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Optec TCF-S Temperature Compensating Focuser, Serial Version w/RS-232

4.3 out of 5 stars
3 customer reviews

Price: $875.00

Unique to the TCF focuser, an electronic controller system monitors the telescope's tube temperature and compensates the focus accordingly. A small temperature probe is attached to the side of the telescope tube and monitors temperature with a resolution of 0.1°C. For a typical Schmidt-Cassegrain of 8 to 11 inches aperture and f/10 focal ratio, the back focus will move approximately 0.010 inches for every 1°C change in telescope temperature. It is not unusual during an observing session for the ambient temperature to change by as much as 10°C within the time span of a few hours. This change in focus due to temperature is a serious problem for most telescope designs and requires frequent re-focusing during long exposures. A typical RGB exposure sequence can last one hour making it imperative that the focus be checked and corrected after each filter change.

A simple learning procedure is used to find the temperature coefficients specific to the user's telescope system. The TCF system allows for two different coefficients (corresponding to two different f-ratio configurations) to be calculated and stored in the EEPROM memory. Once learned, either coefficient can be selected with a simple slide switch. A manual mode allows the user to set the focus manually at any time.

The digital nature of the TCF allows opportunities for truly intelligent focusing. Using TTL level electronics, a programmer can control the focuser from any PC. Exact focus can be found by optimizing a stellar centriod’s diameter.

At the end of an observing session, the TCF focuser remembers the last temperature and position. When the unit is turned back on for a new session, the TCF computes a new position using the current tube temperature and moves to that position. Assuming no changes to the optical configuration, the object will snap into sharp focus.

Customers Reviews

Total 3 reviews
4.3 out of 5 stars

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Most Helpful Customer Reviews

Optec TCF-S is perfect

By Donovan Conrad on October, 16th 2009

NO measurable backlash. No measurable position slippage. Smmooootthhh movement. Perfect position control. It doesnt get better in this class/price range at all.

Top This!

By Carlton Clarke on October, 16th 2009

Absolutely one of the finest focusers available. When coupled with CCDSofts @Focus automatic focusing feature, all you have to do is kick back and let the TCF-S do the mind-numbing work of establishing perfect focus for you. Highly recommended, but get a locking collar for larger SCTs to eliminate mirror flop for best results.

OPTEC Focuser needs help

By Gregory Kelly on October, 16th 2009

The software interface plus the total domination of my imaging kit by a hopeless tangle of redundant cords leaves me wishing I had spent my money elsewhere. This product needs a re-think from the top down. The only thing that saves a partial score is the focuser itself. This unit, while bulky, does what it is suppesed to do. The problems come when you need to interface it with the PC. Not only is it Rs232, the drivers are virtually impossible to load with installation completely un-intuitive and a worthless manual. On top of this, nothing works unless you buy all the accessories. These guys are either hopeless techie geeks or business sharks. In either case I recommend you stay away until they get their act together.

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