WTB : Binoviewer for SLT127

[meteorial]

Hi guys,

I'm a complete beginner and just bought my first scope (slt 127). I saw a packaged binoviewer online from william optics and was thinking that it would ease the strain on viewing with just one eye.

However, I understand that there seems to be some sort of tremendous (at least for a noob like me) science and maths behind getting the right equipments.

I spoke to the nice chap who runs the astro store at science ctr and he recommended that 167x magnification (supplied stock eyepiece) is sufficient for my purpose.

So... I'm seeking some advice...

How different, in terms of detail, magnification and brightness, would planetary viewing be between the packaged william optics binoviewer and the stock 9mm eyepiece. Will it be about the same?


What would be your advice and recommendation?

I am open to buying one here if anyone is selling. Can be other models. Not sure of the prices but currently budget conscious I must say.

Hope your day are going well!

[antares2063]

I dont have one to sell but, Is the SLT a makustov? A binoviewer extends more lightpath (or focal length) to your telescope, you will realise that with 2 x 25mm ep in the binoviewer, the view is magnified too

regards
Junwei

[Hardwarezone]

useful forum link here
http://www.cloudynights.com/forum/65-binoviewers/

Binoviewer splits the beam of light into roughly equivalent 2 output.
Not exactly 50/50 as the prism will have a small bias to one side like 45/55.
With a small % of light loss being absorbed by the glass.
Each eye would be receiving significantly less light , more than 50% cut, you can recover it by using less magnification.

Using 2 eyes to view brings a phenomenon (binocular summation is the exact term) that raises contrast level by about 30%. This has to do with human brain.
Example if it takes you 150x magnification to find this small detail on the Moon or Jupiter , with binoviewer you can pick it out at slightly lower approximately ~110x mag.
Binoviewing also tricks the mind to an illusion that the object you are viewing is 3D.
The comfort of 2 eye viewing instead of contracting muscles to close 1 eye , will tend to let the observer/user stay focused at the eyepiece for longer period before raising head to take a rest. Observing longer will raise the chances of the atmosphere calming down for a few seconds and your observed details getting an immense boost.

Using binoviewer with catadioptric scope (maksutov , sct) which focus by moving the primary mirror , you need to add approximately 30% extra to the focal length.
For example 20mm eyepiece in mak127 (1540mm fl) is 77x mag
mak127 + binoviewer = about 2000mm fl = 100x magnification with same 20mm eyepiece
There is also a slight loss in a few MM of aperture because the internal baffle tubes are not designed for the mirror at this extreme position and therefore block the edge of the light cone. Not a big problem as the pro outweigh cons.

Binoviewer is also one of the more delicate accessories as it's function depends on the precise alignment of the internal prism.
The way the binoviewer works , it is easier to achieve higher magnification with a barlow before the BV and using bigger focal length eyepieces (20 to 25mm) on the BV.
Directly using a pair of eyepieces less than 10mm FL on the BV would require the BV's internal prisms to be very good alignment, mileage may vary and the images may not merge .... fail to function.

Do think about dehumidifying dry storage for your telescope and eyepiece before proceeding.
I personally think it would be bad to be distracted by accessories and getting a shock 2years later when the user discover fungus inside the glass.

[meteorial]

@ Junwei, yes the SLT is a 5" maksutov ^^

@ hardwarezone, wow thanks for all that valuable advice and information. Certainly helped me to understand things better

I didn't think of dry storage until you mentioned.

Will keep reading up more. Used to own a scope when I was a child. At that time, was only interested in viewing and not bothered a single bit on how to care for it until a whole colony of fungus settled in and eventually the scope was accidentally destroyed during house shifting process. Heartbreaking and was only too late when I wanted to revive it. In anyways, will not repeat that mistake.


Zul