Refractor Choice.

[Paz]

If you have a mount that can handle either scope and don't mind the weight and cool down times of the larger triplet then it's more of an even contest as to the views and the facilities each scope had to offer once you're at the eyepiece, but I do think in the long term weight and cool down matters and the longer I own a scope and the novelty has worn off the more it matters. I have a 14" newtonian that weighs in as 2 lumps of around 20kg each, which I can still handle, but when I was looking at 5"+ refractors I was put off by the size and weight  of them. It wasn't that I couldn't handle them, it was thinking about how much effort for how much aperture and would I get a 7.5kg 5" scope out if I had other scopes that were more bang for the buck (or should I say more bang per kg).

The SM125 has weight and cool down on its side, the Askar has more aperture on its side. I would not know myself which if either has better quality optics.

The Askar has a beefier focuser but that may be of no consequence depending on what you put on the scope. I don't know if either has more in focus than the other,  that's one other thing to consider if you binoview, but I find the SM125 fine for in focus. 

[Deadlake]

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.

[Doctor D]

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

[Deadlake]

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...

Edited April 21 by Deadlake

[dan_adi]

On 16/04/2024 at 21:26, bosun21 said:

I am looking at buying myself a new refractor shortly and I can't decide which way to go. The two contenders are the StellaMira 125 doublet with FCD100 and lanthanum glass and the Askar 140 triplet with one ED element (type not disclosed). I have been reading reports from owners of both and both are said to perform very well for visual. The 140 is bino friendly with a 3.5" R&P focuser as opposed to the 2.5" of the SM 125. It's the question of whether the better glass type of the doublet will be better than the supposed better correction of the triplet with one ED element. This being a considerable purchase for me I want to make the best choice possible. Any thoughts on the matter would be appreciated. Thank you.

I would go for the triplet. Neither is top of the line, so might as well get better colour correction 

[John]

57 minutes ago, dan_adi said:

.... so might as well get better colour correction 

Not always the case 😉

[IB20]

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!
 

[mikeDnight]

Not sure if its still available, but there's a Meade 127 triplet on AB&S. It's a terrific scope and colour free. Though it is heavier than a Equinox 120, it is better corrected, yet can be carried on a Vixen GP providing the tripod is very strong. It's very well designed with retractable dew shield and a finder that rotated around the focuser so it would always be accessible. 

Here's the one I used many times from some 13 years ago with my friend Phil standing alongside. It was his scope.

 

[paulastro]

3 hours ago, dan_adi said:

I would go for the triplet. Neither is top of the line, so might as well get better colour correction 

I'm not sure I'd take whether a scope is 'top of the line' into consideration.  There are also different views about which scopes are top of the line anyway.  Also over the years I've had or used a small number of such scopes which have clearly not been up to their elevated reputations

I have an Askar 103 triplet and StellMira 125  f7.8 which I have found to be amazing performers - irrespective of their cost and the names on the side of their tubes.  You could spend an awful lot more money and not get better views.

Of course, I can't say all examples of these scopes will perform as well as as the ones I have,  as I haven't tried any others.  

However, If prospective purchasers of any scope buy from a reputable dealer with a sound returns policy, they can buy without fear.  

 

 

[paulastro]

On 17/04/2024 at 22:33, Doctor D said:

The Askar's are okay but limited in their magnification due to some spherical aberration they often exhibit. This causes stars and planets to breakdown more apparently. 

I've not read any of this.  Happily I must be a lucky chap, as my Askar 103 triplet doesn't suffer with any of these problems 😊.

[Deadlake]

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.

[Doctor D]

On 21/04/2024 at 17:03, paulastro said:

I've not read any of this.  Happily I must be a lucky chap, as my Askar 103 triplet doesn't suffer with any of these problems 😊.

Glad to hear that. Would enjoy having a look at some of your reviews if you'd like to share any. 

[paulastro]

8 hours ago, Doctor D said:

Glad to hear that. Would enjoy having a look at some of your reviews if you'd like to share any. 

I presume you mean reviews re the Askar?  I've put a few comments on SGL but not a complete review - I did do a short 'review' which is on FLO's website  - one of those following  their listing of the scope. Though I've had it since Dec,   I had a heart procedure and  replacement hip in Dec/Jan which laid me up for a bit and with bad weather I've not yet done a complete review.  Pretty much the same for the StellaMira 125 f7.8 which I've had only about four weeks.   I'll  be writing are review for both scopes when weather permits.

If there's anything you'd like to know particularly, pm me and I will make sure I'll give it priority and get back to you.

 

Edited April 23 by paulastro
Typo

[900SL]

On 20/04/2024 at 22:55, Deadlake said:

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.

At that price I'd be tempted to go for the triplet 130. Fpl53 too

https://www.teleskop-express.de/en/telescopes-4/apochromatic-refractor-55/all-apos-und-eds-223/ts-optics-photoline-130-mm-f-7-edt-triplet-apo-refractor-6679

[FLO]

On 21/04/2024 at 18:15, Deadlake said:

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...

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

On 21/04/2024 at 22:25, IB20 said:

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. 🤪

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 

[FLO]

On 21/04/2024 at 22:25, IB20 said:

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

That is good to hear 🙂 

[Deadlake]

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.
 

[FLO]

13 minutes ago, Deadlake said:

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

 

On 22/04/2024 at 00:39, paulastro said:

If prospective purchasers of any scope buy from a reputable dealer with a sound returns policy, they can buy without fear.  

What he said ^ 🙂 

It matters most how the telescope supplied to you works and that there is sufficient redress if it does not work as expected. 

Steve 

[ollypenrice]

23 minutes ago, FLO said:

 

What he said ^ 🙂 

It matters most how the telescope supplied to you works and that there is sufficient redress if it does not work as expected. 

Steve 

What he said^^

lly

[FLO]

On 24/04/2024 at 17:49, Deadlake said:

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

FWIW, the SM125 ED is manufactured to a minimum Strehl of 0.92. 

When considering Strehls, 0.8 is diffraction-limited 1/4 wave, 0.92 is very good, 0.95-0.98 is exceptional, and 0.98+ is essentially perfection. 

The manufacturer assures us no other version of this telescope is made to a higher specification. (We always seek this assurance before adding a StellaMira telescope to our stock). 

HTH, 

Steve