference: https://www.astrobin.com/forum/c/equipment-forums/planewave-cdk14/perplexing-issues-with-cdk14/ 4) Securefit to M54 and M68 adapters are defective, won't mate to reducer Parts (600389) and (600390). Problem reported to Planewave years ago, but the same part numbers are still listed on the website, so it's unclear if they silently fixed it without adding a new part number, or if it's still unresolved. 5) Reducer obstructs the light path Vignetting at the corners, and out of focus stars off axis have a chunk missing. No known fix. 6) Documentation on reducer spacing is incorrect Planewave reports that 44mm of backspace produces the smallest spot sizes. Multiple owners have said that this was off by quite a bit, and finding the correct spacing can be a painful process, as any movement . <More info needed on this point, if anyone can share what the correct measurements were, please do> 7) Aperture ring holes allow stray light, causing aberrations The aperture ring is poorly made, with bulges and unfilled 1/4" holes. The bulging ring is reportedly cosmetic, and this ring is designed to mitigate a limitation of the figuring process they use for the mirrors by covering up bad edges. Put tape over these holes. Reference: https://www.astrobin.com/forum/c/equipment-forums/planewave-cdk14/perplexing-issues-with-cdk14/ 8) The thermal management situation is an absolute hot mess. There's a whole thread about it here, and complaints on PW's support forum. There aren't great solutions. Too much to summarize. Reference: https://www.astrobin.com/forum/c/equipment-forums/planewave-cdk14/fan-operation-without-efa/ 9) The Hendrick focuser is bad for many reasons. Get a different one. Not from planewave. Reference: https://www.cloudynights.com/topic/883724-cdk-telescope-club/?p=12977658 Please post corrections/additions/updates in the thread - especially anything related to light leaks, reflections, surfaces that need painting, holes that need filling, etc. |
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Thanks Jego, for putting this together. This will be very valuable for new CDK14 users. A few comments/additions: 1) Alternatives are: Planewave 3D-printed spacers (expensive): https://www.planewave.eu/zubehoer/teleskopzubehoer/streulichtschutz-set-spandex-4-st-spacer Alu rods with 1/4" connectors (cheap, bit heavier): Rods and Connectors ad 2): My Delta-T came dead in the box. Nothing to do with UPB. Looks like electronics of Delta-T is poorly designed. 7) These are different things: The aperture ring (hovering over the primary) is poorly made, bulges and is fixed on blank-metal connection points, rather than backend ones. The bulging is reportedly cosmetic and unlikely to cause any star-shape issues. Not sure about the blank metal connections points. More logical would be to have them blackened. Purpose of the ring is to cover up bad edges, due to limitations of the figuring process, and reduces the aperture of the purposely over-sized mirror to the desired value. 7b) or 10) The ring at the front of the truss has a total of 20 open 1/4" holes. Such small openings at the front of the telescope can cause aberrations. Closing these holes by putting tape over them has shown to have markedly improved star-shapes of the brighter stars, especially off-axis. 8) The thermal management situation is an absolute hot mess. The Delta-T measures only backplate, secondary mirror and ambient temperature. You need the EFA to measure Primary mirror temperature. Neither of them has a humidity sensor. So there is no option to control dew based on dew point. The result is that the mirrors are often heated unnecessarily, causing poorer image quality than necessary. There's a whole thread about it here, and complaints on PW's support forum. There aren't great solutions. Too much to summarize. 10) PW balancing weights are ridiculously expensive. More versatile and much cheaper alternatives from Smallrig can be found here. Oh, and by the way, there is also a lot of good to say about these scopes...  . Mine never needed collimation and SKW wavefront analysis showed good collimation, even after transport.CS, Willem Jan. |
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| @jego & @Willem Jan Drijfhout thank you for brining this to my/our attention! I’m one that is waiting for a good deal on a used 14” so this is all good information for me to know about in advance! It almost makes me question whether or not to consider on or look else where. I really wish the AG IDK’s were still in business. I’ve heard that there products were in some sense better in that they had addressed these types of issues, but I don’t know this 1st hand. Just had read somewhere that the AG line had the lesser amount of issues the new owners had to deal with! Dale |
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Thanks a lot for this Jego, I am currently planning to install my CDK14" very soon, and this is really valuable information. I imagine that I will have to go through a lot of tests during the installation in order to solve most of these issues, as it will be located about 2000Km away from me, so better to set it up as better as possible to have a pleasant remote experience. I will try to update how it goes with the installation and how I can solve each issue. For the moment what I have planned: - 1. I will need the shroud to reduce dust on the mirror, insects going in, or whatever; I got the spacers from RouzAstro, that he tested them and seems to work well. 1.1. Not a shroud, but where I will have the telescope it is recommended to have an automatic lid to cover/protect the scope and take flats. I gotthe Excalibur from RB focus; how it will be attached, is a solution different to the one offered by RB Focus. Once installed, and tested, pictures will be uploaded. - 2&8. Neither of these. I already own a PrimaLuceLab Eagle 5pro, that can provide energy to the fans. Rouz kept them running all the time, so I will try to do this at 50% of power, this is something only needed during winter months where the scope will be located. Temperature readings, this is a tricky thing. PW has a very poor design on this, forcing to buy their stuff. I will try to see if I can attach a temperature probe where the heating pads for the primary mirror is located, and isolate it, this may let the Ecco 2 to read the primary mirror temperature, as it comes with it's own ambient probe, dew temp can be easily calculated and it might me allow to control until certain extend the heating of the primary. For the secondary, I don't know if I can install a temperature probe without causing the problem listed in the next point. - 3. It seems like my specific CDK14" unit will not have big issues with it, but I need to tested, and I would like to prevent it by tacking the point 2. - 4. I am not using these from PW. - 5&6. I am not using a reducer. - 7. If I appreciate such a problem, holes will be taped as already mentioned. -9. I already own an Esatto3" from Primalucelab, it will be coupled with an Arco 3" also from PrimaLuceLab, and I got a custom made piece designed and manufactured by RouzAstro (Planewave CDK Adapter To Primalucelab ESATTO 3" | Rouz Astro), I hope I can use what I own for a while before going to another option as the Gemini. - 10. Not sure if I will need them, but I have seen that RouzAstro offers an interesting alternative (Planewave CDK Telescope Balance Offset Kit | Rouz Astro). So far my bigger concern is about a good thermal management, as many others, but PW seems to be very stubborn with continuing with the current approach, that for such an expensive device, it is a total senseless situation. I hope I can decently manage it, that would be enough for the moment. Any other issue/solution from my side will be communicated. CS, Obdulio |
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-9. I already own an Esatto3" from Primalucelab, it will be coupled with an Arco 3" also from PrimaLuceLab, and I got a custom made piece designed and manufactured by RouzAstro (Planewave CDK Adapter To Primalucelab ESATTO 3" | Rouz Astro), I hope I can use what I own for a while before going to another option as the Gemini. Hi Obdulio, 9. Once installed, please let us know your experiences of the Esatto3" on the CDK14. I was close to going for that option, but decided in the end for the Optec Gemini, mainly because I had seen well working examples of it, whereas Esatto was still a bit unchartered territory on the CDK's. 10. Ah, that is an interesting option. Had not seen that yet. Looks like Rouz is using the same 1/4" connected Smallrig weights. His solution is for lateral balancing (I believe they call it Z-axis balancing?). It will probably depend on your setup to what extent that is necessary. In my case, the only 'unbalancing' part is the filterwheel, and with a rotator, that will always change. So a fixed solution to the dovetail won't work. I added counterweights to the camera (see image), so however you rotate the camera, it's always in balance.  Also, I'm using them to balance the scope on the Dec-axis. A lot easier than moving the whole rig a millimeter back and forth in the saddle. Moving one 200g weight from dovetail bar to front of telescope (or vice versa), is 0.1% in balancing weight, so you can dial in balance very precisely.  Good luck with your installation and enjoy the telescope! CS, Willem Jan. |
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Dear Willem Thanks a lot for the images and comments. Very useful information for me. I have the ASI6200MM pro, not very clear to me how I would manage to add the counterbalances to it though. For the dovetail, this is a brilliant solution! i am placing an order of a couple of them right now. I will post how it works with the Esatto, so far it was my selection basically because I already own it. Which is installed on my Esprit 120ED at the moment, but it will go on the CDK14". CS, Obdulio |
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Dear Obdulio, Ah, the ASI6200MM does not have the connection points indeed. I've seen something for the 6200 from More Blue, which looks quite nice and does a similar thing. If not, perhaps Rouz can modify his design to use a 90mm ring instead of a dovetail clamp? Just some thoughts. CS, Willem Jan |
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I would add a couple other items. The USB method for connecting the Delta T proved flaky for me - hard to connect reliably and tended to disconnect. Solved by going to the old serial method using the connection described below. The serial has been reliable. Delta-T RS232 Cable Assembly Procedure.pdf Also, they recently added thermal support to PWI4 (which by itself makes sense) but despite numerous requests for months, have failed to make it work with primary heater control for users of non-Planewave focusers, which is a large percentage of users. In that sense it is related to the thermal control issues mentioned above. This is a great thread. It lets prospective owners know what they can expect which is very helpful. Maybe it will finally make Planewave get off the dime and do something. I have to think they if they do not, someone will come along with one or both of two things: 1) A competing scope or 2) Aftermarket fixes for some of these issues. As an owner, I would love to have Planewave fix this stuff but would also be happy with some aftermarket fixes since PW seems uninterested despite being aware of most of these things for years. |
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Dale Penkala: Sorta True. I own both a CDK 14 and a 10 inch iDK. The thermal control on the iDK is vastly better than the CDK and done properly (PW could learn something from AGO in that regard!) and aftermarket focusers are always used since AGO does not make their own. OTOH, the iDK, especially the 10 inch, is far harder to collimate than the Planewave. In fact, I am selling my 10 inch iDK, just put it up on Astromart yesterday. Not because I do not like it but because I had it at home (the CDK is remote) and due to limited sky time in the Pacific NW have decided to go with faster wide FOV scopes (FSQ and Epsilon). |
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Willem Jan Drijfhout: I had a slightly different solution for my Moravian camera. I have a basic machine shop (manual, not CNC) so made up a bar and brass weight system. This is almost more of a "mount issue", not a CDK specific issue so is actually a bit off-topic. Some mounts like the L series just require very precise balance so this is not really a mount defect, more just a characteristic of any direct drive mount.  |
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Bill McLaughlin:Dale Penkala: Thanks for that info Bill! I seen your 10" on Astromart this morning. Wasn't aware they were more difficult to collimate, note for future reference. Dale |
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Dale Penkala:Bill McLaughlin:Dale Penkala: The problem is really twofold. First is the fact that there are really "too many" adjustments. Tip/Tilt of focuser, Secondary centering via spider, secondary collimation, and primary collimation. In the case of the 10 inch the central obstruction is so large that visualizing the needed structures is not easy so one needs to go to a star for most of that part. I suspect that the Skywave system would be helpful but I never bought the data to try it with that scope (I have for the CDK). Not to say it is a bad scope - it is not - just that collimation is more effort than with the CDK or the Epsilon. It is more on a par with the old RCOS scopes, can be done but is a bit more work. They do seem quite stable so it is a once done sort of thing unless you are bouncing it down a gravel road or something.  |
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Bill McLaughlin:Dale Penkala:Bill McLaughlin:Dale Penkala: Well again thanks for this info! I will keep all of this in mind when and if I decide to move to a 14” CDK or IDK. Dale |
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6) Documentation on reducer spacing is incorrect I'm working on my system design currently and this is the critical one to me. I really don't want a system where the backspacing is extremely critical to 1mm or less and yet the documentation isn't right on what it's supposed to be. There are people using it where it platesolves to the right focal length so someone must be able to let us know what this distance is supposed to be exactly (as well as the distance from OTA back plate to reducer, so adapters for the focuser will be correct if not using a PlaneWave focuser). |
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Kyle Goodwin:6) Documentation on reducer spacing is incorrect Actually I should maybe strike that one until the situation is clarified. I have since talked to another owner who said their spacing was almost dead on what the docs say. I do expect a very small amount of variation, but it should be minor. I wonder if the reports that 47-48mm are “optimal” were optimizing for something other than smallest spot size, or had other issues present. According to the docs, smallest spot size does not correspond to fastest focal ratio, which was a bit counterintuitive to me. @Rouz Astro do you have any thoughts there? |
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As @jego says, I achieved consistently smaller spot sizes once I hit a platesolved focal length around ~1716mm, with the focal ratio around f/4.82 and close to 44mm of spacing. The manual says the smallest spots are around f/4.83 which corresponds to ~1719mm. I had @Rouz Astro build me a special variant of his OAG+reducer kit that included the ASG Photon Cage in the train. When I started, my platesolves were coming in around 1697mm (by default, the kit put me around ~46.5mm), and the spot sizes were definitely larger. I was able to adjust spacing using the Photon Cage and I found closer to 44mm to be ideal for my setup. There are going to be manufacturing tolerances in all the optical components, so I wouldn't expect every system to be identical. In fact, I know some scopes at native focal length performing well solve all the way from around 2535mm to 2565mm, so that's around 30mm of variation. In any case, the reducer was a bit of a nightmare to get tuned perfectly, and it took a couple of months to get everything nailed down. |
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Ani Shastry: The documented spec for best spots with the CDK14 is 43.688mm which seems bang on with your report of best performance at 44mm. Is anyone else seeing significant difference from that? I'd be especially interested to know if anyone is using shorter than that spacing since the configuration I'm planning right now would hit just short of that and have several mm of adjustment out possible, but no further reduction of spacing possible.  |
