Newtonian
Focusers
1.25"
A simple rack and pinion design focuser. All metal construction and low cost, perfect for first telescope builders. Profile is 75mm.
This is the single most important component of telescope making. It's profile will determine various other component sizes.
There are many focusers to choose from . Below are the focusers we stock at B & T Shop;
Bintel
Newtonian
Focusers
1.25"
A simple rack and pinion design focuser. All metal
construction and low cost, perfect for first telescope builders.
Profile is 75mm.
2"
An all metal construction 2" rack and pinion
design focuser with 1.25" adapter with Brass catchment ring. No image shift,
A low cost alternative , perfect for novice and advanced telescope builders.
Profile is 75mm
Crayford Design Focusers
Everybody loves the feel of our Crayford Focusers.
Smooth operation with no image shift and none of that sticky grease to
gather dust.
Profile is 75mm. Mounting holes perfectly
match the R&P focusers used on the earler Bintel Scopes. Will fit most
Bintel / SkyWatcherscopes without having to make major changes.
And if that wasn't enough we also have the Bintel
2" 10:1 Micro Crayford Focuser .
Easy to install (can be directly swapped on most
Bintel / SkyWatcher scopes)
10:1 Reduction give Ultra Precise Control for
high powered focusing.
Makes Webcam / Planetary imaging less frustrating.
Refractor Focusers
2"
An all metal construction 2" rack and pinion
design focuser with 1.25" adapter with Brass catchment ring. No image shift,
A low cost alternative , perfect for novice and advanced telescope builders.
Has plenty of back focus.
What
is an Event Horizon Telescope Focuser?
The Event Horizon Focuser (EV) is a low-profile, friction-drive focuser designed for both the amateur and professional market. The highly acclaimed Crayford design (see below) permits tolerances up to 100 times better than conventional rack-and-pinion focusers. Zero image shift and zero backlash makes it fantastic for visual and photographic work and a must for CCD imaging. The modular design makes changes and upgrades extremely easy to accomplish. Add the optional variable-speed Motor and Smart Focus or Digital Readout (DRO) for the ultimate focusing system. The EV is truly a masterpiece of engineering and workmanship that you will be proud to own for years to come.
One of the EV focuser modular bases is designed
for Cassegrain telescopes. The most popular type of Cassegrain telescope
is the Schmidt-Cassegrain Telescope (SCT). These telescopes achieve
focus by moving the primary mirror. This design tends to create image
shift which is especially problematic for CCD imaging. The EV Cassegrain
focusers achieve focus by moving the eyepiece, camera or other equipment
at the back of the telescope instead of the mirror.
Here are a few key features of the Event Horizon focusers:
* Modular
design makes purchasing and installing options and upgrades a snap
* Purchase
one of our regular models or buy a customized focuser using the Build-Your-Own
option
* Low
profile with no unsightly springs
* Zero
image shift and zero backlash
* Up
to eight (8) pounds of lifting power
* Brass
clamping rings hold eyepieces and equipment without scratching
* 48mm
threads on 1-1/4" adapters
* Your
choice of plastic or brass locking screw for different locking characteristics
* Miniature
light-weight, high-torque motor the size of an AA battery (motorized version)
* Small
slender hand control (motorized version)
* Transition
between motorized and manual focusing with the twist of a thumbscrew (motorized
version)
* Dual-speed
drive with counter (EV-1 model)
* 16
times finer focus than most rack-and-pinion focusers (EV-1 model)
* Available
with Digital Readout (DRO) hand control
* Available
with Smart Focus for control from your PC (with encoders and positional
display)
* Available
with PC Focus Control for control from your PC (without encoders or positional
display)
* Quality
construction and just plain beautiful!
The Cassegrain
version (EV-c) is designed for use on 6" to 16" Cassegrain telescopes (e.g.
SCT and Mak-Cas) with standard output threads. It includes an SCT
threaded output adapter to allow use of standard SCT equipment on the output
side of the focuser. The focuser gives 1/2" of travel and is designed
for fine focus after rough adjustment with the normal telescope focusing
knob.
The motorized version comes with a hand control unit.
Although the EV-c models can be plugged into the telescope's base allowing
control from the Meade hand unit, you will have better control with the
JMI hand unit. Our hand unit includes an electronic brake (not included
in Meade systems), which stops the motor as soon as you quit pressing the
keys, and linear voltage control for superior speed control. Also,
older LX200 telescopes do not have enough power to properly run the motor
on the low setting.
The Reverse Crayford Focuser (RCF) is a light-weight,
low-profile focuser with a new revolutionary design — JMI's low-cost, high-quality
answer to plastic focusers. In the reverse Crayford design, the drive-shaft
pressure is applied to a bar which "pulls" the drawtube against its supporting
bearings as apposed to directly "pushing" the drawtube as seen in the normal
Crayford design. This design gives zero image shift and zero backlash
as with our NGF focusers.
RCF 1 A 2" black-anodized aluminum focuser that lifts up to 6 pounds. Manual control is over 1? times finer than most rack-and-pinion focusers.
RCF-Mini1 A 1.25" black-anodized aluminum focuser that lifts up to 4 pounds. Manual control is over 1? times finer than most rack-and-pinion focusers.
An invaluable option for the astrophotographer. From JMI "THE FOCUSER COMPANY"