Bresser Special-Astro 20x80 giant binocular .. let's test it!!

 I've been trying to collect some feedback from owners of this binocular but there are not many information out there so I decided to buy it and share my opinion just in case it could be useful for other potential buyers. Nevertheless, I've found many information about his competitor the Celestron Skymaster 20x80 binocular and even when both of them seem to be exactly the same product there are a few differences between both.

The giant 20x80 binocular from Bresser is an interesting optical resource. Since it is very easy to handle it could be a good option for a quick observing session. Also, it's very affordable depending on where are you going to get it.





 The most noteworthy feature from my point of view is that it is Fully multi-coated (FMC). This kind of coating can only be found in expensive binoculars. For example, the Celestron Skymaster 20x80 is "just" Multi-coated (MC). The main difference between FMC and MC type of coating is that the FMC provides higher levels (90-95%) of light transmission since all glass surfaces have multiple coatings resulting in increased bright, sharp and contrast.




Bresser 20x80 package content: 

• 1x user manual (two pages per language)
• 1x nylon carrying case
• 1x carrying strap
• 1x shammy
• 3x rubber lens covers

Tripod shoe is not included in the package.

You could find its main features (from Bresser home page) at the bottom of this post.

Not a big binocular, as can be seen comparing to my buddy.
Tripod shoe is not included in the package.





You are going to need a tripod, not a very expensive one, but a tripod that can hold no less than 3 kg weight. I use the Ultralyt 6097 tripod and it's perfect also for this binocular:

                 

The Bresser 20x80 is not very big, but you'll need a tripod to hold it.

 One of the biggest worries when buying optical elements through the Internet is the shipping because sometimes the package is not well-managed during the transport. Or maybe they were shipped out from the factory with collimation problems. In my case, it came perfectly collimated (wow!); but just in case, and for sure for future occasions, here you are How to collimate your binocular. In the next picture you could find were the collimation screws are:






Please be so careful when adjusting the collimation screws. Read carefully the previous link "how to collimate your binocular". 






Testing optics:

 Stars do not appear as punctual as I would wished. In addition, there is a significant image distortion, "stretching the stars" when moving out from the centre to the edges of the lenses.

 When observing the Moon it fills more than of the 40% of Field of View (FOV). Very good contrast and sharpness and also very low and acceptable chromatic aberration.

 Moon craters and seas appear in a magical and beautiful image. 

 The Moon terminator reveals the wonderful structures and reliefs thanks to sunlight and the illuminated and dark zones contrasts.

 Jupiter appears like a bright object and Galilean moons can be seen perfectly so to observe the moon's transit is perfectly feasible. Significant chromatic aberration in the edges, but no much more than the Helios Quantum 6 at 20x. Surprisingly, cloud bands appears like a couple of thin brown stripes across the planet with the Bresser as well.
Remarkable chromatic aberration in the edges as well.

 Saturn's rings are visible (no rings division are, obviously) and three of its moons as well. Lovely image for this modest equipment.

 When it comes to deep space, it has a good enough performance. Good images in the centre and high contrasted as well. For wide-field objects, also good performance and clear images except in the edges where distortion is significant. Messier 31, Andromeda Galaxy, appears as a soft cloud and it covers almost the whole FOV.

 Open star clusters such as Messier 44 (NGC 2632),  covers almost the whole FOV.

 Messier 13, the Hercules Cluster, is no more than a little cloud. No stars can be resolved.

 Wishing to point to Sagittarius constellation and the Milky Way to test it with objects like Messier 8, Lagoon Nebula (NGC 6523) and, especially, Messier 20, Trifid Nebula (NGC 6514). Both are still very low in the horizon and must wait until late summer to be in an optimal position.



My own personal feedback:

 This binocular is a good choice if your are not willing to pay lots of money for an entry-level binocular for astronomy. It is well built and has a decent performance for the price. Also it's very easy to handle and not too heavy so it can be held by using a cheap tripod.

 For me it is very interesting the fact that despite of being a Fully multi-coated, something unusual at this price level, it has a significant chromatic aberration. Nevertheless, I think that you get what you paid for.


 Well, I will be very happy if you could share with me your own feedback and, of course, any comment or review of the information of this post :) 


Thanks for reading!!
Daniel Escudero


Bresser Spezial-Astro 20x80 features:

FIELD OF APPLICATION
Field of application	Astronomy Bird watching & Nature observation
TYPE
Type	Standard Binoculars
OPTICAL SPECIFICATIONS
Optical design	Porro
Magnification	20 fixed
LE Eyepieces	✓
Objective diameter	80 mm
Material prismn	BaK-4
Type of coating	Fully multi-coated
Colour of coating	Violet
Eyepieces for eyeglass wearers	✓
Diopter setting	✓
Field of view at 1000m7	56 m (3,2º)
Light intensity7	16
Twilight factor7	40
Near focus from7	9 m
GENERAL TECHNICAL DATA
Bag/Pouch	nylon carrying case with carrying strap
Tripod adapter thread	✓
Focusing system	Central focus wheel
Eyecups	Rubber eyecups, foldable
Colour	black
Body material	Aluminium
Body armouring	Rubber/Plastic
Warranty	5 Years
DIMENSIONS & WEIGHTS
Total length	330 mm
Total width	235 mm
Total height	108 mm
Net weight (without access.)	2100 g

Is a SQM (Sky Quality Meter) as useful as it seems to be?

 I'm sure that each and every amateur astronomer is always searching for best places for observational sessions. No doubt, it´s a hard job since one night can be absolutely different than others... so, what can we use to find a good enough place for our hobby?
 
There are a lot of things to keep in mind before starting to search for a good place, and this is because it depends on many conditions:

- Our own observing preferences:
         - Since planetary observation could take place in the center of our city, a good choice could be in our own terrace or balcony.
         - Completely different is the Deep Space observation. To observe deep space objects such as galaxies, nebulas or even star cluster requires a place without any disturbance light.
         - Single or multiple objects to be observed.

- Meteorological conditions:
          - The same place could have big different observational conditions from one night to other. Some factors such as seeing could dramatically affect to the observing conditions even when at first sight we didn't "detect" anything.
          - Temperature during the day because it affects at ground-layer since during the night you could be affected by turbulences blurring the images.
          - Very thin layers of clouds, which sometimes are almost invisible to naked eye.

- Direction:
         - Depending on the kind of observing session and objects to observe, you could choice different places to go. For example, if you're going to mainly observe deep space objects located in north direction you should keep any medium-big city or any other light-pollution source at your back in south direction.

- Other factors:
         - Such as jet streams, vehicles headlights, dust in suspension, wind, ...

 So, how can we know if a place it's good engouh for us to observe the night sky?

 Most of the listed factors, as well as some others, could change overnight, but "quality" of the sky could be measured by using a SQM (Sky Quality Meter).

A SQM measures how good the night sky or site is and through the night, helps to compare the sky brightness night-to-night and allows us document and share these values to keep the information as historical data. This information is displayed in magnitudes per square arcsecond.




And how do we know if it is good enough? 
There are some accepted values and thresholds to determine if the brightness of the sky is acceptable, good, extraordinary, etc., but, in summary, any value above 20.5 magnitudes per square arcsec displayed in a SQM should be interpreted as good enough to practical observation and near or above 21,5 magnitudes per square arcsec as excellent observational conditions. Just point the SQM* overhead (to the zenith) and you'll get the measure in just a second!

From my point of view and experience, a SQM is a very handy tool and resource to search and find a good place for the observational astronomy. But, on the other hand, and since it is not such an affordable price, you may want to think if it is worth the opportunity cost based on your observational preferences. 



* The SQM sensor is affected by the temperature so (as the manufacturer recommends) "for the most accurate results, it is best to take many readings and disregard the very first reading"

Related and interesting articles and information:
http://www.darksky.org/night-sky-conservation/269
http://www.globeatnight.org/light-pollution-interactive.php
http://www.skyandtelescope.com/astronomy-resources/rate-your-skyglow/
http://www.skyandtelescope.com/astronomy-resources/light-pollution-and-astronomy-the-bortle-dark-sky-scale/
https://en.wikipedia.org/wiki/Skyglow
http://www.lrc.rpi.edu/programs/nlpip/lightinganswers/lightpollution/abstract.asp