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FIELD TEST OF THE BAADER MAXBRIGHT® II BINOVIEWER

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#26 TG

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Posted 03 August 2020 - 05:19 PM

Great review Bill. I would like to add a couple more items which aren't as positive:

 

- My Maxbright IIs came slightly miscollimated vertically. I was able to compensate for it by adjusting the eyepiece holders laterally.

 

- Both the Mark V and Maxbright IIs will show a ghost image of an off axis object which is actually outside your field. This is easily seen on the moon at lowish power (I used 35mm Ultrascopics in a 1500 mm scope with 1.7x Newtonian GPC as well as an 1800mm Mak). The ghost image is bright for the object such as the moon and I wonder if out-of-field dimmer objects also cause a ghost image to appear in-field. This is apparently a quirk of the Mark V/Maxbright II design.



#27 dustyc

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Posted 03 August 2020 - 06:34 PM

Great review Bill. I would like to add a couple more items which aren't as positive:

 

- My Maxbright IIs came slightly miscollimated vertically. I was able to compensate for it by adjusting the eyepiece holders laterally.

 

- Both the Mark V and Maxbright IIs will show a ghost image of an off axis object which is actually outside your field. This is easily seen on the moon at lowish power (I used 35mm Ultrascopics in a 1500 mm scope with 1.7x Newtonian GPC as well as an 1800mm Mak). The ghost image is bright for the object such as the moon and I wonder if out-of-field dimmer objects also cause a ghost image to appear in-field. This is apparently a quirk of the Mark V/Maxbright II design.

Those big binoculars with interchangeable eyepieces seem to be plagued with these ghosts too. Some have called them fingernails and photos show a slit off to the side of the FOV. Too bad they can't fix them.



#28 BillP

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Posted 04 August 2020 - 05:57 PM

Glad you got them collimated, but if that happens just send them back for replacement is what I would do.

 

On the ghosting, I experienced no ghosts whatsoever, including on the Moon.  Not sure it is feasible for a "ghost" to even happen as for an eyepiece this is a reflection from one lens surface back into the FOV and it has a characteristic of moving in the opposite direction of the original to the ghost, so both are present in the FOV at once.  What you are describing sounds more like a secondary reflection from something outside the FOV.  These can be generated by the focuser draw tube, extension tubes placed in the focuser, the diagonal, as well as eyepiece, and I suppose a binoviewer but I've not encountered that with any as of yet.  Did you find that the out of field reflection did NOT occur by taking the bino out and placing the 35mm eyepiece in the focuser and try to replicate the reflection? And if not then replicate it with any other eyepiece in the binoviewer as if it were coming from the binoviewer then many eyepieces would do it.



#29 TG

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Posted 05 August 2020 - 02:42 PM

Bill, I'm pretty sure it's coming from the BVs as I've seen it in both the Mark V and the Maxbright IIs and never without. I called it a ghost reflection for lack of a better term but it's a faint reflection that in the case of the moon is bright when the moon is off-axis. Of course, this will also happen for other objects but they're probably too faint to register unless one has superhuman eyes.

 

I've seen the ghost reflection also with 25mm and 17mm Plossl pairs that I have. The eyepiece has nothing to do with it, I'm pretty sure.

 

Re. returning the BVs, given that they have to go all the way back to Baader, that is a multi month process.

 

TG.



#30 erin

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Posted 08 August 2020 - 10:52 AM

...and that's if anyone has any in stock to replace with.



#31 BillP

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Posted 08 August 2020 - 08:39 PM

Well, ones I have do not do that on the Moon.  So curious.  Can you explain what the "ghost" looks like, and its size in the FOV.  A ghost is typically the exact same image of something, so if a star then a star point, if a planet then the entire planet at same size, and if the Moon, I would expect it to be a duplicate of the Moon in the FOV.  So if using an eyepiece where the Moon fills the FOV, when it is out of the FOV does it fill the entire FOV?



#32 TG

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Posted 08 August 2020 - 11:03 PM

I just remembered I took a picture:

https://i.imgur.com/yW0rkY8.png

#33 pstiverdoc

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Posted 10 August 2020 - 10:36 AM

Great article.  could you comment on which glasspath compensator to use in my case with a C8 classic.  Thanks



#34 TG

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Posted 10 August 2020 - 02:02 PM

Great article. could you comment on which glasspath compensator to use in my case with a C8 classic. Thanks


You can actually use no GPC with SCTs since they have such a flexible back focus but we extending it beyond the nominal 4 inches starts introducing spherical aberration. At f/10 prism induced spherochromatism isn't a big concern so you need just a focal extender, which can also be a Barlow. Placed ahead of the diagonal, it will also reduce spherochromatism. Baader and A-P Barlows will screw into the 2 in Baader T2 nosepiece.

Otherwise, if you are buying GPCs I would buy the 1.7x one as I've never found the 1.25x one sufficient by itself for introducing addition back focus. Apparently, it exists solely to correct for spherochromatism in fast refractors with sufficient back focus.

TG
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#35 BGazing

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Posted 10 August 2020 - 04:13 PM

I use 1.25x with C8 and 2.6x with the refractor.


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#36 desertlens

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Posted 14 August 2020 - 02:51 AM

The 1.25x GPC generates about 30mm of back focus relief, just the ticket for reaching focus in a SV102-Access (ƒ7) with a minimal increase in magnification. 


Edited by desertlens, 14 August 2020 - 03:07 AM.


#37 fallenstarseven

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Posted 06 November 2020 - 02:23 PM

Thanks for this detailed and very useful review.  I am new to astronomy and building up my equipment for my Orion XT10g--I've had it out at a nearby park at least a couple of nights a week for the past 6 weeks, and often 4 or 5 nights.   After assembling a good collection of basic necessities, I became intrigued with the binoviewer concept.

 

After much reading and research and evaluating my own near term and intermediate interests, I decided to pull the trigger and yesterday received my MBII plus the 1.7 GPC.   Now I'm awaiting twins for my ES82* 8.8mm and 14mm eyepieces, although I may be overshooting the capability of the scope with the 8.8.  I've already confirmed they'll fit the MBII.

 

Thanks again for this informative review--it played a key role in my decision and I think it will add greatly to my viewing pleasure and also that of the friends and strangers I share my observing with on many nights at our local astro-friendly park.



#38 TG

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Posted 09 November 2020 - 02:37 PM

After much reading and research and evaluating my own near term and intermediate interests, I decided to pull the trigger and yesterday received my MBII plus the 1.7 GPC.   Now I'm awaiting twins for my ES82* 8.8mm and 14mm eyepieces, although I may be overshooting the capability of the scope with the 8.8.  I've already confirmed they'll fit the MBII.

 

Did you get the Newtonian 1.7x GPC + coma corrector? I found it impossible to reach focus with a 12.5" f/5 with the small 1.7x screwed into the nose of the BV.

 

TG



#39 fallenstarseven

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Posted 09 November 2020 - 03:48 PM

Did you get the Newtonian 1.7x GPC + coma corrector? I found it impossible to reach focus with a 12.5" f/5 with the small 1.7x screwed into the nose of the BV.

 

TG

TG,

 

I did indeed.  However, I haven't tested it yet, and won't be able to until I received second eyepieces to test with, which should happen tomorrow.

 

I did have an issue sorting out how to connect the two.  The GPC can be ordered, apparently, with and without a T2 connector ring installed, and I ordered the former.   With a T2 connector on each unit, it is possible to thread them together, which the manual that came with the MBII stated wouldn't be possible--it instructs you to remove the T2 connector from the MBII and replace it with the Zeiss microbayonet.  Once you do that, if the T2 connector is still on the GPC, there is no way to thread them, which confused me.  Not realizing there was also a connector ring on the GPC, I posted a question on the MBII page at the Baader website, and their reply led me to remove the GPC ring (which to a newbie isn't super self-evident).  Once I did that, the connection via the Zeiss microbayonet works perfectly.  This also removes several millimeters of length from the assembled components.  I'm attempting to post two pictures here that show the first, incorrect way I threaded them together, with the second, supposedly correct way.   If you also purchased the GPC with the connector ring attached, could this added length in the assembled components be throwing off your focus-ability?

 

In any event I'll let you know in the next few days if this newbie is able to achieve focus once my eyepiece pairs arrive and I can take everything out to test.

 

Binoviewer
Above is the reputedly incorrectly threaded pair of MBII and GPC.
 
MaxBrite II Binoviewer with 1.7 GPC
This is the pair connected using the microbayonet, without the two connector rings on the GPC and the MBII respectively.  Note the loss of length to the assembled products.

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#40 fallenstarseven

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Posted 09 November 2020 - 03:51 PM

Just a note, in the first picture above, I had two similarly-sized Explore Scientific eyepieces just to confirm their pairs would fit--that's a 14 and an 8.8, both 82*.   I didn't put the eyepieces back on for the second photo.

 

If you look carefully at the first photo you can see the ridged rings on both the MBII's focuser end, and the GPC's adjacent end.

 

And apologies to all if we've detoured this discussion of the review with a technical problem; if anyone objects I can start a separate thread and copy the thrust of these posts to that.



#41 Kukulkan

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Posted 09 December 2020 - 10:17 PM

Great work, Bill!
I recently got an f5 20" Obsession. I don't see much about using binoviewers with big dobs. If you or anyone reading this have any experience or advice in that regard I would appreciate it. Thanks!

#42 BillP

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Posted 10 December 2020 - 12:56 PM

I do not.  However, Baader does make a special GPC for the MBII that is meant for Dobs so they can come to focus with a bino.  It is 1.7x and a bit pricy - https://www.baader-p...hange-ring.html

 

A threads on the issue -

 

https://www.cloudyni...nian/?p=8016825

 

https://www.cloudyni...or-binoviewers/


Edited by BillP, 10 December 2020 - 01:05 PM.


#43 TG

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Posted 14 December 2020 - 11:19 AM

With truss dobs, if you have some way of shortening the distance of the secondary from the primary, that helps. I have only a medium-sized truss dob but its upper-cage to mirror box length can be varied by a couple of inches for added back-focus length. Note, however, that if you reduce the secondary-primary distance, you might also need a larger sized secondary, especially if you can no longer see your primary's rim through the center of the focuser, which means that you are losing aperture. I had to go from an 18% CO to a 22% CO but no big loss. I also need an extension tube with some eyepieces now.

 

There's also the problem of balance. A BV + OCA + eyepieces can easily reach 1000g+ in weight. A dob with large altitude circles will do best here. Having some way to attach additional weights on lower side of the mirror box helps as well.

 

TG



#44 StarAlert

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Posted 31 March 2021 - 09:02 AM

I’ve been using the Maxbright IIs for several months, now. They are great for DSOs, lunar and planetary viewing, but I not so good for doubles... unless you like looking at quadruples.  
 

See my report here. 
https://www.cloudyni...ar-reflections/



#45 BillP

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Posted 01 April 2021 - 01:21 PM

I’ve been using the Maxbright IIs for several months, now. They are great for DSOs, lunar and planetary viewing, but I not so good for doubles... unless you like looking at quadruples. 

Interesting.  Not my experience, and I put the unit through its paces on lots of doubles and stars, including very bright ones, without it ever generating a single artifact like you reference.  Not saying this is the reason for what you are seeing, but it has been my experience that the synergy between all the components in an optical train can produce some unusual events, so there can definitely be a degree of heightened sensitivity depending on the particular mix of components (i.e., diagonal, eyepiece, filters, extension tubes, etc.).  As example, my 6mm ZAO-II eyepiece in monoviewing mode will show a light artifact in the FOV, but only if I am using a specific 2" extension tube I have.  Take that tube out of the optical train and use any other brand of extension tube and the artifact does not show!  Use that extension tube with other eyepieces and no problem.  That eyepiece has no issue in any other scope or configuration.  So the eyepiece does not have an issue, nor does the extension tube, only when those two particular component are together so the synergy between them is definitely not a good one.  So would be interesting to hear if it also happens for you using different diagonal types (i.e., prisms vs. mirrors), and then different eyepieces designs (simple Abbes vs 5-element designs vs complex positive-negative designs), then without and with OCA (if you cannot do it without OCA then with OCA vs. conventional Barlow so you can test differing effective focal ratios), and then without diagonal in a straight thru configuration to eliminate any synergies from those particular components.

 

As for me, my binoviewing is always done with a Baader Zeiss 1.25" Prism Diagonal to keep my light path short as I bino without an OCA.  I use either my 6" Apo or my 4" Apo.  Eyepiece pairs are mostly BST Starguiders, ES68s, Tak LEs, Morpheus.  I use no extension tubes in the focuser either before or after the 2" visual back.  So with those components I do not get the ghosting/reflection artifacts you are referencing at all.  And when I was doing the tests it is not like I did not use them in double star and bright star observing as I observed and tested using these which includes Castor and found no reflections or ghosts of any kind like you found on that particular star.  Have not had any artifacts like that year of observing since the article I posted either.  Why I am suspecting it may have something to do with a synergy with between specific components since it is obviously not happening for me. 

 

Here are the stars I tested the unit on for my write up.  As you can see, some extremely bright stars generated no such issue for me in my configuration of components.  This is my experience anyway.  Understandable always the adage that YMMV since different components may be used in an optical chain.  Remember that field tests are always complete optical system tests of an optical chain and can never really strictly be an individual component test since all those other components are making a unique interaction with all the individual components.

 

Alpha Gem (Castor)

Algieba (Gamma Leo)

Iota Ori

Lambda Ori (Meissa)

Delta Ori (Mintaka)

Beta Ori (Rigel)

Sigma Ori (Struve 761)

Theta Ori (Trapezium)

Zeta/80 UMa (Mizar/Alcor)

Alpha Ori (Betelgeuse)

Alpha Leo (Regulus)

Alpha CMa (Sirius)


Edited by BillP, 01 April 2021 - 01:37 PM.



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