[Steve Napier]

Hi.I"ve noticed that a lot of people who have compared the 8x32FL to the 8x42FL state that the smaller 32mm has better all round edge performance.
Is there a specific reason for this? Could it be because of the different prisms that are used?
Thankyou,
Steve.

[Rich N]

Originally Posted by Steve Napier

Hi.I"ve noticed that a lot of people who have compared the 8x32FL to the 8x42FL state that the smaller 32mm has better all round edge performance.
Is there a specific reason for this? Could it be because of the different prisms that are used?
Thankyou,
Steve.

Hi Steve,

Maybe, but if there is a difference I would guess it is the eyepieces.

Rich

[Steve Napier]

You could be right there Rich.
Let"s see what latter replies reveal.
Steve.

[trealawboy]

Originally Posted by Rich N

Hi Steve,

Maybe, but if there is a difference I would guess it is the eyepieces.

Rich

This line is quoted from the Alula review of the Zeiss 8x32FL vs the Leica Ultravid 8x32.

"In the 32mm FLs, Zeiss uses a more conventional prism design than in the 42mm models."

I've no idea if that is significant or not.

[mak]

Originally Posted by trealawboy

"In the 32mm FLs, Zeiss uses a more conventional prism design than in the 42mm models."

I've no idea if that is significant or not.

It is for light transmission, especially at dusk and dawn.

[jtpowers1972]

Originally Posted by Steve Napier

Hi.I"ve noticed that a lot of people who have compared the 8x32FL to the 8x42FL state that the smaller 32mm has better all round edge performance.
Is there a specific reason for this? Could it be because of the different prisms that are used?
Thankyou,
Steve.

Hi Steve-

I own a pair of 8X32 FLs, and have looked through the 8X42. Without question the 32's have better edge performance, in my experience. In comparison to the 32's, the 42's seem to have an conspicuous sweetspot surrounded by a relatively lesser quaility image (I may be overstating this for the sake of arguement, but when I compared the two, it seemed obvious to me.).

I believe the main reason for increased edge performance is that the 32mm optical train has a longer focal ratio than the 42mm. Given similar eyepiece design, this alone could account for the improved edge performance.

I should say that for me, the better quality of overall image the 32's have makes up for the increased aperture in the 8X42's. Also, the FOV is wider (which compounds the benefit of better edge perfomrance...).

Best Regards,
John

[henry link]

Originally Posted by jtpowers1972

Hi Steve-

I own a pair of 8X32 FLs, and have looked through the 8X42. Without question the 32's have better edge performance, in my experience. In comparison to the 32's, the 42's seem to have an conspicuous sweetspot surrounded by a relatively lesser quaility image (I may be overstating this for the sake of arguement, but when I compared the two, it seemed obvious to me.).

I believe the main reason for increased edge performance is that the 32mm optical train has a longer focal ratio than the 42mm. Given similar eyepiece design, this alone could account for the improved edge performance.

I should say that for me, the better quality of overall image the 32's have makes up for the increased aperture in the 8X42's. Also, the FOV is wider (which compounds the benefit of better edge perfomrance...).

Best Regards,
John

John,

I like the focal ratio idea, I've suggested it myself, but I don't think it's true. Even if the 8x42 is hypothetically assigned a very low focal ratio for a binocular of f/3.5 and the 8x32 a very high ratio of f/4.5 the actual focal length of the 8x42 would still be a little longer than the 8x32 (147mm vs 144mm). In most daylight conditions the pupil size of the eye restricts the effective aperture of either binocular to less than 30mm, so the effective focal ratio of the 8x42 would be as high or higher than the 8x32. The lower focal ratio wouild only have an influence on edge performance in low light.

I tried an easy experiment today to see how much focal ratio influences the edge performance of the 8x42. First I stopped down one barrel to 30mm and compared that barrel to the wide open one in dull overcast daylight. There was a tiny barely visible improvement in edge performance. A 20mm stopdown improved it a lttle more, but it was still inferior to an 8x32 SE. A 15mm stop improved it even more, but the Nikon was still a little better. The main problem with the edge in the 8x42 FL is astigmatism and it takes quite a high effective focal ratio, perhaps f/7 or f/8 to see a significant improvement.

I've used the 8x42FL for almost two years. It took three samples to find the really good pair I have now. This pair has higher actual measured resolution, lower longitudinal chromatic aberration and a cleaner star test than any small binocular I've tested and in spite of the widely acknowledged edge issues it has become my favorite birding binocular because of the extremely sharp and vividly transparent center 1/3 of the field. I've borrowed two samples of the 8x32 FL for testing and used each for a few days. Neither of these tested as well as the 8x42. Both had much lower measured resolution and showed higher levels of aberrations in a star test. In field use they had slightly better edge performance (lower off-axis astigmatism), but fell short of the 8x42's sharpness in the center and were for me less relaxing to look through. I was always happy to return to the 8x42. Just one more example of how different priorities and values lead to different preferences when it comes to binoculars.

Henry

[jtpowers1972]

Hi Henry-

Your reply is very interesting. I think there must be a fair amount of sample variability within the FLs. The 8X32 I use now is actually the second one I went through before I was happy. This one is noticably better than the previous pair (focuser mainly), and I think this time I got a very good pair. Perhaps I was comparing it to an ok sample of the 8X42 FL. It would be interesting to compare a known solid sample of each, you know? Maybe mine vs. yours??



John

[Steve Napier]

Thanks for all those very interesting replies.
I wonder how the 10x32 FLs compare to the 10x42 FLs?
Perhaps the same findings?
Thankyou
Steve.