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Eyepiece question for APM 100mm APos

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#51 janapier

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Posted 10 February 2016 - 11:29 AM

....

The 32mm Plossls seem to be a better option to me for going after extended nebulae, dark and bright, and nicely framing some of the largest clusters.

 

 

I have the TV 32 mm Plossls for faint extended nebulae. The California nebula has been easy through them with H-betas under SQM-L 21 skies. 

 

Concerning the field stop size: the prisms of the APM 100 ED are too small. This was a deliberate design choice, presumably to keep the price down and make more money. This choice has, in my opinion, prevented a good instrument from becoming great. I've had my field stops widened from 23/23 to 25/27 (there are actually two stops per barrel). The vignetting of the 24 Pans has not completely disappeared, but the false exit pupils have become really, really annoying. I can't say what I dislike more, the vignetting or the false pupils. The only reason these binos sell so well is the lack of true alternatives.


Edited by janapier, 10 February 2016 - 11:53 AM.

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#52 Mr. Bill

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Posted 10 February 2016 - 11:34 AM

Probably 25mm is the best choice to minimize vignetting while controlling ghosting.


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#53 Allardk

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Posted 10 February 2016 - 04:35 PM

 

....

The 32mm Plossls seem to be a better option to me for going after extended nebulae, dark and bright, and nicely framing some of the largest clusters.

 

 

I have the TV 32 mm Plossls for faint extended nebulae. The California nebula has been easy through them with H-betas under SQM-L 21 skies. 

 

Concerning the field stop size: the prisms of the APM 100 ED are too small. This was a deliberate design choice, presumably to keep the price down and make more money. This choice has, in my opinion, prevented a good instrument from becoming great. I've had my field stops widened from 23/23 to 25/27 (there are actually two stops per barrel). The vignetting of the 24 Pans has not completely disappeared, but the false exit pupils have become really, really annoying. I can't say what I dislike more, the vignetting or the false pupils. The only reason these binos sell so well is the lack of true alternatives.

 

If it was that easy someone else would have done that.

 

As long as we are not willing tppay a fortune for a BT, lets say 20.000 euro +, we will run into limitations.

Just read about the limits of the EMS BT, that already costs 7000 euro or more.

 

Use the APM within its design limits with premium eyepieces and you have a nice observation tool. Use other equipment outside these limits....



#54 Mr. Bill

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Posted 10 February 2016 - 04:56 PM

 

 

....

The 32mm Plossls seem to be a better option to me for going after extended nebulae, dark and bright, and nicely framing some of the largest clusters.

 

 

I have the TV 32 mm Plossls for faint extended nebulae. The California nebula has been easy through them with H-betas under SQM-L 21 skies. 

 

Concerning the field stop size: the prisms of the APM 100 ED are too small. This was a deliberate design choice, presumably to keep the price down and make more money. This choice has, in my opinion, prevented a good instrument from becoming great. I've had my field stops widened from 23/23 to 25/27 (there are actually two stops per barrel). The vignetting of the 24 Pans has not completely disappeared, but the false exit pupils have become really, really annoying. I can't say what I dislike more, the vignetting or the false pupils. The only reason these binos sell so well is the lack of true alternatives.

 

If it was that easy someone else would have done that.

 

As long as we are not willing tppay a fortune for a BT, lets say 20.000 euro +, we will run into limitations.

Just read about the limits of the EMS BT, that already costs 7000 euro or more.

 

Use the APM within its design limits with premium eyepieces and you have a nice observation tool. Use other equipment outside these limits....

 

 

Chinese border binoculars (Oberwerk 100mm BTs) have a rear prism face of 32mm, a rear baffle aperture of 25mm, show no discernable false pupils, and don't cost a fortune

Attached Thumbnails

  • BT100 rear prism aperture.JPG
  • BT100 prism masking-2.JPG

Edited by Mr. Bill, 10 February 2016 - 05:11 PM.


#55 Gordon Rayner

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Posted 10 February 2016 - 05:38 PM

The 100mm   APM  ED with 90  deg. deviation  seems  to have  Amici II   prisms,( from the plans shown from Binomania  and linked   by JCB  recently) ,in which  the roof line  is  outside the light cone.   If the  light cone were  large, to  feed   a large focal plane, such as for 2 inch eyepieces  or the Kasai big one (2inch?),  then an Amici II   would be  very  large and heavy.  But since  the cone does not intersect the roof  line,  the roof angle tolerance  is very  relaxable.     So,  the prism cost  for Amici  II   is not  as  high  as one might expect.  

 

And  because   the  90 deg. APM  100mm.  ED    only uses 1 1/4  eyepieces,  with their consequent in this case  reduction  of  apparent  field and/or  exit pupil diameter  and/or  eye relief,  depending upon  the  designer's tradeoffs  and compromises,   the Amici  II  size  is not excessive.    

 

So there is a cost saving  for the  erecting and deviating  prism.   It seems that a further cost saving  is from the  absence  of   ghost/fingernail   or false pupil  eliminating grooves  in the  non-reflecting  sides   of   the rhomboid  prisms  which swing  for interpupillary   adjustment.     

 

The WW II   Schneider- Goettingen  25 x 105 , with 45 deg. deviation of the sight line,   by Albert Tronnier,  ( see my correspondence with him  in Kuhne's  section  of the Seeger  book)    has big  Schmidt roof  prisms,  offset away from  the  centerline of the light cone.   The objectives  are tele-objectives  (Petzval ?).

The   overall F/ratio  is  high  for the  body length.  So  long focal length, large diameter eyepieces,  with their consequent  improved  imagery  and eye relief,  and wide apparent  field,   are used.   There are none  of the  optomechanical inefficiencies  which would come  from  interchangeable   eyepieces.  

 

There are no rhomboid prisms  there.  IPD  change is via  changing the  distance between  the telescopes.  Admittedly,  this would cost more to  implement   than  simple swinging rhomboids.     Images  are very good  at 25x. 

 

  The field corrections  are superior to  the  WW II Zeiss  25 x 100 with  aspheric  eyelens Orthoscopic  oculars due to Albert Koenig.  For IPD change, that one translates  one roof prism  laterally by half  the  lateral  translation  of one of the eyepieces.  That system was also used in the WW II  Zeiss  12 x 60.   Both of those  designs have 60 deg. inclination of the sight line.

 

 

The case against  rhomboid side  grooves  has been overstated .    "enormous",  was  used to  described  the required  rhomb size   to be groovable.   WW II Japanese  20 x 120 x 3 deg  Nikko or Toko   45 deg. deviation   , and their US Navy copies   use  Schmidt roof prisms  followed by  rhombloids  which are not  "enormous". 

 

Again  ,what  is  the ' fingernail' or false pupil   presence or absence situation in the Fuji 45 deg deviation   25 x 150mm?    Externally, they  look to be Schmidt roof prism  followed by rhomboid prism.  We  know that there is a roofline  in their  light cones, from  testimony  by  owners   when asked about roofline spike images,  including Markus Ludes  of APM.   

 

Incidentally,  that Fuji model   is less  than  the  20,000  Euros   mentioned above  in #23 for a binocular telescope,    at least  in  the USA  or Japan.


Edited by Gordon Rayner, 11 February 2016 - 04:14 PM.


#56 Mark9473

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Posted 10 February 2016 - 06:32 PM

 

I've had my field stops widened from 23/23 to 25/27 (there are actually two stops per barrel). The vignetting of the 24 Pans has not completely disappeared, but the false exit pupils have become really, really annoying. I can't say what I dislike more, the vignetting or the false pupils.

 

If it was that easy someone else would have done that.

 

I don't believe it has to be so difficult. Widen the rear field stops to eliminate vignetting and increase TFOV, then put a suitable baffle on the front prism surface to reduce/eliminate the false pupils. It would only result in reduced off-axis illumination, which for many would be an acceptable compromise. Markus has repeatedly said his design goal was "the best illumination" as something to boast with - possibly he has just taken it too far.

 

The only problem is the OEM is also selling these to the military so it might be difficult to change anything at the point of origin.



#57 Gordon Rayner

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Posted 10 February 2016 - 10:03 PM

"selling to the military".   Which  one?   The  Chinese?   The  German?   The  US ?,   NATO? South Korea?

 

There must be a compromise  here.  Most military specifications  have some  humidity  or water resistance  standards, and a  silica gel  packet  containing compartment. This is most important  for maritime use.   Interchangeable  sleeved eyepieces  are  not  easily sealed  with rubber o-rings.  ?????

 

Who is the OEM?   APM?  The Chinese factory?

 

Military use  usually  means wide  apparent   fields.    Political considerations aside,  why not buy the  TAL ( Novosibirsk) 15 x 110,  with its  enormous   90 deg.  nominal field ( actually somewhat less  is the  'real' apparent field).  Have  they fixed the  yellow  glass  tint  yet? Or,  maybe  a Chinese  near-copy  of it?


Edited by Gordon Rayner, 10 February 2016 - 10:17 PM.


#58 Allardk

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Posted 11 February 2016 - 04:54 AM

....so we want the prisms the size of the Oberwerk, but much better quality. Then we need the fluorite KOWA uses. Of course the possibility of 1.25 and 2 inch. Then we want Docter to design at least 2 more eyepieces, one for wide views, one for high magnification. Overall the BT cannot be too heavy and large. Price max 4000 ? Any other wishes ?   :)



#59 Mad Matt

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Posted 11 February 2016 - 06:07 AM

How about washing cloths and doing dishes? :-)

Edited by Mad Matt, 11 February 2016 - 06:08 AM.

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#60 Richard Low

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Posted 11 February 2016 - 09:15 AM

How about washing cloths and doing dishes? :-)

 

:funny: 

 


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#61 ArsMachina

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Posted 11 February 2016 - 09:29 AM

There is one easy solution for most of the problems, it is called EMS :-)

 

Jochen



#62 GamesForOne

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Posted 11 February 2016 - 09:54 AM

There is one easy solution for most of the problems, it is called EMS :-)

 

Jochen

 

Most problems except price.  :foreheadslap:

 

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#63 ArsMachina

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Posted 11 February 2016 - 10:01 AM

What you get is what you pay for :-)

 

Jochen



#64 Richard Low

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Posted 11 February 2016 - 10:10 AM

There is one easy solution for most of the problems, it is called EMS :-)

 

Jochen

 

I find the APM 100-90 ED APO bino is a high quality bino that serves me well. As noted, I find the false pupils are not a major issue. Some may have different opinion and find it an issue. Even if the APM 100 ED APO Bino is improved with larger prisms, the increased price and increased bino weight may not go well with some other people.

 

If you want a bino for (i) scanning around the sky, (ii) and with wider TFOV, and or (iii) with bigger aperture, then I would think that buying or building a proper binocular telescope with 2" interchangeable eyepiece capability would be the best way to go.    

 

Besides larger-sized prisms like the Oberwerk BT100, one could also proceed based on mirrors. EMS is an excellent solution, but there is more than one solution. Mr Bill's binobox is another fine example. I have been studying some of these binoscopes options for many weeks, even before I received my APM 100-90 ED APO bino.


Edited by Richard Low, 11 February 2016 - 10:13 AM.

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#65 GamesForOne

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Posted 11 February 2016 - 10:22 AM

I agree with you Richard. The APM bino is a breakthrough in value in a market that has been historically slim in quality choices. It isn't perfect, but it works pretty darn well. With its optical performance I find myself reaching for more magnification to get a better view of most objects and it delivers on those views. Its portability for the aperture is unmatched.

 

For the price, especially $2500 USD for the 45 degree version, it's a price/value leader.

 

It's a shame there isn't more of a market for large binoculars so that some talented German or Japanese optical engineers could give us closer to a no compromise design and manufacture it at a reasonable price.

 

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#66 Mr. Bill

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Posted 11 February 2016 - 10:57 AM

What you get is what you pay for :-)

 

Jochen

 

Hopefully..... :grin:



#67 Allardk

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Posted 11 February 2016 - 12:05 PM

What Tammy wrote about the EMS doesn't convince me to fork out 7000+ euro.....



#68 Mad Matt

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Posted 11 February 2016 - 12:15 PM

I stepped away from the hobby for almost 10 years partly because things got too "fiddly" and complicated. As much as I have admired (and wanted) an EMS I know it will take me in a direction I really don't want to go.


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#69 Skittersqueek

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Posted 11 February 2016 - 12:38 PM

Before purchasing my APM's 45 degree version + Docters and the binoptic fork II (still am waiting for delivery and cannot wait :p ).  I was dead set on trying to find a Borg125sd.. That proved to be futile at the time because they were not in production anymore and I couldn't find a seller. So I looked and looked for the next best thing and decided on the APM. Honestly I am a tad nervous with all these fingernail and false pupil posts popping up but still think I made the right choice.

 

 

Down the road If I prove myself dedicated enough to my hobby I will most definitely be purchasing an EMS and connecting it to something insane(TEC company is right down the road from me so who knows! :cool: )

 

 

 

Also since this is an eyepiece topic... has anyone tried or heard of the 4.7 or 3.7 ethos sx eyepiecesin the apms? 110deg field of view! Will fingernails or false pupils be an issue in those?


Edited by Skittersqueek, 11 February 2016 - 12:50 PM.


#70 Allardk

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Posted 11 February 2016 - 01:50 PM

Don't worry about all these scary reports :-)

 

At the moment I am testing the APM 100-45 ED against the KOWA Highlander Prominar. They are very close to each other. Both excellent BT's.

 

Just use the APM inside its design limits. With the Docters you will be very happy. Fieldstop of these are 19.27, so far away from the 23mm of the APM. At 44x you are about half way the max magnification, unless you paid more for a higher level. Sharp till the edge. Wide AFOV. Yes, the mentioned issues are there but mild.

 

If you wanna "fiddle" as mentioned above AND fork out another 3000-4000 euro you could go EMS. You will run into other issues, though. 

 

So don't lose sleep over it  :D



#71 Skittersqueek

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Posted 11 February 2016 - 02:51 PM

I did opt for the 150x magnification hence my interest in those Ethos :cool:  I think I just put together the field stop technical stuff and want to keep it under 23mm. 

 

 

I just was looking for something that can rock a little of everything... I am hoping I can get an ok view of planets with this as well as clusters and certain brighter DSO.

 

 

Yep I have been reading your report in the other thread and am enjoying the read.


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#72 Allardk

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Posted 11 February 2016 - 03:17 PM

Unless you want wide views the Docter is good for most open clusters. Bigger ones like M41, M44. Tiny ones like NGC 2169 come out very well.

This is the AFOV....

Attached Thumbnails

  • image.png


#73 Allardk

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Posted 11 February 2016 - 03:18 PM

You actually see it about this size.....

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#74 janapier

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Posted 11 February 2016 - 05:59 PM

In my view there are certain targets that definitely call for the 24 Pans rather than the Docters. I'm thinking about the Veil, h&chi, Rosette, M31, many dark nebulae etc. pp. 


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#75 GamesForOne

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Posted 11 February 2016 - 06:08 PM

In my view there are certain targets that definitely call for the 24 Pans rather than the Docters. I'm thinking about the Veil, h&chi, Rosette, M31, many dark nebulae etc. pp. 

 

True, but the APM binos would not be the first and only optical instrument to have trouble with the 24 Pans. They stretch and break the limits of many 1.25" optical trains. Perhaps consider sacrificing some FOV for less trouble with vignetting and false pupils -- the 19 Pans are a good candidate if Panoptics are to your liking...

 

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