The Takahashi Mewlon 250 Dall-Kirkham Revisited
Submitted: Wednesday, 1st April 2009 by James Edwards
I wanted to write another article about the Mewlon 250, as I have enjoyed this scope through various evenings out, at a number of different viewing locations and using it to view on so many different objects that this is one of the only telescope types I had wanted to get back to a second time, it is just an incredible instrument!
When my second Mewlon arrived, I was smiling like a school kid after receiving his first bicycle as I thought to myself, “Here we go again, off to a distant galaxy”! Not only is this an extremely well made telescope, but it oozes a sleek and well groomed finish, superbly made optics and overall this is an easy to use, take with you anywhere scope and 1 of the only 10” telescopes which can compete with larger aperture scopes. In all fairness, I would rank this 10” right next to what I would consider 1 of the finest 10” scopes ever made, the Astrophysics 10” Maskotov so why doesn’t the 250 get as much or more notoriety???
The answer is easy, you can still order a Mewlon 250, buy 1 used and now you have 2 versions to pick from. The standard M250 with the original “hockey puck” mounting adapter or Takahashi’s newer version (based on my prototype pictured), the “250 S” or “Special” which comes with attached mounting rings and is so apply named.
Technical schematics and Dimensions
With the OTA at 250mm you would swear the looks and feel of this scope give you the impression of its larger silhouette being a big optical assembly, but overall at 850mm it’s still a 10” cassegrain just longer then a SCT. What I like the most about this scope can only truly be explained by taking it out and viewing through it. That isn’t to say that the fit and finish aren’t exquisite with its cream and green color scheme, along with a fantastic adjustable illuminated 7x50 finder scope with its 6.3 degree field of view (my 5 out of 5 rating).
One word of caution, make sure after each use you either remove the illuminator entirely or make sure it is completely turned off. On a few occasions I failed to flick the adjustable knob to the ”off” position and wound up not taking advantage of the illuminated cross hair image from the finder my next time out being without an extra battery * it still functions, but the cross hairs make it better *. One of the best features of the Mewlon 250 is its electronic focuser, although I have never been a big fan of the male plug Tak uses, once you have it attached it is extremely smooth and also allows you to keep your hands off the OTA to focus. I guess for no better way to explain it, there are better options with electronic plug-in’s these days but it is still solid once you have it lined up with its “dot & arrow” and plug it in.
After you get the hang of this hand held focusing unit, you will see how the 250’s focus snaps into place, Zip Zero Mirror Flop, which is very cool! As I didn’t go with the added cassegrain focuser my second time using the 250, I do however make adding 1 a big boost in your overall focusing needs, that being when you need that an extra “tweak” on those hard to see objects or for planetary viewing which is always a bear but gives you an advantage when coupled with the Electronic Focuser. I truly like the Takahashi cassegrain focuser for this need, with it’s built in camera angle adjuster and remarkable quality as you find a noticeable difference. As you use the electronic focuser as your “course” focus to start off, the second option makes perfect sense. The down-side is the cost especially when adding a Takahashi 10: 1 micro-focuser and at another $189.00 brings this version to whopping $700.00 (WOW). For the sake of argument, you can have Feather Touch Instruments make you a “crayford type” or Moonlight focuser manufactures a cassegrain version for Mewlons if that is your preference. ($375 list).
The last 2 items other then a very good assortment of eyepieces ( which I will address later on in this article ), is your need for a good Diagonal ( I’m not talking about a Williams optics, Meade or Celestron type, more like a Tak, TeleVue or AP) . Lastly my favorite item, the Takahashi 1.6x extender. Before you scratch your head and squint your eyes as to why I would mention this accessory, without fail I have used 1 extensively on all 3 Mewlons I’ve owned (see my mini article on the Mewlon 210, I LOVE that SCOPE!!!) and what I found when using this attachment are 3 great elements that add quite a bit to your overall viewing with this scope.
A couple of other technical portions I want to address are limiting magnitude, secondary obstruction and your choice of eyepieces and a mount. To those that image, my dear friends I’m sorry but I am not an advocate of using CCD camera’s having witnessed many objects throughout the sky and in all fairness I can say the majority of images you search and view far surpass imaging. As I am strictly a visual user, every object I have encountered using the Mewlon 250 more then hold a candle to what CCD images are processed to look like, they actually have a “life-like” quality not mixed with a Kaleidoscope of colors. Don’t get my wrong; I will gladly take any color I can gain from viewing!
To further explain, when you own a telescope at the level of a Mewlon, unless you can get into the higher reaches of camera types vs. using a great cross section of eyepieces, the later will enable you to capture visual images at scale, give you more detail to black mater not processed and stacked with the loss of depth. Before you imaging fanatics start bashing my article, I do appreciate amateurs who spend their time capturing images, many of which are very good friends, in fact some of the very best imagers in the game are some I admire not only for their ability but taking that process to another level. (Richard Crisp and Michael Downing to name just 2).
As Takahashi list “limiting” magnitude at 13.8, with exceptional skies and the increase to your elevation the 250 will increase that figure by 2 to 3 points easily. I’ve found when the transparency is at its optimum your can press the 250 at higher magnifications and extended your reach. The point of obstruction to me has never been of noticeable concern or a problem, my comment is simple, It isn’t IMPORTANT!
Lastly as with my comment regarding your choice of Diagonals, which is equally as important, Your eyepiece collection and some necessary filtering are essential or you won’t gain the advantages of the 250 let alone enjoy its superior optical performance. Anymore the market is flooded with a number of manufacturers offering various eyepieces. To me it’s as plain as the nose on your face, BUY Quality vs. Quantity! I’d rather have 4 excellent pieces of glass at my disposal rather then an entire array of “cheapies” in order to justify owning an entire collection. High, Mid-range and Low power eyepieces should do the trick. Takahashi’s and TeleVue for Higher Power ( Le’s, Radians and Naglers), the 4000 series Meade’s ( 8.8mm and the 14.5mm especially, not the Flimsy new 5000’s ) and some great TeleVue Panoptic or Naglers as your Mid-range pieces with your Low end pieces starting at a 35mm Panoptic or the 41 Panoptic as a MUST then onto your Low range, finishing off with a 55mm TV plossl or the exceptional 50 TAK LE or what I like the best is the Meade 56 mm Plossl together with a solid OIII, UHC and a variable polarizing filter, that should pretty much round out the field! (2” filters!!! Attach them to the barrel of your diagonal and call it a day)
To wind up this section, the only other aspect to mention is a solid EQ mount. I have used 4 different versions of a German Equatorial mount for the Mewlon 250, a Fantastic Takahashi EM200 Temma 700x go-to ( My first choice, it seems to be made for this scope), a Losmandy GM8 non-go-to ( it worked alright, but kind of felt flimsy) and my last 2 Losmandy G11’s, the Gemini and a non-go-to version. I truly liked the G11’s not only for its stability when using the 250 (the OTA w/ Diagonal and eyepieces round out at roughly 31 lbs.) but it’s a solid performer, actually more mount then needed, but a super well built unit and a great FIT for this scope!
Location, Location, Location
Before you decide on owning a Mewlon, carefully consider your immediate viewing conditions, where you plan on using it the most and where you can take it to gain that extra advantage when you’re able to. I happen to live in a heavy light polluted area, but I am only a hop-skip-n-jump to surrounding areas where the overall conditions bring the most out of this scope.
Although I’m only 30 ft. above sea level when the conditions allow, choosing the Mewlon is a no-brainer, its a great scope to get out and enjoy as I’ve never been disappointed using it, light pollution or not. Those few outings I had the fortune of using the 250 at higher elevations over 5000 ft., not only did the 250 reach its technical capabilities but far exceeded what I had thought it was capable of.
Going back to my yearly trip to Southern Oregon (4100 ft.), I gained more appreciation for this scope then I ever dreamed possible. (The seeing transparency was OFF the scale!) Whether I was viewing a Faint Object, Galaxies, Open Clusters, Nebula, Planets or the Milky Way, or whatever eyepiece I used the 250 ONLY got better! I also like the fact that if conditions go to the opposite end of the scale, dew or colder weather doesn't seem to affect the 250’s optical performance and you don’t need a dew shield or heater! I also like the front opening, as opposed to a front objective as with the SCT’s.
The other up-side with Cool down is the ability to remove the back cover of the 250, which when the weather is hot during those summer months, your cool-down time is quite a bit faster. You can use the 250 without replacing the cover, once you Re-attach your 2” visual back and insert your Diagonal, your pretty much set! Realistically if you plan on year around viewing, you’re sure to gain a greater perspective about this scope rather then spring or summer viewing, you truly don’t want to miss just how special this scope truly is.
To me as I have mentioned countless times before, it really doesn’t matter what scope type you prefer, or the size, make or model, or if your game is imaging vs. visual use it really starts and finishes with going outside to view, which is where the Mewlon 250 belongs, scanning the heavens for all she’s Worth!
I can say in all honesty and fairness, this is a fantastic scope to aspire to, or one in which you can use throughout many years in this Hobby, I highly recommend it to anyone looking for a great piece of equipment, The Mewlon 250 without a doubt is a 10” MEGA SCOPE!