34 replies to this topic

[denis0007dl]

Many people ask me whats best to use to achieve higher magnification using binoviewers, and how they can use barlows, Powermates, Explore Scientific Focal Extenders, GPCs with binoviewers.....

 

Probably most binoviewer users know how to use GPCs (for example Baader Glasspathcorrectors), where you simply screw GPC on bino back or prism or mirror diagonals on T2 side (binoviewers which can support it), like its situation with Baader Maxbright I, Baader Maxbright II, and Baader Mark V binoviewers.

 

GPC main function (installed on binoviewer back directly, or screwed on T2 prism or mirror diagonals) is to reduce false colours and spherical error induced by binoviewers with all prism sytem.

 

The bigger prisms are, more false colours and more shperical error you have.

 

Not only that, GPC will also change focus position, by pushing focus of whole binoviewer system OUT. Thats good for users who dont have binoviewers friendly telescopes, so GPC will compensate some of backfocus takes from binoviewer itself. How much, depends of GPC user use, so more magnification GPC have, more backfocus it compensate, some will say "save". 

 

But thats not excellent option for users which have already binoviewers friendly telescopes, so GPC will unnecessarly push binoviewer setup OUT, so users usually need using additional extensions, which making more stress for focusser. There is not only additional sress on focusser, but also stress on mount and telescope balance. Not only that, but user observing position usually changes drastically at higher magnifications GPCs, often making very uncomfortable observing position.

 

Simillar effect you will get using barlows and Powermates, by putting barlow or Powermate on binoviewer back.

But adding barlows, especially lower and middle quality ones on binoviewer back, you will get a lot of image degradation because you are forcing barlow to be what was not he made for (you will get effect like you add 10cm or more extension between barlow and eyepiece).

But if you add quality barlows like TMB 1.8x ED, Zeiss Abbe 2x barlows and simillar ones, your image wont be affected a lot, except you can NOT here reach low powers because barlows will then work with lot more power then they originally work.

Thus Powermates are excellent in that regard (less or none image quality impact vs quality barlows) where they holding way better adding additional light path from binoviewer. 

Not only that, but Powermates 2x, 2.5x, and 4x magnification factors when using on binoviewers back almost does NOT change, with exception of Powermate 5x where magnification increasing faster, what you can check here on TeleVue original site

https://www.televue....?id=53&Tab=_app

 

----------------------------------------------------------------------------------------------------------------------------------

 

What I like using most is, using binoviewer with mirrors (optical system contains 3 mirrors and 1 cube prism beamsplitter), so false colours and spherical error are not nearly close presented (I can say freely eliminated) as its situation in binoviewers with all prism system.

 

These binoviewers dont need any GPC etc for reducing false colours and to reduce spherical error.

 

How I use it: I already have binoviewer friendly telescope, so I simply attach binoviewer to Baader BBHS T2 mirror diagonal, and use eyepieces alone, or, if I want enjoy in some longer focal lenght eyepeices I love, I simply add Powermates 2.5x or 5x, or TMB 1.8x ED or TMB 2.7x ED barlows in pairs, between eyepieces and binoviewer eyepiece holders, which looks like in pictures attached in reply.

 

What are actual advantages of this?

 

1. mechanical very important advantage: NO (or in some situations very small) focus shift

2. another important mechanical advantage: no serious impact on mount and telescope balance

3. optical advantage: no FORCED magnification like you gor when using barlows

 

Hope I covered good amount of infos here 

 

Kind regards

CS

Denis

 

 

 

 

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[denis0007dl]

...another example...

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[denis0007dl]

...another example...

 

[ngc7319_20]

...another example...

 

 

 

...

2. another important mechanical advantage: no serious impact on mount and telescope balance

 That bino setup looks like it weighs 3 times what my 80mm APO weighs.   I'm not convinced it won't impact balance.  A single little 2.6x GPC lens looks much more sensible in comparison.

[denis0007dl]

 That bino setup looks like it weighs 3 times what my 80mm APO weighs.   I'm not convinced it won't impact balance.  A single little 2.6x GPC lens looks much more sensible in comparison.

Thanxs for comment.

Of course it will impact balance by adding barlows or Powermates, but read down below.

 

APO SS binoviewer weight is approx 500g only, so its much less heavy than most binoviewers, and comparing it lets say Mark V binoviewer, its more than twice lighter.

 

In scenario where you not need changing focus, and where you add two Powermates or best two light barlows, balance wont change nearly as close when you lets say using GPC 1.25x and after using GPC 2.6x, where will be:

 

1. way longer overall setup in last scenario, and scope balance will be way different (2.6x push a LOT MORE FOCUS OUT than 1.25x does)

2. observing position will change dramatically (tott diff lenght of setup)

Another thing is, changing GPCs is not nearly simple as changing/adding/removing barlows or Powermates.

 

Now you get it more clear.

 

Denis

[Doug Culbertson]

None of my telescopes are binoviewer friendly so I have to use some sort of Barlow to reach focus. This setup with a 2.5x Powermate with T ring saves me a lot of back focus over attaching the TMB 1.8x Barlow directly to the binoviewer nosepiece.

 

With my 1.25” Herschel wedge, for example, I reach focus just as I run out of focuser travel when using the TMB. With the Powermate I have close to an inch left on the drawtube. 
 

 

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[denis0007dl]

As always, love these Powermates a lot!

[denis0007dl]

None of my telescopes are binoviewer friendly so I have to use some sort of Barlow to reach focus. This setup with a 2.5x Powermate with T ring saves me a lot of back focus over attaching the TMB 1.8x Barlow directly to the binoviewer nosepiece.

 

With my 1.25” Herschel wedge, for example, I reach focus just as I run out of focuser travel when using the TMB. With the Powermate I have close to an inch left on the drawtube. 
 

Same way you can attach 2" Powermates 2x and/or 4x, Astro-Pyisics 2" 2x BARCON and/or BARADV, Carl Zeiss 2x Abbe barlow, APM 2.7x ED barlow, which I also like, and used many times.

 

Denis

[betacygni]

Thanks Denis, that makes a lot of sense. I have a few binoviewer friendly refractors and it is indeed a pain to use extension tubes to reach focus if I want higher powers (particularly for balance since I use only alt/az mounts). Never occurred to me to use powermates at the eyepieces, simple solution. I’ll have to give it a try, always wanted to try out the powermates anyway.

Edited by betacygni, 02 August 2023 - 12:45 PM.

[Doug Culbertson]

I’ve been thinking about the AP BARADV, but I don’t know if it will have any advantages over the Powermate.

[betacygni]

I’ve been thinking about the AP BARADV, but I don’t know if it will have any advantages over the Powermate.

The BARADV is very good, though I’ve not compared it to powermates. It gives me approximately 2.2x when used with a t2 adapter as a binoviewer nosepiece (not in its native 2” adapter form). Going off memory (which might be wrong) I think it takes a fair amount of extra inward focuser travel though.

Edited by betacygni, 02 August 2023 - 12:59 PM.

[Doug Culbertson]

The BARADV is very good, though I’ve not compared it to powermates. It gives me approximately 2.2x when used with a t2 adapter as a binoviewer nosepiece (not in its native 2” adapter form). Going off memory (which might be wrong) I think it takes a fair amount of extra inward focuser travel though.

Thanks for that information. The 2.5x Powermate reportedly provides around 2.1x with a binoviewer, so I might as well stick with what I have. What I would really like is to find somthing that would give me a bit less than 2x with the binoviewer, but I don't particularly want to use a Baader GPC with my mirror based bino that I got from Denis. 

 

Does anyone have any experience with the Dakin Magic Barlows; either the 1.25x or 1.5x when attached to the nose of a binoviewer? 

[betacygni]

Thanks for that information. The 2.5x Powermate reportedly provides around 2.1x with a binoviewer, so I might as well stick with what I have. What I would really like is to find somthing that would give me a bit less than 2x with the binoviewer, but I don't particularly want to use a Baader GPC with my mirror based bino that I got from Denis.

Does anyone have any experience with the Dakin Magic Barlows; either the 1.25x or 1.5x when attached to the nose of a binoviewer?

I don’t, but found this text on the 1.25x barlow off the Agena website: “ For the Vernonscope binoviewer, with an optical path of 80mm, the 1.25x MDB will provide approximately 2.9x magnification.”

This matches my experiences with all regular barlows used with binoviewers, the magnification goes up considerably. You might try seeing what Siebert has, I believe they advertise some fairly low power options for binoviewers.

Edited by betacygni, 02 August 2023 - 06:20 PM.

[Doug Culbertson]

I don’t, but found this text on the 1.25x barlow off the Agena website: “ For the Vernonscope binoviewer, with an optical path of 80mm, the 1.25x MDB will provide approximately 2.9x magnification.”

This matches my experiences with all regular barlows used with binoviewers, the magnification goes up considerably. You might try seeing what Siebert has, I believe they advertise some fairly low power options for binoviewers.

Thanks, I somehow missed that when I was looking. I had no idea that the Vernonscope BV was so short. I believe that mine is around 118mm. 

[denis0007dl]

I’ve been thinking about the AP BARADV, but I don’t know if it will have any advantages over the Powermate.

My easy pick would be Powermate!

 

Denis

[faackanders2]

Many people ask me whats best to use to achieve higher magnification using binoviewers, and how they can use barlows, Powermates, Explore Scientific Focal Extenders, GPCs with binoviewers.....

 

Probably most binoviewer users know how to use GPCs (for example Baader Glasspathcorrectors), where you simply screw GPC on bino back or prism or mirror diagonals on T2 side (binoviewers which can support it), like its situation with Baader Maxbright I, Baader Maxbright II, and Baader Mark V binoviewers.

 

GPC main function (installed on binoviewer back directly, or screwed on T2 prism or mirror diagonals) is to reduce false colours and spherical error induced by binoviewers with all prism sytem.

 

The bigger prisms are, more false colours and more shperical error you have.

 

Not only that, GPC will also change focus position, by pushing focus of whole binoviewer system OUT. Thats good for users who dont have binoviewers friendly telescopes, so GPC will compensate some of backfocus takes from binoviewer itself. How much, depends of GPC user use, so more magnification GPC have, more backfocus it compensate, some will say "save". 

 

But thats not excellent option for users which have already binoviewers friendly telescopes, so GPC will unnecessarly push binoviewer setup OUT, so users usually need using additional extensions, which making more stress for focusser. There is not only additional sress on focusser, but also stress on mount and telescope balance. Not only that, but user observing position usually changes drastically at higher magnifications GPCs, often making very uncomfortable observing position.

 

Simillar effect you will get using barlows and Powermates, by putting barlow or Powermate on binoviewer back.

But adding barlows, especially lower and middle quality ones on binoviewer back, you will get a lot of image degradation because you are forcing barlow to be what was not he made for (you will get effect like you add 10cm or more extension between barlow and eyepiece).

But if you add quality barlows like TMB 1.8x ED, Zeiss Abbe 2x barlows and simillar ones, your image wont be affected a lot, except you can NOT here reach low powers because barlows will then work with lot more power then they originally work.

Thus Powermates are excellent in that regard (less or none image quality impact vs quality barlows) where they holding way better adding additional light path from binoviewer. 

Not only that, but Powermates 2x, 2.5x, and 4x magnification factors when using on binoviewers back almost does NOT change, with exception of Powermate 5x where magnification increasing faster, what you can check here on TeleVue original site

https://www.televue....?id=53&Tab=_app

 

----------------------------------------------------------------------------------------------------------------------------------

 

What I like using most is, using binoviewer with mirrors (optical system contains 3 mirrors and 1 cube prism beamsplitter), so false colours and spherical error are not nearly close presented (I can say freely eliminated) as its situation in binoviewers with all prism system.

 

These binoviewers dont need any GPC etc for reducing false colours and to reduce spherical error.

 

How I use it: I already have binoviewer friendly telescope, so I simply attach binoviewer to Baader BBHS T2 mirror diagonal, and use eyepieces alone, or, if I want enjoy in some longer focal lenght eyepeices I love, I simply add Powermates 2.5x or 5x, or TMB 1.8x ED or TMB 2.7x ED barlows in pairs, between eyepieces and binoviewer eyepiece holders, which looks like in pictures attached in reply.

 

What are actual advantages of this?

 

1. mechanical very important advantage: NO (or in some situations very small) focus shift

2. another important mechanical advantage: no serious impact on mount and telescope balance

3. optical advantage: no FORCED magnification like you gor when using barlows

 

Hope I covered good amount of infos here 

 

Kind regards

CS

Denis

I expected you to put the focal extenders (powermates) in front of the binoviewer (like an OCS) so you would only need one; but was also thinking 5x is way too high for a binoviewer (lower power multipliers are more practical).

[faackanders2]

Thanxs for comment.

Of course it will impact balance by adding barlows or Powermates, but read down below.

 

APO SS binoviewer weight is approx 500g only, so its much less heavy than most binoviewers, and comparing it lets say Mark V binoviewer, its more than twice lighter.

 

In scenario where you not need changing focus, and where you add two Powermates or best two light barlows, balance wont change nearly as close when you lets say using GPC 1.25x and after using GPC 2.6x, where will be:

 

1. way longer overall setup in last scenario, and scope balance will be way different (2.6x push a LOT MORE FOCUS OUT than 1.25x does)

2. observing position will change dramatically (tott diff lenght of setup)

Another thing is, changing GPCs is not nearly simple as changing/adding/removing barlows or Powermates.

 

Now you get it more clear.

 

Denis

You can't beat the Denk power switches for weight, less eyepiece pairs (and in this case less telecentrics/powermates).

[denis0007dl]

Denk Powerswitch is really practical in SOME occasions,

BUT with each magnification change, you change focus point a lot, and there often users need add focal extenders when you use binoviewer friendly telescope.

Denis

[Highburymark]

What I would really like is to find somthing that would give me a bit less than 2x with the binoviewer, but I don't particularly want to use a Baader GPC with my mirror based bino that I got from Denis.

That’s an interesting point - do GPCs introduce errors with a mirror based binoviewer?
I use a 2.6x GPC with my TV85 and Solarscope Ha filters to reach focus. Although I mostly use a Maxbright II for solar, I also have one of Denis’s excellent Zeiss BVs. Thing is with Ha that seeing is so variable it’s difficult to compare different set ups unless they are side by side. Next time, I’ll try another barlow with the Zeiss BV and see if it’s more suited to mirrors than the GPC.

[Doug Culbertson]

That’s an interesting point - do GPCs introduce errors with a mirror based binoviewer?
I use a 2.6x GPC with my TV85 and Solarscope Ha filters to reach focus. Although I mostly use a Maxbright II for solar, I also have one of Denis’s excellent Zeiss BVs. Thing is with Ha that seeing is so variable it’s difficult to compare different set ups unless they are side by side. Next time, I’ll try another barlow with the Zeiss BV and see if it’s more suited to mirrors than the GPC.

I'm probably being paranoid, but since the GPCs correct for errors in prism based systems, I'm afraid that it might introduce errors in my binoviewer. Besides, back when I was discussing purchasing my binoviewer from Denis I asked about GPCs and he told me that I could use them but he wouldn't. 

 

I use a Quark for my Ha observing so I don't  need any type of OCA or GPC in my system due to the 4.2x telecentric barlow built into the Quark. For white light,  whether with a wedge or a front mounted WL filter and a Baader T-2 BBHS mirror diagonal, I do need something to reach focus. I really like the Powermate for this. 

[planedriver]

The 2.5x Powermate reportedly provides around 2.1x with a binoviewer, so I might as well stick with what I have. What I would really like is to find somthing that would give me a bit less than 2x with the binoviewer

 

 

I had the same issue - here's my story: The bino + ADC + prism increased the focal lenght dramatically with the 7 inch Mak I have - I would estimate the three components having roughly 180-200mm lightpath. This focal length increase has a secondary effect of reducing the effective aperture meaning loss in image quality so I had to reduce that. After trying out several setups I figured out that the 2.5x Powermate works at rougly 1.5 -1.6x-ish if placed before the prism diagonal - this is also beneficial as the Powermate will not exaggerate any optical imperfections coming from the prism. 

 

It's a heavy setup and you have to make sure the weight of the bino+zooms are actually pulling the whole setup CW thus tightening the Powermate+T2adapter+prism attachment - for me it's perfect orientation when looking at the planets coming from the left (East towards South).

 

Of course this is a high-power setup as at the widest angle of the zoom the magnification is 180x already ( 24mm/1.6 = 15mm -> 2700mm/15) but this is where Maksutovs and binos shine I think.( I also had to make sure the finderscope is rock solid and remains aligned with the scope)

 

Long story short views are stunning and the setup works very well. 

Andras

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Edited by planedriver, 05 August 2023 - 04:17 AM.

[Eddgie]

I have a binoviewer ready 130mm Apo and I can easily reach focus using a 2" diagonal, and I have more than enough outward travel for a 1.7x GPC. Without the extension, using a Baader Clicklock 2' diagonal with about 112mm of light path, I still have 20mm of inward focuser travel (using the binoviewer with a 2" nose mounted into the standard Clicklock eyepiece holder) and when I use the 1.7x GPC, I still have about 20mm of outward travel remaining.

 

I would think that any binoviewer ready telescope using an 80mm or 100mm extension tube between the focuser and OTA tube would be the same. 

 

Anyway, I have owned two binoviewer ready telescopes that used the 80mm to 100mm extension and both reached focus with a standard BV, and both had enough outward travel to use the 1.7x GPC.

 

That being said, the Explore Scientific "Binovewer Ready" telescope used an extension built into the focuser tube, and this extension was only about 40mm long, and using this, you had to use a T2 digaonal and BV to reach focus without a Barlow, and in this case, you could indeed run into travel issues because the focuser had only about 40mm of travel when the extension was removed. It would be hard for me to call it binoviewer ready because you had to use a T2 setup to reach focus with the extension removed.  To me, binoviewer ready means the only thing you need extra is the binoviewer and your existing 2" diagonal will work with it and be able to reach focus. 

[Spikey131]

Most of my binoviewing is high magnification solar system observing.  The 2x Powermate with a  T2 adapter gets the magnification I need in my scopes.

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[vicuna]

i'm still not quite following two things:

 

1) why you would ever use two powermates under the eyepiece over one powermate on the binoviewer itself? is that just for convenience of swapping eyepieces out?

 

2) if you have a binoviewer from Denis, would a powermate be preferred over a GPC?

 

tyty

[Eddgie]

i'm still not quite following two things:

 

1) why you would ever use two powermates under the eyepiece over one powermate on the binoviewer itself? is that just for convenience of swapping eyepieces out?

 

2) if you have a binoviewer from Denis, would a powermate be preferred over a GPC?

 

tyty

 

i'm still not quite following two things:

 

1) why you would ever use two powermates under the eyepiece over one powermate on the binoviewer itself? is that just for convenience of swapping eyepieces out?

 

2) if you have a binoviewer from Denis, would a powermate be preferred over a GPC?

 

tyty

A GPC is most useful when you are using a faster telescope an in particular, a very fast Apo, when combined with a standard prism binocular when the desire is to keep the true field as wide as possible.  

 

They offer no major benefit to a binocular that uses mirrors. 

 

Anything that you use that makes the focal ratio slower than about f/10 will reduce the spherochromatism from the binocular to a level where the spherochromatism is not really a factor. You can use a GPC, Barlow, Powermate, or telecentric barlow, and all will give about the same result. 

 

If you are using a fast FPL-53 triplet Apo and you want to use low power but still enjoy a color free view, the 1.25x GPC is a great choice.  I use the 1.25x or the 1.5x in my 130mm Apo and with either of these, the views are completely free of color fringing.  Without them, I can see fringing on bright stars. For low power observing of wide fields, I take them out, but for doubles and planets, where the highest possible performance is desired, I use one of the other.

 

A Barlow would work as well, but this would give far more power than I could use with my zoom eyepieces. With the 1.25x, the range of power is perfect with the 3-8mm zoom. and with the 1.7x it is perfect with the 8-24mm zooms. With  2x, the highest power would be too high for even the 8-24mm zooms.  So, if I am doing planets, I use the 1.25x with the 3-8s, and if I am doing doubles, I use the 1.7x with the 8-24s for the wider field, which makes it easier to locate doubles.

 

For many, it is only about reaching focus, but for me, it is about achieving the right power for the task and the zoom eyepeices that are best suited to that task, and Barlow lenses are almost always too high for the shorter focal length setting of even the 8-24mm zooms and even the 1.7x, which only gives 1.5x, is too much for the 3-8mm zooms. The 3mm setting with the 128.x is a whopping 458x, but with the 1.25, it is 381x, which is still high, but the 4mm setting now gives a much more usable 286x, which a lot, but I can sometimes use this on very small objects like Mars.  Also, the individual steps are much closer when using the 1.25x than they are at 1.5x.

 

If you use zooms, using GPCs can be a real benefit to tuning the power so that the range is more useful.