Can a Takahashi 100 DZ Outperform a Non Premium 120-127mm ED Refractor

[johnturley]

I have owned several different scopes both Reflectors and Refractors over the years, but have never previously owned a Takahashi Refractor, and have been intrigued by claims from some Tak owners, that their scopes provide razor sharp images of planets at 100x or even 120x per inch of aperture, which would equate to around 400x for a 100mm scope. I found this somewhat surprising, as it is very rare that I can use to advantage, a magnification in excess of 300x with either my 14in Newtonian or 150mm Esprit Refractor.

Earlier this year I injured my back trying to lift a gate off its hinges, and its taken nearly 6 months to recover, hence I came to the conclusion that at my age (74) my CPC 9.25 was now getting a bit heavy to lift comfortably. In addition I was also under some pressure from my wife to reduce the number of scopes in the conservatory (which housed both my CPC 9.25 and Explore Scientific 127 Refractor), and to be honest I’d hardly used the CPC since in 2019 purchasing my Esprit 150 (which gives similar planetary performance), and which is conveniently mounted piggyback on my 14in Newtonian in my observatory shed. I purchased the CPC back in 2014, as at the time I was thinking over moving house, and wanted something at was at least semi-portable, and with a computerised GOTO facility. The C9.25 was at the time recommended by Damien Peach for its performance on planets, but with hindsight it might have been better purchasing a C9.25 OTA and GEM separately, but at the time I don’t think that most GEM’s offered a computerised GOTO facility.

At 9kg (with tube rings, finder and diagonal) my ES 127  (which used to be mounted piggyback on my 14in before I purchased the Esprit, and is currently mounted on a Skywatcher AZ-EQ5) is no lightweight either, and ideally I could do with something more portable. I worked out that if I sold both the CPC and the ES 127, I could roughly fund the purchase of a Tak 100DZ. However I decided that I would sell my CPC first, and keep my ES 127 a little longer, so that I could also satisfy my curiosity as how the Tak would compare to a larger non premium scope such as the ES 127. I have already compared the ES 127 to the Esprit 150, and found the latter to be streaks ahead, more than you would expect from just an extra 23mm of aperture, which I put down to the superior quality of the Esprit lens, and I am not expecting a 100mm Tak to come close to this.

I will mount the 100 DZ on my existing AZ-EQ5 mount, and for the purpose of doing the comparison,  can potentially mount both scopes on it in AZ mode. The AZ-EQ5 mount is not exactly lightweight either, and I might in future look for a lighter mount for the Tak, but should only require one rather than two balance weights with the 100 DZ, making it marginally lighter.

I finally sold my CPC 9.25 last week, and contacted Rother Valley Optics to order my 100 DZ, which they expect to come into stock next week. At £2,905 for the DZ OTA, this did seem a high price for a 100mm Refractor, and I was tempted by the cheaper 100 DF, which RVO currently have on offer at £2,049 for the OTA, and the performance of which some have stated is virtually equal to that of the DZ. However I decided to stick with my original plan to go for the longer focal length DZ, with its sliding dewshield. I have also decided to pay the extra for a Zygo test, so that I can be 100% certain of its optical quality, Es Reid (whom I know personally) told me that he has occasionally come across what he described as a ‘Friday afternoon’ Tak. Adam at RVO informed me that if the scope does not come up to the expected optical standard in the test, then they sent it back to Tak and get a replacement. I will be picking up the scope from RVO, who are only about 15 miles away from me, so I can be 100% certain that no damage, or mis-alignment of the optics takes place in transit.  I decided to go for the basic OTA as @mikeDnight  kindly offered me a spare Tak clamshell, and rather than pay £171 for a Tak 6x30 finder, or £322 for a 7 x 50 finder, I have purchased a second hand Skywatcher 9 x 50 finder for £30, but I expect that I will need to buy the genuine Tak finder bracket.

I will post an update after getting the 100 DZ, and after I have had a chance to compare it with my other scopes.

John

 

Edited January 22 by johnturley

[The60mmKid]

The impression that I have after owning and using multiple good scopes and premium scopes is that the results are predictable. The view through the premium scopes is sharper, more contrasty, and better corrected than through good scopes of the same design and aperture. Aperture and exit pupil are aperture and exit pupil, and they behave predictably when other variables are controlled. (And those variables are more easily controlled in a refractor than in other telescope designs.)

So, I predict that your Tak will offer exactly what one would expect: some of the most outstanding views that a 100mm scope can provide. It'll do what we can expect from it, just like your other scopes (e.g., C9.25) will. No disrespect intended, but I'll be surprised if there are any surprises 😉

Edited November 8, 2023 by The60mmKid

[The60mmKid]

It's also worth noting that, under certain conditions (i.e., bad seeing), smaller, premium telescopes can be pushed to higher magnifications than larger scopes since they are magnifying a narrower column of turbulent air. But resolution is related to aperture, so 200x through my intrepid 60mm Tak, while impressive, is not necessarily 2x better looking than 100x through my 6" mak-newt unless the seeing is truly dire.

Edited November 5, 2023 by The60mmKid

[dweller25]

Hello @johnturley, this may be of interest…

https://www.firstlightoptics.com/takahashi-other-accessories/more-blue-universal-finder-base-for-tak.html

[johnturley]

36 minutes ago, dweller25 said:

Hello @johnturley, this may be of interest…

https://www.firstlightoptics.com/takahashi-other-accessories/more-blue-universal-finder-base-for-tak.html

Thanks for the info, this might be useful, although according to FLO's website its out of stock at present. 

John 

Edited November 5, 2023 by johnturley

[dweller25]

Hello @johnturley

I also have a bad back and have recently totally changed my telescopes to suit this.

I sold my TSA102 and replaced it with a DZ - the DZ is lighter, cools quicker and optically I see no planetary performance difference. This is my keeper scope and will grow old(er) with me 🙂

I sold my FS128 as the whole setup was just too heavy - the FS128 outperformed the DZ in all areas.

I have only ever used the DZ up to x232 on Mars and it was very sharp, I don’t know how much higher I could go as my local seeing conditions just North of Manchester are not good.

Your question about how the DZ compares to a non- premium 120-127 ED is very interesting and one I have mulled over for quite some time because I miss the FS128 views - but not the weight 🥴

After doing a bit of research I decided that if I wanted a larger but lightish refractor then I probably would not see much difference at the eyepiece with a SW120ED.

The new crop of 125mm FPL53 F7.8 ED’s could give a reasonable improvement but are not light enough or short enough for my Vixen GP. Perhaps your ES127 will be similar ?

The obvious refractor choice would therefore be a TSA120 but at £4.5k I’m not sure the wet, cloudy Lancashire skies are worthy of it.

So I bought a used Mewlon 180 !

The M180 is light and short and sits nicely on my light Vixen GP, it outperforms my DZ in all areas - apart from cooldown - by a significant margin. I suspect it has very similar performance to the FS128. So I no longer need to consider another refractor.

Just giving you a data point on your question and I’m looking forward to your comparison  👍

 

 

Edited November 5, 2023 by dweller25

[johnturley]

3 hours ago, dweller25 said:

 

 

The new crop of 125mm FPL53 F7.8 ED’s could give a reasonable improvement but are not light enough or short enough for my Vixen GP. Perhaps your ES127 will be similar 

 

 

I agree that the 100 DZ might be hard pressed to outperform, or even equal the performance of the new crop of 125mm FPL53 ED Doublets, but I am getting the 100 DZ partly because I want a lighter and more portable instrument.

Unfortunately for me, the new crop of  125mm ED Doublets  costing around £1,500, might also make it more difficult for me to get a decent price when it comes to selling my Explore Scientific 127mm FCD100 Refractor, which currently costs around £2,200 new. About 10 years ago Explore Scientific 4-5in ED Refractors, alongside the Skywatcher ones, were quite popular choices for Amateur Astronomers, but currently, although still in production, they rarely get a mention.

John 

Edited November 5, 2023 by johnturley

[Stu]

I view the performance of my FC-100DC in the context of everything else it has to offer, namely being just about the most compact, lightest 4” scope around which is airline portable and cools very quickly. It doesn’t defy the laws of physics, but gives excellent views of a whole range of targets; Lunar, Solar, planetary, doubles and widefield deep sky. You could argue it doesn’t have the aperture to do too well on DSOs but within its limitations it does well enough.

Mine remains my most used scope, not because of its brand name or anything daft like that, but simply because it is always ready to go, sitting on its ScopeTech mount and Gitzo tripod, able to take advantage of even a 15 minute window. You could argue that it shows me much more than a larger scope, just because it is used so much more.

I hope you enjoy the DZ 👍

[Peter Drew]

I have a 4" Vixen FL, widely regarded as being on a par with some 4" Takahashi's, unsurprising as Canon supply the objectives for both makes.  The Vixen gives textbook quality star images and virtually no false colour.  However, these days I need in excess of 200x magnification to comfortably see much detail on planets and at that magnification, in my average seeing conditions, the planet gets dim and often agitated.  So although I've often been tempted, for me it looks like it might be money wasted as I can't remember the last time that I used the Vixen.  I still believe that the experience of the observer and seeing conditions play a large part in what "beats" what.    🙂  

[johnturley]

3 hours ago, Stu said:

I view the performance of my FC-100DC in the context of everything else it has to offer, namely being just about the most compact, lightest 4” scope around which is airline portable and cools very quickly. It doesn’t defy the laws of physics, but gives excellent views of a whole range of targets; Lunar, Solar, planetary, doubles and widefield deep sky.

One of the reasons I went for the 100 DZ was that according to Takahashi it is easily carried on most commercial flights, although I have received conflicting reports about that, so it probably depends on the airline, and would need to check with them.

I did have some thoughts of taking it to Mexico when we go to view the total solar eclipse next April, but as this trip involves multiple internal flights, probably best not to risk it on this trip, and confine taking it to Tenerife some time, where we usually fly with JET2, who are usually fairly relaxed about what you can take in the cabin, and I wouldn't mind paying a bit extra for it if needs be. 

John 

[Stu]

3 hours ago, Peter Drew said:

 

I have a 4" Vixen FL, widely regarded as being on a par with some 4" Takahashi's, unsurprising as Canon supply the objectives for both makes.  The Vixen gives textbook quality star images and virtually no false colour

 

Having both an FC-100DC and Vixen FL102S, I can confirm there is nothing in it optically between the two, to my eyes at least 👍.

I do find floaters an increasing issue with smaller scopes at high power, binoviewers are the only way for me now, or more aperture of course.

[JeremyS]

11 hours ago, johnturley said:

One of the reasons I went for the 100 DZ was that according to Takahashi it is easily carried on most commercial flights, although I have received conflicting reports about that, so it probably depends on the airline, and would need to check with them.

I did have some thoughts of taking it to Mexico when we go to view the total solar eclipse next April, but as this trip involves multiple internal flights, probably best not to risk it on this trip, and confine taking it to Tenerife some time, where we usually fly with JET2, who are usually fairly relaxed about what you can take in the cabin, and I wouldn't mind paying a bit extra for it if needs be. 

John 

Indeed, different perspectives on airline portable. I would not want to unscrew components which leaves me with an OTA ca 62 cm long (dew shield retracted, no diagonal). This is too long for carry on baggage on any airline.

I have an FC 76DCU, which splits into 2, for airline carry on.

[JeremyS]

20 hours ago, johnturley said:

I have owned several different scopes both Reflectors and Refractors over the years, but have never previously owned a Takahashi Refractor, and have been intrigued by claims from some Tak owners, that their scopes provide razor sharp images of planets at 100x or even 120x per inch of aperture, which would equate to around 400x for a 100mm scope. I found this somewhat surprising, as it is very rare that I can use to advantage, a magnification in excess of 300x with either my 14in Newtonian or 150mm Esprit Refractor.

Earlier this year I injured my back trying to lift a gate off its hinges, and its taken nearly 6 months to recover, hence I came to the conclusion that at my age (74) my CPC 9.25 was now getting a bit heavy to lift comfortably. In addition I was also under some pressure from my wife to reduce the number of scopes in the conservatory (which housed both my CPC 9.25 and Explore Scientific 127 Refractor), and to be honest I’d hardly used the CPC since in 2019 purchasing my Esprit 150 (which gives similar planetary performance), and which is conveniently mounted piggyback on my 14in Newtonian in my observatory shed. I purchased the CPC back in 2014, as at the time I was thinking over moving house, and wanted something at was at least semi-portable, and with a computerised GOTO facility. The C9.25 was at the time recommended by Damien Peach for its performance on planets, but with hindsight it might have been better purchasing a C9.25 OTA and GEM separately, but at the time I don’t think that most GEM’s offered a computerised GOTO facility.

At 9kg (with tube rings, finder and diagonal) my ES 127  (which used to be mounted piggyback on my 14in before I purchased the Esprit, and is currently mounted on a Skywatcher AZ-EQ5) is no lightweight either, and ideally I could do with something more portable. I worked out that if I sold both the CPC and the ES 127, I could roughly fund the purchase of a Tak 100DZ. However I decided that I would sell my CPC first, and keep my ES 127 a little longer, so that I could also satisfy my curiosity as how the Tak would compare to a larger non premium scope such as the ES 127. I have already compared the ES 127 to the Esprit 150, and found the latter to be streaks ahead, more than you would expect from just an extra 23mm of aperture, which I put down to the superior quality of the Esprit lens, and I am not expecting a 100mm Tak to come close to this.

I will mount the 100 DZ on my existing AZ-EQ5 mount, and for the purpose of doing the comparison,  can potentially mount both scopes on it in AZ mode. The AZ-EQ5 mount is not exactly lightweight either, and I might in future look for a lighter mount for the Tak, but should only require one rather than two balance weights with the 100 DZ, making it marginally lighter.

I finally sold my CPC 9.25 last week, and contacted Rother Valley Optics to order my 100 DZ, which they expect to come into stock next week. At £2,905 for the DZ OTA, this did seem a high price for a 100mm Refractor, and I was tempted by the cheaper 100 DF, which RVO currently have on offer at £2,049 for the OTA, and the performance of which some have stated is virtually equal to that of the DZ. However I decided to stick with my original plan to go for the longer focal length DZ, with its sliding dewshield. I have also decided to pay the extra for a Zygo test, so that I can be 100% certain of its optical quality, Es Reid (whom I know personally) told me that he has occasionally come across what he described as a ‘Friday afternoon’ Tak. Adam at RVO informed me that if the scope does not come up to the expected optical standard in the test, then they sent it back to Tak and get a replacement. I will be picking up the scope from RVO, who are only about 15 miles away from me, so I can be 100% certain that no damage, or mis-alignment of the optics takes place in transit.  I decided to go for the basic OTA as @mikeDnight kindly offered me a spare Tak clamshell, and rather than pay £171 for a Tak 6x30 finder, or £322 for a 7 x 50 finder, I have purchased a second hand Skywatcher 9 x 50 finder for £30, but I expect that I will need to buy the genuine Tak finder bracket.

I will post an update after getting the 100 DZ, and after I have had a chance to compare it with my other scopes.

John

 

I think you will find the FC 100 a very big step down from the C9.25 on planets. I realise you want to do this for weight reasons, but just commenting so your expectations are moderated.

Having said this, I find the Tak FC 100DZ a very fine telescope.

[Paz]

My preferences are influenced partly by my eyesight. I find that at smaller exit pupils what I can see seems to drop off what others can see. So I observe with as much aperture as I'm prepared to set up and that the conditions will allow.

My 4" f7 refractor has been my most used scope, because of the relationship between how easy it is to use and how good the views are. The set up time for my 4" and 3" refractors is the same and so the 3" is not used except for travel or for solar Ha with a Quark where I need to keep the magnification down.

Since I got a light weight 125mm refractor that has become my most used scope, now that  I'm used to balancing and using it I can set that up as quickly as the 3" or 4" and I benefit from the bigger aperture.

It does require a little more effort to handle but luckily I'm currently able to handle it and it looks like that's taking over as my most used scope.

However, I still fantasise about owning a DZ one day!

[Mr Spock]

I have had the Starfield 102mm and currently have a FC100. I can can say there isn't much difference between them as far as revealing detail is concerned. As someone said though, they don't defy the laws of physics. A 120mm or 125mm apo will show more detail, but, you have to decide if the increased weight and size are suitable. My 4" works great on an EQ5 - the 120mm achro I have does wobble in the wind. I'd suggest for a 120mm+ class at least an HEQ5 or EQ6 would be better. Plus the 4" is ready to go as soon as I put it outside - the ultimate grab and go? As for magnification I find it at it's best at around x230. More just makes things bigger and darker.

As for image quality of the Tak. I can say the views I've had of Jupiter recently are far better than any view I had in the ten years I owned a C9.25  The C9.25 was great on the moon, but on planets it was soft and mushy; I never could pick out belt detail on Jupiter. I did comfortably split a 0.7" double with it though. My previous scope, a 10" Newt, was far better and gave me the best views of Mars I've had. I swapped it for a C9.25 because the 10" was a pig to lift onto the EQ6. I've yet to point the 12" at Jupiter but I have high hopes for it as on the moon it leaves the 4" way behind 

[johnturley]

3 hours ago, Mr Spock said:

 

As for image quality of the Tak. I can say the views I've had of Jupiter recently are far better than any view I had in the ten years I owned a C9.25  The C9.25 was great on the moon, but on planets it was soft and mushy; I never could pick out belt detail on Jupiter. I did comfortably split a 0.7" double with it though. My previous scope, a 10" Newt, was far better and gave me the best views of Mars I've had. I swapped it for a C9.25 because the 10" was a pig to lift onto the EQ6. I've yet to point the 12" at Jupiter but I have high hopes for it as on the moon it leaves the 4" way behind 

Hi Michael

That's interesting, a couple of years ago I did a shoot out under good viewing conditions, looking at fine craterlets in the Mare Crisium on the moon between my 14in Newtonian, Esprit 150, and ES 127 Refractors, I would have included the CPC 9.25, only my wife had boxed it in in the conservatory with a large potted Argave that she had taken in for the winter (which is another reason besides my back that I decided to sell the CPC). Although of course the 14in Newtonian gave a much brighter image, there was very little to chose between it and the Esprit 150 regarding the visibility of the small craterlets and sharpness of the view. The ES 127 was on the other hand some way between the other two, the view was less sharp, and it failed to show some craterlets that were clearly visible in the other two scopes. As I mentioned previously, the CPC more or less became redundant after I purchased the Esprit, but held on to it as I don't like parting with telescopes, and based on your experience on Jupiter with your CPC 9.25, it sounds like the Esprit is superior to it on planets, as I have recently been able to see a lot a detail in the cloud belts of Jupiter through it. In fact 9 out of 10 nights it gives a more pleasing view, than the 14in Newtonian, but the latter does give a better view under very good seeing conditions. However when it comes to deep sky objects and comets, there is no comparison between the two instruments, the larger reflector wins hand down every time, but the wider field of the Esprit does however enable me to fit the whole of the Pleiades and most of the Andromeda Galaxy in one field of view (using the Vixen 42mm LVW). I am fortunate perhaps that my 14in Newtonian is on a massive fork mount built by Astro Systems (Luton) in the 1980's , which can also handle the weight of the Esprit, and would cost a fortune these days. In fact the mount has its similarities to the Taurus Fork Mount which costs £18,000 at FLO, but with a larger 720 teeth brass worm, but of course no computer control or GOTO. 

I do not expect the 100 DZ to come close to either of the above two instruments, but I purchased it to provide me with high quality portable instrument, and will enable me to move it around the garden to view objects which are blocked off from my observatory shed by trees and houses, and possibly take on holiday, although for the latter I will require a lighter and more portable mount than my current AZ-EQ5. It will be interesting to compare it with my ES 127 Refractor before I sell it, but I will not be unduly disappointed if it turns out to be not quite as good. 

John 

Edited November 6, 2023 by johnturley

[MartianHill]

I use my 4” refractor on a Skywatcher AZ4 and it’s a really good combination for getting out quick and viewing. Even high power planetary is possible.

[Stu]

@johnturley have you considered the  Sightron AltAz mount? Looks very similar to the ScopeTech Zero which is no longer available and suits my FC-100DC perfectly. I use mine of a Gitzo tripod but one of the lighter Berlebachs would work well I’m sure.

https://www.firstlightoptics.com/alt-azimuth-astronomy-mounts/sightron-japan-alt-azimuth-mount.html

[johnturley]

1 hour ago, Stu said:

@johnturley have you considered the  Sightron AltAz mount? Looks very similar to the ScopeTech Zero which is no longer available and suits my FC-100DC perfectly. I use mine of a Gitzo tripod but one of the lighter Berlebachs would work well I’m sure.

https://www.firstlightoptics.com/alt-azimuth-astronomy-mounts/sightron-japan-alt-azimuth-mount.html

Thanks for the info, I might need something like that if I decide to take the scope on holiday.

[mikeDnight]

Hi John,

 When I bought a FC100DC in early 2015 I was able to compare it on the night of first light to my Equinox 120ED. The 120ED had given me many stunning planetary views, but in side by side comparison on that first night I remember giving a rather loud "WOW!" when looking through the DC at Jupiter. The belts were visible in both scopes but through the DC they appeared much more vibrant. I've mentioned in a previous post that the belts appeared almost as if they were braided around the planet. Festoons, garlands and white ovals were more obvious - better defined in the DC. 

 During the 2016 apparition of Mars the planet was pitifully low in our UK skies, and I remember a few grumbling on SGL that it basically wasn't worth observing. Throughout that apparition I observed the planet at virtually every opportunity and made many sketches. It really was an awesome experience! Even when Mars was shrinking and becoming very tiny, the DC still kept on surprising me with its high definition, high contrast views.  I know looking at looking at someone's sketches may not float everyone's boat, but I've attached these sketches, the first made at the telescope and the second a cleaned up version made shortly afterwards. Note the diameter of the planet, the magnification, and the level of detail still visible over time. The planet was under 6 arc seconds, so how small were some of the features? I was using a binoviewer which I believe helps, but never the less it still leaves me amazed when I look back and remember such awesome performance from such a small scope.

 

There may be times when your 127ED outperforms your new DZ, but when you consider our poor UK seeing, it wouldn't surprise me if you DZ gives better performance much more often. I now have a FC100DZ and can tell you there's virtually no meaningful difference between the DC/DF and the DZ visually other than the DZ being a touch cooler in tone. Both will give high power views when seeing allows. Tak boast about the DZ being a high power scope in their user manual, so I thought I'd see how true their claim was, so I barlowed my 1.6mm Vixen High Resolution eyepiece giving 1000X in the DZ and checked out a few close binaries. The views were simply gorgeous! I never did push my DC so much, stopping at a mere 474X, but I'd be fairly confident that it too wouldn't disappoint on a steady night.

 

Edited November 6, 2023 by mikeDnight

[Sunshine]

Hello! I would like to add my two cents worth, regarding magnification per inch of aperture you may want to knock down expectations a bit when it comes to numbers like 100-120x per inch. These numbers can be done with a 4" scope but not without image breakdown and only on those RARE night where the atmosphere seems to have disappeared. Rarely can I push past 230-250 without noticeable image breakdown on planets, Saturn holds up the best when pushing high numbers but in the end there is no substitute for aperture. As much as I love my 102, I do recall having some memorable planetary images with my 6" SW Mak, when it comes to splitting stars, well that's a different story. No mirrored scope I ever had presents stars like my 102, I don't care how big they were. With the DZ you will have a supreme example of a 4" refractor, and even though it may be 20mm smaller than a SW 120, the SW may be able to produce more detail but the Tak will quickly show it's mettle in the contrast and clarity department, you will see what I mean, Tak 4" scopes are special.

[John]

I'm a bit late on this (I've been away) but I have a Tak FC100-DL (the F/9 limited edition that the F/8 DZ replaced) and also an early gold tube Skywatcher ED120.

While not a DZ I believe that the performance of the Tak DL is very, very close to that of the later DZ model. 

I have found that the FC100-DL gets very close to the performance of the ED120 on planetary and lunar resolution and contrast, especially if the seeing conditions are less than very good. It never quite beats the ED120 though, at least to my observing eye.

On double stars the ED120 will resolve tighter splits as the aperture difference suggests it should. 

On DSO's the additional 20mm of aperture also gives the ED120 an edge in terms of, for example, depth of resolving globular clusters, spotting a faint galaxy or the extent of nebulosity that can be seen.

At focus the ED120 shows a touch of CA around the brightest point sources such as Sirius or Vega. Nothing detectable on the lunar limb or around Saturn or Jupiter. The Tak FC100-DL shows no discernible CA at focus or either side of it on such targets.

I thought I might move the ED120 on when I got the Tak FC100-DL and a TMB/LZOS 130mm F/9.2 triplet back in 2016 but I've not found it out classed by any means and it's still a valued and much used scope.

I find that both the FC100 and the ED120 useful at up to 300x quite regularly (on suitable targets of course) and sometimes push up to the 350x mark on tight doubles or for faint point sources such as supernovae or faint planetary moons.

I hope that helps a little at least. 

Edited November 7, 2023 by John

[Fedele]

On 7/11/2023 at 17:27, John said:

Sono un po' in ritardo su questo (sono stato via) ma ho un Tak FC100-DL (l'edizione limitata F/9 sostituita dall'F/8 DZ) e anche uno dei primi Skywatcher ED120 a tubo dorato.

Pur non essendo un DZ, credo che le prestazioni del Tak DL siano molto, molto vicine a quelle del successivo modello DZ. 

Ho riscontrato che l'FC100-DL si avvicina molto alle prestazioni dell'ED120 in termini di risoluzione e contrasto planetari e lunari, soprattutto se le condizioni di visibilità non sono molto buone. Tuttavia non batte mai del tutto l'ED120, almeno al mio occhio osservatore.

Sulle stelle doppie l'ED120 risolverà divisioni più strette come suggerisce la differenza di apertura. 

Sui DSO i 20 mm aggiuntivi di apertura danno all'ED120 un vantaggio in termini, ad esempio, di profondità di risoluzione degli ammassi globulari, di individuazione di una debole galassia o dell'estensione della nebulosità che può essere vista.

Alla messa a fuoco l'ED120 mostra un tocco di CA attorno alle sorgenti puntiformi più luminose come Sirio o Vega. Niente di rilevabile sul lembo lunare o attorno a Saturno o Giove. Il Tak FC100-DL non mostra alcuna CA distinguibile al fuoco o su entrambi i lati su tali obiettivi.

Pensavo di poter spostare l'ED120 quando ho acquistato il Tak FC100-DL e un tripletto TMB/LZOS 130mm F/9.2 nel 2016, ma non l'ho trovato classificato in alcun modo ed è ancora un telescopio apprezzato e molto utilizzato .

Trovo che sia l'FC100 che l'ED120 siano utili fino a 300x abbastanza regolarmente (su obiettivi adatti ovviamente) e talvolta si spingono fino al limite di 350x su doppi stretti o per sorgenti puntiformi deboli come supernovae o deboli lune planetarie.

Spero che questo aiuti almeno un po'. 

I had  the same 120 ED golden version and the FC100 DL. I sold the 120 ED with no dubt, but FC100Dl have clour intra ed extra. 
I buyed the TSA120 and i sold with no esitation the FC100DL

[John]

7 minutes ago, Fedele said:

I had  the same 120 ED golden version and the FC100 DL. I sold the 120 ED with no dubt, but FC100Dl have clour intra ed extra. 
I buyed the TSA120 and i sold with no esitation the FC100DL

Sounds like you had different experiences with both your ED120 and your FC100-DL to mine then. 

My FC100-DL performs very much like a smaller aperture version of my TMB/LZOS 130mm F/9.2 triplet. No false colour visible (to me) in either scope.

 

Edited November 8, 2023 by John

[dweller25]

1 hour ago, Fedele said:

FC100Dl have clour intra ed extra. 

 I find best results are at perfect focus.