Canon 10x42 IS L Tripod vs hand-held vs IS testing (1 Viewer)

That was the "probable cause", subsequent testing using the Roddier method found somewhat more error than predicted.

This method uses a star test based on the fact that known defocus intra and extra focus should be exactly the same. The light is measured and Zernike polynominals are generated to form a wavefront diagram. The corrective lens, at least to my understanding , was made from this data.

The best data I read prior to the Roddier discussion of the group is attached.

Of course this is all from memory, which has become a source of amusement for my friends.

PS, this was a spacing error of the null corrector.

etudiant, I found an old pdf that shows some of the math and star images used. From memory I think the 1 mm null corrector error produced a outside edge flat by 4 microns. I think they also found pupil 1 and pupil 2 to be misaligned. This was one of the early papers of many, I am not sure but I think they used a series of tests by Dr. John Barretta.

The team went to work after the initial news media blurbs as to fault went out and decided to use a independent method to verify the problem instead of making the assumption about the reported faults. The original launch was 1990 and the correction did not happen til 1993.

. Thanks Surveyor,
I have repeatedly tried to mention that the Dawes limit and other similar limits are empirical and that the Dawes limit was for two equal double stars, I think of sixth magnitude with a certain size refractor telescope.
But some seem to believe that these limits are theoretical, but as with many other similar measures they are empirical.

And yes, these were obtained through our atmosphere etcetera by someone with very good eyesight who maybe was very shortsighted?

There have been frequent observations by people with exceptional eyesight, which have been dismissed by their peers. For instance the observations by George Alcock with a 100mm Ross F/12 triplet refractor of the planet Mars.
Also of people reading newspaper fine print right across the other side of the room, and seeing stars of magnitude 8.5 with unaided eyes.

Regarding telescope mirror accuracy, I recall one 10 inch Newtonian mirror I think in the USA (maybe Cave??) that could not be tested because it exceeded all known limits.

I think that the Nordic telescope mirror of around 100 inches made in Turku Finland may be the best large mirror and may be better than the Hubble mirror. They are I think presently finishing an even larger mirror.
Incidentally, Prof Vaisala probably invented the Schmidt telescope before Schmidt, from diagrams and notes in his notebooks
.The Hubble telescope mirror was a very silly mistake.

A little while ago I saw an image of the planet Uranus taken by one of the very best imagers, which showed detail which I thought was not real. There was frankly too much detail, even though it had been obtained by stacking thousands of images that were taken in superb conditions.
The imager did eventually say that the so-called fine details were in fact artefacts.

Even though amazing images are taken by amateurs of planetary detail, these are again actually obtained by what the imagers think the images should look like visually. In other words they are also based on empirical data.

I have no problem at all with Kimmo or David's measurements.

Incidentally, astro telescope diagonals are usually mirrors, not prisms and can be of fine quality, but I always preferred no diagonal for better accuracy.

Surveyor said:

etudiant, I found an old pdf that shows some of the math and star images used. From memory I think the 1 mm null corrector error produced a outside edge flat by 4 microns. I think they also found pupil 1 and pupil 2 to be misaligned. This was one of the early papers of many, I am not sure but I think they used a series of tests by Dr. John Barretta.

The team went to work after the initial news media blurbs as to fault went out and decided to use a independent method to verify the problem instead of making the assumption about the reported faults. The original launch was 1990 and the correction did not happen til 1993.

Click to expand...

Thank you, Surveyor, for the paper and the article. They offer a much more comprehensive analysis and review than anything I've seen elsewhere.
Such a lot of good work correcting an error that could have been avoided initially with a minute fraction of the effort later required.

kabsetz said:

When you do your two-eyed acuity tests, do you use your (possible) eyeglasses or not? As I said, I can no longer focus on a test chart with my eyes only, but when I test binoculars I never wear glasses so it is only my eyes and the bin or scope. I do not think I could go much under 60".

Kimmo

Click to expand...

Kimmo,

Yes I use my glasses. I developed a little astigmatism in middle age and it gives me a extra 5"-7" using them. Same when using binoculars. They are actually progressives and so far I get the same results at 2m as 10m which was a little unexpected. They were expensive though.

My two eye acuity varies a bit day to day, but providing I can get the light level I like, I get 54" about 1/3 occasions.

David

David,

Pardon me for being nosy, but is your prescription for myopia or presbyopia?

Kimmo

kabsetz said:

David,

Pardon me for being nosy, but is your prescription for myopia or presbyopia?

Kimmo

Click to expand...

I have a very mild hyperopia, presbyopia and the astigmatism I mentioned.

David

Kimmo et al,

Don't want to get hung up on this head movement thing too much, but learned a couple of things today. First and quite obviously I should compare observations between optics on the same day! (which I didn't do previously between the scope and bins) I seemed to be more "wobbly" today for some reason, maybe because I just came back from a long walk, and when I mounted the 10x on the tripod there was obvious slight side to side movement but also a different movement which I realized was in time with my pulse. I can stop the "swaying" movement by even the slightest contact with the eyepieces but then the view is no longer rock solid. The pulse is actually there all the time even when using the binoculars handheld it's just that I've never noticed it before. The swaying is still there with one eye closed and I think is just tiny balance compensations. I then tried the scope on the same target and realised that I'm not looking through it in the same way - perhaps because I am so much more familiar with looking through the scope - I'm automatically placing my eye deeper into the eyepiece and although I'm barely touching it the swaying movement stops. As soon as I move back a fraction so that contact is lost the movement returns. This happens with the scope in it's normal angled position and with it turned horizontally. The movement does seem to be more pronounced with the bins but I'll wait till I'm back home where I have several tripods (and also a straight through scope) and can make a side by side test. I imagine that if you had a really heavy tripod or some kind of bench mount that you could prevent head movement completely without introducing any vibration into the image by contact with the eyepieces.
A couple of questions, when you tripod mount your binoculars for testing are you standing? Also are you in contact with the eyepieces or just fractionally off?
It's interesting that the novelty of trying binoculars on a tripod has made me aware of things I'd not previously noticed. Going straight from tripod mounted to handheld also made me realise just how unsteady the handheld view really is - though half an hour later looking at a black wheatear they seemed fine!
Something else that I'm wondering about, would differences in resolution be more pronounced over longer distances? I appreciate that for controlled indoor testing 10m is a practical testing distance but as I'm trying outdoors I'm not so constrained.

I am getting a bit frustrated with trying to find some way to go further with my test other than to say that I can see more detail with A than with B.
I still don't have any kind of chart but came across the bank note idea which I tried today, Euro notes don't warrant close examination in my opinion but there is fine detail, they're readily available (at least the small ones are in my case!) and they are made to very fine tolerances. Unfortunately I soon encountered this phenomenon of knowing what something looks like means that your brain tells you you're seeing it! The only time that I really seemed to be getting anywhere was with the odd foreign word on the notes.
I'm gaining more respect for what you guys are doing all the time.

Thanks Torchepot for your observations.
There is pulse, breathing, nervous system and micro muscle correction going on all the time.
We would probably fall over without these corrections.
And rested, tired etc.
I suppose someone has done a thorough investigation, but yours is a good start.

Thanks Binastro,

I've just been reading the other recent two threads on the Canon IS models again and there is some really fascinating stuff. I really like your idea of printing random groups of letters (though when I first read it I didn't get it). The brain is brilliant at recognizing even just the shape of words otherwise and it makes it so hard to judge what you're really seeing. When I get back home I'll print something out and give it a try.

All the best

Phil

Phil,

I tend to stand when doing tripod-mounted tests. Mostly I keep my face from touching the binocular, but it depends on what seems to give the best view. With the scope, usually my brow is touching the eyecup, since the one on the ATX is so large that it is almost unavoidable. But the scope sits on a 830 series Velbon carbon, which is ridiculously stable.

Being able to lean your head against something immovable while viewing might improve things slightly, but it would also be a highly unrepresentative way of viewing, so I haven't resorted to that.

Viewing over longer distances in my experience changes things, but overall I prefer shorter distances. It is much harder to keep atmospheric effects out of the picture outdoors, and even indoors there may be radiators or other sources of local turbulence that factor in. Fortunately, you can see whether or not the air is stable. Most optics have less SA at longer distances, and their nominal magnification should be for infinity. However, it seems that internal focus binoculars don't change their magnification as much over distance.

The bank note target works well enough even for quantifying differences if with each optic you try to find the limiting distance for resolving a certain detail. Line patterns are good for this, but you need to control for possible astigmatism by rotating the target or the binocular. If the limiting distance for one 8x binocular is 12 meters and for another 13, you get their practical visual resolution difference right there. Only you have to control very carefully for light, focus and diopter, your own visual freshness in the moment of testing and for astigmatism. Going back and forth between the binoculars helps a lot here.

With more experience it matters less that you know what the detail that you are looking for is. If you don't jump on the first and perhaps only instance where you think you see it, but look for a more consistent detection, you'll find that the results are very repeatable. It does take practice, though, and not many are willing to practice such a silly and non-productive skill.

Kimmo

. Yesterday, I tried to see the pimple on the chimney pot about 400 feet away that I use for my critical testing. It can be seen with very good 10×42 binoculars pretty easily handheld but I've never seen it with a handheld eight times binocular which does not have stabilisation.
Yesterday, I was using a very old Swift 8.5×44 binocular of fine quality. It is built like a tank and seems to be as heavy as one.
I did manage to glimpse the pimple, but only for perhaps one 10th of a second about three times in a couple of minutes observation. The weight and bulk of the binocular means that it is a bit more stable, but I certainly prefer the Swift 8.5×44 HR 5, which is a lot lighter.
The heavier binocular has a wider field of view, about 8.50° against 8.26° for the HR 5.

Thanks Kimmo,
I guess what I was asking was that if the relationship between the relative resolution of two binoculars was ten percent at 10m i.e. 1metre difference wouldn't it amount to 2m at 20m and so on - just thinking that the difference at distance would be much more noticeable and might be easier for me to perceive. I take your point that light and air quality might change more too, but it should be the same for both optics if they are alternated often. Ten percent is probably more difference in respective resolution than might be expected between the very best optics of identical configuration e.g. two alpha 10x42 (though the difference handheld between an alpha 10x and an 8x could be much bigger for some observers) but would mean (if I'm thinking right) that to resolve the same degree of detail at 150m one observer would have to be fully 15m closer. Putting this into real life situations and thinking of the potential (possibly conservative) 30 percent advantage that may be gained with the Canon 10x42IS is real food for thought.

You mentioned earlier that it would be wise to carefully check before any purchase for collimation, the only way I know is to look at a something like a horizontal power line with the binoculars held away from the eyes and see if the images line up. Is this a good way to test? (no good for vertical misalignment).
Sorry if this may seem like groundhog day sometimes - I was a bit embarrassed to find that you and Henry were fielding questions about resolution on Cloudy Nights way back in 2006!! and presumably many times since.
Thanks for your patience,

Phil

Phil,

No problem on the patience front. Understanding binoculars and resolution is a learning process, and I for one am still learning more, including during the testing done during the short life of this present thread.

For instance, inspired by the unexpectedly good results with the 8x20 Ultravid, yesterday I tested the ATX 95 scope carefully for limiting resolution at ca 0.8 exit pupils. I could resolve 4,2 at 10.3 meters which comes to 107/D. With a 20mm aperture mask and 30x magnification, I got 2/1 at 10m = 104/D. These results are now with the closest to perfect optics I have had the privilege of using, and put the Ultravid results into a more reasonable perspective. On the other hand, only three weeks ago I believed that line-pair orientation readings under 115/D would be virtually impossible to achieve.

Your reasoning about differences as distances increase is in accordance with mine. It is true that a ten percent difference between two alpha binoculars of equal magnification is a bit much (although possible if one of them is a lemon and the other one a cherry), but 5% is not particularly far-fetched for a viewer with excellent visual acuity.

The advantage coming from the stabilization is another matter on top of it. Last night I spend some time comparing a Zeiss SF 8x42 and Swaro SV EL 8.5x42 viewing the skyline of the city through my window, sitting down and leaning my elbows solidly on a desk in front of the window. This was much more stable than my normal hand-held viewing, but not nearly the same as using a tripod. I could see small differences in detail detection between the two, in favor of the slightly higher magnification of the SV, and neon light texts just barely readable were more readable with the Swaro. Taking the Canon 10x42 IS L into the mix without the IS on, due to its 10x power advantage it made reading easier and enabled reading some texts and detection of detail not possible with the other two. Engaging the stabilization again dramatically improved the view, making it possible to read signs that I had hardly noticed with the 8x and 8.5x binoculars.

About checking collimation, there are two types of collimation that are important. One is the binocular collimation, or proper alignment of the optical axes of the left and right eye tubes. The best layman test for this is to have a point of light or some other easily detectable and smallish object that is at least 300 m away. Focus on it, and start moving your head away from the binoculars. You want to be able to see the centered object with your left eye in the left exit pupil and with your right eye in the right exit pupil at least up to about 30 cm away from the binocular. Not many binoculars will have perfect collimation, so you need a bit of experience to be able to decide what is good enough, but this test works well. However, for normal binoculars you need to have them resting on something stable, otherwise it is very hard to keep alignment between the target, the binocular and your eyes. With the Canons, the IS makes this possible even without mounting the bins, at least up to the length of your arms.

The other type of collimation I was talking about with regard of testing the Canons, or any other binoculars for that matter, is centering of optical elements along a single and precise optical axis within each tube. This sound fancy and technical, but what you need to do is only to find a tiny point of light (a star, a glitter point, anything really that is small enough that your eye should see it as a point and not an extended object through the binocular). You focus it as sharp as you can, and if the binocular is in collimation, it looks like a point. If it isn't in collimation, it looks like a tiny shuttlecock. You should check this separately for both tubes and make sure that what you may be seeing is not a defect of your eye. Miscollimation of this latter kind is dishearteningly common even in top-range binoculars, and always degrades the image. Since the Canon shows you a virtually still image much of the time, you will see flaws in its image that will largely go undetected in the image of an unstabilized binocular. Additionally, since the stabilization prisms do induce some wedge into the optical path whenever the momentary correction angle is not very small, this will induce some miscollimation-like effects into the image which will add up to whatever miscollimation there may be to begin with. So, the better the optics of the individual Canon specimen you have, the better the stabilization will work.

Kimmo

Brilliant Kimmo!

Muchas Gracias!
I was surprised to hear from you, knowing that you were in possession of such highly sought after optics - I'd have been like a kid in a sweet shop! Thanks for finding the time for such a detailed (and very useful) response. Very interested in your initial impressions (which are actually reinforcing my desire to try the Canons).

Thanks again

Phil

. There is an excellent article in Sky and Telescope magazine for 2015 March, page 54.

It discusses the useful maximum magnification that planetary observers use with different aperture telescopes.

This is probably not of much interest to the general binocular user, but should be very useful to those who test binoculars for resolution.

The conclusions drawn and the statements fully fit into my own observations.

It also emphasises how different people prefer different magnifications, and also the effects of low contrast on the magnification chosen for best resolution.