5 replies to this topic

[Binofrac]

Greetings esteemed stereo viewers.

 

I’m happy with my current binoculars for wide low power views but need to look at what to do about higher powers. I have a BST (Arcturus) binoviewer which I use in my 102/F11 refractor (my only scope), but with the necessary barlow the magnification is often too high. I’ve seen the Altair Planeta scope that has the removable section to allow barlow free viewing and this is probably where I’m heading. It is £849 and so this sets my budget. It occurred to me that if I’m spending up to that price then there are other alternatives.

 

The Analogsky Magic binocular is very interesting. It offers great flexibility with 2” eyepieces possible and can apparently go up to a magnification of 75x which would be very handy. It looks quite novel and fun and only needs a lightweight video tripod or similar. I don’t have a 3d printer and so would order the full kit. There are binocular telescopes of course but they don’t fit my budget.

 

There’s also the possibility of getting a Skywatcher Startravel 102 OTA which being shorter would offer lower magnification and wider views even with a barlow. It would also be a very flexible unit as it could offer a lot of viewing choice, and for about a quarter of the cost of the Planeta.

 

The other possibility is buying a linear binoviewer that doesn’t require a barlow in my scope. I’m not overly keen on this idea as it seems that quite a few people had to `learn to live` with the device and it has often been a difficult journey. I would like to binoview terrestrial views occasionally and it seems my current binoviewer would be better suited. I would live with the image orientation.

 

So far I’m thinking of the Planeta as the best option followed very closely by the Startravel 102 and then the Analogsky Magic. I’m not really considering the linear binoviewer. I imagine this will whirl around in my head for some time yet.

[betacygni]

Bit confused as to why you’re getting too high of powers with your binoviewers and the f11 scope. Any refractor should come to focus with a worst case 2x amplification value (most will do 1.5x). With a 32mm eyepiece that’s only 70x.

My suspicion is you might need to reevaluate your amplifier and eyepieces. A faster travelstar will perform much worse than your f11 for high powers. The Planeta is a nice scope, but there is no reason you should need to buy a new scope for medium to high powers (unless for other reasons). I always use amplifiers even in my scopes with removable sections for high powers. They improve eyepiece and binoviewer performance.

Edited by betacygni, 28 April 2025 - 11:04 AM.

[photoracer18]

Well the amplification of a Barlow goes up the farther it is physically from the eyepieces. For instance a Barlow that is installed before the diagonal and is rated at 1.5x will be around 2.25X if you put it in front of the diagonal. However tele-extenders and Powermates produce the same amplification multiplier no matter where you put them. The extra elements reshape the light cone so that its multiplication factor stays the same which is an advantage in imaging and also why you can buy Powermates that go as high as 4x and 5x.

[Binofrac]

Bit confused as to why you’re getting too high of powers with your binoviewers and the f11 scope. Any refractor should come to focus with a worst case 2x amplification value (most will do 1.5x). With a 32mm eyepiece that’s only 70x.

My suspicion is you might need to reevaluate your amplifier and eyepieces. A faster travelstar will perform much worse than your f11 for high powers. The Planeta is a nice scope, but there is no reason you should need to buy a new scope for medium to high powers (unless for other reasons). I always use amplifiers even in my scopes with removable sections for high powers. They improve eyepiece and binoviewer performance.

My thoughts were spurred on by experiments with using the binoviewer without a diagonal so that I could see what the views were like without a barlow and I really liked them. The tortuous positions required weren't so great. I was therefore keen to see how I could get the same views in a more comfortable manner, hence the removable section scope. My general binoviewing eyepieces are 25mm and the native view is great but a barlow magnifies it too much. The bundled 32mm eyepieces are good but a barlow puts their eye relief too far out. I have the bundled 1.85x (with the flipped element) and 3x and also a GSO 2x barlow that screws on to the empty binoviewer nosepiece. The 1.85x doesn't give a great experience, and the 2x is more like the 3x view. 

 

In the past I've experimented with T2 diagonals, barlow and focal reducer combinations but haven't managed to get a combination to go low enough. I've wondered if I could cobble something together with the Baader 1.25 GPC as I don't know of anything else to try.

[betacygni]

How low of power are you trying to achieve?

Not sure what you mean by the flipped element on the 1.85x, flipping an element will cause it to perform very poorly.

Sorting out the amplifiers and eyepieces certainly cheaper than a new scope. It’s common for 32mm plossls to have excessive eye relief. You could try the Vixen 30mm plossls instead, they are very comfortable for most with adjustable eyeguard to compensate for long eye relief. Another very comfortable option are the Baader 32mm plossls. They include optional eyeguard extenders.

[Binofrac]

Thanks Betacygni.

 

The 1.85x flipping is mentioned here- https://www.cloudyni...barlow-problem/ and I have much the same issues as the OP. 

 

The 1.85, 2 and 3x barlow views are all roughly similar and give a factor of around 3x which is why the magnification is too high. Unfortunately the Arcturus binoviewer has an odd thread where the nosepiece fits which reduces some possibilities. I'm trying to get as near native as optical physics allows but for the moment my minimum magnification is over 100x.