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New apm 100 mm 90 degree ed apo binocular

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#26 Rich V.

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Posted 24 January 2015 - 12:40 PM

AFAIK, both models use roof prisms but the roof edge is not splitting the optical axis.  The 45°s use a Schmidt roof prism with four reflections and the 90°s use an Amici roof prism with two reflections.  With the rhomb turrets added into the mix with their two reflections, that's six total reflections in the 45°s and four in the 90°s...

 

Rich



#27 camvan

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Posted 24 January 2015 - 12:54 PM

Hi, Cameron, this new offering has a 90° eyepiece inclination instead of 45° like Mr. Bill's.  It's mainly a consideration for easiest astro use; the 45° would be a better choice for mixed astro and terrestrial viewing.  Having an option is a good thing...

 

Rich

thank you for the reply, Rich...but this leads to anothe question.

 

will these also suffer from the finger nail issue that Mr. Bill has in his Lunts?



#28 Rich V.

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Posted 24 January 2015 - 01:01 PM

Cameron, that's a good question that will likely have to wait until someone can evaluate the new 90° model. 

 

If the off-axis reflections are originating in the rhombs, since both models appear to use the same rhombs, I'd expect similar issues.  If the reflections come from the main prisms, we'll have to wait and see...

 

Rich



#29 Vondragonnoggin

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Posted 24 January 2015 - 05:50 PM

 

Hi, Cameron, this new offering has a 90° eyepiece inclination instead of 45° like Mr. Bill's.  It's mainly a consideration for easiest astro use; the 45° would be a better choice for mixed astro and terrestrial viewing.  Having an option is a good thing...

 

Rich

thank you for the reply, Rich...but this leads to anothe question.

 

will these also suffer from the finger nail issue that Mr. Bill has in his Lunts?

 

Try to keep I mind the "fingernail issue" is nothing new and if that is the only drawback to owning these, it's a lot less drawback than any other 90° that's been available and reviewed here in the last several years with the exception of true binoscopes. Chordal cutoff, fingernail, less than true aperture. The list the other 90°'s had was full of issues with the exception of the Garret BT70/90 which had full illumination, but still exhibits the fingernail issue. My pair also had one barrel with astigmatism too. They are still awesome to use. The Semi-Apo is awesome to use. These will just be bees knees if they have full 100mm and full illumination, even with fingernail issue. 



#30 GamesForOne

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Posted 24 January 2015 - 08:05 PM

in telescopes, 45 degree is lower quality than 90 degree diagonals

does that have any relationship to binoculars?

 

edj

 

I doubt the 90 deg bino design is going to use one mirror to turn the optical path like a star diagonal.  ;)

 

Rich describes the optical path as requiring two less reflections than the 45 deg design -- that could yield a brighter image since each reflection suffers some light loss.

 

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Edited by GamesForOne, 24 January 2015 - 08:09 PM.


#31 schang

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Posted 24 January 2015 - 08:37 PM

It will be interesting to compare these two designs when they become available, theory/construction aside.  The more critical test would be at high magnifications, not only from the viewpoint of light transmission, but also from the viewpoint of chromatic aberration... 



#32 Mr. Bill

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Posted 25 January 2015 - 12:32 PM

The problem will be to get these together side by side....

 

Rich V, are you listening?

 

;)



#33 Rich V.

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Posted 25 January 2015 - 01:33 PM

The problem will be to get these together side by side....

 

Rich V, are you listening?

 

;)

 

I'll definitely consider the 90°s; want to read some initial impressions first.   Maybe by summer.  It would be interesting to compare the two versions during our summer outings.

 

Of course, Jean's got plans for some of my "fun money" too...    :grin:

 

Rich



#34 faackanders2

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Posted 25 January 2015 - 02:15 PM

Well if it's €1K more, or higher, I'm going to go for a Borg binoscope as that would have 2" EP capability.

We'll see what he announces.

Not 2" capable for ultra wide views?



#35 ArsMachina

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Posted 25 January 2015 - 02:40 PM

Well if it's €1K more, or higher, I'm going to go for a Borg binoscope as that would have 2" EP capability.

 

I have also been waiting for the 90° APM but now I decided for a Borg 125 ED binoscope with EMS.

The 2" eyepieces are really nice to have, thinking of Nagler 22 and Ethos 17 :-)

 

Jochen


Edited by ArsMachina, 25 January 2015 - 02:41 PM.


#36 Mr. Bill

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Posted 25 January 2015 - 03:25 PM

 

Well if it's €1K more, or higher, I'm going to go for a Borg binoscope as that would have 2" EP capability.

 

I have also been waiting for the 90° APM but now I decided for a Borg 125 ED binoscope with EMS.

The 2" eyepieces are really nice to have, thinking of Nagler 22 and Ethos 17 :-)

 

Jochen

 

 

Hope you got the IPD and a narrow nose bridge....



#37 Mark9473

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Posted 25 January 2015 - 03:54 PM

Actually the Nagler 22 decloacks quite nicely, and has good eye relief.

My only question is where he'll get two Borg 125 ED's?



#38 Mark9473

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Posted 25 January 2015 - 03:55 PM

 

Well if it's €1K more, or higher, I'm going to go for a Borg binoscope as that would have 2" EP capability.

We'll see what he announces.

Not 2" capable for ultra wide views?

 

 

I'm sorry, I don't understand your question. Could you please make a whole sentence?



#39 Mike Harvey

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Posted 25 January 2015 - 06:58 PM

If Markus has a pair of the 90's with him at WSP (and I think he will), I'll try them side by side with my 45's.

 

Mike



#40 Vondragonnoggin

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Posted 25 January 2015 - 07:16 PM

I wonder if there will be the third straight through model that was talked about? There is probably a whole other group of daytime large bino enthusiasts we never cross paths with on this website.  Maritime use, surveying, etc. 

 

Probably a lot of reasons a straight through would work for daytime use. 

 

I could see all three types coexisting nicely on the market. 



#41 faackanders2

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Posted 26 January 2015 - 12:13 AM

 

 

Well if it's €1K more, or higher, I'm going to go for a Borg binoscope as that would have 2" EP capability.

We'll see what he announces.

Not 2" capable for ultra wide views?

 

 

I'm sorry, I don't understand your question. Could you please make a whole sentence?

 

Just wondering why they did not make a 2" eyepiece option for wider views, but the reason may be the extra cost of larger 2" prisms.



#42 Mark9473

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Posted 26 January 2015 - 03:30 AM

That is an interesting question. There must be some fundamental reason that not even the very large 150 mm binoculars have this option.

 

Of course, when you start looking into it, there are not that many 2" eyepieces that are sufficiently small in size to be used side by side, while at the same time offering a substantial improvement of the 27-28 mm field stop size allowed by the 1.25" format.



#43 ArsMachina

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Posted 26 January 2015 - 03:54 AM

Hi Mark,

 

you are wrong, the 150mm 45° APM does have the 2" option, but you can only see this in the German description.

The binos are coming with a set of 2" 32mm SWA eyepieces

 

http://www.apm-teles...ernglas-45.html

 

But the weight of this beast is 22 Kg, this is twice the weight of a Borg 125 Binoscope ...

 

I also believe the reason why we do so rarely see 2" eyepieces at binos are the costs for the prisms.

This is probably also the reason for all these complaints about "too small prisms" we are hearing so often when we are talking about big binos...

Prims size is money.

 

Jochen


Edited by ArsMachina, 26 January 2015 - 04:01 AM.


#44 Mark9473

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Posted 26 January 2015 - 04:27 AM

Thanks Jochen that is interesting to know.

Apart from the weight of the instrument, I wouldn't be too interested in a pair of eyepieces giving me a 5.8 mm exit pupil size, to be honest. But a pair of 22mm Naglers would be an interesting option for that one.



#45 ArsMachina

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Posted 26 January 2015 - 04:34 AM

Hi Mark,

 

I recently hat the opportunity to look through a binoscope with a pair of 22mm Naglers.

This was really impressive, but the look through a pair of 13mm Ethos also was not bad :-)

This experience was the reason why I decided to go for a binoscope instead of big binoculars.

 

I believe the 17mm Ethos would also be a nice match, nearly the same field as the 22mm Naglers but with a higher magnification and a lower exit pupil.

 

Jochen



#46 Mark9473

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Posted 26 January 2015 - 04:57 AM

That is a dream instrument for sure.

I asked a bit higher up, but where do you think you'll find two Borg 125ED OTA's?

Myself, I'm keeping an eye open for another WO 80mm FD which, with a set of 2" EMS mirrors and a pair of 22mm Naglers would give me a 3.2° FOV at 25x magnification - that is the sweet spot for me.



#47 ArsMachina

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Posted 26 January 2015 - 05:44 AM

Hell Mike,

 

I had a big luck last week and was able to buy two Borg 125 ED tubes at the very same day, one in Germany and one in the USA :-)

 

Jochen



#48 Mark9473

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Posted 26 January 2015 - 06:44 AM

Awesome. Please start a thread on that instrument once you start building it.



#49 Val'Easy

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Posted 26 January 2015 - 12:02 PM

AFAIK, both models use roof prisms but the roof edge is not splitting the optical axis.  The 45°s use a Schmidt roof prism with four reflections and the 90°s use an Amici roof prism with two reflections.  With the rhomb turrets added into the mix with their two reflections, that's six total reflections in the 45°s and four in the 90°s...

 

Rich

 

Hi Rich,

 

What do you think about these previews of this optical design? Especially for the 90° model?

 

http://www.binomania...e-ultima-parte/

 

Did you look them and inspired by them? Even if it is only rough drawing of a possible optical design and solution.

 

On this drawing it seems it is just a pentaprism not an Amici roof prism.

 

Wait and see...

 

Emmanuel



#50 Rich V.

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Posted 26 January 2015 - 01:18 PM

Hi, Emmanuel, that's a good article.

 

 

On this drawing it seems it is just a pentaprism not an Amici roof prism.

 

 

Regarding your question about the prisms; The linked drawings do not show the roof faces, only the profile of the prism.  When you use rhombs for the turrets as the APMs do,  the image orientation is not changed by them.  To get the correct up/down, left/right oriented image that we want with binoculars, a Schmidt roof or Amici roof is necessary as they provide both the 45° or 90° deviation as well as image inversion.  

 

If a semi-penta or penta prism were to be used with rhombs as you suggest, you would get an upside-down image.  The image is passed through the penta prism directly without being inverted.  Only the deviation angle is created.  When these prisms are incorporated in the design, the large 'tuna can" Porro II prism turrets are required so that the image will be upright.  This design is common to Vixen BTs, some Miyauchis, the Oberwerk BT100 and all previous 90° BTs from China I've seen so far.

 

Rich


Edited by Rich V., 26 January 2015 - 01:40 PM.



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