Baader ClicklockTM 2" Dielectric Mirror Diagonal
30 November 2008
click any image in this article for a larger view
Second only to eyepieces, a new diagonal tends to be high on a new scope
owners list of "must haves". Most new telescopes ship with a sub-par
diagonal, both optically and mechanically. Plastic housings,
low-quality mirrors, a single set screw with no protection from marring the
shiny barrels of your new eyepieces - it is soon obvious that a replacement
is in order.
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Baader
Clicklock Diagonal at a Glance
Format: 2" diagonal
Mirror Type: 1/10 wave dielectric
Approximate Street Price: $259
Weight: 17.5 ounce (495g)
Manufactured by: Baader Planetarium
www.baader-planetarium.de
Distributed in USA by: Alpine Astro
www.alpineastro.com
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Many popular eyepieces today sport a 2" barrel, so sales of 2" diagonals
outnumber 1.25" diagonals by far. Of course, most 2" eyepieces are
fairly heavy and many are quite expensive so you'll want that new diagonal
to hold your prize oculars firmly without leaving so much as a scratch on
the barrel. The Baader Clicklock diagonal employs a unique twist-lock
eyepiece holder that grasps an eyepiece so firmly you could actually carry
most telescopes by the eyepiece (not that I would recommend it!). A
simple twist and the eyepiece is firmly locked or quickly released. No
more fumbling with thumbscrews. Baader Planetarium has a long history of designing and manufacturing
dielectric mirror diagonals. They were the first to bring a dielectric
diagonal to market. The Maxbright was introduced to North America when
Baader licensed the name to Astro-Physics and starting providing the mirrors
for AP's diagonals. Some years later, AP switched manufacturers for
their dielectric diagonals; Baader in the meantime developed new coating
processes to address a dielectric mirror's primary weakness - the dielectric
coating process stresses the mirror substrate leading to optical deformity.
The 1/10 wavefront error specification stated in other manufacturer's
marketing material is before coating, even for those premium quartz
mirrors. After the reflective dielectric coatings are added, only the
center of the mirror remains flat - the closer you get to the edge, the
worse the optical performance. In fact, one prominent equipment
manufacturer recommends you only purchase 2" dielectric diagonals so that
the sweet spot covers wider fields of view. For most eyepieces you
will never |
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Pluses |
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Excellent optical performance
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ClicklockTM eyepiece clamp is
quick, simple to use and holds your eyepieces like a (gentle)
vise
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Fully-machined premium housing
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| Minuses |
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A bit too heavy for some lightweight scopes/mounts, but then
this quality of diagonal would be overkill on such equipment
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see the difference, but for high quality wide field eyepieces in a short to
medium focal length telescope, the distortion is noticeable. Enter
Baader's dielectric diagonals. The Baader Maxbright diagonal (reviewed
here)
utilizes a dielectric coating process with an equal number of layers on
both sides of the mirror substrate. This results in 1/10
wavelength performance after coating. The Clicklock diagonal reviewed
in this article uses a new proprietary coating process which Baader is
currently keeping secret. The result is on par with the premium
Maxbright process, but at a much lower cost. |
Out of the Box
The Clicklock diagonal is a solid piece of gear weighing
in at just over 1 pound. The distinctive machined aluminum
body features a two layer airbrush paint in an off-white color and
accented with a red stripe and the Baader Planetarium logo on both
sides. The barrel and eyepiece clamp are both a semi-gloss
black. The barrel is threaded for 2" filters and includes
baffling groves and evenly applied flat black paint to reduce
internal reflections. The entire assembly is a fine piece of
equipment.
The dielectric mirror is scratchproof and should last a lifetime of
cleaning with reasonable care. The mirror is oversized to
ensure full illumination of the widest field 2" eyepieces.
Further along those lines, the barrel and eyepiece clamp have no
restrictions impeding the light path. The Clicklock diagonal gets
its name from the unique eyepiece holder shown in Figure 1. The brass
compression ring (no marks on your eyepiece barrels) hides a unique locking
system which securely holds any 2" eyepiece with just a simple twist of the
barrel with the knurled rubber ring. The finger lever (that is not a
thumbscrew) makes this motion yet easier, even with gloved hands.
Additionally, you can feel several click stops which get closer together as you
turn the clamp into the locked position. This works nicely in the dark
providing positive feedback to indentify the clamp is fully engaged.
Figure 1 |
In discussing the clamp with Baader, they stressed the fact that
disassembly of the clamp or removal of the brass compression ring will
void the warranty. In fact, it was emphasized that if you remove
the brass compression ring, you will not be able to return the clamp to
useable service. This should not be an issue (except for the
incessantly curious among us) as the clamp requires no lubrication or
maintenance.
It always surprises me just how much thought goes into even the most
subtle detail when Baader designs a product. Considering that
individuals might prefer the finger lever to be at a different
orientation, Baader made it possible to rotate to clamp by loosening
six recessed set screws, turning the clamp and retightening the set
screws. For example, those who are left-handed may prefer to orient
the lever to the left. |
A cosmetic point should be made here. An excess of thread lock
compound was used on a set screw located on back side of the
rotating ring. An attempt was made to wipe it off but there was
still a lot left. This did not affect performance in any way
and could be remedied by the owner. |
Mounting
Attaching a refractor-style diagonal to the rear of an SCT scope is
usually accomplished with a 2" visual back or adapter. Figure
2
shows the Clicklock diagonal mounted on the NexStar 11 GPS using Baader's
new 2" Clicklock
adapter (part number 2956233). You might notice that this looks a lot like the eyepiece
holder sticking up from the top of the diagonal. In fact they are
the same part though this adapter is connected to a 3.25" threaded ring
designed for 11" and larger SCT scopes. This adapter provides a
true 2" aperture. You must first remove the stock reducer ring and
then screw the adapter ring directly onto the rear cell. A similar
Clicklock |
Figure 2 |
Figure 3 |
adapter is available for 8" and 9.25" SCTs - Baader part
number 2956220. Baader makes additional 2" Clicklock adapters for
the visual back of Zeiss, Astro-Physics, TEC, Takahashi and Pentax
scopes. Contact Baader or Alpine Astro for more details.
An added advantage of the Baader Clicklock diagonal is that it can be mounted
directly to the rear cell of an SCT as shown in Figure 3. With the
NexStar 5/8/5i/8i this is a must as these models do not include a sliding
dovetail mount and thus most 2" diagonals will not clear the base.
Even the new NexStar SE benefits from the added clearance as it is not
necessary to push the optical tube so far forward which will result in a
heavily misbalanced scope when a dew shield is in use. |
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Any 8" or smaller SCT will actually benefit from this direct mount
method. A 2" diagonal always increases the total focal length
necessary to reach the focal plane of the eyepiece. Depending on
the design of the diagonal this could result in a focal ratio of f/10.5
or even higher. The optics were designed to function at f/10 - any
deviation from this introduces subtle optical aberration. Mounting
the diagonal directly on the back of the rear cell keeps the focal ratio
as close as possible to f/10. However, I wouldn't recommend this
on 10" and larger SCTs as it requires the use of the manufacturer's
reducer ring on the rear cell, restricting the rear aperture to about
1.5" - in this case use a full 2" aperture adapter like part number
2956233 discussed above. The direct mounting method requires that you remove the front barrel as shown in
Figure 4. A large locking ring (Figure
5 - also available from Baader) is used to orient the diagonal and prevent
it from rotating upside down, potentially dropping an eyepiece in the process.
Figure 4
Figure 5
Optical
Performance
Optically, this diagonal is as perfect as my eyes can perceive.
Collimation was spot-on, as one should expect from a precision machined
diagonal such as this. When comparing a variety of eyepieces
placed both in the diagonal and directly in the scope (no diagonal),
there was no perceptible difference in either my 11" SCT or my 4"
refractor. Stars were sharp to the edge in both cases and there
was no difference in light levels. There is not much more you can
say about a diagonal - it should be optically invisible and this one is. |
A Unique 1.25" Adapter
And what about the use of 1.25" eyepieces or web cams?
Figure 6 shows one of Baader's 2" to 1.25" adapters - the
Pushfix 2" to 1.25" Reducer. Though not included with the
Clicklock diagonal, I thought I would mention it here.There are three
methods for using this adapter. First is a traditional thumbscrew
(protruding to the left) which presses against a bronze compression
ring. With most diagonals, including the Clicklock, this is not
the best method. In order to reduce the height of the adapter to a
mere 1mm (useful in some refractors with minimal in-focus travel),
Baader located this thumbscrew down on the barrel area. This
arrangement was designed to work with other Baader 2" eyepiece holders
with a special slot for the thumbscrew. |
Figure 6 |
The two other methods call for removing the thumbscrew entirely.
The first of these methods is intended to convert a 1.25" eyepiece to 2"
barrel size semi-permanently. In Figure 6, you will see two holes in
the front of the barrel. The top opening holds a set screw which
tightens against the bronze lock ring using an included hex wrench. In
this manner you can attach the Pushfix to a 1.25" eyepiece and use it in a
2" eyepiece holder or diagonal. To complete the eyepiece's transition
to this larger format, the Pushfix is threaded for 2" filters.
A second method uses a set of three nylon setscrews which are evenly spaces
around the bottom of half of the Pushfix barrel. The lower hole in the
front of the barrel in Figure 6 houses one of those nylon setscrews. With
a little trial and error you can adjust the three nylon screws to allow an
eyepiece to be pushed into the adapter and pulled out with just enough force to
keep it in place.
Conclusion
If you felt the Maxbright diagonal was too expensive but you still want a
premium diagonal, the Clicklock is just what you've been waiting for. The
Clicklock is a clear step above the competition in optical performance and
loaded with unique and useful features, yet competitively priced.
Join the Baader Planetarium discussion group on Yahoo
Groups:
http://groups.yahoo.com/group/Baader-Planetarium
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