Deadlake

6 hours ago, dweller25 said:

This will work…

 

The 250 has built in fans if so recall.

Dr D made a cool down device for the Mewlonif memory serves.

1 minute ago, John said:

Would a Mewlon 250 need a refrigeration facility for cooling ? 😃

Damian Peach presumably has some interesting options available to him re: housing / locating such a scope.

Put it’s in a sealed plastic box and leave outside to acclimate.

There are other tricks, Dr D has a youtube linked above on what to do…

2 hours ago, MalcolmM said:

Now you tell me! Maybe that explains the hairy stars 🙂

Malcolm 

There is a thread on CN around this, just search for Mewlon 250…

Its becoming increasingly hard to source a 250,  but very tempting…

1 hour ago, dweller25 said:

No scope is going to be safe near the coast 😱

I'd rather clean the corrector plate than a mirror in this use case.

35 minutes ago, JeremyS said:

Hmmm those M250s must be good…..https://www.astrobuysell.com/uk/propview.php?view=214871

Mewlons are not meant to good  near the coast due too sea salt carried in shore on the wind.

Any photos from Damien of C11/4 vs Mewlon 250?

Surprised Takahashi have not shipped one to him...

4 hours ago, JeremyS said:

I’ve not used my C11 visually.

The M210 is about the same as my C9.25 on planets, but not done side by side comparison. On stars there is no doubt: the Mewlon puts up far better images, more refractor like than SCT.

C9.25 is meant to have better contrast then the C11 as a smaller corrector, but not surprised star test is better for the Mewlon. I use the C11 is low power mode, however where it wins is larger image scale then APO's.  
I suspect the Mewlon is the same when compared to smaller aperture scopes.

On 17/05/2024 at 01:36, JeremyS said:

 I’m a refractor man, but the Mewlons are great (if you don’t mind diffraction spikes). The resolution on planets with my M210 is significantly greater than with my Tak TSA 120.

How does the Mewlon compare with a C11 planets. Presume you’ve given your C11 time off from spectro duties to compare? I’d expect the Mewlon to be sharper then the C11 as the mirror has a higher MTF, but how sharp compared to your TSA120?

19 hours ago, GirtAllerton said:

Deadlake. 

Thank you for the clarification on the balance with heavy EPs & NV that was one of my major concerns. If I understand you correctly, you are recommending the y axis adapter but Not the altitude adjuster. 

Appreciated, 

Girt

If your scopes are tail heavy then yes, the Y axis adapter makes a large difference....

For you use case of an NVD and I presume you are using a reducer for the C8 to get a little more speed (F7?) then the Y axis adapter is a must have to balance the scope. If you get this then the altitude adjustor (to make a pair of scopes point to the same position) is not of any use.

The YAB is so good I have it on an AZ75 and AZ100. See it in action here, the scope with a NVD attached also has a reducer mounted internally to the FT3545 and is tail heavy.

 This SQM meter turned up earlier this week, however as usual no clear skies to make a reading…

1 hour ago, FLO said:

Probably best that I do not comment on another retailer's sales spiel 😇 

Some manufacturers include a Strehl report, but I wish they wouldn't. I don't like the way they are used for marketing. A Zygo is intended for use during the manufacturing process.

And, let's face it, you don't have to search far on this or any other large astronomy forum to find telescopes that don't match their included report. 

FWIW, we have two optical benches and a Shack Hartmann. We use them when appropriate. 

HTH, 

Steve 

Thats fine, however I think over companies offer a minimum value (tolerance), instead of offering an actual value.
 

8 hours ago, IB20 said:

I read a lot about Strehl ratios. Visually, is there much difference between 0.9 and 0.95? Could an experienced observer tell them apart?

I wonder if @FLO receive the Strehl reports for the SM125s like Astronomics do for the AT125 EDLs? Apparently they choose not to send out the reports cos buyers end up quibbling over a 1000th of a difference with other users’ scopes and start returning for higher Strehl scopes. 🤪

I have a SM125. It’s a blummin’ fantastic scope. It’s left my 4”  102ED-R collecting dust!
 

Short answer yes. I can tell the difference between 4” scopes with a Vixen with a Strehl of 0.96 and an LZOS of 0.98. 
 

With stars more focused (tighter) brighter stars.

With the moon more contrast on shadow details.

With Jupiter, more detail of festoons and belts within the planet.

But generally the presentation of the image is sharper.

Also the LZOS Is a faster scope, not exactly sure of this myth of slower scope higher contrast comes from, I suspect all down to the MTF of the scope. 

It’s really that obvious you do not need to be an experienced observer to see the difference, however making use of it is another question.

4 hours ago, Doctor D said:

There's so much rebranding now, it's laughable. 

I did think that, however one scope has a carbon tube but no quoted Strehl tests and the other has an Aluminium tube but a quoted Strehl.

I suspect both scopes  are made in the same factory however to slightly different specifications which I understand is quite common to confuse the buyers even more.

Quite common with APM EP's (different coatings on lens to meet different price points for different vendors all made in the same factory), or so Marcus L and Rupert S tell me...

7 hours ago, bosun21 said:

I was, but on looking deeper I have decided on the StellaMira 125. It seems that this is the best option for visual!

There is one other option, again a 125 mm double however this has a minimum Strehl or 0.95 in the green.

https://astrograph.net/epages/www_astrograph_net.sf/en_GB/?ObjectPath=/Shops/www_astrograph_net/Products/AGTEC125F78

I have no ideal of the Stellamira performance measured empirical in any thread.

3 hours ago, mikeDnight said:

Doesn't this go to show there's nothing written in stone when it comes to one aperture or scope design vs another!  A number of years ago I'd been loaned a very nice SW 8" Dob which I'd set up in my garden at around 3pm on a clear afternoon. Alongside the Dob was my Equinox 120ED and both spent a good six hours standing in the cool air before being aimed at the Moon. My friend Derek witnessed this event as we looked at the Moon using the 8" and both genuinely felt the view was quite literally as good as it could ever possibly be. I knew in my heart that the 120ED would be hard pushed to get anywhere close to the 8", but when we looked at the Moon through the 120ED standing alongside, we were both in awe at the improved sharpness. The night had excellent seeing and both scopes were giving their best.  It would have been very easy to assume the 8" would be unbeatable by a smaller scope had the smaller scope not been standing right alongside, and anyone with that 8" would have had a seriously great scope.  

 It didn't stop there however, as we next aimed the 8" at Saturn which was high in the south east, and again the 8" gave what appeared to be another unbeatable view of the planet and its rings. Again I felt that the 120ED would struggle to get close to the view given by the 8" as it was perfection. Anyone seeing that 8" perform as it did on Saturn would be convinced it wouldn't be possible to get a better view through a smaller scope, as the A ring, Enke minima, Cassini's division, variations in the brilliance of the B ring, and the Crepe ring were all visible with ease, as well as globe detail. Nervously I aimed the 120ED at Saturn and Derek took the first look. His response to what he saw was littered with expletives which made me want to push him out of the way and look for myself. Instead I patiently waited for my turn to look, and when it came I was gobsmacked at the improved definition. The rings in the 120ED were as in the 8", but unlike the 8" were littered with the finest grooves similar in appearance to the grooves on a vynil record.  Derek likened the view to a Voyager image! 

I think there is a wish that everything is simple however we know that many things are not.

In this case the MTF of the scope and not just the aperture needs to be taken into account. 

The C11 although good, its mirror cannot really compare with the optics of a top tier APO and if the C11's mirror was manufactured to the same tolerance I'm sure it would be a 12K scope.

Having said all of that the C11 is a great light bucket, but to get contrast and detail on objects needs a better mirror....

 

Ok here is one I cannot explain, and maybe a little of topics.

I had a 105 mm and C11 mounted side by side.

Observing Orion's Nebulae I can make out more nebulosity using the 105 mm then the C11. 

A 20 mm XWA in the 105 mm and a 30 mm UFF in the C11.

The C11 is wrapped.

I was surprised.... 

Shouldn't this post be moved  into EAA section?

@josefk I did discuss having a top mount saddle with Derek however impractical as it would collide with the motors on the top of the AZ100.

Either an AZ150 is needed, APM AtlZ heavy mount or you could look at a HAZ71 that will easily take the load.

15 hours ago, Stu said:

Hopefully not having a screen will keep costs down. I use SkySafari anyway so not too much of an issue. I have it (yet to be used in anger) on a Boox e ink tablet which can be completely unlit, or very dim so works well for dark adaptation.

Interested to hear out you get on with e ink tablet. I was hoping maybe an OLED based tablet would be close to simulating the red led screen of the Nexus….

The joystick removes the need to keep the web front end running to control the AZ100 via a wireless gamepad.

The remote however does not have a screen. 

I would of liked the option to select a target and perform two star alignment via the  controller. A bit like the Pegasus controller:

At the moment the other option is a Nexus, that has the advantage of less screen light as the red led can be made very faint.

If anyone with an interest in the AZ100 has gone to the Practical Astro Show maybe they could tell us  about this upcoming AZ100 remote control.

Thanks

4 hours ago, Space Hopper said:

I thought they'd solved that with the ring thing......?

 

Is is still one more thing to do. 

it's a trade off between compactness for the aperture compared with a Newtonian and adding shield to handle  the dew build up.....

Since this thread is so old I would how many who posted have still got there SCT’s?

I sold a Vixem SD103S to fund a C11. 

Should I have kept the SD103S, probably, however I sold it because I thought it would keep my wife happy and the C11 was actual sold to keep the owners wife happy.

Maybe we need a thread title how many scope have you sold or relocated to keep you partner happy?

1 hour ago, Roy Challen said:

Can you believe it? Mention Starfire and one appears on ABS, a 152mm no less! I need to ban myself from looking.

Quite a good price, that’s cheaper then what is being asked for a Stowaway new at Skypoint.