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The scourge of porro's (1 Viewer)

matt green

matt green

Norfolkman gone walkabout
Thought I'd start this thread off to ask about folks experiances of porro prism binoculars and (in my opinion) their only downfall as far as design is concerned..namely the bridge piece!!

I'm currently using an Opticron TGA 7x42, these have an excellent bright and very sharp image but because of the amount of movement of the focusing mechanism image quality is greatly affected by what direction I am focusing from, ie if I focus from near to far one of the barrels will be out of focus compared the the other..focusing from far to near and the problem seems to be resolved but as you can imagine this is far from ideal!!

From handling different models of porro's from different makers there seems to be a great deal of variation in the movement..or lack of in the bridge despite the fact that most of the budget models (excluding Swift and Nikon)look identical and probably originate from the same factory?

Matt
 
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Matt, that very problem was the main reason I switched to internal focussing roof prisms a good many years ago. I too had major grief with the barrels becoming 'out of sync', usually when I'd taken the focus to the extreme and was bringing the barrels back 'in'. I had several pairs of porro prisms, indeed there are 4 pairs in the loft now gathering dust.
 
Most helpful you should post this today, Matt, as I encountered this problem for the first time yesterday.

I have no such problem with my Nikon E2s, and would not expect to at that price. In fact I have never had this problem at all, but found yesterday that my old pair of Swift Audobon Mk2 8.5x44s, bequeathed to my parents, have developed exactly this problem. My Mum was struggling with them and I was shocked to find it was impossible to get both barrels in focus even with the diopter set all the way round way beyond the markings. There was a huge amount of play in the bridge - far more than I rememberm but they swear they've never dropped them.

Is there a solution? Can the bridge be tightened? Is it a pro repair job?

Thanks,
Graham
 
Sadly it is a pro repair job, which is why I have 4 pairs in the loft. Last time I priced up getting them repaired it was gong to be about £40 per pair....they are not worth it so I never bothered.
Thing being they need to be collimated after resetting the barrels, that is the costly bit apparently.


Graham
that is why I haven't been in touch to offer you one of these pairs for your forthcoming trip.

bitterntwisted said:
Most helpful you should post this today, Matt, as I encountered this problem for the first time yesterday.

I have no such problem with my Nikon E2s, and would not expect to at that price. In fact I have never had this problem at all, but found yesterday that my old pair of Swift Audobon Mk2 8.5x44s, bequeathed to my parents, have developed exactly this problem. My Mum was struggling with them and I was shocked to find it was impossible to get both barrels in focus even with the diopter set all the way round way beyond the markings. There was a huge amount of play in the bridge - far more than I rememberm but they swear they've never dropped them.

Is there a solution? Can the bridge be tightened? Is it a pro repair job?

Thanks,
Graham
Click to expand...
 
Opticron and Minox do internally focussing porros - sharp, waterproof and bright but not wide fov.
Otherwise I have several conventional porros that don't have the problem, though I have owned some that did. It seemed less of a problem some years ago when there was more use of metal for bridges (as with Nikon Es).
It was probably the reason you were always told to bring your bins into final focus from the same direction every time.
At the end of the day its whatever works for you - I use both types about equally depending on what I am doing.
 
Keith Dickinson said:
Sadly it is a pro repair job, which is why I have 4 pairs in the loft. Last time I priced up getting them repaired it was gong to be about £40 per pair.... ...that is why I haven't been in touch to offer you one of these pairs for your forthcoming trip.
Click to expand...

Cheers, Keith, That's what I feared. Will have to look out for another pair to give the folks.

Jim (JTW521) has very kindly lent me some for my trip anyway - collected this eve. Still in the market to buy a couple of pairs now as well - one to lend non-birders and one to replace the Audobons.

G
 
iveljay said:
Opticron and Minox do internally focussing porros - sharp, waterproof and bright but not wide fov.
Click to expand...

I have actually owned a pair of those Opticron HR WP binoculars, and agree the optics were extremely good..I bought them on the spot after finding they had a significantly better image than the BGA Classic roofs from the same company that cost £429!! However the focus was painfully slow, coupled with limited field of view and close focus I passed them on...

Matt
 
bitterntwisted said:
Most helpful you should post this today, Matt, as I encountered this problem for the first time yesterday.

I have no such problem with my Nikon E2s, and would not expect to at that price. In fact I have never had this problem at all, but found yesterday that my old pair of Swift Audobon Mk2 8.5x44s, bequeathed to my parents, have developed exactly this problem. My Mum was struggling with them and I was shocked to find it was impossible to get both barrels in focus even with the diopter set all the way round way beyond the markings. There was a huge amount of play in the bridge - far more than I rememberm but they swear they've never dropped them.

Is there a solution? Can the bridge be tightened? Is it a pro repair job?

Thanks,
Graham
Click to expand...

A word in defense of your inherited 804 Audubons, which might be as much as sixty years old. Just letting them sit in a closet allows the internal cement to dry and powder, and the grease pack to lose its lubricating ability. The same happens with roof binoculars, incidentally, or will happen given enough time. Like it or not, the seals also dry out on waterproof models, eventually allowing contaminants to enter.

Personally, I've found that it pays to have fine quality optics like the Swift 804 Audubon, Nikon Es, Zeiss BGAT, Bushnell Custom, etc. refurbished. Here in the US we still have master repairmen like Nicolas Crista to make them work like new — or even better than new in some cases — at a reasonable cost (< $80). In my opinion, if the bridge mechanism is a problem for Porros (and some roofs), it's primarily because of cheap plastics being used in the current versions.

Incidentally, (changing the topic) the US Navy instructs users to arrive at a final focus by dialing inward from infinity. This allows the eye to maintain a resting accommodation during the process, which in turn makes long term observation more comfortable. Of course, this would be most relevant for tasks like astronomy or shipboard viewing of the horizon, and less meaningful for near-in birding.

Regards,
Elk
 
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elkcub said:
A word in defense of your inherited 804 Audubons, which might be as much as sixty years old. Just letting them sit in a closet allows the internal cement to dry and powder, and the grease pack to lose its lubricating ability. The same happens with roof binoculars, incidentally, or will happen given enough time. Like it or not, the seals also dry out on waterproof models, eventually allowing contaminants to enter.

Personally, I've found that it pays to have fine quality optics like the Swift 804 Audubon, Nikon Es, Zeiss BGAT, Bushnell Custom, etc. refurbished. Here in the US we still have master repairmen like Nicolas Crista to make them work like new — or even better than new in some cases — at a reasonable cost (< $80). In my opinion, if the bridge mechanism is a problem for Porros (and some roofs), it's primarily because of cheap plastics being used in the current versions.

Incidentally, (changing the topic) the US Navy instructs users to arrive at a final focus by dialing inward from infinity. This allows the eye to maintain a resting accommodation during the process, which in turn makes long term observation more comfortable. Of course, this would be most relevant for tasks like astronomy or shipboard viewing of the horizon, and less meaningful for near-in birding.

Regards,
Elk
Click to expand...

Hi Elk,

The Audubons are a pair of "Type 3a" per your article with Renee. Gold ribbon, focus wheel is painted metal. When I bought them a couple of years ago they came in excellent condition and even included the original receipt (bought in the UK in 1984) I loved them and was very pleased to let my parents enjoy them when I upgraded to the much lighter and smaller E2s.

I must say I was really taken aback to find the problem. The Swifts are a very very chunky binocular and I am sure my parents have treated them very carefully.

I don't know anywhere in the UK that will do a professional repair - the difficulty of finding anyone to fix anything economically in this country is a bugbear of mine - seems we are expected to 'help the economy' by buying new and throwing things with one broken screw in landfill.

I do have a friend visiting from Seattle soon. I will see if he can take them into Bill Cook's shop and get them fixed up, although they may take him over his baggage limit on the flight home! That is, unless someone knows a good repairer in the north of England?

Graham
 
When I can afford it, possibly at retirement, I'll treat myself to the latest top of the range bins to enjoy my birding retirement with. In the meantime I'm still more than happy with my Adlerblick porro's. I honestly don't feel they've ever let me down or I've missed a bird in poor light conditions as a result of them.

In the time I've owned them I've felt the need to update telescopes, tripods, camcorders a couple of times, digital cameras a couple of times, but not my bins.

There an old friend of at least fifteen years and they've seen some pretty special birds in that time.
 
bitterntwisted said:
Hi Elk,

The Audubons are a pair of "Type 3a" per your article with Renee. Gold ribbon, focus wheel is painted metal. When I bought them a couple of years ago they came in excellent condition and even included the original receipt (bought in the UK in 1984) I loved them and was very pleased to let my parents enjoy them when I upgraded to the much lighter and smaller E2s.

I must say I was really taken aback to find the problem. The Swifts are a very very chunky binocular and I am sure my parents have treated them very carefully.

I don't know anywhere in the UK that will do a professional repair - the difficulty of finding anyone to fix anything economically in this country is a bugbear of mine - seems we are expected to 'help the economy' by buying new and throwing things with one broken screw in landfill.

I do have a friend visiting from Seattle soon. I will see if he can take them into Bill Cook's shop and get them fixed up, although they may take him over his baggage limit on the flight home! That is, unless someone knows a good repairer in the north of England?

Graham
Click to expand...

Graham,

Oh, a Type 3a. Nice. No mention whether you tried to contact Pyser, Ltd., but they can probably help to locate a qualified repair facility. Several of my older Swifts were bought from the UK (including my precious 804ED), and they all had been serviced at some point before I got them. This according to Nicolas Crista. http://www.nrcoptics.com/

Of course you are right, poor quality mass production leads to a throw-away mentality, and we're not immune from it in the US by any means. I've been trying to develop a wisdom that goes something like this: "Never buy a new binocular that ain't worth repairing." But, that assumes there is a repair facility in the first place. ;)

Regards,
Elk
P.S. Kay Optical is said to be very good. Must be true, — they have an Audubon for sale. http://www.kayoptical.co.uk/servicing.htm
 
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I can use porros for looking at things 50 ft or further. If the object is closer, I get eye strain. My brain does not understand the stereo view one gets with lenses further apart than my eyes.

I no longer have porros, other than two reverse porros, small pairs.
 
Tero said:
I can use porros for looking at things 50 ft or further. If the object is closer, I get eye strain. My brain does not understand the stereo view one gets with lenses further apart than my eyes.

I no longer have porros, other than two reverse porros, small pairs.
Click to expand...

In general, I'd agree, except that 12-15 ft. is more typical. The problem is that near focusing requires eye convergence. The Pentax Papiio not only is a reverse Porro, it also allows converge with the prisms. But, I reinvented something less expensive and more portable — my eyes. |8.|
 
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