tell me the differences between FC100DZ, TS 115 TRIPLET, TS 125 DOUBLET LANT for visual use

[John]

5 minutes ago, Robindonne said:

I'm so glad we were able to help Fedele choose from the 3 options

So what is your contribution going to be ?

 

 

[johninderby]

Will he choose what’s behind door number 1: 2 or 3. 😁

[Robindonne]

1 hour ago, John said:

So what is your contribution going to be ?

 

 

Considering he owns a 120ed, and on the hunt for a WOW, the biggest improvement in my opinion would be the 115 triplet. Door no.2

Edited June 14, 2021 by Robindonne

[John]

35 minutes ago, Robindonne said:

Considering owning a 120ed, and on the hunt for a WOW, the biggest improvement in my opinion would be the 115 triplet. Door no.2

Good luck with that

 

 

 

Edited June 14, 2021 by John

[johninderby]

Considering the 115 triplet is cheaper than the 125 doublet makes me wonder how good the triplet optics are? 🤔

[Robindonne]

34 minutes ago, John said:

Good luck with that

 

 

 

No but serious.  If there’s a final answer on his 3 scope question, i would love to know it.  
Although i dont think any of the 3 will give a huge improvement over a good 120ed, (plus a mewlon 180), i had to base my opinion on the shared experiences by the ones that actually used at least 2 of the 3 mentioned options. But also a bit on the op’s reason behind this question.  What i made of it is he owns a mewlon for planetary/solar-imaging but decided to swap the mewlon for a refractor for planetary, and i perhaps accidentally assumed also solarimaging based on the op’s videos and photos.  All combined would make it for me the  (fpl-53) 115 triplet as the best addition to that famous hard to beat 120ed.  

Edited June 14, 2021 by Robindonne

[johninderby]

The specs on the TS website give the glass used as FPL51 for the TS 115 TRIPLET.

[Robindonne]

10 minutes ago, johninderby said:

The specs on the TS website give the glass used as FPL51 for the TS 115 TRIPLET.

Oh that i didnt know.  

[vlaiv]

7 hours ago, johninderby said:

Considering the 115 triplet is cheaper than the 125 doublet makes me wonder how good the triplet optics are? 🤔

https://www.youtube.com/watch?v=sE18PBQRzDQ

Does not really answer how good the optics are, but compared to FS 102 following comment is given:

"Tak has better star image, but in focus, you really can't tell".

Start at about 8:00 for comparison of two scopes ...

[mikeDnight]

I'd imagine the better star image of the Tak is due to it having better spherical correction rather than colour correction. Spherical correction is far more important for planetary observing than colour correction, so I'd personally go for the scope that showed the least spherical abberation. Doublet or triplet is irrelevant to me - its all down to the quality of the figure and polish. It wouldn't surprise me if the 125mm had better spherical correction than the 115mm triplet.

[Fedele]

Solar image take a great place now in my work. 
Like tiplet i m evaluate the TSA120. I  think that doublet are best for solar observation and if triplet they should be of the best quality possibile (similar thermal coefficent of lenses etc). So i m not interested in triplet made inb china.

I m interested anyway to diameter...so  a large option can be an idea. for example now the choice is betwen: 

TSA120, TS 125 f 7 ED lanthanium FPL53, APM 140 ED f7. 

The second as cheap option to the first

the third as best resolution 

I don t want to pay near 5000 euro and dont see  great plus rspet the 120ED (that i like yes but i want more quality and contrast)

also i don t want to pay 3000 for the GREAT finally APM and  to remain with the doubt of the TSA120...."AND IF..."

what i want first, is a sufficente disk dimensions for planets. and a good quality

[KP82]

The 120ED is already very good optically, I doubt you would be able to see any "great" improvement from those 3 scopes you listed. Improvements will be there but whether they are worth 5000 euros or not is up to you. Honestly at this level the only major improvement I could think of would be bigger apertures for more light and resolution. But to get a noticeable difference compared to 120mm, I'd say 6" is the minimum (152mm f/8).

Skywatcher Esprits are highly regarded by many astrophotographers, so I wouldn't dimiss those Chinese triplets so quickly (I love my APM107 which is another triplet made in China).

[michael.h.f.wilkinson]

On 14/06/2021 at 04:22, johninderby said:

The specs on the TS website give the glass used as FPL51 for the TS 115 TRIPLET.

FPL 51 combined with a Lanthanum glass element

[michael.h.f.wilkinson]

1 hour ago, Fedele said:

Solar image take a great place now in my work. 
Like tiplet i m evaluate the TSA120. I  think that doublet are best for solar observation and if triplet they should be of the best quality possibile (similar thermal coefficent of lenses etc). So i m not interested in triplet made inb china.

I m interested anyway to diameter...so  a large option can be an idea. for example now the choice is betwen: 

TSA120, TS 125 f 7 ED lanthanium FPL53, APM 140 ED f7. 

The second as cheap option to the first

the third as best resolution 

I don t want to pay near 5000 euro and dont see  great plus rspet the 120ED (that i like yes but i want more quality and contrast)

also i don t want to pay 3000 for the GREAT finally APM and  to remain with the doubt of the TSA120...."AND IF..."

what i want first, is a sufficente disk dimensions for planets. and a good quality

For purely solar imaging, I wonder if a triplet is really needed, or even ED glass. I image the sun quite a bit, and for H-alpha and Ca-K at 0.3 Å and 2.4 Å respectively, CA correction is totally unnecessary. Even in the solar continuum band, very little CA can be noticed. Spherical aberration is probably more important, as is sheer aperture (although seeing in Ca-K can spoil matters above 4" aperture).

Of course, an apo scope is a better all-round imaging