| review: Takahashi FS-60C Fluorite Apochromatic Refractor (appr. € 800,-) |
This little refractor is also known as the Baby-Tak.
Indeed it's a cute little and highly portable telescope.
The basic dimensions are:
- 2 lens fluorite apo design
- aperture 60 mm
- focal length 355 mm
- f-stop f/5.9
- max field of view 7 degrees
- rack and pinion focuser with 2 inch + adaptor to 1 1/4"
- rigid mounting ring included
The design has only two lenses.
This is good for low loss of light an reduced internal reflections.
On the other hand the color correction cannot be as good as for the 3-lens-designs with fluorite.
The flourite lens is in front giving the Fraunhofer design and hence there is a better correction for spherical abberation compared to the Steinhell design with the flourite element in the middle.
The lenses are in finest multi-coating and there is a 30 years warranty for the flourite front element (remember that untreated flourite is sensitive to moisture).
The color correction is very good to the near infra red but a bit worse in ultra violett.
This might be a problem for traditional film but is perfect for CCD cameras.
CCD cameras in general do not respond to ultra violett very much but more to infra red.
In deed, I use the FS-60C *without* IR-blocking filter for LRGB pictures.
This reduces the necessary exposure times for the luminence frame and makes the scope faster than f/5.9 would promise.
I expose all of the LRGB frames with same focus.
So no seperate focus correction for red, grren and blue is performed.
This gives only a slightly unsharp red and blue frame with the Tak.
That is not a big problem anyway in LRGB because the *sharpness* comes from the luminenece frame only.
Usage
The FS-60C is fun to use.
The focuser is very smooth in operation and allows very precise focusing which is a key to good pictures.
With that small focal length it is very good matched to my HX916 CCD camera with it's small pixels.
This combination gives a field of view of almost 1 1/2 degree!
One pixel then covers about 4 arc secs which means I can use the scope even when the seeing is on the worse end.
In other words: this scope is perfect for the bigger show pieces in the heavens like M31, M42 and others...
Example Photo
Image was taken with Starlight XPress HX916 without IR-blocking filter but with neutral grey filter to avoid over exposing.
The focal length was increased with a teleconverter 2x.
Slightly Unsharp Mask was applied.
Conclusion
The Baby-Tak is a very fine wide-angle telescope for astrophotography.
It is built to the highest standards and worth the money.
Because of low aberration and hence high sharpness you can reach *deeper* photos than you would expect with that small aperture.
Use the search tool on this site to find more astro photos taken with that scope:
Search more about FS-60C
Comment by the author 01.09.2002:
After working with the Baby-Tak for several months now, I found a little problem.
In fact the mounting ring is a bit too flexible.
During very long exposures the telescope is moving severeal arcsecodns in DEC.
I am using very small pixels in my CCD camera so the effect is visible.
Most of the other CCD or film camera users might never notice it.
Comment by Holger Dahlmann 22.10.2002:
I myself have Tak FS 60C too.
I'm very happy with this telescope, in other words, I'm totally into it.
The more I'm excited about finding your breathtaking pictures taken by the Tak.
I use mine only for observing, while watching the big planets with such a sharpness, contrast and colourfulness is incomparable with anything I have seen so far.
Some time ago I've asked for comments of those who already have the TAK at Message Board of www.astronomie.de.
Unfortunately, I didn't get too many of them.
I assume that most of the people underestimated efficiency of a perfect 2.5 inch telescope!
Nevertheless, I was very much delighted by your website.
With best regards
HD
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