Tak FC100DL F9

[25585]

Having just acquired a 4 inch F9 900mm SW Equinox, I looked up the Tak equivalent and the DL is it. https://www.takahashiuk.co.uk/Refracting-Telescopes/Takahashi-FC100-DL/374-/Takahashi-FC100-DL

Has anyone got the DL, as it would be cool to know how that particular FL compares with SW best 100mm doublet?

[John]

I have one. A few other members do on here as well. The 1st run was limited to 100 units worldwide. The 2nd run added a further 100 units to that. Don't know if any new ones are left in the UK now

It's the best scope optically that I've observed through (well, joint best with the TMB/LZOS 130 F/9.2) It's been a long time since I had the SW 100ED so I can't compare directly. I have compared with my Vixen ED102SS and the Tak FC100DL produces a slightly tighter star test and shows no CA on any object either at focus or either side of it and supports higher magnifications than the Vixen can. I can't see how a 4" scope could perform better than the Tak does.

The shorter F/7.4 version of the Tak (not a limited production) is very similar to the longer one in performance.

 

[25585]

Ian King (whom I rang about the discontinued TSA102 triplet) said he has a few DL left, then they are gone. DF on order, DC in stock. 

[mikeDnight]

The difference is essentially the quality of optical figure! The figure on the lenses used by Takahashi is truly top class, hence the very high price.

The SW100ED F9 is a very good telescope and performs way above what its price point would suggest. The Takahashi FC100DL however is in another league as far as optical quality goes. This doesn't mean that there's an immediate difference in performance. You would notice the colour correction on the FC100DL is better, with absolutely no CA visible, while there is some residual CA in the SW ED. It should be noted however, that CA is NOT the big bad guy that many often portray it as, at least in a well corrected ED such as the SW100. Eyepieces introduce CA as well, especially wide angle designs, yet we all use eyepieces! The greatest difference would probably be in regard to spherical aberration, which is essentially non-existant in the Tak. This will allow the Takahashi to take higher magnification on nights of good seeing, and the Taks fluorite element will offer greater light transmission than the ED's FPL53 objective, though this would probably only be noticeable on dso's on a transparent night.

[AstroSylv1]

I have a DL that I got from the first run, it is my first Tak, I had a SW 100ED gold version before that. Everything is better in the DL, optics and mechanics.

[Doc]

The Tak FC100DL does sound an awesome scope and being F9 great for double stars, and Lunar but just thinking out loud for a moment.

How would it compare against a Skywatcher 120ED Esprit triplet F7.5.

Would the extra aperture make much difference, would the triplet to doublet make a difference?

[Stu]

49 minutes ago, Doc said:

The Tak FC100DL does sound an awesome scope and being F9 great for double stars, and Lunar but just thinking out loud for a moment.

How would it compare against a Skywatcher 120ED Esprit triplet F7.5.

Would the extra aperture make much difference, would the triplet to doublet make a difference?

That would make a very interesting comparison.

@John has a 120ED and a DL, not sure I've seen a direct comparison from him between those two but I guess it would be indicative of the Esprit?

I've always thought my DC would be a little behind a 120ED in resolution but the portability makes up for it in terms of useability for me.

[25585]

For the DL, does the lens at the back of tube impair back focus, in the same way a Petzval might be affected?

If so would one of the shorter focal lengths be better for bino viewers and attachments that may need more focuser travel?

[Stu]

17 minutes ago, 25585 said:

For the DL, does the lens at the back of tube impair back focus,

What lens at the back of the tube? There isn't one...

[John]

10 minutes ago, 25585 said:

For the DL, does the lens at the back of tube impair back focus, in the same way a Petzval might be affected?

If so would one of the shorter focal lengths be better for bino viewers and attachments that may need more focuser travel?

As Stu says, there is no lens at the back of the tube. It's a straightforward doublet with a flourite element. The flourite element is now the rearmost wheras with the FS 102 it was at the front I believe.

The ED120 does a little better on DSO's but on double stars, the planets and the moon, the two are very similar. The ED120 shows a little CA around the brightest stars at focus, which the Tak does not and the ED120 shows a small about of CA inside and outside focus on the lunar limb, but no CA at focus on that target. I have a triplet in the TMB/LZOS 130 F/9.2 and that performs like the Tak FC-100DL but more of it.

The Tak seems comfortable with similar magnifications to those which I can use with the ED120, ie: 200x - 300x and occasionally a little more for a really tight double star.

 

[25585]

What I was referring to and probably over-interpreting was from the description thus;

"Utilizing a Steinheil design, the objective places the fluorite element at the back of the f/9 optical tube and with a 900mm focal length, the observer can view both terrestrial and deep sky objects objects at high magnification with color free views."

[John]

[Stu]

7 minutes ago, 25585 said:

What I was referring to and probably over-interpreting was from the description thus;

"Utilizing a Steinheil design, the objective places the fluorite element at the back of the f/9 optical tube and with a 900mm focal length, the observer can view both terrestrial and deep sky objects objects at high magnification with color free views."

Ah, that looks like a bit of cumbersome language, it just means the element which is nearest the back of the tube, even though it is still at the front. Hope that makes sense...

[AstroSylv1]

Together with my DL, I had a TSA 120, and well, after half a year, I sold the TSA : here is why : for long nights of DSO, I have a large 16inch Dobsonian, therefore, my little refractors are mostly for shorter nights of Lunar, planetary, double stars and carbon stars. The extra gain of aperture of the 120mm could never justify the extra weight (like 2 or 3 kg extra), and the cooling time was significantly longer in the triplet... all in all, the DL gives me more observing time and less hassle, for a very tiny small compromise in light gathering power. Don’t get me wrong, on a night of good seeing, the gain in aperture is visible, but most nights, it is not « that » obvious, added to the weight and cooling time, I kept the DL...

now, I think the Esprit 120 triplet might just be as heavy and as long to cool down as the TSA.

[AndyH]

Someone(importer?) should have edited the original blurb, replacing 'back' with 'rear' and 'tube' with 'cell or lens cell' . i think would have read better

[25585]

15 minutes ago, John said:

 

Susceptibility to atmospheric attack. I remember that being said about early Vixen flourite refractors, which maybe were Steinheil, or all-flourite. ???

 

[AndyH]

Does the DL come with the Tak fine focus knob add on as standard?

[John]

3 minutes ago, AndyH said:

Does the DL come with the Tak fine focus knob add on as standard?

The 1st run had a 2.5" single speed focuser. Not sure about the 2nd run

[25585]

1 minute ago, John said:

The 1st run had a 2.5" single speed focuser. Not sure about the 2nd run

IK said they were single speed on the shorter fl models, but the DF focuser, still single, is better than DC as meant for imaging, and is designed for heavier loads.

[John]

5 minutes ago, 25585 said:

 

Susceptibility to atmospheric attack. I remember that being said about early Vixen flourite refractors, which maybe were Steinheil, or all-flourite. ???

 

A flourite+flourite doublet won't work !

I think the Vixen FL 102's used a flourite crown element in a fraunhofer configuation so the CaF2 element was at the front

 

[AndyH]

Mmmm. perhaps the pics i've seen of folks posting their new precious, have added that item.

I wasn't sure of the black focuser at first, but the shock a non green/blue Tak rear end has softened since

[Stu]

3 minutes ago, 25585 said:

IK said they were single speed on the shorter fl models, but the DF focuser, still single, is better than DC as meant for imaging, and is designed for heavier loads.

Not sure why the DL would be any more suitable for imaging than the DC? Perhaps planetary imaging but not deep sky...

[AndyH]

there was something about having to be careful about coatings and fluorite. Perhaps a modern HD coating still can't be done, hence the change in design. Not sure, but something in my brain is niggling me reg coatings and fluorite. 

[Doc]

19 minutes ago, disciplus55 said:

Together with my DL, I had a TSA 120, and well, after half a year, I sold the TSA : here is why : for long nights of DSO, I have a large 16inch Dobsonian, therefore, my little refractors are mostly for shorter nights of Lunar, planetary, double stars and carbon stars. The extra gain of aperture of the 120mm could never justify the extra weight (like 2 or 3 kg extra), and the cooling time was significantly longer in the triplet... all in all, the DL gives me more observing time and less hassle, for a very tiny small compromise in light gathering power. Don’t get me wrong, on a night of good seeing, the gain in aperture is visible, but most nights, it is not « that » obvious, added to the weight and cooling time, I kept the DL...

now, I think the Esprit 120 triplet might just be as heavy and as long to cool down as the TSA.

I couldn't agree more with everything you have said.

The weight and cool down time is what lets the Esprit 120ED down. But I do love the Esprit, there is no CA at all and once cooled the views are to die for so you have to make compromises somewhere. I would love a Tak though 

[John]

 

7 minutes ago, Doc said:

I couldn't agree more with everything you have said.

The weight and cool down time is what lets the Esprit 120ED down. But I do love the Esprit, there is no CA at all and once cooled the views are to die for so you have to make compromises somewhere. I would love a Tak though 

Thats the same with my TMB/LZOS 130 F/9.2. Weight, cool down, mounting and setup combine to require quite a bit more effort than the Tak FC-100DL but the results are also quite superb so you don't regret making the effort. It is nice to have the choice though - tonight the FC-100DL is out (prompted by this thread of course !)