Meade Telescope TMB 80CF User Manual

TMB Optical TMB-80CF  
Thoma a  
s M. B ck  
Signature Series  
Congratulations on your purchase of the TMB-80CF carbon fi-  
2” accessory  
holder  
ber body FPL-53 ED apochromatic triplet refractor. Its exceptional  
optical and mechanical quality will provide you with many years  
of highly portable observing and imaging enjoyment.  
2” accessory  
lock knob  
(1 of 2)  
MOUNTING POSSIBILITIES  
2” accessory  
lock knob  
(2 of 2)  
Your TMB-80CF is usable with many different telescope mounts.  
It comes with two 90mm felt-lined hinged split mounting rings  
that have five 1/4”-20 thread holes drilled and tapped into the top  
and bottom of each ring. You can use these to install the scope  
directly on many German equatorial mounts, or on a telescope  
mount dovetail plate such as those from Losmandy or Vixen. They  
also let you mount an accessory plate on top of your scope.  
A quality altazimuth mount, such as the Astro-Tech Voyager or  
Vixen Porta mount, would also be a good choice for grab-and-go  
visual use. Either mount can be used with the TMB-80CF simply  
by adding a Vixen-style dovetail plate to the tube rings.  
FOCUSER  
Your focuser is a backlash-free dual-speed 2” Feather Touch  
Crayford from Starlight Instruments. Its drawtube terminates in a  
2” compression ring accessory holder to allow visual use with 2”  
accessories and imaging with large format CCD cameras. The non-  
marring soft brass compression ring won’t scratch your 2” star  
diagonal barrel as an ordinary thumbscrew can.  
There is also a 2” to 1.25” compression ring adapter for visual  
use with 1.25” accessories and for imaging with standard format  
CCD, webcam, and 35mm photo adapters. Its barrel is threaded to  
accept standard 2” filters and has a slight taper at the top that en-  
gages the compression ring of the 2” adapter. This prevents the  
1.25” adapter from slipping out of the focuser should the two 2”  
accessory holder thumbscrews accidentally loosen during use.  
Your focuser has two coarse focusing knobs. The right knob has  
a smaller concentric knob with a 10:1 reduction gear microfine  
focusing ratio. This provides precise focusing during high magni-  
fication visual observing and critical 35mm or CCD imaging. The  
focus knobs have ribbed gripping surfaces so they are easy to op-  
erate, even while wearing gloves or mittens in cold weather.  
Because the focuser is so smooth in operation and moves so  
freely, it can only hold a limited amount of weight (generally about  
1 lb.) without drifting out of focus when the focuser drawtube is  
tilted vertically. The focuser therefore contains an adjustable ten-  
sion internal brake system to allow astrophotography (and visual  
use with heavy eyepieces) without the possibility of focus shift.  
A knob under the focuser lets you adjust the tension on the draw-  
tube to accommodate differing equipment payloads. If the thumb-  
screw is turned all the way in (only 1 to 1½ turns), the drawtube is  
locked in position for long exposure astrophotography. Partial tight-  
ening of the knob offers a virtually infinite range of braking force  
to accommodate various eyepiece weights for visual use.  
FINDERSCOPE MOUNTING  
Coarse  
focus  
knob  
Fine  
focus  
knob  
1.25”  
accessory  
lock knob  
Coarse  
focus  
1.25” accessory  
Drawtube  
adapter  
knob  
lock and brake  
adjustment knob  
under focuser  
Focuser Features  
temperature must change from a typical indoor temperature of 72°  
Fahrenheit to an outdoor temperature that can range from a high of  
over 100° down to 10° below zero or less. In 80mm refractors, the  
cool down (or heat up) time in most situations is often quick, usu-  
ally less than 30 minutes. In subfreezing temperatures, though, it  
may take an 80mm refractor twice that time or more to reach peak  
performance. This is particularly true with a triplet like the TMB-  
80CF, where the thermal load of the center lens is isolated from  
the open air by the lenses on either side of it. This slows the trans-  
fer of the center lens heat load to the outside air.  
If you’d like to shorten the wait to reach thermal equilibrium,  
placing the telescope in an unheated garage for an hour or two  
before observing can shorten the cool down process considerably.  
Another technique is to retract the dew shield to allow direct expo-  
sure of the lens to the night air so it can reach thermal equilibrium  
faster. Once the lens has cooled, extend the dew shield again. This  
provides a faster cool down time, and generally will still keep the  
lens from dewing up. Only on the highest dew point nights will the  
objective lens form dew on its front optical surface.  
The dew shield is oversized, with a 124mm o.d. compared to the  
80mm lens diameter and 90mm tube diameter. This assures that  
tube currents, which typically follow the walls of telescope tubes  
and dewshields, will be out of the 80mm light path for the most  
part and will have only a minimal effect on your images as your  
scope cools down to ambient temperature. You can begin serious  
observing sooner with your TMB-80CF than you can with an alu-  
minum tube 80mm triplet with a conventional dew shield design.  
A lock knob built into the dew shield lets you lock the dew shield  
firmly in place so it can’t slip down while aiming at the zenith.  
The best way to avoid dew forming on the lens after you bring  
the scope into the house is to take your closed scope case outside  
when you observe, so it can also reach ambient temperature. When  
you are finished observing, cap the telescope with its dust caps  
and place it into the carrying case. Bring it into the house and let it  
slowly warm back up to room temperature, then remove the dust  
caps to allow any trace of dew to evaporate. Once the objective is  
free from dew, replace the dust caps and store the scope away.  
CLEANING  
Your scope’s carbon fiber body does not have any attachment  
points for a finderscope bracket. However, the 1/4”-20 holes in the  
top of the tube mounting rings offer several possible mounting  
locations for an optional finderscope. However, it is worth noting  
that the scope’s short focal length, combined with the wide fields  
of many eyepieces, makes the TMB-80CF its own best finderscope.  
For example, a 2” 40mm TMB Paragon eyepiece on the TMB-  
80CF yields a wide 5.4° field at 12.6x, thereby converting the scope  
into the optically finest 80mm superfinder ever made.  
COOL DOWN TIMES  
For any optical system to perform at its best, the optics must be  
at or very near the air temperature. The “cool down” time needed  
to reach this ambient temperature varies considerably, as the scope  
The best policy is not to let the lens get dirty and/or dusty in the  
first place. The regular use of the dust caps is highly recommended.  
However, no amount of preventative measures will keep your ob-  
 

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