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Porro prism versus Roof prism?

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#1 cbullock

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Posted 25 June 2020 - 07:51 PM

I have always been a porro prism guy, never felt that roof prism was as good. I am now wondering why the two different types? Is there an real advantage of one over the other? Why have manufacturers started really going to roof prisms? Is the image quality superior in every respect? Is there inherently greater potential for superb images which surpass the finest porro prism binocular? Is the light transfer equal or better in one over the other? 

Interested in your thoughts and insights. You can listen to the so called experts, but I would rather hear what the "boots on the ground have to say"

 

Chris



#2 Pinewood

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Posted 25 June 2020 - 08:02 PM

Hello Chris,

 

With the exception of close focussing, there is no optical advancements which could not be applied to Porros and Porro binoculars do not need neither phase coating nor dielectric mirrors.  There are advantages in compactness and robustness in roof binoculars, which is why my primary bird watching glass is a roof prism binocular.  Poorly made roof glasses do have a problem with spiking of bright objects in the night sky, which is not problem for Porro glasses.  But there is one advantage for the manufacturers:  higher per unit profit.

 

Stay safe,

Arthur 


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#3 DrJ1

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Posted 25 June 2020 - 08:24 PM

I have many of both and tend to prefer porro prisms.  In addition to Pinewoods points, most porros have greater spacing between the objectives which gives better depth perception.  As a novice in repairing legacy binocs, I can get by repairing many porros but I don't think I could handle repairing a roof prism binoc.  Concerning roofs, I was traveling light in Europe and my small Nikon 8x20 roof was a good choice.  I looked through my friends $2800 Swarovski EL roof binocs and they were spectacular!  DrJ1 



#4 TOMDEY

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Posted 25 June 2020 - 09:10 PM

I love this one... the view is spectacular, but it may be more the quality than the prism type.    Tom

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#5 edwincjones

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Posted 26 June 2020 - 04:49 AM

I love this one... the view is spectacular, but it may be more the quality than the prism type.    Tom

I have the 8x56 dialyt model and also like it-quality plus cool design.

From what I read this was the alpha of its day.

 

edj


Edited by edwincjones, 26 June 2020 - 04:51 AM.


#6 Erik Bakker  Happy Birthday!

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Posted 26 June 2020 - 07:31 AM

These classic Zeiss Dialyts have a wonderful combination of quality AND prism type: Abbe Koenig.
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#7 Antonio R.G

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Posted 26 June 2020 - 09:46 AM

I think in same price (generally) Porro prism give better image quality, is very difficult find a good roof binocular cheap (about 100€, for example..) in Porro binoculars is not so difficult.
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#8 Pinewood

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Posted 28 June 2020 - 06:10 AM

I love this one... the view is spectacular, but it may be more the quality than the prism type.    Tom

Hello Tom,

 

The 7x42 Dialyt or Dialyt ClassiC lived up to its name of ClassiC.  The later models had multi-coating and phase coating which were  improvements, as the model had roots in the Hensoldt binoculars.  The 7x42 was bright, low in chromatic aberration, probably because of a long focal length objectives,  and surprisingly handy.  The design included a touch of stereopsis as well as a wide field of view.  It avoided the use of internal focussing and had a moveable bridge like a traditional Porro, so it was not close focussing.  The 8x56 and 10x56 were  built along similar lines.  

 

The 8x30 and 10x40 Dialyt binoculars used Schmidt Pechan prisms and the objectives moved in the barrels.  Two decades ago, they were all highly regarded but the 56mm models  seemed to be a handful.  If I recall correctly, the 8x56 model was the end of the line.

 

With multi-coating and phase coating your 7x42 could be a better choice for astronomy than some older 7x50 binoculars.  With its Abbe-König prisms, its light transmission is a close match to a Porro glass, compensating for the increased number of air to glass surfaces of the roof prism.

 

Stay safe,

Arthur


Edited by Pinewood, 28 June 2020 - 07:09 AM.

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#9 Grimnir

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Posted 28 June 2020 - 06:33 AM

The 8x56 and 10x56 were  built along similar lines.  

 

 

 

Hi Arthur,

 

I know about the 8x56 Dialyt of course but have never heard of the 10x56 - was there a 10x56 Dialyt?

 

Graham



#10 Grimnir

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Posted 28 June 2020 - 06:42 AM

Hi Arthur,

 

I know about the 8x56 Dialyt of course but have never heard of the 10x56 - was there a 10x56 Dialyt?

 

Graham

 

Ah - Arthur I think maybe you were referring to the Design Selection 10x56. Is that right?

 

Graham



#11 Pinewood

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Posted 28 June 2020 - 07:07 AM

Hi Arthur,

 

I know about the 8x56 Dialyt of course but have never heard of the 10x56 - was there a 10x56 Dialyt?

 

Graham

Hell Graham,

 

I thought so but my memory is a bit muddled of late.

 

Stay safe,

Arthur



#12 Pinewood

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Posted 28 June 2020 - 07:08 AM

Ah - Arthur I think maybe you were referring to the Design Selection 10x56. Is that right?

 

Graham

Most likely.

 

Arthur



#13 Senex Bibax

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Posted 17 November 2020 - 06:36 AM

Very similar to this pair I picked up yesterday - Dr. Hans Hemsoldt 8x56 - I understand they were owned by Zeiss. I'm looking forward to trying them out this evening, it was overcast yesterday:

 

HansHensholdt2
HansHensholdt1

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#14 gwlee

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Posted 17 November 2020 - 03:13 PM

To me, excellent porros and excellent roofs work equally well for astronomy, but excellent porros cost much less, so, I use for 50mm porros astronomy.

#15 Binojunky

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Posted 18 November 2020 - 01:01 PM

Roofs are coming down in price, for example I can buy the Celestron Nature DX ED 10x50  for less than the porro Nikon Action Extreme10x50 . Once in a while you can drop on a real deal, Orion Shoreview pro ED10x42  roof prism for $120 Canadian, it just a matter of luck and shopping around, and preferences to which style suits the buyer best, Dave


Edited by Binojunky, 18 November 2020 - 01:55 PM.


#16 SandyHouTex

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Posted 18 November 2020 - 05:29 PM

I have always been a porro prism guy, never felt that roof prism was as good. I am now wondering why the two different types? Is there an real advantage of one over the other? Why have manufacturers started really going to roof prisms? Is the image quality superior in every respect? Is there inherently greater potential for superb images which surpass the finest porro prism binocular? Is the light transfer equal or better in one over the other? 

Interested in your thoughts and insights. You can listen to the so called experts, but I would rather hear what the "boots on the ground have to say"

 

Chris

Porros have more light through put due to complete internal reflection, and no seams in the field of view.  Stay with the porros.


Edited by SandyHouTex, 18 November 2020 - 05:30 PM.

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#17 Pinewood

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Posted 18 November 2020 - 07:10 PM

Very similar to this pair I picked up yesterday - Dr. Hans Hemsoldt 8x56 - I understand they were owned by Zeiss. I'm looking forward to trying them out this evening, it was overcast yesterday:

 

Hello Senex* Bibax,

 

Hensoldt became part of the Zeiss family in the 1920's, and became a  wholly owned subsidiary.  The Zeiss Dialyts are descendants of the Hensoldt Dialyts, which were roof prism binoculars.   According to a search Hensoldt optics  was acquired by Airbus DS Optronics GmbH,

 

Dr. Hans Hensoldt had difficulties after WWII because of close ties with the Nazis.  He set off on his own and produced binoculars under his own name.

 

* I am also a senex if my long, ago, study of Latin still serves me.

 

Stay safe,

Arthur



#18 Rich V.

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Posted 18 November 2020 - 08:14 PM

 

* I am also a senex if my long, ago, study of Latin still serves me.

 

 

I think there's a likelihood a number of us could be described as senex bibax.  Nice handle!

 

I'm 55 years past having to remember much Latin.  Now, where's my wine?

 

Rich


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#19 Senex Bibax

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Posted 19 November 2020 - 09:05 AM

Hello Senex* Bibax,

 

Hensoldt became part of the Zeiss family in the 1920's, and became a  wholly owned subsidiary.  The Zeiss Dialyts are descendants of the Hensoldt Dialyts, which were roof prism binoculars.   According to a search Hensoldt optics  was acquired by Airbus DS Optronics GmbH,

 

Dr. Hans Hensoldt had difficulties after WWII because of close ties with the Nazis.  He set off on his own and produced binoculars under his own name.

 

* I am also a senex if my long, ago, study of Latin still serves me.

 

Stay safe,

Arthur

Makes sense, they do look a lot like the Zeiss Dialyts. Can I assume they are of similar quality and value to the Zeiss? So far, the optics appear to be top notch. The only thing I want to do is to clean one prism surface and to clean and lube the focuser, but I'm wary of opening them up. I've disassembled porro prism binoculars before but nothing like these.

If I was bothered by the Nazi associations after 80 years (as awful as they were), then I never would have owned a Volkswagen or a Hugo Boss jacket.

 

You're a *Senex* too?  I got the nickname when my oldest studied Latin in high school and she decided to call me Senex from then on. I added "Bibax" as a qualifier after I joined another web forum that already had a "Senex". I considered "Ferox" but it doesn't really fit me.



#20 Binojunky

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Posted 19 November 2020 - 01:18 PM

Porros have more light through put due to complete internal reflection, and no seams in the field of view.  Stay with the porros.

That,s not written in stone, a good roof design can still be preferable and perform better than a poorly executed porro prism, Dave.


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#21 SandyHouTex

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Posted 19 November 2020 - 06:04 PM

That,s not written in stone, a good roof design can still be preferable and perform better than a poorly executed porro prism, Dave.

I assumed everyone knew that.  A pair of plastic porros at Walmart for $10 will be optically bested by a pair of Vortex Razor roofs that are 100X the cost of the porros.  However the $10 porros will still have better light through put due to complete internal reflection.



#22 The Ardent

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Posted 19 November 2020 - 06:37 PM

Chris

Have to taken your concerns to Swarovskioptik.com ?

They describe their current binoculars as “The Legend” “The Peak of Perfection” and other advertising puffery.

Is it your experience to agree or disagree with these descriptions?

I have always been a porro prism guy, never felt that roof prism was as good. I am now wondering why the two different types? Is there an real advantage of one over the other? Why have manufacturers started really going to roof prisms? Is the image quality superior in every respect? Is there inherently greater potential for superb images which surpass the finest porro prism binocular? Is the light transfer equal or better in one over the other?
Interested in your thoughts and insights. You can listen to the so called experts, but I would rather hear what the "boots on the ground have to say"

Chris



#23 Mark9473

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Posted 19 November 2020 - 06:59 PM

$10 porros will still have better light through put due to complete internal reflection.

Then why do even $100 porros score about 80-85% light transmission?



#24 KennyJ

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Posted 19 November 2020 - 07:04 PM

I think this subject has been discussed on this forum before ( probably at least 20 times in the years I've been active here)

 

1. There is a lot more profit in selling top rated roof prism binoculars than top rated Porros.

 

The profit margin alone in some of the best 42mm roof prism models is probably higher than the street price of 95% of any 42mm Porro prism model.

 

2. By far the vast majority of people who spend a lot of money on binoculars prefer "the look and feel" of roof prism models

 

Roof prism binoculars are "sleeker", "more fashionable" and the result of practically 100% of all research and development funding that has been invested in by leading manufacturers for more than 20 years now.

 

I personally don't think designers and market researchers at the likes of Swarovski, Zeiss, Leica and Nikon ever give more than a few moments thought in a whole year, if indeed any at all, about the needs or preferences of "astro users".

 

They concentrate on binoculars and spotting scopes for the vast majority of people with money to spend on such items -- namely birders, wildlife lovers, hunters, travellers and sports watchers.

 

Kenny


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#25 Jon Isaacs

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Posted 20 November 2020 - 06:34 AM

I assumed everyone knew that.  A pair of plastic porros at Walmart for $10 will be optically bested by a pair of Vortex Razor roofs that are 100X the cost of the porros.  However the $10 porros will still have better light through put due to complete internal reflection.

No.. 

 

Walmart does not sell 42mm or 50mm binoculars for $10.  There is far more to binocular throughput than whether or not the prisms have total internal reflection on one surface, that surface can be coated so there is essentially no loss. 

 

In terms of binocular through-put, the quality of the coatings on the optical surfaces is very important since there are so many elements.  Multiply the number of surfaces by 0.99 versus 0.96.. 

 

A high quality roof will have high quality coatings and much better transmission than inexpensive binoculars.  One issue with inexpensive porro prism binoculars is that they are not operating at full aperture.  I own a pair of 10x50 Simmons. $30 at Walmart is what I paid. Their actual aperture is right at 40mm because the prisms are undersized.  That's loss of brightness of 36%.  

 

My 10x42 Eagle Optics Roof prism operate at full aperture and are brighter than the Simmons Prosports 10x50s.

 

I once bought a pair of Vivitar 7x50's at ACE Hardware for $10 just to see what they were.  You wouldn't bother measuring the through-put, they turned everything green and though the focuser moved the eyepieces, they did not actually focus, just different levels of mushiness. 

 

Jon  




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