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Takahashi FSQ 106


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It is amazing how whenever you buy a nice new astronomical toy the first time you look through it you'd swear it gave the best views you've ever seen

Takahashi FSQ 106

 

It is amazing how whenever you buy a nice new astronomical toy the first time you look through it you'd swear it gave the best views you've ever seen. Well, that is how I felt last night after setting up my new FSQ-106 on my balcony. Even though it was a full moon and I haven't got a good mounting system worked out yet, I couldn't resist the temptation to bring out the new toy.

 

Since the moon was full, and the roof on my balcony seriously restricts the amount of sky available for viewing, I focused on the moon. The back focus on the scope is unusually short, so much so in fact that you cannot use a standard diagonal on the telescope, you have to purchase one designed by Takahashi it you want to use one. For this test I looked straight though much of the time. I also used my Televue 2" apo 2x Powermate for part of the test. This extended the back focus far enough back so that I could attach a 1-1/4" diagonal.

 

Honestly, I really was amazed at the views this scope gave. When the image of the full moon snapped into focus I was mesmerized. Detail on the moon seemed cry out for attention, keeping my eyes glued to the eyepiece. I was able to see minute features inside of small craters that I can't recall seeing with my 8" SCT. What really knocked my socks off though were the jet black shadows. On the edge of the moon near Tycho there are many mountains that, even at full or near full moon, cast shadows. Well, in the FSQ those shadows were incredibly black. It was stunning to see the mountains in the foreground and their inky shadows silhouetted behind them—it was like there were holes in the moon that let you look through the surface and out beyond it into deep space. I got so excited about the view that grabbed my lunar 100 card and started to ID craters. It was great fun.

 

I've always liked going out observing bright objects during a full moon, but the views never seemed to be this good with my other scopes. Don't get me wrong, I love my other scopes. I own an 8" SCT, a 120mm achromat, an 80mm semi-apo, and a 60 mm achromat, but these views with the FSQ just seemed so much better.

 

As for flatness of field, the FSQ did great. I tested the optics with a few setups. I started with a straight through look using a 26mm Orion eyepiece, then moved to the Televue 2" apo 2x Powermate with the same 26mm eyepiece and an Orion 1-1/4" diagonal, then used the Powermate with a Televue 7mm Type 6 eyepiece and the diagonal. With each optical train I centered Betelgeuse and then ran it around the FOV to check for flatness. The star remained the same shape everywhere in the FOV--I tried it while wearing my glasses (they correct for my astigmatism) and without the glasses. In all instances the star did not distort from its original starting focus point at the center of the FOV. Of course without the glasses on the star was slightly distorted by my astigmatism, but even then the distortion did not change as I moved the star around in the FOV. With the glasses on, the star came to sharp crisp focus and stayed that way no matter where I placed it.

 

Color correction on the scope was flawless. This was true even at high power. The reason I wanted first light to be under the full moon was to specifically test this aspect of the scope. Looking at a full moon makes things about as bad as they can get for inducing chromatic aberration. The color correction test was conducted by pointing the FSQ at the full moon using the same setups as above (straight through with a 26mm eyepiece / Powermate with the 26mm and diagonal / Powermate with a 7mm eyepiece and diagonal). There was no chromatic aberration in the images that I can attribute to the FSQ. Surprisingly, the inexpensive Orion eyepiece faired better than the Televue. In part this is because the Orion 26mm eyepiece produced a much lower magnification than the Televue 7mm Type 6 eyepiece. The Televue eyepiece, however, had a brown fringe around the outer edge of the FOV. This fringe was there even if I took the eyepiece out of the scope and held it up to a lamp, so it is caused by the way the lens is secured within the barrel of the eyepiece. With the Televue eyepiece in the FSQ, as I moved the moon to the edge of this brown fringe the moon would start to show slight fringe color. It was a brownish color and not red, green or violet. I attribute this completely to the Televue eyepiece and not the FSQ. Even at the highest magnification (the Powermate and 7mm eyepiece brought the magnification up to 151 power) there was absolutely no chromatic aberration caused by the FSQ.

 

The last test conducted was photographic. I mounted my Nikon 35mm FM-10 film camera on the scope and shot the moon with some hypered techpan film. Focusing for the camera was accomplished with a Stellar Technologies International Series IV Stiletto focuser. The moon was photographed both with and without the Televue Powermate to compare the quality of the FSQ’s images at its native f/5 and at f/10. It will be several more weeks at best before I finish the roll of Tech Pan, but when it gets developed the photos will be posted.

 

The scope does have its shortcomings. First, it is very heavy. The OTA alone weights 14 pounds. After adding the Powermate and camera, I could not get it to balance in the dec axis. This test was conducted using an Orion Astroview equatorial mount that is designed for lightweight scopes. Balance would not be a problem on a heavier mount. I'll be putting it piggyback on my Meade 8" LX200GPS, so balance shouldn't be an issue. Were you going to use this on an equatorial platform, even just for visual use, you'd have to invest in at least a mid-range mount that would allow better balancing in declination.

 

The second problem I noted was that the FSQ has an extremely short back-focus. I was able to do everything I wanted, but the focuser was racked virtually all the way in when I photographed the moon without the Powermate. With the Powermate back focus is not an issue. Use of the Takahashi Extender Q would probably eliminate the back focus problem as well, but that was not tested. Also, a standard 1-¼ diagonal will not work on the scope due to the short back focus. Takahashi does sell special adapters for astrophotography and special diagonals. These are designed to work on the FSQ and will eliminate all back focus shortcomings. I've ordered them.

 

Overall, I am very excited to add the FSQ to my slowly growing collection or telescopes.

 

Now all I have to do is work out a good way to mount this on the LX200 and I'll be dangerous!

 

Bill Drelling




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