Review of NL PURE 12x42 with Iphone video sample - 4K (2 Viewers)

[SuperDuty]

I haven't seen Binomania's USAF 1951 results for SRBC 12x50, but the 12x42 NL Pure results are certainly wrong or mislabeled. I think the red arrows were probably intended to point at Group 0 and Group 1 rather than Group -2 and Group -1. As shown the results would be impossibly poor. However, if the labeling is corrected the results at 36x then become a bit too good (better than diffraction limited.)

I just noticed that Binomania's USAF chart measurements for the new Nikon 10x25 IS are also a bit too good to be true. In this case it's the complete impossibility of a human being resolving 5.89 arc second line pairs through a hand held 10x binocular. Something appears to be off with their chart or their methods. Perhaps their chart has been incorrectly sized or the 35 meter distance has been incorrectly measured. Some investigation is needed.

Hi Henry, these are the two charts.

 

[henry link]

Thanks Superduty. Yes, the SRBC is resolving one element smaller (by about 12%) than the NL, but both of these images appear to be pointing red arrows toward groups that are much too large. If this were truly the best these binoculars could do they would be very poor indeed, with images that would look no sharper than if the observer had a bit worse than uncorrected 20/30 eyesight.

While it has its own oddities (for instance, Group 0/Element 1 cannot possibly be resolved through 10x hand held binoculars at 35 meters), the image below from the recent Binomania Nikon 10x25 IS review is at least pointing the red arrows toward the group that was probably intended.

 

[SuperDuty]

Thanks Superduty. Yes, the SRBC is resolving one element smaller (by about 12%) than the NL, but both of these images appear to be pointing red arrows toward groups that are much too large. If this were truly the best these binoculars could do they would be very poor indeed, with images that would look no sharper than if the observer had a bit worse than uncorrected 20/30 eyesight.

While it has its own oddities (for instance, Group 0/Element 1 cannot possibly be resolved through 10x hand held binoculars at 35 meters), the image below from the recent Binomania Nikon 10x25 IS review is at least pointing the red arrows toward the group that was probably intended.

Thanks for the information.

 

[binomania]

Hi Harry, thanks for the suggestion. I need to double check the NL table, I'll do it over the weekend. Regarding the 10x25 I can only tell you that I use a USAF printed in the 30x40 format at 35 meters telemetered with two types of instruments. How do you calculate the resolving power if you don't know what format I printed it in?

 

[binomania]

Regarding the USAF CHART tests, guys, I have always written that they should not be taken as absolute truth because performance can also vary due to subjective factors, such as visual and physical fatigue and also weather conditions. Although the map is only 35 metres away, I notice differences with binoculars that I always use between winter and summer, I try to take an average between three daytime observations (morning, midday, late afternoon) but there can be differences because the human factor intervenes. Please refer more to the text than to the USAF which is not a photographic test.

 

[henry link]

Regarding the 10x25 I can only tell you that I use a USAF printed in the 30x40 format at 35 meters telemetered with two types of instruments. How do you calculate the resolving power if you don't know what format I printed it in?

Hi Piegiovanna,

The USAF chart is only accurate if it's printed so that the sizes of the Groups and Elements correspond exactly to the line pairs per millimeter indicated by the numbers next to each Element and at the head of each Group. A correctly sized chart can be completely accurate if it's used properly.

Edmund Optics sells excellent correctly sized glass slides with completely sharp vapor deposited line pairs down to Group 7, Element 6. They provide a conversion table with their charts and on their website to convert the Groups and Elements to line pairs per millimeter and then (if the distance to the chart is known) a formula for converting the lps/mm to arc seconds of resolution. I calculated the resolving power in your tests by applying those tools to what I assumed was a properly sized chart viewed at 35 meters.

It's true that daylight measurements of binoculars offer some peculiar problems since it's likely that the binocular magnification is too low to see the binocular's true full aperture resolution without the magnification being boosted. Typically, "resolution" at normal magnification will simply be the observer's eyesight acuity at a particular time and at an unknown pupil size modified by the binocular's magnification. I get around that by making several measurements at boosted magnification with stop down masks covering the objective lens to make exit pupils that correspond to eye pupil sizes from 2mm up to the full aperture exit pupil.

Henry

 

[binomania]

Hi Henry, thanks for your valuable advice. I actually had the USAF printed by a graphic designer friend of mine, the same one who made the clothing and logos for binomania. He used a professional high resolution printer and all the lines are resolved, I think it is in the 30x40 format but he could have also resized the file a bit for his printing. When I presented this test, I said that it was mostly for me to get an idea of the general performance of a binocular even if there are various subjective and environmental factors to consider. Thanks

 

[henry link]

I can't be sure, but it looks like your chart must have been arbitrarily sized by your friend and therefore doesn't conform to the USAF 1951 specifications. That would certainly explain the inaccurate results in your reviews.

 

[binomania]

Non ne sono sicuro, ma sembra che il tuo grafico sia stato dimensionato arbitrariamente dal tuo amico e quindi non sia conforme alle specifiche USAF del 1951. Ciò spiegherebbe sicuramente i risultati imprecisi nelle tue recensioni.

Gr

I can't be sure, but it looks like your chart must have been arbitrarily sized by your friend and therefore doesn't conform to the USAF 1951 specifications. That would certainly explain the inaccurate results in your reviews.

Thanks Harry, I will treasure your precious advice to improve my reviews

 

[Canip]

I can't be sure, but it looks like your chart must have been arbitrarily sized by your friend and therefore doesn't conform to the USAF 1951 specifications. That would certainly explain the inaccurate results in your reviews.

I think you brought up an interesting point, Henry. If I am not mistaken, when most people on this forum and others report their results of „tests“ on the USAF, they use whatever size and quality print-out they got, often used at random distance. That includes myself. Probably few people observe the details you mention in your post # 26. But I believe that‘s fine if the USAF is just used for simple comparisons between binoculars („how far down on the chart does each model go“), keeping the limitations of such comparison - and the reliability of the entire procedure, since your using your own eyes - in mind. But perhaps I am mistaken?

 

[binomania]

Penso che tu abbia sollevato un punto interessante, Henry. Se non sbaglio, quando la maggior parte delle persone su questo forum e altri riportano i risultati dei loro "test" sull'USAF, usano qualsiasi dimensione e qualità di stampa abbiano ottenuto, spesso usata a distanza casuale. Questo include me stesso. Probabilmente poche persone osservano i dettagli che hai menzionato nel tuo post n. 26. Ma credo che vada bene se l'USAF viene usata solo per semplici confronti tra binocoli ("quanto in basso sulla tabella va ogni modello"), tenendo a mente i limiti di tale confronto e l'affidabilità dell'intera procedura, dal momento che stai usando i tuoi occhi. Ma forse mi sbaglio?

 

[binomania]

Hi, Canip, my intention in fact, was to have a yardstick for my tests, from the distance that I could get from home and with the best printout that the graph could make. Obviously Henry can't follow all my lucubrations on binomania and on my forum and rightly pointed out the issue. For example, he will be pleased that instead we have created a table for telescopes to be placed at 1050 meters of distance to have the correct resolving powers. It was made by my architect friend Angelo Cutolo and I will go and place it in the mountains above my house as soon as possible. Now honestly I don't feel like making further changes to the table that I use from home, because by now I have many comparisons visible in the articles and people would get even more confused

 

[henry link]

Sorry gents, I had no idea that the USAF chart was only being used to give the appearance of measuring something. However, even if there are no real measuremts involved there are still serious comparative inconsistencies with the labeling of the photos.

I would point to the results of the 12x42 and 14x52 NLs using the Zeiss tripler, since those were done with tiny enough exit pupils to guarantee that the eye would be able to see the full aperture resolution of the binoculars. The same can also reasonably be said of the 2.5mm exit pupil of the Nikon 10x25 S.

I'll do the math for you. If we accept the positions of the red arrows in the photos then (using an accurately sized chart) the 12x42 would have to have absurdly bad resolution for a 42mm telescope, 13.33 arc seconds or 560/D, with D being the diameter of the objective lens. You would expect the other binoculars to fall in line with similarly bad looking results if the only problem were the sizing of the chart, but notice that the arrows in those tests are pointing at much smaller Groups, so instead we see comparatively good resolution from the 25mm stabilized Nikon (5.56" or 132D) and from the 14x52 a bit worse, but still plausible for a binocular (2.95" or 153/D.)

I suspect the 12x42 and SRBC 12x50 results are so far off because the arrows are mistakenly pointing toward the wrong Groups. Consequently those results shouldn't be used for comparison to anything else you've tested until they have been corrected. The Nikon and 14x52 NL are probably pointing toward the right Groups, and would be plausible if the chart were accurately sized.

Piergiovanna, all you need is an accurately sized chart and your Zeiss tripler and you can do real measurements just as easily as what you're doing now.