Best refractor 120/140

[Fedele]

Hi. in your opinion, for mere visual purposes (large fields in turret, Sun, Moon, Planets) and imaging (Sun, Moon, Planets), what is the best compromise between diameter (the more the better), size and weight (the less it weighs and the more compact, the better), cost (budget 3000/5000 euros approximately).
The refractor  will support a 100ED binoculars.
i want to have discs with a higher image scale than those offered by the FC100 (and also resolution for imaging planets).

Thanks

[Peter Drew]

Unobtainium I think.  Your ED binoculars will be better for wide field than a single refractor, your FC 100 should cover the middle ground and refractors are not large enough in common use for planetary photography at the highest level.  What you lack in your line-up is a 100"+ SCT which offers the size, weight and cost of the rest of your other requirements.        🙂

Edited September 11, 2021 by Peter Drew

[Fedele]

47 minutes ago, Peter Drew said:

Unobtainium credo. Il tuo binocolo ED sarà migliore per un ampio campo di un singolo rifrattore, il tuo FC 100 dovrebbe coprire la via di mezzo e i rifrattori non sono abbastanza grandi nell'uso comune per la fotografia planetaria al massimo livello. Quello che ti manca nella tua formazione è un SCT da 100"+ che offre le dimensioni, il peso e il costo del resto delle tue altre esigenze.        ?

Ok you are right but is not what i m asking. 

[Andrew_B]

The TSA-120 would tick a lot of boxes although it's obviously at the lower end of your aperture range and may not be a big enough step up from your current FC-100. Never had the pleasure of using one myself but I know some of the members here own or have owned one. Stepping up to the TOA-130 would get you optics that are about as good as it gets but you'd have to find one on the secondhand market to be within your budget.

An APM/LZOS scope might be an option but it would be the same situation as the TOA-130 of you needing to find a pre-owned example.

[JeremyS]

The TSA 120 is a good balance between the factors you mention. The next step up, TOA 130 is quite a bit heavier.

The C9.25 is another option, but not what you are asking 

[jetstream]

I see no "need" to go bigger than 120mm with a frac and the TSA120 works superbly. Mind you I have lots of "wants and desires" with respect to larger fracs.

[KP82]

+1 for TSA120. It's also the one most likely in stock if you want one urgently. TOA130 is out of your price range. APM-LZOS 130 f/9.2, TEC 140FL, CFF 135 and 140 are all out of your range plus there is substantial amount of waiting time for all of them.

[Highburymark]

Having just upgraded from an FC-100 to a TSA-120, I’ve been impressed by the extra resolution on planets and the Sun. I think that extra 2cm collects 44% more light. Yet to use it for lunar or deep sky. The optics are to my eyes perfect, no false colour on the brightest stars even out of focus, but there are also several other scopes out there that deliver essentially perfect views. But you can’t underestimate the physical implications of moving from a 3kg to a 6.7kg scope (around 9kg fully laden - pics show two scopes together for comparison). For me, everything had to to be reassessed - dovetail, clamp, mount, tripod, storage space, routine for setting up the scope, and of course cooldown time, though I won’t know exactly how fast it cools until we get further into autumn/winter - at the moment it’s usable immediately. Most of the 130mm/140mm scopes represent another step up in bulk, so making sure you can physically accommodate whichever choice you make must be the first question to be asked.
 

[Fedele]

Many thanks...

wich Fc is this

Thanks for the first-hand response. Do these larger sizes discourage you from using it compared to the FC?

[Stu]

2 hours ago, Fedele said:

Many thanks...

wich Fc is this

Thanks for the first-hand response. Do these larger sizes discourage you from using it compared to the FC?

Just to chip in on this. It is absolutely a consideration for me. I have an FC100DC which I normally use on a Gitzo tripod and a giro-wr mount. This is a one handed carry around the garden.

The 130 f6 LZOS I’ve just got goes on an AZ100 mount and planet tripod which I tend to carry separately and the scope needs a lot more cooling, so yes I’m more likely to use the FC100DC for quick sessions and save the LZOS for when the forecast looks very good all evening.

[Stu]

Just took a quick pick of the FC100DC side by side with the LZOS. Surprisingly little difference in length with the LZOS dew shield retracted. BIG difference in weight and bulk. The 130 is very front heavy when carrying it but still quite manageable.

[Andrew_B]

3 hours ago, Fedele said:

Many thanks...

wich Fc is this

Thanks for the first-hand response. Do these larger sizes discourage you from using it compared to the FC?

Looks like it's an FC-100DC with a Starlight 2.5" Feather Touch focuser. Hadn't realised just how compact it is compared to the TSA-120!

[Stu]

27 minutes ago, Andrew_B said:

Looks like it's an FC-100DC with a Starlight 2.5" Feather Touch focuser. Hadn't realised just how compact it is compared to the TSA-120!

Yep, that looks right. Mark’s looks like it has the A20-302 adaptor which retains the silver ring. I have the 304 on mine which you remove the silver ring to fit.

[Highburymark]

5 hours ago, Fedele said:

Many thanks...

wich Fc is this

Thanks for the first-hand response. Do these larger sizes discourage you from using it compared to the FC?

Yes - it’s a DC with the green ‘spacer’ section removed (shown at side) as I needed the extra light path for binoviewing. 
The size doesn’t stop me from going out, but whereas before I had two refractors of similar size (85mm and 100mm), I now have greater distance (between my TV85 and 120mm TSA) - so if I want a really short session I grab the TeleVue, and for longer sessions, particularly in good seeing, I’ve got the bigger aperture.
I know I won’t be able to handle the TSA for ever due to my bad back. I’m hoping I can get at least 5-7 years out of it before it proves too much. But that might happen far sooner.
I am 100% sure that I will then go back to a light fluorite doublet - almost certainly an FC-100DZ  (or an FC-115DZ would be nice if anyone from Tak’s product development department is reading). 

[Deadlake]

I think the limit of how big to go with a APO is how much mount you out able to accommodate. The weight of my 4" can be taken easily by a Scopetech Zero whereas my LZOS needs an SXP2 mount , a SXD2 would not be able to point it reliably.

For size comparisons:

 

Note the dew shield stick out more on the AG scope than the KUO tube (the one @Stu has), but the tube length is 4 cm shorter. (Corrected focal to tube length)

Tonight, well scope night app was all over the place. Either takeout the SXP2 early which is a must for tracking planets or go with the 4" and the Scopetech Zero.

The SXP2 is around 11 kg, plus 6.5 kg of weights and other bits I need a good night and set up early for this to be worth while. The AZ100 is still 10.5 kg plus saddle etc, not grab and go. The other option would be to get a Crux mount which is 4.5 kg or maybe an Alt-Z like the new NOH CT-20 (2 kg).

Bill P tells me even with the nudge method for moving he can still use is 152 APM ED at x600 (another option you can buy) on the moon using the CT-20 and its smoother to manoeuvre then mounts with slo mo's. The CT-20 a weight of 2.5 kg and a light weight tripod makes 130 mm LZOS becomes a lot easier to get out with since I don't need a heavy mount, I could even move it around connected which is not some thing I could attempt with the SXP2 or AZ100. The Crux is great however I'd need to sell the SXP2 as I cannot justify having both mounts. To make say a TOA-150 (not mine) more transportable the RST-300 is used, again not cheap, but adding up the weight of the tripod and mount below is under 10 kg, considering what its carrying lightweight.



In summary its the weight of the mount that limits me in taking out a 5" APO. Cool down, well thats 30 minutes and you are ready, so not a big deal.

@Fedele Have you worked out how to mount this scope (AZ100?), I think that limits what you can do.

Rupert @ Astrograph tells me no more LZOS lens cells till Jan 2023, all allocated, so unless you can find one second hand you might have to cross that off you list. TEC 140 from last year have still not been delivered. It's a long wait for a premium APO. Maybe the APM 152 mm ED is the way to go, very good reports on this scope.
 

 

Edited September 12, 2021 by Deadlake

[Stu]

21 minutes ago, Deadlake said:

but the focal length is 4 cm shorter. 

Thought both were 130/780?

[Deadlake]

12 minutes ago, Stu said:

Thought both were 130/780?

Mine has 4 cm’s less to be more bino friendly. 

[Stu]

1 minute ago, Deadlake said:

Mine has 4 cm’s less to be more bino friendly. 

That’s tube length not focal length.

[Deadlake]

1 minute ago, Stu said:

That’s tube length not focal length.

Yes, typo on my part.

[Fedele]

so I  risk that the AZ100 is too heavy and for  fixed location. What motorizable alternative do I have? and as an alternative even without motorization to always remain on quality, elegance, compactness, transportability

[Andrew_B]

3 hours ago, Highburymark said:

Yes - it’s a DC with the green ‘spacer’ section removed (shown at side) as I needed the extra light path for binoviewing. 
The size doesn’t stop me from going out, but whereas before I had two refractors of similar size (85mm and 100mm), I now have greater distance (between my TV85 and 120mm TSA) - so if I want a really short session I grab the TeleVue, and for longer sessions, particularly in good seeing, I’ve got the bigger aperture.
I know I won’t be able to handle the TSA for ever due to my bad back. I’m hoping I can get at least 5-7 years out of it before it proves too much. But that might happen far sooner.
I am 100% sure that I will then go back to a light fluorite doublet - almost certainly an FC-100DZ  (or an FC-115DZ would be nice if anyone from Tak’s product development department is reading). 

You should drop Tak a line about wanting a larger fluorite doublet. I'm sure they're aware that there's demand for one but more evidence of that can't hurt and even the biggest companies do pay attention to customer feedback - I once emailed Apple about overly aggressive noise reduction algorithms in their smartphone cameras and they came back to me about it asking for more information and example images.

[Space Hopper]

2 hours ago, Deadlake said:

Rupert @ Astrograph tells me no more LZOS lens cells till Jan 2023, all allocated, so unless you can find one second hand you might have to cross that off you list. TEC 140 from last year have still not been delivered. It's a long wait for a premium APO. Maybe the APM 152 mm ED is the way to go, very good reports on this scope.
 

 

Yes, 13 month wait for my 140 (delivered Sept 2019)

I did a bit better with the 105 : Rupert supplied that in a couple of months. Timed it right i guess.

[Deadlake]

7 hours ago, Andrew_B said:

You should drop Tak a line about wanting a larger fluorite doublet.

Ageema already make them, however a long wait time and not that much lighter then many triplets.

[SimonIRE]

Although weight is perhaps a negative, the TOA130 is the best corrected refractor you can buy in my opinion. The only comparable scope that I haven't looked through is the AP130GTX which I expect is very very good too. 

[Deadlake]

10 minutes ago, SimonIRE said:

TOA130 is the best corrected refractor

How does colour/contrast compare between your LZOS and TOA?