FeatherTouch Microfocusers (TVRF & TVRFB) for Televue

http://www.buytelescopes.com/product.asp?pid=9960

Has anyone retrofitted their Televue focuser with one of these FeatherTouch units? ...or had a chance to use one? Looks like an attractive option if you're content with the stock TV focuser travel.

Was wondering if it performed to expectations and how difficult it was to install. How does it compare to the full FT focuser?

At $220 to $250 they seem a little pricey for what you get, but an easy bolt on upgrade beats replacing the whole focuser.
Bob

Bob Young said:

http://www.buytelescopes.com/product.asp?pid=9960

Has anyone retrofitted their Televue focuser with one of these FeatherTouch units? ...or had a chance to use one? Looks like an attractive option if you're content with the stock TV focuser travel.

Was wondering if it performed to expectations and how difficult it was to install. How does it compare to the full FT focuser?

At $220 to $250 they seem a little pricey for what you get, but an easy bolt on upgrade beats replacing the whole focuser.
Bob

Hi Bob,

I would recommend using the TeleVue upgrade for your focuser. With the Feathertouch version, you risk upsetting the collimation of your scope and would most likely void the warranty. I admit that I have little experience with either version, I use the stock focuser on my TV-85.

I replaced the stock TeleVue Pinion on my TV-102 with the TVRFB unit from Feathertouch a while back, and I couldn't be happier! The quality of the FT unit is excellent, the feel of the focuser during high speed movements is very smooth, and the fine adjustments when you are looking for that perfect focus at high mags is unbelievable. I've used mine with a diagonal and eyepiece......and with a five eyepiece TEC turret (loaded) and the added weight didn't seem to phase it. I'll tell you about use with a Bino set in a few weeks.

These are great - high recommended!

I had tried to install one of these but found TeleVue loc-tited or otherwise overtorqued the pinion block screws on my TV85 and the heads on two rounded out on me. Rather than try for a repeat on the other two screws and be stuck with a focusmate which I think is horribly bulky, I scrapped the entire TV focuser with a Feathertouch 2025BCR and used the TeleVue adaptor that screws on to the tube in place of the stock focuser. To do this, the epoxied over set screw on the bottom of the focuser body had to be carefully dug out with small jewelers screwdrivers and picks until I could back it out.

The FT replacement is gorgeous and makes the scope so much more usable! Collimation is perfect and precision is a dream and I can set it for no creep when looking overhead. Here is where the brake is a must have as you can eliminate any tendancy for the focuser to rack itself out but keep the fine focus extremely light in required force to allow precise focusing even on a lightweight mount. The config shown here allowed me to just focus with a 22mm Pan on a AP Maxbright. Eyepieces requiring more out travel caused e to add a 0.65" riser block between the focsuer and tapered adaptor, or to use an extension tube in the focuser or diagonal.

I think the only thing you'd potentially screw up on a TV by removing the pinion is if you removed the draw tube from the focsuer and dropped the shims that set the drawtube in position. It is a red herring issue. After adding the FT, I realized I'd never been able to really get critical focus at high power with the stock focuser and it behaves and balances like a whole bunch nicer scope!

Dave

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Bob Young said:

Has anyone retrofitted their Televue focuser with one of these FeatherTouch units?

I've installed two of them on my scopes. After seeing what TeleVue's Focus Mate looked like, I put myself on the waiting list for the first TVRFB's to be delivered. My first TVRFB went on my old TeleVue Genesis SDF (see attached photo) and it worked great, so I kept an eye out for a used one and grabbed the first one I saw on A-mart (another TVRFB) and installed it on my TV76. I considered putting one on my Pronto but since I only use it for Solar viewing, I saw no need.

Was wondering if it performed to expectations and how difficult it was to install.

They both perform flawlessly. The TVRF(B) have a 10:1 fine focus as opposed to the Focus Mate's 6:1 ratio. It takes a little careful adjustment to get them just right but it's not difficult. Some words of warning:

1. The original TV pinion block screws will be TIGHT. Also, the screw head sockets will be filled with black paint which must be scraped out first to ensure a good Allen wrench fit. To remove them, use a good quality US made Allen wrench of the proper size and grind the end of it flat to give a full depth hex shape which will bite into the screw head.

2. Upon removing the original TV pinion block and pinion shaft, DO NOT pull the focuser draw tube out of the focuser housing - you will never get it back in right. (This is a warning from David Nagler himself.)

3. Follow the TVRFB instructions carefully and you should have no problems. Installation took me about 45 minutes, being slow and careful.

How does it compare to the full FT focuser?

Dunno, never had one.

At $220 to $250 they seem a little pricey for what you get, but an easy bolt on upgrade beats replacing the whole focuser.

When you see and feel the quality of the TVRFB, you will know you got your money's worth. Also, I like the version with the brake screw as it enables you to vary the tension of the focuser easily for just the right feel.

Attached Image:

I installed one of these on my TV-102 (a recent black draw tube model). Though a dual speed focuser is likely superfluous at f/8.6 given its significant depth of focus, the precision of the Feathertouch was heads and shoulders above that of the stock Televue knob and pinion assembly. Prior to installing the upgrade the stock focuser displayed some side to side rocking as the draw tube was racked out, though it was quite smooth. The twisting is gone post Feathertouch and the action is even smoother.

I have two left thumbs and found the installation to be completely simple. The only "adjusting" I needed to do was adjusting the contact tension of four small nylon ball bearings against the draw tube. This sounds harder than it is. Inset allen screws pressure the back side of the nylon bearings. I had them a bit loose at first, then a bit tight, and then backing them off got them perfect. It's an amazing upgrade over the stock focuser and I would call it a "must" on any of the fast Televue Petzvals.

Regards,

Jim