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Mewlon 300

Posted by Mark Keitel   05/27/2004 12:00AM

Mewlon 300
[ARTICLEIMGL="1"]This is the first article that I have ever written. I have been an amateur Astronomer (and I mean amateur) for 20 years. My first scope was a Bushnell Sky chief that I purchased for $150 in 1982. At the time $150 was all the money in the world to me and a stretch for my new wife and myself. I quickly got frustrated with it since the planets and the moon were really all that I could see and they were not that breathtaking through the scope. After years of trading and saving I bought my first big scope. A Meade 8”LX50. I was in heaven, at least for another few years. Then I started buying scopes and comparing them to one another and keeping the ones that I liked and getting rid of the ones that I did not (not to mention all the mounts that went with them). I finally found the Takahashi Mewlon line and tried the Mewlon 210. I was not thrilled with it due to mirror flop that I really did not like, so against better judgment I bought the Mewlon 250, and life was good once again. The primary mirror in the Mewlon 250 and Mewlon 300 are stationary, the secondary mirror moves in order to bring the scope into focus. I loved the scope and finally started going to some Star Parties here in Florida. After talking with a friend and the folks at Texas Nautical I learned how great the Mewlon 300 was. I thought about it and felt that the price was too much and then would need another mount. I kept thinking about the scope and then one day a friend informed me of his quest to upgrade his scope and that he was thinking about a Mewlon 300.

After I told him about the mount he would need and the price of the scope he said he was unaware but would try to look for one anyway. He placed an ad on Astromart looking for a Mewlon 300 (a great place to be aware of). Within a few hours of placing the want ad he had a response. After talking with the individual he agreed with me that this would be too expensive. Fortunately I had a mount that would hold the Mewlon 300 and called the respondent to my friends’ ad and found out that I actually knew the person that was selling the scope. This Mewlon 300 had been out of the box once and then never used again. I made the deal and actually the person had his friend drive the scope down to me from the upper Midwest and we met him at my home one evening.

Physical Description

My wife and I met them in the drive way and they unloaded the scope in the box to my living room. When we opened the box my wife looked at the scope and her immediate words were; “ Now I know why the scope is twice the price of the Mewlon 250”

I paid the man and off they went. Taking the scope out of the box was a two-person job. The finder had the same aperture as my first scope. The scope was magnificent and I could not wait to set it up on the mount.

Effective Aperture 300mm
Effective Focal Length 3572mm/2739mm reducer
Focal Ratio F/11.9- F/9.1 with reducer
Resolution 0.40”
Limiting Magnitude 14.2
Light Grasp 1837x
Image Circle 25mm / 42mm with reducer
Photographic Field 45’ with reducer
Total Length of Main tube 1094mm
Diameter of Main Tube 324mm
Primary Mirror 310 f/3
Secondary Mirror 95mm /x4
Secondary Obstruction 29%
Finder Scope 11 x 70mm 4.2 fov
Gross wt. Main tube 57.2 lbs

The specs say weight at 57lbs, for the tube only once you add the rings, I have the heavy-duty top plate on it so that I can mount another scope on top. The double finder bracket, 11 x 70mm finder, I am using an AP 900gto mount so I have an adaptor plate on the bottom and the Losmandy plate on it (this might be best, I have two weights I think they are 3.5lbs each, for the tube. Since the M300 is so back heavy, if you can not slide the tube up on the mount you will definitely need this extra weight to balance the tube correctly). I do not have to use this extra 7 lbs though. So this weighs in at about 74lbs. Not the 57lbs that I was thinking before I got the M300. I was not taking into consideration all the extras.

Takahashi’s Mewlon series are Dall-Kirkham design, except the Mewlon 400. What is a Dall-Kirkham you ask? Rather than going into the design here lets make it really simple and say that it is similar in design as a Classis Cassigrain yet there is no front corrective plate. Making this scope an open tube, very nice for cool down. To further aid in the cooling of the mirror Takahashi designed this scope so that the back plate can be removed with ease, (just like in the Mewlon 250). This scope also has panels on the side by the mirror that are also easily removed.

With the open tube design and the back and side plates off this scope cools down very fast without the need for fans or water-cooling. And you can also view with the plates off if you wish. Though I did read somewhere that Takahashi warns you body temperature may increase air turbulence if you view with all the plates off. Though I have not found that to be true as of yet.

Since there is no front corrective plate on this scope the primary mirror being very heavy, the scope inherently is back heavy since the massive mirror in the back has most of the weight. Takahashi supplies two counterweights for this scope that attach onto a bar on the bottom of the scope. This makes balance of the scope very easy even with large oculars and extra scopes mounted as I have on my set-up. The focuser on this scope is exactly the same as the Mewlon 250 with one added feature. This scope has an electric focuser, and in my opinion works just great, though you really have to get use to it. On one side is a toggle switch for movement of the secondary, and on the other side is a toggle for fine movement and course movement.

Within one night of observing though you will be comfortable using it and love it at high power. This allows you to bring the scope up to high magnifications and you do not have to touch the scope to fine tune the focusing, no more moving the scope on the mount with your hand and since the secondary is what moves to focus, say goodbye to mirror flop too. The added feature on this scope is that you can make course adjustments to focus on the back of the scope. Takahashi placed a drawtube on the back where your ocular or diagonal go and you can move it in and out for focus. Though this is crude and you cannot get a critical focus easily. It is a great idea since a small 9volt battery governs the focus on this scope. If the battery goes so does your focus without this addition. I always keep a spare battery with me. And yes the battery went dead on me in May at about 2am at a star party. I had a spare and popped it in. I was lucky enough that I went into town the next day and bought my replacement, because as luck would have it two nights later the battery died again. I bought a bum battery and I replaced it and it is still going strong now in September.

My original mounting plate was Losmandy universal plate. I found it inadequate for the load that I will be having on the mount. I searched and then re-searched for a plate that would meet these needs. I found one and ordered the Mueller Plate. Excellent plate and gives me the gripping strength needed for this set-up

First Light

I am in Florida where humidity gets to be about 96% at night. Sunday night at 3am it was reading 99% humidity and the scope had no dew on it. The oculars again were a different story.

WOW what a scope

I have only had it out three nights now since it is so new and the skies have not cooperated all the time.I keep the scope on my back porch and when I took it out and set it up I tried to look at Jupiter right away. Within about 30 min. the air looked like it was boiling. What currents. I took the back of the scope off and the side plates. Went inside to have dinner and waited for the sky to really get dark. After an hour, the tube currents were non-existent. I placed the side caps back on the scope but left the back off for the rest of the night.

The dew was so bad that when I came back out the finder was 100% fogged up. I forgot to hook up the Kendrick system. When I did, it was clear within 30 min. The scope however needed nothing all night. At about midnight when viewing at Zenith the scope was dripping onto me yet there was no dew on the optics.
I noticed clusters that I had never seen before with my M250 and Jupiter took on a whole NEW look.

Using a Nagler 31mm for my wide field viewing giving me a .7-degree field at 115x. I tried a 50mm Tak that was also the same field at 71x. I just got hold of a 40mm Meade Super Wide that will give me an .8-degree field of view and at 89x. A nice ocular was the 14mm Meade Ultra Wide giving me a .3-degree field at 255x. I used the 20mm Nagler with a .5 degree field and 178x. I used a Tak 30mm giving me a .4degree field and 119x (used the 31nagles more). I did not have time to try out all my other oculars but will over the next several weeksI was looking at M38 and decided to slew around slightly to see what was there. OH another star cluster. But it was bright and on the large side. Defiantly NOT an M object. Since I did not have my star charts out I took a mental note of it and went on. Looking at my chart the next morning it was NGC1907. But on the chart is so small. What can I say this scope just brings everything in closer.

I have to say that I was never impressed with the planets. BUT now I am becoming more and more. I put my Zeiss binoviewer with a pair of 19mm Panoptic and an AP Barlow on. 451X and the views were spectacular. Never saw one of the bands being a blue in color before. We
were able to see a several spots in the bands. My wife and I looked at Jupiter for 2 hours that night.

The next morning over breakfast when I took some books out and we looked at the pictures taken by the Hubbell and Explorer of Jupiter my wife's comment. " We saw that" " it looked almost like that" "lets look again tonight".

I will be observing much more at the WSP, having a good week in and then be able to really put the scope through its paces.


I took the 11x 70mm finder off the scope and put a Takahashi FC-60c on in its place. Even though the aperture is smaller it gives me more versatility than the 70mm finder. I put the focal reducer on the scope and a 2” adaptor and then the Takahashi 50mm ocular giving me about a 5.2 FOV at about 8x. The Mewlon300 has a top plate that you can mount things onto; I put a Takahashi FSW 106 on top. I had Parallax make me rings for the scope with ¼” nylon screws instead of the delrim tipped ones. The nylon ones held fantastically without a mark on the scope. The reason that I mounted the FSQ on top of the scope was for wide field viewing that the Mewlon 300 lacks, even with the Nagler 31 in place. Just a side note, I used the FSQ at the WSP and then changed the scope out for an AP 155 on top. After a few months of viewing I then decided that the AP scope was not getting enough use since I only used it for wide field viewing. I got rid of it and went back to the FSQ 106.

Second longer test:

I took the scope and mount, and all my other goodies down to the Winter Star Party 2002. My friend and I met and set-up next to one another (He is sporting a C-14). He was set-up in a Kendrick tent and I was set up next to that and had a nice cover for the set-up. The first night was spectacular seeing. Jupiter and Saturn were both placed perfectly and the sky was clear and dark. I set-up the binoviwer with the AP Bacron Barlow with extension, and a pair of 19mm Panoptic oculars. This brought the mag up to 602x. I had a few people early in the evening asking if they could look and I got comments like, “WOW never saw Saturn like this before it looks like a photograph”. Within about an hour I had a line of people wanting to view through the Mewlon 300. One by one they looked and walked off in amazement. At about 11 I finally cut the line off from viewing and looked myself. I turned to Jupiter where ganamyne was visible, and could actually see detail on the moon itself. At this point I wanted some confirmation of this, and got if from a few well-known people. (Names on this article will be changed to protect everyone).

Needless to say I thought that this scope was tops when I was in the backyard with my wife but now that I have hundreds of people saying the same things you no longer wonder if you are right. There was a Takahashi FCT150 about 40 yards down the beach. Though this was not a side-by-side comparison it did allow the owner of the Tak and two others a chance to view Saturn through both scopes. We brought both scopes up to 400x and decided that the Mewlon gave better contrasts and more detail than the Tak FCT150 did on Saturn and Jupiter. We did not compare any Deep sky objects since it was agreed by all of us that with the extra aperture of the Mewlon 300 the FCT 150 would not be able to hold up. The owner of the Tak 150 even concluded that his scope was no match for the M300.

There were numerous high-end scopes on the beach and I was lucky enough to have a TMB 9” refractor only a few feet away from mine. The views were nice but the first views of surface detail on ganamyne were noticed through the Mewlon 300. When you walked back to the TMB 9” you were able to make out what you were looking for. Both scopes were at about 600x and the Mewlon was able to capture more detail than the 9” APO. On deep sky objects the TMB could not gather as much light as the large 12” Mewlon against the 9 ” APO. Both gave jet-black backgrounds but the light gathering capabilities of the extra aperture was just too much for the 9” scope.

There was a line of people that viewed through the Mewlon 300 the first night. I lost count after 200 of them viewed Jupiter and Saturn. When viewing Saturn through the Mewlon 300 at 600x it looks as if you can drive a Mack truck through the Cassini Division. The next morning I was amazed that everyone complimented my scope, saying that the views were the best at the WSP. When I asked them to clarify, they all made reference to viewing through the Takahashi FCT150, TMB 9”, AP 178, AP 155, and StarMasters up to 24” and the list went on. Personally I had the AP 155 on tope of the Mewlon for over six months and sold the AP 155 since I opted for the views in the Mewlon 300 every time. The Mewlon 300 gave better views of the Planets and deep Sky objects.

The Mewlon 300 gave better views of the Planets and deep Sky objects. I can say that there was a 36” Dob there that did give better views than the Mewlon 300 that was my opinion though I heard different from others.

My favorite of all the Deep Sky objects are Globular Clusters. There is just something about viewing them and being able to see individual stars at the core of them. Well finally with the Mewlon 300 I am able to. At about 1am we started to view M13 with the 31mm Nagler. We decided to go to the 20mm Nagler and see what happened. At 178x the center stars were resolved nicely and had a few people coming over to view this. We decided to bring the power up to 255x by using a Meade 14mm Ultra Wide. This brought the object in closer but did not give us any more resolving power on the object. It was nice to view M13 at such a magnification but it was not necessary to resolve the core with. We also did this exercise on M3 and found the same to be true.

Over the months after the WSP I have viewed numerous Globular Clusters and have found that with the Mewlon 300 178x is perfect for them. The fainter ones are nice at 255x bringing them closer and bigger for the thrill of seeing. In fact just the other night viewing M15, M92, M7, M13 all brought me the same conclusion, that at 178x you can actually resolve the core and at 255x the fainter one got bigger but with my eyes there was no difference in the resolving power of the Mewlon 300. The same night I brought M31 into view with the 31 Nagler and the 20mm Nagler and my wife kept asking me what is that. Looks familiar but I cannot place it. When I told her what it was she could not believe me since she remembered the view through the Mewlon 250 and this was so much more defined she said and much larger.


I cannot ever see selling this scope unless maybe one day I win the lotto and buy the Mewlon400. Not only does the Mewlon 300 give you refractor like images of the Planets, on Deep sky objects, its aperture is far superior to the refractors too. I had a few people come up to me at another Star Party and after looking through the Mewlon 300 at M13 they commented that it gave a better view than their 18”, 22” and 24” dobs. The reason they said the background was jet black making the object stand out better, and that the stars in the cluster were pin point just like in a refractor. What more can one want from a scope?

Click here for more on the Mewlon 300. -Ed.