Zeiss SFL 10x50 review with digiscoping video samples (9 Viewers)

[HenRun]

Maybe the term CA tolerance is better.

Given identical conditions (subject, lighting, position in the field of view, visual acuity, eye placement), CA should be the same, and the ability to detect CA should be the same. But some individuals are more tolerant of CA than others.

To me, the term "CA sensitivity" is ambiguous as to whether it is referring to the lack of physical ability to detect CA or to psychological indifference to the presence of CA.

I agree to the second paragraph.

I agree somewhat to the third but altering the descriptive wording would also be shifting the goal post to alter the wording from being CA "sensitive" to being (more or less) CA "tolerant".

Since it refers to the personal ability it will still be subjective - even though the subjective findings can also often be linked to an objective measurement.

Personally I am CA "sensitive" but I have also become more CA "tolerant" over the last few years.

In spite of my recent postings I personally don't have CA as the number one deal breaker but unfortunately this was the case in the SFL50mm binoculars I was most interested in, the 10X and the 12X.

As per Hermanns post about CA (detectability) varying with light conditions:
I would like to learn more about why and how CA differs and becomes more or less detectable under different light conditions (diffuse light, scattered light, high/low contrast on cloudy days etc) because even if I can see it clearly under certain conditions - and therefore know it is present in the optics - there are many times where it does not pop up to remind me it is there.

In case of my first gen Meopta B1 8x32 it is definitely there - and more than in my SFL 8x40 - but it is managed to a point I still enjoy using the little one practically everyday. It was on an outing the other week where I happened to watch a woodpecker against a bright sky at close range and the Meopta "flared up" with CA to the point of being distracting.

This was 25 to 30m from the house so I went back and got the SFL8x40 which also has CA under these conditions but the SFL40 manages it so much better than the Meopta that the "worst case level" was not distracting. On the contrary it was great, despite "some" CA.

EDIT: I have told this story once before but I don't know if I mentioned that I also brought my CA champion: the Meopta Meostar 12x50 B1 +.
And yes, the CA was practically absent in the Meopta 12X but in this case the SFL8x40 was still the better choice due to the angle and distance so after five to ten seconds of shaky CA free viewing with the Meopta I switched back to the SFL8x40 and it proved the better observational instrument as I could more easily ID the Woodpecker as b*stard #3 (out of 4). They start out early in the morning, often right outside the bedroom window...

Still, I use the heck out of the little Meopta. I would not do that if I wasn't both CA sensitive and CA tolerant. Winter time I use it a lot less though, since the high contrast CA can be a little too much. And this was - for me - the case with the 10X and 12X50 SFL's; I can predict how they would perform under the common worst case scenarios for my eyes and sensitivity and I don't need very long time behind a bino to see where the threshold is for me.

 

[Yarkho]

Okay, I take the criticism that I have not looked through as a fair one. But: Zeiss literally has only one official vendor in my country. It is on the other side of the country, which would require a full-day trip on my part. Furthermore, they do not have them in stock. I know of another Zeiss vendor, slightly closer (about 150 km), which again does not have them in stock.

Other than that, I do not necessarily need to see for myself to make an evaluation as enough information is already available. Regarding photographic equipment, I regularly rely on detailed reviews (such as lenstip.com - an allbinos-like web) that include evaluation of various aberrations. Similarly with binomania.

And HenRun's assertion of CA being present when the scene has depth (i.e., not everything is in the same distance) confirms longitudinal CA to me, something I really dislike. I have learned to tolerate it in smaller 30-42mm binoculars that I have, but it's always a bit of a struggle, not worth the SFL price tag and a day trip. Sorry.

 

[Ignatius]

I stand by my choice of words @HenRun.
One person, who has actually handled the bino in question, mentioning CA and suddenly everyone jabbering about it without even having handled the binos is very much a panic or hysteria.
A second person making a video of testing the bino and coming to a somewhat different conclusion than the first person is very much putting that panic/hysteria into perspective.
But then again it all is always a matter of individual perspective. Yours, mine, hers, theirs, ... YMWV

 

[Holger Merlitz]

What happens if the object through the binocular is not perfectly in focus, and then we use a phone, which takes videos and therby brings it back into focus? The image may be sharp then, but since it was taken off the prime focus of the binocular's objective, an out of focus CA may be present (even at the field center) that would not be there if the binocular itself were perfectly focused. Similarly with observers who have a significant myopia and observe without glasses: They would set the binocular off the prime focus and perceive a sharp image, but being shifted out of the focal plane, the image may now have some colors from residual spherical chromatic aberration (also known as 'Gauss error', where different colors focus onto different focal planes) which would be invisible if the binocular were on the focal plane and the observer were using his glasses. Could this possibly explain why people experience different degrees of CA with the same binoculars? BTW, spherical chromatic aberration increases dramatically as the focal ratio of the objective gets faster.

Cheers,
Holger

 

[Yarkho]

Thanks Dr. Merlitz for this comment. I will look up the formulae for the dependence of spherochromatism on aperture and f-ratio.

I have just conducted a quick CA test using Meostar B1+ 8x42 (not HD) and NL Pure 10x42, looking at my usual antenna against the sky. You are right that the "CA" is ever so slightly worse without glasses than with glasses. With glasses, the NL Pure has almost none except at edges and even the B1+ 8x42 is reasonably free of it in the center.

 

[tenex]

Could this possibly explain why people experience different degrees of CA with the same binoculars?

Yes, but how severe must myopia be to produce a "significant" difference here, and how many such people are also free enough of astigmatism to be using bins without glasses?

 

[Yarkho]

I am in the ballpark of 4dpt give or take, with mild astigmatism, and the effect is small if at all perceptible.

 

[HenRun]

I stand by my choice of words @HenRun.
One person, who has actually handled the bino in question, mentioning CA and suddenly everyone jabbering about it without even having handled the binos is very much a panic or hysteria.
A second person making a video of testing the bino and coming to a somewhat different conclusion than the first person is very much putting that panic/hysteria into perspective.
But then again it all is always a matter of individual perspective. Yours, mine, hers, theirs, ... YMWV

I get your point! It is a fair one.

I misinterpreted it slightly, I did not read it in the context you provided - which I also agree with.

😊

 

[Maljunulo]

People who have assessed a bunch of optics over time and have a memory bank or an actual comparison sample will of course be able to see if there is CA in a binocular or if there is not. Regardless of it they "expect it or not".

I think discussing such a personal, subjective, and inherently unmeasurable thing as CA perception is more or less idle, but when we throw in memory, we go exponentially further afield.

As always, just my opinion.

 

[Yarkho]

"Inherently unmeasurable"?

You know that various aberrations as well as wavefront and Strehl are routinely evaluated in test reports of astronomical telescopes, right? Or that the allbinos evaluate them for binoculars?

 

[leviathan]

CA is very much measurable. It's just that some people are more and others are less sensitive to it.

 

[HenRun]

I think discussing such a personal, subjective, and inherently unmeasurable thing as CA perception is more or less idle, but when we throw in memory, we go exponentially further afield.

As always, just my opinion.

I agree, CA perception is individual and unmeasurable.

But, I think that that does not speak against memory of assessments of anything in the past. You either did see it or you did not.
If you have a working standard of assessment for finding out the good and the bad in any set of binoculars is not that hard, really.
It is still subjective though.

To prove my point: at first I did the peer to peer judging from memory when it came to CA when looking through the SFL 50's.

And you know what, I could confirm that by simply picking up the corresponding binocular I had related to from the past right then and there and compare again. And, the results were the same going from memory from a few years back when comparing to Ultravid in this case.

It is quite irrelevant if I noticed CA five years ago or yesterday when I am comparing - or relating to - a binocular I have seen through in the past. I cannot see how that would be taking things "exponentially further afield". It is still a subjective component.

It makes it easier in having the same environment as I have looked through dozens of samples and binoculars at the same place and under different light conditions. In binoculars I have been really interested in I have taken them home but the last couple of years the "gut instinct" after a half an hour at the shop has never changed for the better if you have second thoughts about a binocular.

As in the case of the SFL I did revisit them to have a second look, I wanted to make sure I checked them on two different days and conditions.

EDIT: only my opinion, of course.

 

[Maljunulo]

I agree, as long as we don't go beyond "either you see it or you don't".

 

[Ignatius]

How about cases of 'now you see it, now you don't'?

 

[HenRun]

Ignatius: I think we have taken it as far as it's going to go with the exponential semantics. But it is an interesting side topic.

I am a bit envious of those who claim they don't see CA. I wonder how that is possible to not register something that is clearly visible to others and also that is something that can be measured and has a long history of being a part of evaluating optics.

I am not making fun of anyone here, I just wish my own perception of it was lower.

 

[leviathan]

Yeah, me too. Even a slight amount of CA on telescopes, spotting scopes and binoculars drives me crazy.

 

[Yarkho]

I think it may be useful if we could establish a correlation between those that see CA / CA bothers them and some other factor.

Do you wear glasses? I do, have for a long time. I am in my mid-40s.

 

[Ignatius]

Ignatius: I think we have taken it as far as it's going to go with the exponential semantics. But it is an interesting side topic.

I am a bit envious of those who claim they don't see CA. I wonder how that is possible to not register something that is clearly visible to others and also that is something that can be measured and has a long history of being a part of evaluating optics.

I am not making fun of anyone here, I just wish my own perception of it was lower.

I was just being a little facetious. Of course I can see CA. I've had some terrible binos in hand. BUT, either all my binos are really good, or I can see it, but am not that susceptible to it. What I am trying to say is that for a given, measurable amount of CA I possibly notice it less than others. That is why somewhere else I asked what exactly it is, that lets people perceive a measurable physical phenomenon differently. But maybe this is similar to pain threshold. People perceive/experience physical very differently. Although that is not nearly as measurable as CA afaik.

 

[Richard D]

Colour of CA fringing makes a difference - I can tolerate more yellow-green than purple-magenta even if the quantity is pretty similar.

 

[HenRun]

I wear glasses now.

CA used to be a pet peeve up until a few years back. Now, honestly, it is not THE ONE THING that I base a purchase decision off.

It was a bit unfortunate that it happened to be the case for me with the 10/12X SFL50 binos and that most of the discussion ended up being about CA.

I am of course largely but not solely responsible for that.

The SFL50 line up is in good company: I looked through the newest Leica 15x56 rangefinder and I think it too has excessive CA, even more than the SFL’s and to the point I lost interest in it based on that, and on the price. If a new high end 15x56 can’t equal an old Meopta 15x56 that I can pick up for a 1/3 of the cost it is not worth considering. For me.