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Am I nuts to think of Mewlon 180 when I already have a 4” Tak APO (and a bigger SCT)?

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#1 Axunator

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Posted 12 April 2019 - 07:38 AM

Would they be too close in performance? Competing against instead of complementing each other?

I really like my FC100DF. Glorious wide fields under dark skies, performs above its size on DSOs at medium powers,
so sharp at silly high magnifications that it must be illegal in EU, post-Brexit Britain and all 50 states of US of A.

Hyperbole aside, it has only four inches of aperture and, contrary to some old wives tales about Taks and some other brands making highly regarded refractors, obeys the laws of physics.

Small aperture translates to small exit pupils when one uses magnifications usually employed while looking at Moon and planets. And that’s about the only thing to look at from my downtown backyard (well, even planets are missing from the menu for some time at 60 degrees north), save for occasional double star hunts.

I happen to have quite a bit of floaters, so small exit pupils on extended objects can be rather annoying. Luckily, my dominant right eye is better in that regard. Not so luckily, retinal and vitreous detachment on my left eye about 6 months ago (now succesfully treated to stabilize the situation) made it poor enough for binoviewing not to be a realistically viable option to improve the views.

All of which have made me consider Mewlon 180 for my backyard scope. Even if it wouldn’t be awesomely, significantly superior to FC100DF, it would have 1.8x larger exit pupil at a given magnification, aiding in ignoring the floaters while studying our closest celestial neighbours.

And it does not have to be clearly superior as a DSO scope; I’ll anyway take the my larger SCT (along with the APO for wide fields) when I drive to a dark sky site.

If I break down my internal argumentation about the whole idea, it would go like this:

Pros

- 1.8x the exit pupil, means less floaters and brighter image at a given magnification
- Compact and light - almost g&g for my purposes, and would ride well on my RA-driven, non-goto EQ5-class mount on Berlebach UNI, for super-simple tracked viewing experience. And compactness is also important as the real estate in our small downtown apartment is in short supply
- Fast cooldown - important for shortish sessions on weeknights
- Large enough to be seeing-limited 80-90% of the time, especially within the city

Possible cons/reasons for hesitation?

- Still too close to the 4-inch APO to be a meaningful improvement for the intended purpose?
- Still too slow to cool down (cannot store outside; temp deltas in/outside can easily be 30-40C)

Just for the record: as much as I’d love the idea of an even larger Mewlon, for this specific purpose - narrow-field, high-mag viewing at our current residence - they just won’t cut it. Way too big, especially with the required mount. I hardly ever set up my C9.25 at home, because it is not worth the hassle. M210 would be even larger. So swapping the SCT to 210 or - praise the lord! - 250, wouldn’t solve the current problem at hand, however amusing and tempting the idea might otherwise be. And I’m currently quite content on my C9.25 as a DSO scope, and it complements the 4” Tak very nicely on that role.

Having said all this, if someone has directly compared M180 to a quality 4” APO and found the difference to be *meh...*, I’d like to hear about it. The 4” Tak doublet is no slouch, cools rapidly, and is very fast to setup on the mentioned mount. I could easily abandon the idea of the Baby-Mew and spend the money on something more useful.

And no, there’s no chance that I can think of getting a look through a Mew 180 - short of buying one myself. Rare as hen’s teeth up here.

Sorry for the long post, killing time in a hotel room..
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#2 Spikey131

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Posted 12 April 2019 - 07:57 AM

The Mewlon is not going to replace the 4” refractor.  FL too long, long cool down etc.

 

So I’m not sure what it would do for you that the combination of the refractor and the C9.25 isn’t doing.

 

It might give better views of the planets, but Finland in the coming years is not the place for planetary observing.  You would be better off spending the money for an astronomy vacation to New Mexico.


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#3 Axunator

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Posted 12 April 2019 - 08:21 AM

The Mewlon is not going to replace the 4” refractor. FL too long, long cool down etc.

So I’m not sure what it would do for you that the combination of the refractor and the C9.25 isn’t doing.

It might give better views of the planets, but Finland in the coming years is not the place for planetary observing. You would be better off spending the money for an astronomy vacation to New Mexico.

Not to replace the APO - the Mew would serve as a bit brighter lunar/planetary scope (OK, only lunar for the next few years, but I’m not a compulsive swapper of scopes once I find a keeper) at home.

C9.25 with required mounting is no home backyard scope for me. It’s an apartment backyard (non-private) in the middle of Helsinki, and requires multiple trips to set up and tear down.

I hate shaky mounts, so EQ6 class is minimum for C9.25 for me - couldn’t stand the vibes when I had it on HEQ5, and even HEQ5 is a handful for shorter sessions. Baby Mew is much, much more compact than a C9.25 (I have seen one, even though have never looked through one - and it’s much lighter than C9), and I’m confident my EQ5/UNI would carry it with grace. And that’s a single-hand job to take outside, even with the mount head on the tripod (OTA and CWs separated, of course).

Besides, even though I do like my C9, I wouldn’t be surprised if Baby-Mew offered more pleasing lunar/planetary views, especially here under the jet stream.

Nothing against an astro vacation in New Mexico, though
;-)

Edited by Axunator, 12 April 2019 - 08:32 AM.

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#4 macdonjh

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Posted 12 April 2019 - 08:43 AM

Mewlons are great.  I've been lucky enough to observe through a M210 a few times.  I'd be hard pressed to choose between a M210 or C9.25 based solely on the image.  Even with the slight aperture advantage going to the C9.25, my friend's M210 held its own.  Since the Mewlons don't have correctors, cool down is shorter than for SCTs typically, and dew isn't as big a problem.  I think I'd opt for the M210 over the M180...

 

The Mewlon may replace your refractor...  At home I used to use a 6" f/12 achromat.  It gave wonderful views, but required my big mount and was a pain to set up.  It got to the point I wasn't using it often.  I built an 8" classical Cassegrain.  That scope also gives wonderful views.  Plus it is carried well by an HEQ-5 mount which I can leave assembled in my garage and carry in one trip (another trip for the scope, and a final trip for eye pieces and a battery).  Since I can be observing in five minutes now rather than twenty when I had to set up my big mount, I'm happy with the change from a refractor to a Cassegrain.


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#5 Richard O'Neill

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Posted 12 April 2019 - 08:43 AM

Sleep on it awhile longer.


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#6 Axunator

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Posted 12 April 2019 - 09:35 AM

Sleep on it awhile longer.


I’ve slept on it quite a while, and intend to do so still for some time ;-) And no, I’m not letting the APO go to get the Mewlon, I love those wide field views too much.. this is a completely separate decision.

#7 Cali

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Posted 12 April 2019 - 09:37 AM

Yes, you're nuts. I get by just fine with this little guy in really dark skies. 

 

That'll be a $300 diagnosis fee please.

 

- Cal


Edited by Cali, 12 April 2019 - 09:50 AM.

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#8 Axunator

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Posted 12 April 2019 - 09:55 AM

Mewlons are great. I've been lucky enough to observe through a M210 a few times. I'd be hard pressed to choose between a M210 or C9.25 based solely on the image. Even with the slight aperture advantage going to the C9.25, my friend's M210 held its own. Since the Mewlons don't have correctors, cool down is shorter than for SCTs typically, and dew isn't as big a problem. I think I'd opt for the M210 over the M180...

The Mewlon may replace your refractor... At home I used to use a 6" f/12 achromat. It gave wonderful views, but required my big mount and was a pain to set up. It got to the point I wasn't using it often. I built an 8" classical Cassegrain. That scope also gives wonderful views. Plus it is carried well by an HEQ-5 mount which I can leave assembled in my garage and carry in one trip (another trip for the scope, and a final trip for eye pieces and a battery). Since I can be observing in five minutes now rather than twenty when I had to set up my big mount, I'm happy with the change from a refractor to a Cassegrain.

I could think of swapping my C9.25 to M210, but I wouldn’t be using it at home any more I currently use my C9.25 for the very reasons stated above. Just too large. The best scope is the one you use most often, even if the bigger one offered better views.

And compared to a 6” f/12, one can hold the 4” f/7.4 doublet Tak between one’s fingers like a pencil - I can imagine how a large, long-tube frac can become a chore to setup, no matter how great the views... The compactness of Cassegrains is a major part of their attractiveness, but wide fields provided by small APOs is a major part of theirs. I cannot think of my life as an amateur astronomer completely without one anymore. Of course, it all depends on one’s interests and preferences.

Edited by Axunator, 12 April 2019 - 09:56 AM.


#9 Axunator

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Posted 12 April 2019 - 10:03 AM

Yes, you're nuts. I get by just fine with this little guy in really dark skies.

That'll be a $300 diagnosis fee please.

- Cal


In the grand scheme of things, everyone on CN is nuts and needs therapy. You can book an appointment with my secretary. I’ll deduct the $300 from your first bill.
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#10 bobhen

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Posted 12 April 2019 - 10:44 AM

The Mewlon 210 will ride fine on a Celestron AVX mount and will deliver sharper stars and more contrast on deep sky objects than the 9.25. The Mewlon 210 is also a killer lunar scope delivering etched-like views.

 

The 9.25 is an fine scope it’s just that the Mewlon 210 has better optical quality.

 

Another suggestion might be to sell the FC100 and purchase a Tak TSA 120. You’ll get a performance boost on all objects and with a 13-pounds OTA the TSA will also ride nicely on an AVX-class mount or a suitable alt/az mount.

 

You can always get an inexpensive, fast achromat like a 102mm F5 or F6 for low power, wide field viewing.

 

A Takahashi TSA 120 and a C.925 would make a very nice combination.

 

Bob


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#11 Astrojedi

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Posted 12 April 2019 - 11:10 AM

You don’t need the Mewlon if you have the C9.25. But I buy scopes I ‘want’ but not necessarily ‘need’ all the time. So I don’t consider that an obstacle if you really want the Mewlon. : )
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#12 Terra Nova

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Posted 12 April 2019 - 11:23 AM

I’d get the Mewlon 180 and sell the C9.25. You can always take the Mewlon with you when you want to use a scope at your downtown Helsinki apartment location. As you said, the C9.25 doesn’t see much use and the the best scope is the one that gets used. The M180 will be much more transportable and being an open system, will equilibriate with temperatures much more quickly. Go for it!
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#13 Dennis53121

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Posted 12 April 2019 - 01:35 PM

It's not nuts to want a Mewlon 180 when you already have a 4” Tak APO (and a bigger SCT). I typically use both of mine together when observing.

 

Dennis


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#14 Axunator

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Posted 12 April 2019 - 01:55 PM

You don’t need the Mewlon if you have the C9.25. But I buy scopes I ‘want’ but not necessarily ‘need’ all the time. So I don’t consider that an obstacle if you really want the Mewlon. : )


I like the way you think 😁 Except that small Mewlon actually would even serve a purpose the C9.25 cannot, in my case. It gets hard on the wallet to listen to you guys.
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#15 Axunator

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Posted 12 April 2019 - 02:16 PM

I’d get the Mewlon 180 and sell the C9.25. You can always take the Mewlon with you when you want to use a scope at your downtown Helsinki apartment location. As you said, the C9.25 doesn’t see much use and the the best scope is the one that gets used. The M180 will be much more transportable and being an open system, will equilibriate with temperatures much more quickly. Go for it!

Thanks for the encouragement Terra (as if I really needed that 😅).

I wouldn’t need to sell my C9.25 to finance the Mewlon, nor to free up storage space (Casses are nice that way, you can just pile them up on a closet 😉). And I probably wouldn’t, because it’s probably a better DSO scope just because of brute force provided by the extra aperture, regardless of likely better optical quality in the M180 (M210 would be a tougher contender for C9, I think, just as Bob wrote). And my SCT is not even a bad specimen.

Even if I’d use my C9 only few times a year it would be worth keeping, because I have so little capital tied in it. It was a good second hand deal, worth maybe a single very good eyepiece - although it took some tender loving care and patience from my part to rescue it from the sorry state I received it in. So the M180 wouldn’t need to outperform or replace it - except for being more mobile and backyard-friendly for quicker sessions.

Edited by Axunator, 12 April 2019 - 02:41 PM.

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#16 Astrojedi

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Posted 12 April 2019 - 02:38 PM

I like the way you think Except that small Mewlon actually would even serve a purpose the C9.25 cannot, in my case. It gets hard on the wallet to listen to you guys.

I don’t even bother rationalizing my purchases anymore. Just go for it grin.gif


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#17 Axunator

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Posted 12 April 2019 - 02:46 PM

I don’t even bother rationalizing my purchases anymore. Just go for it grin.gif

I need someone to come here and tell me that the difference in views between the 4” APO and M180 is nil, otherwise I’m doomed.

#18 Kunama

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Posted 12 April 2019 - 03:17 PM

I need someone to come here and tell me that the difference in views between the 4” APO and M180 is nil, otherwise I’m doomed.

Not going to happen........

 

I just bought another Mewlon and had first light last night...... such a sweet scope.  The M180 will eclipse the 4" on lunar detail as well as DSOs.


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#19 bobhen

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Posted 12 April 2019 - 03:21 PM

I need someone to come here and tell me that the difference in views between the 4” APO and M180 is nil, otherwise I’m doomed.

The Mewlon 180 will best the refractor on any deep sky object that fits in the field of view. Everyone that owns a Mewlon comments on the excellent contrast these scopes have. 

 

For lunar/planetary the 4” might do better in average seeing but when seeing is good (doesn’t have to be excellent just better than average) and allows the Mewlon to take advantage of its larger aperture it will best the 4”.

 

But the Mewlon comes with some issues as well.

 

It’s not a quick look scope. You will need to be more cognizant of cooling and allow the scope to acclimate, which can take hours compared to the refractor. And the Mewlon will need to be collimated, which is easy and holds but it will need to be done.

 

I have a Mewlon 210 and a Tak 120. The Tak 120 gets more use because it’s less fussy and here in Pennsylvania the seeing is not as good as I would like. But when the seeing is good and the moon or planets are high, the Mewlon will really thrill.

 

Bob


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#20 Steve D.

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Posted 12 April 2019 - 04:30 PM

I haven't had a chance to use my 180 yet but I have a 4 inch refractor too.   To me, it's all about exit pupil.   A .75 exit pupil is 136X with the refractor and it's 240X with the Mewlon 180.   Huge difference on the planets.  So yes, you need both.

 

Anyone else need me to spend their money?  lol.gif


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#21 Astrojedi

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Posted 12 April 2019 - 05:08 PM

There is only a 4.5lb difference in weight between the 2 scopes (14lb vs. 18.5lb) and both have a sizable central obstruction. The Mewlon 180 will have almost the same mount requirements and same issues (time req to cool, central obstruction, poor planetary performance relative to aperture in poor seeing etc.) as the C9.25 but the 9.25 will be superior on deep sky. At best the Mewlon will be at par to the C9.25 on planetary. 


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#22 Axunator

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Posted 12 April 2019 - 07:06 PM

Not going to happen........

 

I just bought another Mewlon and had first light last night...... such a sweet scope.  The M180 will eclipse the 4" on lunar detail as well as DSOs.

Kiitos Matti - I knew that I could trust you on nudging me off the cliff grin.gif

 

All the sarcasm and jesting aside, the essence of your reply is exactly what I needed and based on experience waytogo.gif And seems to favor my own initial thoughts and alleviate the doubts I had.


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#23 Axunator

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Posted 12 April 2019 - 07:18 PM

The Mewlon 180 will best the refractor on any deep sky object that fits in the field of view. Everyone that owns a Mewlon comments on the excellent contrast these scopes have. 

 

For lunar/planetary the 4” might do better in average seeing but when seeing is good (doesn’t have to be excellent just better than average) and allows the Mewlon to take advantage of its larger aperture it will best the 4”.

 

But the Mewlon comes with some issues as well.

 

It’s not a quick look scope. You will need to be more cognizant of cooling and allow the scope to acclimate, which can take hours compared to the refractor. And the Mewlon will need to be collimated, which is easy and holds but it will need to be done.

 

I have a Mewlon 210 and a Tak 120. The Tak 120 gets more use because it’s less fussy and here in Pennsylvania the seeing is not as good as I would like. But when the seeing is good and the moon or planets are high, the Mewlon will really thrill.

 

Bob

Thanks Bob - good info to base my realistic expectations on waytogo.gif Reasonable cool-down times (like 1 hour) are not a problem even at my downtown backyard. It’s just that there’s absolutely no way to store anything outside, and the gear has to be stored pretty much completely disassembled inside due to space requirements. And the inner-city skies are so compromised anyway, that the setting up and tearing down need to be simple enough for it to be worth it.



#24 Axunator

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Posted 12 April 2019 - 07:21 PM

I haven't had a chance to use my 180 yet but I have a 4 inch refractor too.   To me, it's all about exit pupil.   A .75 exit pupil is 136X with the refractor and it's 240X with the Mewlon 180.   Huge difference on the planets.  So yes, you need both.

My thoughts exactly waytogo.gif



#25 Axunator

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Posted 12 April 2019 - 07:49 PM

There is only a 4.5lb difference in weight between the 2 scopes (14lb vs. 18.5lb) and both have a sizable central obstruction. The Mewlon 180 will have almost the same mount requirements and same issues (time req to cool, central obstruction, poor planetary performance relative to aperture in poor seeing etc.) as the C9.25 but the 9.25 will be superior on deep sky. At best the Mewlon will be at par to the C9.25 on planetary.

Mounting requirements for visual is a hugely individual and subjective thing. I know I’m at the end of Gaussian curve at CN who tends to overmount for visual. Most people here talk like it’s normal to have the scope shaking for 2 seconds after touching the focuser. I don’t get it at all. Kills the enjoyment of observing for me if the image jumps around for two seconds every time I touch the scope or there’s a lightest breeze.

I have observed with C9.25 on multiple mount and tripod combinations, and have found one that works for me: AZ-EQ6 on Berlebach Planet. The scope won’t mind if I poke and nudge it in the dark, and dampening time after focusing - even at really high magnifications - is zero seconds. That’s the way I like it.

I’m pretty sure I’d be happy with M180 on a lesser mount than that. In addition to weight difference (which would be more than 4.5 lbs since C9.25 requires a dew shield and/or insulation in my climate, although I don’t want to start an insulation debate here), the moment arm is likely more forgiving in M180 because most of the mass ends up closer to mount saddle in all dimensions (smaller diameter tube, no corrector plate and corrector cell at front, no need for dew shield, placing also the primary closer to dec axis once the position is balanced). OK, the dampening time of M180 on EQ5/UNI might not be zero seconds, but I wouldn’t use fully-loaded & equipped C9.25 on it even in my dreams (or, rather, nightmares).

Edited by Axunator, 12 April 2019 - 08:48 PM.



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