Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

SW 120ED and binoviewers

  • Please log in to reply
24 replies to this topic

#1 Victor Martinez

Victor Martinez

    Viking 1

  • -----
  • topic starter
  • Posts: 588
  • Joined: 05 Feb 2007
  • Loc: Cadiz - Spain

Posted 23 March 2020 - 01:07 PM

Hi,

I am thinking of buying the new Baader MaxBright® II Binoviewer when it goes on the market (if it does). I was wondering, if someone who has the SW 120ED optical tube can tell me what elements are necessary to be able to focus.
Thank you



#2 c2m2t

c2m2t

    Vostok 1

  • -----
  • Posts: 123
  • Joined: 03 Oct 2017
  • Loc: Pembroke, Ont.

Posted 23 March 2020 - 04:02 PM

Hi Victor!

Before I continue, I would highly recommend that you read this discussion/review found here on CN. I suspect that it is not the only discussion that you will find. 

 

https://www.cloudyni...noviewers-r1144

 

For me, the primary issue/concern has been the need to incorporate a barlow in the light path so that the image can be focused. This reduces the light and in most cases adds unwanted magnification resulting in dimmer images. A number of telescope manufacturers used to offer OTA's with 2 pieces. The shorter part was removed (screw thread) so that bino-viewers could be used without a barlow. Stellarvue was one manufacturer but they no longer manufacture this scope.

 

The view through bino-viewers are some of the best I have experienced, but for most, the idiosyncrasies have made their use, not overly popular. One issue is that sharing views with others is not recommended since no ones eyes are the same as another. With a single eye, changing focus is a simple matter...with binos it is not. 

 

What I did in the early going as an experiment was to purchase inexpensive used telescopes and shorten the OTA by 50  to 100 mm. This allowed my bino-viewers to be used without a barlow. Even with an inexpensive  telescope, the advantage of seeing with 2 eyes was very obvious. 

 

My recommendation to you is to see if you can find anyone close to you who has a scope set up for bino-viewers (no barlow) and who would allow you to do a test drive. If you come away with the impression that bino-viewing is the way you would like to go, then, consider finding a scope that has been designed for bino-viewers or consider seeking some professional advice and have your Evostar shortened to a suitable length. To go back to single eye viewing, you will need to attach the appropriate extension tube to make up for the amount of tube that was removed.

 

I hope this helps.

 

Cheers, Chris.


  • AndresEsteban likes this

#3 Reid W

Reid W

    Viking 1

  • *****
  • Posts: 868
  • Joined: 06 Oct 2010
  • Loc: Shreveport, LA

Posted 23 March 2020 - 04:43 PM

Victor, get the binoviewers and at least one of the corrector(s) that are offered.  

 

A few years ago, we observed Mars with an Ed120  and my Denk II binoviewers and had excellent views.



#4 c2m2t

c2m2t

    Vostok 1

  • -----
  • Posts: 123
  • Joined: 03 Oct 2017
  • Loc: Pembroke, Ont.

Posted 23 March 2020 - 06:51 PM

Hi Reid!

I notice that the MaxBright bino's have an effective focal length of 110 mm, which is quite short. You mention a corrector, I see that...but not sure about the corrector-diagonal interface. Can one use a traditional 2"diagonal or does one need a specific Baader diagonal or a special adapter to make this all work? I would appreciate your insight.

 

Cheers, Chris.



#5 c2m2t

c2m2t

    Vostok 1

  • -----
  • Posts: 123
  • Joined: 03 Oct 2017
  • Loc: Pembroke, Ont.

Posted 23 March 2020 - 07:16 PM

Hi Victor! 

I just found this on the Baader website:

 

We will soon publish an extensive manual that shows the multitude of accessories that we recommend to combine with the MB II in order to adapt this onto most every telescope with the shortest possible optical length.

We cannot equip the MB II with the star diagonal that you certainly would need with your refractor in order to have a convenient way of looking through the telescope, because all users of Newtonian telescopes could not make use of this star diagonal. Accordingly it will be a matter of the customer or the dealer to help finding the appropriate adapters or star diagonals for the telescope in question and most of all, to enable this adaptation without wasting precious backfocus. This is the reason why we have developed a multitude of T-2 prism star diagonals with T-2 threads on both sides. Because you could choose for your refractor whether you want to use a 2" nosepiece to put it in front of the star diagonal or whether you opt for a 1.25" nosepiece.

So please have a bit more patience until we publish the MB II manual and check our website for star diagonals. Because furthermore we are preparing an extensive document to explain all the differences and benefits of our various star diagonals in exhausted detail, this will also be published within the next month.
Answer by: Baader Web Team (Admin) on Jan 20, 2020 4:46:00 PM.

 

This was written on Jan. 20, 2020. They may have something now. I would contact Baader directly to best answer your question. They don't want to call these adapters barlows but if they are increasing the focal length of the telescope, they are acting as a barlow, in the most basic use of the terminology. I may be looking for a better bino-viewer and these MaxBrights may be the best value. I am still thinking that a shorter OTA tube may be more adaptable and allow a greater range of eye pieces. 

 

I would be very interested in hearing what you get back from Baader in response to your inquiry.

 

Best regards,

 

Chris.



#6 Reid W

Reid W

    Viking 1

  • *****
  • Posts: 868
  • Joined: 06 Oct 2010
  • Loc: Shreveport, LA

Posted 23 March 2020 - 08:49 PM

Hi Reid!

I notice that the MaxBright bino's have an effective focal length of 110 mm, which is quite short. You mention a corrector, I see that...but not sure about the corrector-diagonal interface. Can one use a traditional 2"diagonal or does one need a specific Baader diagonal or a special adapter to make this all work? I would appreciate your insight.

 

Cheers, Chris.

Alpine Astro has an page that provides some teriffic info on the Baader unit.  About half-way down is a link to tge Baader data sheet pdf.

 

http://www.alpineast...binoviewers.htm

 

As far as diagonals.  You can use either 1.25 or 2"; it just depends on your corrector size.

 

Another alternative is the Denk PowerX switch.  It's a 2" diagonal with a built-in power switch and a separate 2" corrector.  Whats really slick about this unit is you can use it in single eyepiece mode too.  Any binoviewer can "plug into" this  rig.

 

https://www.denkmeie...tar-diagonal-r1



#7 Victor Martinez

Victor Martinez

    Viking 1

  • -----
  • topic starter
  • Posts: 588
  • Joined: 05 Feb 2007
  • Loc: Cadiz - Spain

Posted 24 March 2020 - 05:30 AM

Thank you for your appreciations. As a first step I have contacted to the Sky Watcher USA distributor to see if he can provide me with the exact information about the 120ED backfocus length. When I have this information I will contact Baader to see what they tell me.

I've also been thinking about this binoviewers an option to the MaxBright II

What about  Baader Glasspathcorrector?

https://www.baader-p...ult/?q=glasspat

https://www.teleskop...Telescopes.html

Reid,

Do you remember the settings you used with your Denk II to see Mars? 

Thank you


Edited by Victor Martinez, 24 March 2020 - 05:41 AM.


#8 Reid W

Reid W

    Viking 1

  • *****
  • Posts: 868
  • Joined: 06 Oct 2010
  • Loc: Shreveport, LA

Posted 24 March 2020 - 07:13 AM

I'm pretty sure we used my Baader Zooms set at 16mm with the Denk system and the integrated power switch set at 3x.  The standard corrector was set on the scope side of a Baader T2 prism.

 

I cannot speak to the TS binoviewers, but I am sure they are a fine product and it is good to see that they are compatible with the Baader correctors (glasspath compensators).

 

I can say that *any* quality binoviewer will provide a very satisfying planetary, lunar and solar view.  For me, solar granulation is much more enhanced; fine detail in Jovian features are far easier resolved.  



#9 Eddgie

Eddgie

    ISS

  • *****
  • Posts: 25,770
  • Joined: 01 Feb 2006

Posted 24 March 2020 - 08:34 AM

I see that you are not getting an answer to your question and while I can't be sure the answer I am going to give you is accurate, I can say that my own SW 120ED did not reach focus without an GPC, but it is possible that later models would.  I can only speak for the older model I used to own and it did not reach focus without a GPC.

 

As others have mentioned, in many refractors, it will be necessary to use some kind of glass path corrector or Barlow to reach focus.

 

How much amplification that requires will depend on the flange to focal plane distance (what others call "back focus".)

 

It is almost assured that you will not be able to reach focus with a 2" diagonal without using at least 2x.  If you want to be able to go back and forth between 2" eyepieces and the binoviewer, I recommend that you get a T2 binoviewer and use the Televue 2x Bino Vue amplifier.  This is a proper glass path corrector that will make you binoviewer parfocal with a regular 1.25" eyepiece.

 

If though you want to use lower powers, how low you can go will be very much dependent on the diagonal and the interface of the diagonal.

 

A 2" diagnal will have a light path length (the distance between the front of the mirror box and the top of the eyepiece holder) of about 96mm to 112mm, depending on the model.  Binoviewers will have a light path between 96mm and 130mm, depending on the model.  This means you would have to have a flange to focal plane distance of 200mm or more and the very vast majority of refractors do not provide that. About the only way to reach focus at a reasonbly low power without using a Denk or Earthwin with an OCS would be to use the Televue Bino Vue 2x amplifier, which again, makes the binoviewer parfocal with regular eyepieces, but of course this is 2x.

 

You can shorten the light path by about 35mm by using a 1.25" prism diagonal and in some cases, if you use the 1.9x Barlow that comes with some binoviewers, you might be able to reach focus.  This will shorten the light path of the binoviewer by about 60mm, so if the BV has maybe an effective light path of 40mm and the diagonal is 67mm, then if you can reach focus with a 2" diagonal and have at least 10mm of focus travel left (and you are using a very short light path binoviewer) then you might reach focus this way.

 

If you eliminate the eyepiece holder by using a Baader T2 standard prism diagonal, this shortens the light path to 39mm so now, most  T2 binoviewers (binoviewers that have a T2 thread at the entry, or have been equipped with a T2 adapter) will reach focus if you use the Baader 1.7x GPC (which actually gives more like 1.5x).  Some particularly short BVs might reach focus with the 1.25x GPC, and this would give the lowest power and widest field of any GPC.

 

Now again, my version would not reach focus with just the T2 prism and T2 binoviewer, but newer models might, and this was your question and I know I have not answered it really because I cannot be sure the scope you get will have the same flange to focal plane distance.

 

One last option is the Denk or Earthwin. These come with an OCS or OCA, which is a form of amplifier, and this allows you to work at 1.3x to 1.4x for your lowest power and have arms that slip in and out so that you get three magnfications.  Now they seem to be much more expensive, but I can tell you from my experience that it is (in my opinion) a superior way to go because it is far more convenient than changing eyepieces and since you can do a great deal of observing with just one good pair of eyepieces, in the end, it is not really that much more expensive than buying a special diagonal (these work with your 2" diagonal) special GPC, and a bunch of extra eyepieces. In my opinion, unless the goal is the widest possible true field, the Denk or Earthwin is the best possible binoviewer system to use because all scopes can be made to reach focus with this setup.

 

So, I am so sorry that I cannot answer your exact question with high level of assurance but I can tell you that I needed to use a T2 prism, and 1.25X GPC with my binoviewer to reach focus with my 120ED.  I had considered cutting the tube to get the extra 20mm or so it would take to not have to use the GPC, but since the scope was already kind of big, I decided to simply sell it and buy a smaller scope with a wider field that would reach focus with no GPC (a 106 LE Apo triplet). 

 

If you are just going to do mostly solar system, I recommend the Televue Bino Vue 2x amplifier and a T2 binoviewer.

(a note on the Televue and Baader GPCs...  These are not just Barlow lenses.  The prisms in the bioviewer induce spherochromatism, which is spherical aberration by color wavelength.  Only one wavelength can have perfect SA, and as you move away from that wavelength, the SA gets worse.  Now it might not be much, but since people obsess over "planetary" eyepiece performance, I would argue that if the absolute best quality view possible is the goal, then using either the Televue or one of the Baader GPCs will give the best possible result because these units are designed to correct the spheocrhomatism induced by the prisms in the binoviewer.  Technically, it would be best to use a mirror diagonal as well.  This is what Roland Christen at AP recommends and he equipped the Mark V binoviewer kit with the Baader T2 mirror rather than the Zeiss prism diagonal.)

 

Hopefully someone will actually answer your question though.  I said at the very beginning that I was not positive my own answer was of any value.


  • eros312 and c2m2t like this

#10 c2m2t

c2m2t

    Vostok 1

  • -----
  • Posts: 123
  • Joined: 03 Oct 2017
  • Loc: Pembroke, Ont.

Posted 24 March 2020 - 09:10 AM

Hi Eddgie!

I suspected as much. Is your SW 120 ProED at F7.5 also? I am guessing it is.

 

Thank you for your response...it sheds a lot of light on the subject and presents issues with the prisms that I was not aware of. I have a set of the inexpensive Chinese bino-viewers and with an old Orion 120 @ F9 which I shortened to accommodate the bino, I am very pleased with the views that this combination provides...the closest to 3-D viewing that I have ever experienced. It provides the higher magnification that I use along side a SW 120 F5 achro with a long 22mm eyepiece to give a widefield fov when doing Messier Marathons. Silly question but I could not find an answer on the Baader website...does Baader make a basic 1.25" nosepiece  for their bino-viewers that one can use in anyone's 2"diagonal with 1.25" adapter? 

 

Thanks again! Much appreciated!

 

Cheers, Chris. 



#11 Victor Martinez

Victor Martinez

    Viking 1

  • -----
  • topic starter
  • Posts: 588
  • Joined: 05 Feb 2007
  • Loc: Cadiz - Spain

Posted 25 March 2020 - 06:00 AM

I see that you are not getting an answer to your question and while I can't be sure the answer I am going to give you is accurate, I can say that my own SW 120ED did not reach focus without an GPC, but it is possible that later models would.  I can only speak for the older model I used to own and it did not reach focus without a GPC.

 

As others have mentioned, in many refractors, it will be necessary to use some kind of glass path corrector or Barlow to reach focus.

 

How much amplification that requires will depend on the flange to focal plane distance (what others call "back focus".)

 

It is almost assured that you will not be able to reach focus with a 2" diagonal without using at least 2x.  If you want to be able to go back and forth between 2" eyepieces and the binoviewer, I recommend that you get a T2 binoviewer and use the Televue 2x Bino Vue amplifier.  This is a proper glass path corrector that will make you binoviewer parfocal with a regular 1.25" eyepiece.

 

If though you want to use lower powers, how low you can go will be very much dependent on the diagonal and the interface of the diagonal.

 

A 2" diagnal will have a light path length (the distance between the front of the mirror box and the top of the eyepiece holder) of about 96mm to 112mm, depending on the model.  Binoviewers will have a light path between 96mm and 130mm, depending on the model.  This means you would have to have a flange to focal plane distance of 200mm or more and the very vast majority of refractors do not provide that. About the only way to reach focus at a reasonbly low power without using a Denk or Earthwin with an OCS would be to use the Televue Bino Vue 2x amplifier, which again, makes the binoviewer parfocal with regular eyepieces, but of course this is 2x.

 

You can shorten the light path by about 35mm by using a 1.25" prism diagonal and in some cases, if you use the 1.9x Barlow that comes with some binoviewers, you might be able to reach focus.  This will shorten the light path of the binoviewer by about 60mm, so if the BV has maybe an effective light path of 40mm and the diagonal is 67mm, then if you can reach focus with a 2" diagonal and have at least 10mm of focus travel left (and you are using a very short light path binoviewer) then you might reach focus this way.

 

If you eliminate the eyepiece holder by using a Baader T2 standard prism diagonal, this shortens the light path to 39mm so now, most  T2 binoviewers (binoviewers that have a T2 thread at the entry, or have been equipped with a T2 adapter) will reach focus if you use the Baader 1.7x GPC (which actually gives more like 1.5x).  Some particularly short BVs might reach focus with the 1.25x GPC, and this would give the lowest power and widest field of any GPC.

 

Now again, my version would not reach focus with just the T2 prism and T2 binoviewer, but newer models might, and this was your question and I know I have not answered it really because I cannot be sure the scope you get will have the same flange to focal plane distance.

 

One last option is the Denk or Earthwin. These come with an OCS or OCA, which is a form of amplifier, and this allows you to work at 1.3x to 1.4x for your lowest power and have arms that slip in and out so that you get three magnfications.  Now they seem to be much more expensive, but I can tell you from my experience that it is (in my opinion) a superior way to go because it is far more convenient than changing eyepieces and since you can do a great deal of observing with just one good pair of eyepieces, in the end, it is not really that much more expensive than buying a special diagonal (these work with your 2" diagonal) special GPC, and a bunch of extra eyepieces. In my opinion, unless the goal is the widest possible true field, the Denk or Earthwin is the best possible binoviewer system to use because all scopes can be made to reach focus with this setup.

 

So, I am so sorry that I cannot answer your exact question with high level of assurance but I can tell you that I needed to use a T2 prism, and 1.25X GPC with my binoviewer to reach focus with my 120ED.  I had considered cutting the tube to get the extra 20mm or so it would take to not have to use the GPC, but since the scope was already kind of big, I decided to simply sell it and buy a smaller scope with a wider field that would reach focus with no GPC (a 106 LE Apo triplet). 

 

If you are just going to do mostly solar system, I recommend the Televue Bino Vue 2x amplifier and a T2 binoviewer.

(a note on the Televue and Baader GPCs...  These are not just Barlow lenses.  The prisms in the bioviewer induce spherochromatism, which is spherical aberration by color wavelength.  Only one wavelength can have perfect SA, and as you move away from that wavelength, the SA gets worse.  Now it might not be much, but since people obsess over "planetary" eyepiece performance, I would argue that if the absolute best quality view possible is the goal, then using either the Televue or one of the Baader GPCs will give the best possible result because these units are designed to correct the spheocrhomatism induced by the prisms in the binoviewer.  Technically, it would be best to use a mirror diagonal as well.  This is what Roland Christen at AP recommends and he equipped the Mark V binoviewer kit with the Baader T2 mirror rather than the Zeiss prism diagonal.)

 

Hopefully someone will actually answer your question though.  I said at the very beginning that I was not positive my own answer was of any value.

 

 

 

Thank you.

I was thinking of using a Baader 2 "ClickLock Diagonal Mirror (Optical length: 112mm, The required backfocus can be reduced from 112 mm with the ClickLock to approximately 71,5 mm without the ClickLock),  with the MaxBright II, if finally go out (Optical length: 110mm), or TS-Optics 1.25" Wide-field Binoviewer with 30mm Prisms (118 , 66 mm).  I understand that TS is compatible with Baader accessories. I am also planning to directly buy a Denkmeier Binotron 27super system:

https://www.astrosho...ab_bar_0_select

I will have to study the matter carefully


Edited by Victor Martinez, 25 March 2020 - 06:32 AM.


#12 25585

25585

    Cosmos

  • *****
  • Posts: 7,993
  • Joined: 29 Aug 2017
  • Loc: In a valley, in the UK.

Posted 25 March 2020 - 08:58 AM

Hi Victor! 

I just found this on the Baader website:

 

We will soon publish an extensive manual that shows the multitude of accessories that we recommend to combine with the MB II in order to adapt this onto most every telescope with the shortest possible optical length.

We cannot equip the MB II with the star diagonal that you certainly would need with your refractor in order to have a convenient way of looking through the telescope, because all users of Newtonian telescopes could not make use of this star diagonal. Accordingly it will be a matter of the customer or the dealer to help finding the appropriate adapters or star diagonals for the telescope in question and most of all, to enable this adaptation without wasting precious backfocus. This is the reason why we have developed a multitude of T-2 prism star diagonals with T-2 threads on both sides. Because you could choose for your refractor whether you want to use a 2" nosepiece to put it in front of the star diagonal or whether you opt for a 1.25" nosepiece.

So please have a bit more patience until we publish the MB II manual and check our website for star diagonals. Because furthermore we are preparing an extensive document to explain all the differences and benefits of our various star diagonals in exhausted detail, this will also be published within the next month.
Answer by: Baader Web Team (Admin) on Jan 20, 2020 4:46:00 PM.

 

This was written on Jan. 20, 2020. They may have something now. I would contact Baader directly to best answer your question. They don't want to call these adapters barlows but if they are increasing the focal length of the telescope, they are acting as a barlow, in the most basic use of the terminology. I may be looking for a better bino-viewer and these MaxBrights may be the best value. I am still thinking that a shorter OTA tube may be more adaptable and allow a greater range of eye pieces. 

 

I would be very interested in hearing what you get back from Baader in response to your inquiry.

 

Best regards,

 

Chris.

https://www.baader-p...-with-case.html


  • c2m2t likes this

#13 c2m2t

c2m2t

    Vostok 1

  • -----
  • Posts: 123
  • Joined: 03 Oct 2017
  • Loc: Pembroke, Ont.

Posted 25 March 2020 - 09:52 AM

Greetings 25585!

Ahhh...there it is on the bottom line of accessories...not seeing the forest for the trees!!

Thank-you for that !!

 

It surprises me...just a little...that OTA manufacturers have not tried to market purpose meant telescopes to be used with bino-viewers. It would be interesting to get a stat on how many amateur observers have actually looked through binos. For anyone with an alt-az mount I can not imagine a better way to observe. German equatorial mount are a hassle due to the huge weight that gets off center on many/most occasions. Even with low-end achromatic refractors and inexpensive mass produced binos, the views with 2 eyes and well adjusted diopters, for me is more impressive than views through a high-end apo and a Ethos eyepiece...the magic happens because of having 2 eyes looking at the object. 

 

I understand that the shortening of a tube, for many, is a criminal act, my thinking is that if you enjoy a binocular view and you intend to do it for many years to come, shortening a tube is a no-brainer. If one wishes to occasionally resort back to a single EP than one just just has to add an extension tube of the required length to be able to bring the system to focus.

This gives you greater range of eyepiece focal length as well. The key is to have a quality focuser that can  handle the weight...even if the tube is not shortened, a quality focuser is a necessity. The other option that shortening a tube allows is the use of a flip mirror system. I do a lot of double star imaging and the ability to flip between my eyepiece and camera is essential. You can't add a 2" flip-mirror system to most refractor OTA's. 

 

Bottom line, modifying equipment to serve a special/desirable need, makes sense. The pro's do it all the time.

 

Victor..keeps us posted on how you fair out. I am interested to to know how things work out for you.

 

Best regards, Chris.


  • AndresEsteban likes this

#14 25585

25585

    Cosmos

  • *****
  • Posts: 7,993
  • Joined: 29 Aug 2017
  • Loc: In a valley, in the UK.

Posted 25 March 2020 - 04:54 PM

That 102mm ED F11 refractor from various makers has a removable tube section to make it suitable. Astrojensen & some others have that scope. Altair & TS sell it.

 

Be good if a larger aperture model similarly designed came out, say 120mm to 130mm. But there may be other makes that take bino viewers without needing any accessories to tailor their light path.



#15 c2m2t

c2m2t

    Vostok 1

  • -----
  • Posts: 123
  • Joined: 03 Oct 2017
  • Loc: Pembroke, Ont.

Posted 25 March 2020 - 09:42 PM

Hi 25585!

Thank you for that information. The Altair and TS brands are not common to the North American market. The only mention I see of the F11 version of the 102mmED scope is in a review from Sky at Night Magazine (2019) but there is no mention of the 2 pc tube . I see nothing on the Altair website for the F11 scope in any configuration...I wonder if it has been discontinued. For me it is not an issue. The thought of shortening a tube does not frighten me. 

 

Interesting discussion!!

 

Cheers, Chris.



#16 c2m2t

c2m2t

    Vostok 1

  • -----
  • Posts: 123
  • Joined: 03 Oct 2017
  • Loc: Pembroke, Ont.

Posted 25 March 2020 - 09:48 PM

Hi All!

I just noticed that Land Sea and Sky from Houston Texas is retailing the F11 with the 2 pc tube. They talk about it in the literature but their tube photos do not show the seam in the OTA. So...it would appear that the 2 pc tube is still available.

 

Cheers, Chris.



#17 Victor Martinez

Victor Martinez

    Viking 1

  • -----
  • topic starter
  • Posts: 588
  • Joined: 05 Feb 2007
  • Loc: Cadiz - Spain

Posted 26 March 2020 - 02:17 PM

I will hope to the Baader MaxBright II, and then I will see I do. I intend to use the binoviewer exclusively for plantary and the moon, and 120 mm refractor seems too small to work in the deep sky with the loss of light caused by binocular vision (at least I have read that because I have never been able to observe by none), so in principle I could use a GLASSPATHCORRECTOR 1: 1.25 or 1:1.70 to compensate for the shortage of focus. I don't want to cut the optical tube.



#18 c2m2t

c2m2t

    Vostok 1

  • -----
  • Posts: 123
  • Joined: 03 Oct 2017
  • Loc: Pembroke, Ont.

Posted 26 March 2020 - 04:05 PM

Hi Victor!

Your scope will do very well in a dark sky on many DSO's so don't sell your telescope short and certainly don't limit yourself to only the planets and moon.  There is certainly no issue with using the corrector/barlows that have been discussed throughout this topic. I do my Messier Marathons exclusively with 120mm refractors, of less quality than yours and there is not a single Messier object that I cannot observe. Because you will need the barlow/corrector which increases the focal length of your telescope, I would suggest that you start out with a pair of good quality long focal length eyepieces, say in the 25 to 35mm FL range and 38mm (1.25 inch) diameter. If you can find some that are described as SWA (super wide angle) these will insure that you get a decent wide field view. They may not give you the magnification you want for your lunar and planetary work, but you will be surprised at how much you can see both with DSO's and lunar planetary targets. If the seeing conditions are not good, all the magnification in the world will not render a better image. In fact it is the opposite. High magnification is only useful on crisp clear nights when the air mass above you is still, Unfortunately.. that is a very rare occurrence...almost never unless you observe from the top of a mountain. I spend more time observing with lower magnifications simply because it provides a cleaner crisper view. I believe most experienced observers will tell you the same.

 

I hope this discussion has not confused you. I certainly don't want to do that. I wish you good observing with what ever equipment you purchase.

 

Best regards, Chris.



#19 Victor Martinez

Victor Martinez

    Viking 1

  • -----
  • topic starter
  • Posts: 588
  • Joined: 05 Feb 2007
  • Loc: Cadiz - Spain

Posted 26 March 2020 - 05:43 PM

Thank you,

I have been observing for 30 years, until recently I had a 16 "with Ostahowski optics, but although I have observed through some refractors, I have never owned one, always reflectors. Finally, due to personal circumstances, I decided to change to a lighter equipment , and I chose this 120 mm refractor that had such good reviews for value for money. The fact is that even having used many quality eyepieces over the years, from a Pentax XO to an Ethos 21mm, I had never given because of the binocular vision, but now I'm curious, that's why I've started to investigate it. I have to do calculations to see how I can accommodate the 2 "Diagonal Baader, the GLASSPATHCORRECTOR 1: 1.7, and the Binoviewer. I will give a try to DSO


  • c2m2t likes this

#20 Jeff B

Jeff B

    Fly Me to the Moon

  • *****
  • Posts: 6,541
  • Joined: 30 Dec 2006

Posted 26 March 2020 - 07:52 PM

Victor, in case you have not already seen it, this thread may be useful to you:

 

https://www.cloudyni...y-measurements/

 

While you wait for the Baader viewer, I can certainly echo Eddgie's recommendation to get a used Denk II with the OCS power switch system.  They go for between $500 and $600, used, in excellent condition and are very much a high end viewer.  When the the Baader finally shows up, just sell the Denks or dig up a Denk newtonian  spacer tube and use it with the 16".

 

Why wait for the Baader when you can have some visual ice cream right now?

 

Just a thought.

 

Jeff



#21 Victor Martinez

Victor Martinez

    Viking 1

  • -----
  • topic starter
  • Posts: 588
  • Joined: 05 Feb 2007
  • Loc: Cadiz - Spain

Posted 27 March 2020 - 05:37 AM

Hi Jeff,

Thanks for the link

In Europe it is practically impossible to get a second-hand Denk II. I don't have the 16 "anymore, I sold it a one year ago

By the way,  does anyone know what the difference is between this two elements to optical level?

https://www.baader-p...s-and-sc's.html

https://www.baader-p...nd-mark-v).html


Edited by Victor Martinez, 27 March 2020 - 05:43 AM.


#22 Rutilus

Rutilus

    Mercury-Atlas

  • *****
  • Posts: 2,511
  • Joined: 17 Dec 2010

Posted 27 March 2020 - 06:20 AM

I will hope to the Baader MaxBright II, and then I will see I do. I intend to use the binoviewer exclusively for plantary and the moon, and 120 mm refractor seems too small to work in the deep sky with the loss of light caused by binocular vision (at least I have read that because I have never been able to observe by none), so in principle I could use a GLASSPATHCORRECTOR 1: 1.25 or 1:1.70 to compensate for the shortage of focus. I don't want to cut the optical tube.

Also remember that you will most likely have to cut the focus mount drawtube down as well as the tube.

As it could cut into the light path of the lens.

All my scopes are modified for bino-viewers,I  never cut my tubes down, instead I use different focus mounts

and make adapters for them to fit into the tube.  

Just remember that for viewing the planets without barlow etc, will result in low magnification(with normal range eyepieces).

For viewing Mars, I have to go back to a Barlow, which results in me having to fit  extension tubes  

to get focus. 



#23 Jeff B

Jeff B

    Fly Me to the Moon

  • *****
  • Posts: 6,541
  • Joined: 30 Dec 2006

Posted 27 March 2020 - 09:04 AM

Also remember that you will most likely have to cut the focus mount drawtube down as well as the tube.

As it could cut into the light path of the lens.

All my scopes are modified for bino-viewers,I  never cut my tubes down, instead I use different focus mounts

and make adapters for them to fit into the tube.  

Just remember that for viewing the planets without barlow etc, will result in low magnification(with normal range eyepieces).

For viewing Mars, I have to go back to a Barlow, which results in me having to fit  extension tubes  

to get focus. 

If you want the option for it to be "bino-friendly" (no barlow elements in the viewer nose), and want to keep the stock focuser, yes, you absolutely have to cut back both the main and focuser draw tubes to allow the light cone to pass without vignetting the aperture.  You will also have to either remove or reposition the light baffles in the focuser draw tube as well.  See the pictures attached.  Actually, while the stock focuser works rather well, I will eventually replace it with either a Feather Touch or Moonlite 2.5" focuser.

 

Jeff

Attached Thumbnails

  • Scope A.jpg
  • Stuff cut off.jpg
  • High Power Position.jpg


#24 c2m2t

c2m2t

    Vostok 1

  • -----
  • Posts: 123
  • Joined: 03 Oct 2017
  • Loc: Pembroke, Ont.

Posted 27 March 2020 - 11:24 AM

Hi Jeff!

That looks familiar. I am not using the stock focuser. I have swapped in  WO Crayford focuser and I don't appear to be getting any vignetting. This is for an old model F9 Orion 120. I suspect the longer focal length on the optics is minimizing the issue with drawtube interference.

Cheers, Chris.



#25 Jeff B

Jeff B

    Fly Me to the Moon

  • *****
  • Posts: 6,541
  • Joined: 30 Dec 2006

Posted 27 March 2020 - 12:12 PM

Chris, the stock focuser on my sample was really loooong and it had a light baffle right up front which made for a very small fully illuminated field of view in my older sample.   Though the modifications were straight forward, the 2" diameter of the inlet to the focuser draw tube still limits the size of the fully illuminated FOV to just about 5-6mm.  Going to a 2.5" focuser would pop that up to ~12-13mm for my sample.  Yes, the F9 focal ratio of your Orion scope does help quit a bit compared to the F7.5 focal ratio for the 120 ED.

 

Jeff




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics