TS-Optics Doublet SD Apo 102 mm f/7 - FPL53 or TS-Optics PHOTOLINE 115 mm f/7 Triplet Apo

[Marian M]

Hi friends!

Have succeeded to get the budget for the 102 APO after a long time and just saw a slightly larger aperture- the 115mm triplet

Any experience/ idea if would be worth waiting some time for the bigger one or just pull the trigger for the 102 APO; any substantial difference in terms of light gathering and image quality?

The APO will be used for visual only, kind of grab and go/ all around (Moon, planets, some DSO), mostly for better quality view vs current 120/600 achro and 127Mak, on either EQ5 or AZEQ6

Also have to acknowledge that TS 152 F5.9 is tempting  

Thank you!

[badhex]

6 minutes ago, Marian M said:

Hi friends!

Have succeeded to get the budget for the 102 APO after a long time and just saw a slightly larger aperture- the 115mm triplet

Any experience/ idea if would be worth waiting some time for the bigger one or just pull the trigger for the 102 APO; any substantial difference in terms of light gathering and image quality?

The APO will be used for visual only, kind of grab and go/ all around (Moon, planets, some DSO), mostly for better quality view vs current 120/600 achro and 127Mak, on either EQ5 or AZEQ6

Also have to acknowledge that TS 152 F5.9 is tempting  

Thank you!

Hi Marian, 

Is the 102mm the Photoline model you're referring to? 

https://www.teleskop-express.de/shop/product_info.php/info/p9868_TS-Optics-Doublet-SD-Apo-102-mm-f-7---FPL53---Lanthan-Objective.html

Assuming it is, I can strongly vouch for this telescope as I have the same one. It is also identical to the Starfield model which many of our UK based friends on SGL own. It's a fantastic scope!

As far as I can tell, the 115mm is essentially identical but scaled up, which means a bit more light grasp, but I believe it's almost 2kg heavier as well which makes it less portable, so won't work as well for grab and go. The additional light grasp might not be worth the trade off. 

One other thing is that with a low power 40mm EP you'll be able to get about 4 degrees of sky in the 102mm vs about 3.5 degrees in the 115mm.

 

[bosun21]

If I remember correctly the triplet 115mm has one lens of FPL51 and not the FPL53 that the 102 doublet you are considering. I know this because I was in the exact same position as yourself a short time ago. I ended up buying the 102 FPL53 doublet (Starfield) and have been more than satisfied with its performance. Not a hint of CA that I can detect. The combination of FPL53 and Lanthanum in the doublet definitely pays dividends.

[badhex]

I've just realised I misread, I was thinking the 115mm was a doublet. Although technically 'better'  in terms of colour correction, as @bosun21 has said, the doublet is essentially CA free for visual, which I understand is your main use case and not AP. This leans even more into the 115mm not being very grab-and-go compatible, as the additional element will increase cooldown time quite a bit. Honestly I don't think you will be disappointed with the 102! 

 

[Marian M]

Dear Joe, dear @bosun21, thanks a lot for your kind and quick revert! All reviews around 102 F7 I have read are positive, and your experience push me towards the same choice

Still to think a little by end of the month, when budget should be enough for the acquisition

One question - have you tried bino on this scope, without GPC? Theoretically MB2 + T2 should enter in focus (11+4=15cm of optical path), by disassembling the 2" to M68 part of the focuser and replacing with a very short M68 to T2 adapter- on the technical description of the scope is written that there are 16 cm back focus from M68

Regards,

Marian 

[vlaiv]

If you are visual only - go with 102mm scope.

115mm is triplet and is better corrected for color, but this is only visible in images (human eyes are mostly not sensitive enough at far ends of spectrum to notice this).

Triplet is heavier, and cools down slower.

These are things that are often important for visual observers. If you don't mind a bit more weight and a bit longer cool down time - and you think 15mm more aperture is worth it - then obviously the triplet.

Between the two - I'd go for triplet - but then again, that is me with my priorities.

[Louis D]

I'd go for the doublet for G&G.  I picked up a used TS Photoline 90mm FPL-53 Triplet for about $800 pre-C19.  While it has very nice in-focus sharpness and is color-free, it takes over 30 minutes to equilibrate just 20 °F (11 °C) warmer or cooler.  Star images are all spiky in focus during this time, which is disconcerting when the seeing is rock steady.  By comparison, my 72ED doublet is good to go straight away with no cooling/warming.

Be aware of how large a 100mm ED or APO can be.  My 90mm is about at the limit of what I'd want to deal with for G&G.

[michael.h.f.wilkinson]

A 102mm ED doublet should provide a very nice, reasonably portably scope, with a nice wide FOV. I myself have an APM 80mm F/6 triplet, both for imaging and wide-field viewing. For planets, I would guess the little 127 mm Maksutov will give the 4" ED doublet a very serious run for its money. Those 5" Maks punch well above their weight for planetary viewing and imaging. I would certainly not ditch that Mak.

[Marian M]

Thank you for sharing your thoughts!

Once I will decide and acquire, will share my thoughts here.

I have seen the Moon through an APO (100EDSW) one single time, power probably around 200x, and was amazed about the purity and contrast of the image

Mak127 is indeed phenomenal on Moon, mostly through the bino, but still keep in mind that view through the APO

 

Well, once will do the step, for sure will compare with both 120/600 achro and Mak 127. with the new APO. Let us see my (very personal and subjective) opinion   

[Marian M]

Here it is the beast 😀!!

 

Finally decided to go with th TS-Optics doublet SD Apo 102mm f/7 and very happy with it!

Not too much testing so far but will come soon. The Apo come from TS-Optics extremely well protected and in less than one week (Germany to Romania) after the order was placed. Together with a more "specialist" friend, we have tested it and the collimation is very close to perfection

 

No chance to go out of the city, but we have seen few times the Moon, Jupiter, Saturn and Mars. Some little colors on Jupiter but minimal and could have been induced by the prism used with binoviewer.

 

We have tested the TS Apo with SW 80 ED one time and with 120 ED second time. Both comparisons were done with Maxbright binoviewers :

• SLV25mm, Lacerta UWAN 17mm, Lacerta UWAN 7mm, Baader prism diagonal for TS apo
• Morpheus 9mm Baader T2 BBHS prism for the 2 SW
• All with various GCPs and Barlow combinations: Baader 1.7 GPC, 2.7 GPC, APM 2.7 barlow

 

The differences between the 2 (either SW80/ TS 102 one evening or SW120/ TS 102 another evening) have been minimal in details on Jupiter. Whatever was seen in one instrument, has been seen in the second one. Maybe some minimal details, with some effort, could have been seen at some moments of time. Power used was up to 300 times (one of the nights excellent) but probably the same details as up to 150x- 200x

 

SLVs barlowed are excellent for planets, incredible sharp. For Moon/ DSO SLVs are losing ground against wide field eyepieces. In between I bought also 2 Morpheus 17.5. Fantastic for DSO/ Moon, but a little more difficult than SLV on eye positioning

 

Regards,

Marian 

[Moonlit Knight]

I own the same scope by Altair Astro, a Starwave 102 EDR with fpl 53 glass. An excellent telescope optically with a super build quality. Absolutely remarkable value for money. I have had mine for 3 years. FLO have them in stock for 899 quid. But you need a finder and a diagonal on top, and I might suggest a case also. 

[Mr Spock]

These fpl53 102s are difficult to beat. Mine is sharp and contrasty with no false colour. Inside and outside of focus the rings are identical indicating little or no spherical aberration; again there is no false colour.

For the money they are a real bargain. 

[badhex]

Glad you went for the 102 - an absolutely fantastic scope! 

[Marian M]

Thank you all to suggest this!

[Nicola Fletcher]

On 27/11/2022 at 16:47, Moonlit Knight said:

I own the same scope by Altair Astro, a Starwave 102 EDR with fpl 53 glass. An excellent telescope optically with a super build quality. Absolutely remarkable value for money. I have had mine for 3 years. FLO have them in stock for 899 quid. But you need a finder and a diagonal on top, and I might suggest a case also. 

Me too, and I completely agree, I’m so glad I bought mine. The focuser on them is really nice to use as well. Still can’t believe I got such a nice refractor for that price!

[Moonlit Knight]

2 hours ago, Nicola Fletcher said:

Me too, and I completely agree, I’m so glad I bought mine. The focuser on them is really nice to use as well. Still can’t believe I got such a nice refractor for that price!

I know, you almost wonder where the catch is, except there’s none. I know it’s 900 quid for a naked scope and there’s still a finder and diagonal to find, but it’s still a lot of scope for the money.

Edited November 28, 2022 by Moonlit Knight