English Deutsch
BA2454400

Baader
Delivery time expected 1 - 2 w
Alan Gee II - variable focal reduction


190,00 EUR
incl. 19 % Tax
excl.Shipping costs
Description
Alan Gee reducer Alan Gee - variable focal reduction for Schmidt-Cassegrains, Refractors and Maksutovs (2454400 #20)

The Alan Gee is a variable focal reductor system for many telescopes. It has been designed by Roland Christen (Astro Physics). This reducer is particularly interesting because of its versatility and its wide adaptation possibilities.

Especially with Schmidt-Cassegrain telescopes, the Alan Gee offers good field correction and can reduce the focal ratio down to a value between f/3.5 and f/5.9. We recommend the Alan Gee for CCD cameras with a maximum sensor size of APS-C (24x16mm) or equivalent.

Fields of use for the Alan Gee:

The main application is surely photography. Here, the focal length can be reduced down to 35% of its original value. If you, for instance, have a classical 200/2000mm SC telescope, you can turn it into a fast system with a focal length of 700mm. We recommend using this extreme factor only in conjunction with small CCD cameras. With DSLR cameras similar sized CCDs, a reduction down to 60% of the original focal length has proven best.

Find a photo of M31, made with a C8 and the Alan Gee, in the "user reports" folder.

Telescopes without main mirror focusing are limited in their ability of focal reduction. The bigger the distance between AlanGee and sensor (and therefore the reduction factor) is, the further the focal plane moves into the telescope. At a certain point, focusing is not possible any more. This is also the reason why the Alan Gee does not work with Newtonian telescopes.

The Alan Gee can also be used for visual observation.
The image remains sharp and contrasty. Especially telescopes with long focal lengths are worth a try.

How does the variable focal reduction work?
The Alan Geeer Alan Gee consists of a compressor lens system and a couple of spacers. The bigger the distance between reducer and sensor, the bigger is the reduction factor. The maximum useful reduction factor is reached when the image becomes vignetted or cannot be focused any more.

We recommend to experiment with several spacer combinations in order to find out the best reduction factor for your telescope / camera combination. Then, the configuration can be noted for later reference.
________________________________________________________________________________________________

Alan Gee with a C8 Schmidt-Cassegrain:

The reducer can be used directly with the C8. It is placed inside the baffle tube followed by the T2 adapter who also locks the reducer.
The adapter C8 - T2 is found in the "accessories" folder.

Alan Gee adaptation scheme
___________________________________________________________________________
Alan Gee / T2 Alan Gee to 2" - with adaptation to T2:

this is surely the most common application. The Alan Gee fits directly into every 2" receptacle and enables the adaptation to:

-- Schmidt Cassegrains with 2" focuser or 2" adapter
-- Maksutov Cassegrains, refractors and similar systems

You need the following parts in order to adapt the Alan Gee to 2":

-- BA 2" - T2: Adapter with 2" receptacle and T2 male thread
-- BA T2a - T2a: Adapter with end-to-end T2 thread for locking

Both articles are found in the "accessories" folder.
____________________________________________________________________________
Alan Gee / 1.25 Alan Gee to 2" - with adaptation to 1.25":

an application mainly for visual purposes. You can enlarge the field of view of 1.25" eyepieces. We recommend removing two of the three spacers. Then, the Alan Gee does not extrude so far as depicted on the left and a 2" diagonal can be used also.

You need the following parts in order to adapt the Alan Gee to 1.25":

-- BA 2" - 1.25": Adapter with 2" barrel and 1.25" receptacle
-- BA T2a - T2a: Adapter with end-to-end T2 thread for locking

Both articles are found in the "accessories" folder.






nach oben
We recommend following products:
Adaptors:
25,50 EUR*
Baader adapter from 2
Baader adapter from 2" to T2
38,00 EUR*
2
2"/1.25" reducer with many additional functions
16,00 EUR*
Adapter: Continuous male T2 thread
Adapter: Continuous male T2 thread
nach obenUser reports

Picture: M-31 Andromeda nebula / (c) by Wolfgang Ransburg
Captured with a C-8 and Alan Gee focal reduction to 1400mm
Exposure time: 688sec. with DSLR Canon EOS 20DA

M31 with C8 and Alan Gee


nach oben
E-Mail: info@teleskop-service.de · Telefon: +49 (0)89-1892870 · Fax: +49 (0)89-18928710
Parse Time: 0.463s