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Hey Everybody, I'm trying to plan a home observatory build and looking into where best to the spend the money investing in a longer F/L scope. I figure who better to ask than people who own or have used these scopes for their expertise and experience with them! :-) I have experience and currently use everything from wider field Radian 61 and Radian 75 refactors, to longer focal length Celestron Edge 8 and C11 XLT (with and without reducers and hyperstar) OTA's. This is probably a largely subjective question but I'm looking at a budget for the scope of up to around $15,000 (not counting accessories needed) and am torn between a few options. This question probably largely begins with "what are you looking to do with the scope?" In a word, further out galaxies and smaller/fainter objects such as planetary nebulae. I'm located on the mid-Atlantic coast in the U.S. with Bortle 4 skies, and maybe 10 ish days a month clear ideal skies for imaging. I realize my seeing will limit me some, but these are some of the options I'm considering (if there are others I should consider, by all means please do mention them): -AG Optical iDK 14.5" -Planewave 12.5" CDK -Celestron Edge 14 The main thing is, imaging time is limited in my location due to sketchy weather (but i'm trying to make the most of it), so I was shooting for the best f stop/focal length balance for the buck. I liked that the AGO iDK had a great balance of f/6.7 but still with great focal length, but didn't know how much 1/3 or 2/3 f stop would really make a difference with that aperture for DSO's and Galaxies compared to F/7.7 or F/8 with the planewave or C14 Edge. All 3 seem to have very good optics. Any insights anyone has on these larger scopes (or others in that price range I may not have considered) are welcomed and hugely appreciated, I just want to try to make the right choice and do my homework prior to spending that kind of $$$ Thank you everyone, and clear skies to all! |
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Hi DJ, I have used larger Celestron scopes for years, my current large instrument being the EdgeHD 11". For my location in New Mexico, conditions are just right for my needs, and the 11" gives me very satisfying results. I shoot at full resolution (f/10). While the scope is Hyperstar-capable, I've not used it (not yet, at least). Like you, I image galaxies, nebulae, etc., currently with an older QSI CCD camera and Optolong filters. For wide-field imaging, I also use an 80mm Stellarvue APO refractor with a ZWO ASI183MC-Pro CMOS camera; this is mounted on the Celestron. If your conditions will support the larger scopes, your choices are excellent. Hope this review helps. - - Steve  |
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| I'd ask myself what's my typical seeing and how clear night have in the average month. If you are anything like me (not many clear nights and not great seeing but on average < 3" fwhm) you would prioritize speed above else so my choice would be a light bucket kind of scope, e.g., a 14" f/4 newtonian. |
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| Since your imaging time is limited, you could get a CDK14 with a reducer. It is somewhat of a light bucket at f/4.8, and the 1700mm focal length still gives you enough of a deep field for smaller galaxies and nebulae. And when you want to go deeper, you can go native without the reducer at 2563mm and f/7.2 and bin2x2 depending on your seeing (which should give you equivalent SNR of f/5.1 or so). |
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DJ Van Bourgondien: Hi DJ - I run an Edge 14 in my B8 backyard (no pod, but a permanent pier and a *huge* custom telegizmo cover!) and, although I have the 0.7 Celestron reducer (didn't like the reducer), I run it at the native 3910 mm (using *ON* axis guiding) - I also have a Hyperstar that I've never even opened and may never use now - I love the F11 3910 mm ! It offers great targets all year round. I use a ladder and I can uncover and/or recover the entire assembly in minutes (However, I do add and remove the metallic dew shield each time). I'm sure that the cover will eventually break down a bit but I've already got a back up cover on order. I like that the Edge 14 is a reasonably "sealed" unit (I also have an Optec secondary focuser but haven't installed it yet; that would required a more customized scope cap - I may just cut down another metallic dew shield and permanently afix it) I see that you have an iOptron CEM70; I have the 120 but the 70 could handle the load in any case. I'm completely satisfied with this set up (at least until the day that I consider a larger remote unit!) Please message me if you have any questions; Pete |
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| Those are all great scopes. I have been thinking about something like this too. The one question that keeps bugging me are seeing conditions. Mine often hover around 3" so I am concerned about how this would affect imaging at or above 2000mm. The other scope I have considered is a 12" newtonian which would for sure work great most of the time and offer much faster imaging. ONTC and TS seem to make well regarded versions. |
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| I know it still shows on the website (all of the iDKs do), but I don't think the AGO 14.5 iDK is available anymore. Pretty sure Dave Tandy has gotten out of the scope business. Pretty sure my 14.5 iDK delivered last year was from the very last production run. It is a shame since it is a great scope and one I would have highly recommended out of your list. So, might want to up your price by just a hair and go for the CDK 14? |
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I am just south of you in central Florida and I also have spotty seeing conditions and limited clear nights. I am in Bortle 7 (was Bortle 6 up to two years ago) skies where you have a major advantage at Bortle 4. I built my home observatory on the top of my 4-car garage. https://astrob.in/tag3ti/0/ I image faint and small planetary nebulae, large emission nebulae, some galaxies, etc. To cover all bases, I have a C11" EdgeHD and a small refractor (Tak FSQ-85 EDX) piggybacked on top of it. With these two scopes, the options to image almost anything is limitless. Exceptions are objects like dark nebulae but you will be fine at Bortle 4. And don't let so-called rated below seeing conditions influence your thinking that you cannot capture very faint nebulae. I do it all the time with my C11 @ f/10. [i] [/i] |
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Hi DJ - I run an Edge 14 in my B8 backyard (no pod, but a permanent pier and a *huge* custom telegizmo cover!) and, although I have the 0.7 Celestron reducer (didn't like the reducer), I run it at the native 3910 mm (using *ON* axis guiding) - I also have a Hyperstar that I've never even opened and may never use now - I love the F11 3910 mm ! It offers great targets all year round. Hey Pete! That is pretty awesome that you are running native F11 in Bortle 8! How are your exposure times? The 14" scope is one heck of a light bucket for aperture, are you still able to capture the fainter galaxies without really excessive amounts of data? I've always been leary of going F/10 or F/11 in this case with the C14 on galaxies or higher magnitude objects and always worried you'd have to spend several nights just trying to resolve a decent amount of detail for galaxies. If that resolves fairly well at 3910 mm, that would be epic! |
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Jeffery Richards: Hi Jeffery, that is definitely sad if they are getting out of the business. From all that I could see it looked like they made a really great product. The CDK 14 is definitely an option. I think at this point its coming down to the CDK 14 or the C14 Edge (seems a really good price at half the cost of the CDK14, but not sure how the optics compare between the two). Its really hard looking online to compare photos from the C14 Edge vs CDK14 just because there are so many variables between processing styles. I feel like I've gone blind trying to compare the 2 scopes with same objects/equipment. I've been super curious if anyone has any experience with both. It also throws me some because I've seen some C14 Edge owners that are considering a move to the CDK14, and wonder if the optics and system really are that much better with the Planewave over the Celestron. I don't have alot of experience with the Newtonian scopes but it does seem tempting with the much "faster optics" and lower f/stop. |
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Bruce Donzanti: Thanks Bruce! You guys are restoring my faith in imaging at native focal lengths! I don't know why I've been so fearsome of it, i think just hearing stories of how long it takes to get quality detail on faint objects. Its really great to hear the success stories from you all at native F/L! |
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Adding another opinion from the peanut gallery. As an owner of a Celestron EdgeHD 11 (which should be exemplar of the C14) and a PlaneWave CDK14, the two scopes are not in the same ballpark: 1. The focusing mechanism for the CDK14 just works. With the EdgeHD, you need to figure out how to lock the mirrors otherwise mirror flop is just a non-starter particularly at f/10. I use the Optec SMFS, which is really nice, but it does add a bunch of complexity and cabling to the front of the telescope. 2. Thermal management solutions are weak at best with the EdgeHD. There are no cooling fans unlike the CDK14. And the large corrector plate at the front of the scope is a dew magnet. I use the heater ring and a dew shield. The CDK14 is an “open” design and has fans and heaters built in out the box. 3. f/10 is slow, the reducer at f/7 is janky. The CDK14 clocks in at f/7.2 native which is technically 2x faster than the f/10 (actually f/11?) C14 native. 4. The spot sizes are also different, with the CDK14 offering much tighter spot sizes than the EdgeHD both on axis and off axis. I hope that is helpful. |
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| To Ani comments I'll add that the guys that designed the Edge optics for the Celestron scopes are the same guys that started Planewave. Before Planewave existed, those guys designed a CDK for Celestron of I believe 20" or 24" size. Not sure how many (if any) Celestron sold of those scopes but you get the idea. This was occurring right around the time Celestron was bought by Synta. |
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I have an AG Optical FA12 (12.5", f/5, FL 1570). I got it second hand for a great price. It is a great scope with a full frame sensor. That being said, I would rule out the AG iif buying new or close to full price. AG Optical is not making them anymore, and support is very limited to Dave Tandy answering his emails. Parts are mostly whatever he has available left over. Another thing that I don't think others have mentioned is collimation. AG Optical has movable primary and secondary (in addition to a tip/tilt plate) and all of that can be challenging to get working. The Planewave has a fixed primary making life easier since all you have to do is worry about your secondary. I don't think the EdgeHD is in the same league as a Planewave though in terms of optics and mechanics. The planewave also has a reducer that can bring the focal ratio close to f/5. So between the 3 you listed, the Planewave CDK 12.5 would be my choice. |
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Ani Shastry: Thank you Ani, that is very helpful! It sounds like, although a bit pricier, the CDK 14 just works and is a little less fiddly as far as dialing it in. I don't mind some of that, that is part of the fun of this hobby, but at the same time, spending that kind of money for what is getting into a really professional setup, it would be nice to have a system that just works together. I was looking at pairing this with a Software Bisque mount with encoders, although at that point in time, if I have to use a heftier mount than the MyT, it might be the same price to go with the planewave mount as well. I did like the MyT for its integration and dome automation features though, and it would be slightly cheaper than the L-350 mount from PW. If you don't mind me asking, which mount do you use for your CDK14 Ani? |
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Ashraf AbuSara: That is very helpful Ashraf! if the quality is better with the Planewave, that might be the direction I think I should start leaning in. |
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DJ Van Bourgondien: Hi again DJ, I've been pretty satisfied (so far) with faint galaxies on the Edge 14; I usually use 300 seconds and 0 gain for RGBL and 600 seconds and 100 gain for SHO (both offset at 25) - I've collected some Stephan's Quintette and NGC 7331 data (but not yet enough for an Astrobin image); and so far it's not bad - I run a FF ASI6200 MM at Binning 2 which is a good match for the 3910mm - so in addition to aperture I've got more effective SN and well depth. Very good flats are required especially for RGBL - I have a 24" square dimmable LED panel from Home Depot - seems to work well. I used to run an Edge 11 with a OSC and could never get anywhere close to the data that I get now ( I realize that I could have done some of the same things with the Edge 11 but I always wanted the 14 anyway!) Here's an example of NGC1514 from last night (75 percent moon not too far away and of course B8)- so far only 3 hours total of RGB and L - I'm not going to post this yet until I can collect a good deal of OIII data and some more RGBL (don't know if Ha helps on this target?)  Hope this helps! Pete |
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DJ Van Bourgondien:Ani Shastry: @DJ Glad it was helpful. I initially went back and forth as well between choosing a Bisque MX Series 6, or a PlaneWave L-350 on an equatorial wedge. The delay on the MX Series 6 meant I chose the L-350 instead, and turns out that delay was serendipitous. I absolutely love the L-350. It has high precision encoders and you don’t have to deal with meridian flips. And the slews are mind-numbingly fast, faster than any mount I have seen. The software also just works with the L-350. Tracking/Guiding performance is phenomenal; I can easily do 300s subs unguided, 600s unguided subs are usually just fine. I do bump guiding with PhD2 and can typically get sub 0.4” guiding when the seeing is reasonable. One downside is that the space occupied by the L-350 on an EQ wedge is more than what the MyT or MX would. Another downside is that while there is tons of space for through-mount cabling, it is bare bones: you supply the cables unlike having a couple of XT60 and USB ports with the MX/MyT Series 6. But something like a Pegasus UPB works really well here. Oh, and you can add a smaller refractor for a wider FOV on the other side of the fork arm with the L-350. This would be somewhat non-trivial with the MX. All else being equal, if I had to pick between an MX/MyT and an L-350 in the future, I would go with the L-350 again. Happy to answer any other questions you may have. Ani |
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I've imaged for years with a C14 Edge system and more recently with a Planewave CDK20 and an Astro-Physics GTX130. Here's my two cents. 1) If you want the best possible images, stay away from reducers. In theory, a reducer can be designed to provide good performance but in practice, only a few work well; most don't. If you want a bigger field of view, get a bigger sensor. You'll struggle less and get better results. 2) Celestron actually makes some very good optics. I've posted PhaseCam data for my former Edge 14 and for my CDK20 on my image page and frankly, the Celestron optics are better than the Planewave optics. The problem with Celestron is that they occasionally make some poor optics as well and since they don't supply any test data, it's hard to tell what you might get. Unfortunately Planewave occasionally suffers from the same problems; although they have recently invested in a Phasecam, which I believe will eventually help to raise their quality level over time. The good news is that both companies work very hard to supply high quality optics. 3) In terms of price vs performance, the Edge 14 is the highest value telescope available but it does have some limitations that need to be addressed. First, the focusing system is mechanically poor. The best way to handle that issue is to lock the primary and to equip the scope with an Optec secondary mirror focusing system (SMFS). By locking the position of the primary, you eliminate "mirror flop" and the SMFS provides virtually backlash free precision focusing with zero hysteresis. The closed tube of the SCT scopes can generate "baffle plume" turbulence but in my experience adding Tempest fans are cheap and completely eliminate that problem. I mounted my Edge 14 on a AP1600 and I achieved down to 1" FWHM when the conditions would allow it. 4) Total exposure time is determined by the focal ratio of the system AND the size of the pixels that you use. If you pick your sensor size to critically sample the image, you will optimize image "sharpness" (for small DSOs like galaxies) AND for a given aperture the focal ratio will not matter. That right...I am saying that you will achieve roughly the same signal level at F/10 as you will with a Hyperstar at F/1.9 for a given exposure time. In that case, you will need a camera with VERY small pixels at F/1.9 to achieve critical sampling and that's why the signals will be equal. The main advantage of a faster focal ratio is a wider field of view. It won't help to battle sky fog or to shorten your exposure time (unless you don't want to be critically sampled.) Planewave and AG Optical scopes have better mechanics than Celestron but Celestrons can perform extremely well and given your limited budget, my advice would be to save on the OTA and put more money into a high end mount. Rowland at AP says, "There are three thing that are important for imaging: The mount, the mount, and the mount. Get the picture?" And, assuming you have decent optics, he's right. Check out my image page to see what you can do with an Edge 14. Everything on or before 2/18/21 was taken with a Celestron. I love higher end telescopes but it's hard to argue with what you can achieve with a Celestron at a much lower cost. John |
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To add to my previous comments and to emphasize two points John just made: 1- I purchased the Optec secondary mirror focusing system (SMFS) a couple of years ago. It is easily the best investment I made for my C11" EdgeHD. 2- I ditched the reducer a long time ago. Shooting @ f/10, even with a small pixel size (3.76um), can produce sharp images of very faint objects. BTW- I do have an AP mount. Add the two above with a very good mount and obtain good guiding, you will enjoy what you can capture. |
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John Hayes: You have made some excellent points here John, Thank you so much. Your C14 images are AMAZING!! Yours were actually some of the images I was looking at trying to benchmark the optics between the planewave and C14 scopes. I really appreciate all of your feedback and sharing of experience. Your 3rd point is something I definitely think I need to focus on and put more attention into. I had never really thought of the F/stops / pixel size relationships that way when talking about the light gathering power. I learn something new from you guys everyday on here! Also I was looking through the images and diagrams you did up for the CDK20. That looks like an amazing project and can't wait to see what you are able to do with it! Definitely going to take you advice on the mount upgrade. That may be phase one of this whole project before the scope/OTA. |
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Hi again DJ, I followed John's advice when I purchased my Edge 14 (On axis guiding, no Reducer, Secondary Mirror focuser etc.) ; And I'm glad that I did ! (in fact I haven't yet installed the secondary focuser ! Waiting for warmer weather! - I'm sure that I'll have further improvement then)) It can be a confusing community with so many opinions out there. RE: Celestron / Planewave - I think that we would all love a PW scope if possible but budge and set up location (and space) are critical - also , B8, Bad seeing, four distinct seasons AND a very heavy pollen season make unsealed units less desirable for me in my backyard. Pete PS - I'm also following John's new 24" Planewave project! |
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At the price Planewave has today for the CDK14 OTA ($16k) there's no way I would buy one. Prior to their two price increases, one could get the CDK14 OTA with the same mirror substrate (Fused Silica) for $12.5k, which IMO was good value. I've enjoyed using mine in New Mexico and the scope has been an excellent performer in that environment. I live in the Pacific Northwest though, so I'm not a very tough customer to please in terms of clear nights and sky quality. Both of those are terrible here at home. My chief complaint about the CDK14 is that the dew control and fan system control was designed poorly. There's ways to work around that, but I won't get too deep into that as there's a long thread folks can read about it. Just know it's something you'll want to research if you decide to get into the Planewave camp. I also have an AGO 12.5" iDK which uses the same mirror material, but has optics from Ostahowski which are likely better than the ones in the CDK14. That scope has a much easier fan and dew control system to operate, but Dave is no longer making scopes, which means the control boxes will become impossible to find, very similar to what happened to RCOS. Try finding a control box for one of those and you'll see how bad it can get. Hopefully we'll see some community driven replacements, but that's a major thing to consider. In terms of support overall from AGO going away - it's not really a huge loss as Dave quite frankly wasn't the most responsive person in my and others experiences. The control boxes though, that's the big loss over time. Collimation of either of these telescopes is very easy with SkyWave, which I strongly recommend to everyone serious about imaging with these types of scopes. It's the best thing that ever happened to amateurs in terms of mirror collimation tooling. I can't speak to the C14, but John responded here and he's the most knowledgeable about those systems. Bill |
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RE: Celestron / Planewave - I think that we would all love a PW scope if possible but budge and set up location (and space) are critical - also , B8, Bad seeing, four distinct seasons AND a very heavy pollen season make unsealed units less desirable for me in my backyard. Pete you nailed it with that statement there. I'm on the eastern shore of Maryland, and between the humidity, 4 seasons, pollen and CLOUDS ALL THE TIME, I feel your pain 110%. I'm glad we at least have decent skies out here at Bortle 4, but man its tough to come by good imaging nights! I'm with you in that I really want the planewave setup, but given the budget, number of other house projects we need to afford moving in to this place just last year, and accessories, the Edge is really starting to stand out from a budget perspective, and leaves money on the table towards a superior mount and then towards dome / automation stuff later on. I'll probably be joining you guys in the ONAG / secondary mirror camp when it comes to the purchase of the scope. All of you guys are awesome in this community and I really thank you and everyone else who is responding, plus I'm learning alot from you all in the process! Yeah I think we are all going to be partially living vicariously through John with that Chile project! =) |
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DJ Van Bourgondien:RE: Celestron / Planewave - I think that we would all love a PW scope if possible but budge and set up location (and space) are critical - also , B8, Bad seeing, four distinct seasons AND a very heavy pollen season make unsealed units less desirable for me in my backyard. The C14 Edge system will cost you much less than a fully kitted out CDK14. I would put that saved money toward an AP1100 non encoder mount. You can always add the encoders later if you decide you want them. It's a great mount. Observatory class, and also extremely portable if you decide to take the scope on a trip. |
