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ZEISS DTI thermal imaging cameras. For more discoveries at night, and during the day.

Ultravid 7x42's and stargazing (1 Viewer)

Marley

Well-known member
Hi everyone,

I have a pair of Leica Ultravid 7x42's that are wonderful during the daytime. As others have noted, the clarity in the center of view is just outstanding.

I do, however, like to use these bins at night as well and when I focus on a star, I don't get a nice pin point, but rather a "star" shape, with spikes of light coming from around the edge of the star itself.

I believe that the "star" test is a standard for quickly determining colimation etc and distortion is typically a sign of misalignment or some other problem.

Is this worth addressing with Leica or should I just leave well enough alone? I had a pair of 8x32 Ultravids in the past and they would focus down to an absolute pinpoint. It's just a shame that my 7x won't do the same.

Thanks for any advice,

Steffan
 
Steffan,
Large exit pupils have sharpness advantages by day, when the eye pupils stop down, and as a result only the sweet middle zone of optics and eyes get used. At night the eyes open up, so the stars, which are very demanding point sources, require the entire binocular and virtually the entire eye lens, and so ask a lot.

If there are flaws in the binocular, it is unlikely that the flaws in the two sides will be identical. Similarly, if there flaws are in your eyes, it is unlikely that the two eyes will be the same. Here is a "logical" (HAW!) procedure for unravelling the difficulty. Do some one-eyed star viewing, using each barrel with both eyes.

If the spikes in the left barrel look the same to the left and right eyes, your eyes must be very similar, hence your eyes are probably both ok. Repeat with both eyes looking through the right barrel, for a consistency check.

If the spikes look different in the two sides of the binocular, when viewed by the same eye, it suggests a flawed binocular.

It may be that both the binocular and eyes are contributing, in which case you'll need to estimate the portion of trouble due to each--not easy, and decide from there. But I hope these tests help. (Hey, it seemed to make sense at the time!) Sorry to be so tedious, just trying to be clear. Good luck.

Just up the road,
Ron
 
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Just to add to Ron's suggestions, try also to view one-eyed and rotate the binocular to see if the spikes rotate with the binocular or not.

Kimmo
 
Thanks guys,

I couldn't sleep this morning and ended up outside looking at the early morning sky.

I ran the various checks noted above and the view didn't seem to change, either from barrel to barrel or eye to eye.

I will do a bit more checking to see if rotating the binoculars around my eye makes a difference, but the one test that I did showed that the "starring" remained in place (did not rotate with bin rotation).

I pulled out my 8x32 FLs and my 8.5x42 ELs for comparison and both do much better at resolving stars, with the FL being the clear winner (but not by much).

I'll post again in a few days. Perhaps the 7x Ultravid just doesn't do well resolving stars for the reasons that Ron notes above. Perhaps others with 7x bins might comment as well.

Thanks again!

Steffan
 
Me again but just to say I do a lot of stargazing, especially close double splitting, with both a 7x50 Fujinon and 8x42 Trinovid BA, and both give very sharp images. But my eyes aren't perfect, and to get the very best resolution, I have to position the star off center in the field of view. This turns out to be a tad up and to the left of center in these two very different binoculars, suggesting that it's mainly my eyes at fault.

Kimmo's rotation test is simpler and better than my 4-way switcharoony suggestion.
Ron
 
Time for an eye test I think.

The newer wavefront systems they precheck your eye's with (at a lot of places) also give values for the higher orders of astigmatism. Ask to see the output of these to see if any of them look large.

BTW, you haven't had laser eye surgery, have you?
 
Yes, an eye test is a good idea.

I'm 46 years old, have never worn glasses or had laser surgery but I am starting to need reading glasses at night after a long day.

Isn't it strange though that my FLs, ELs and 8x32 Ultravids would give excellent star gazing performance and the 7x42 Ultravids just seem to fall a bit short?

Still curious.

Thanks!

Steffan
 
Now that you tell us your 8.5x42 EL gives sharp stars, I'm beginning to wonder about that Leica. It's hard to believe your eyes do so well up to 5mm, then suddenly turn to glop between 5 and 6mm.

If the Leica really has a problem, it may very well show even with the outer part of the objective masked off to 35mm, giving it the same exit pupil as the Swaro. Cutting out the donuts is 30 min. of careful busywork, but I think it would be a useful test. If stars look clean in both the stopped down Leica and the Swaro, the test will be somewhat inconclusive. But, if the stars in the Leica are still spiky with the stops in, while the Swaro looks sharp, the Ultravid definitely has a problem.

The true binophile will hope to God it's only his eyes going bad, oh please not a defective binocular!
Ron
 
Now that you tell us your 8.5x42 EL gives sharp stars, I'm beginning to wonder about that Leica. It's hard to believe your eyes do so well up to 5mm, then suddenly turn to glop between 5 and 6mm.

That is where most of the wacky abberations usually are in the outer part of the cornea.

Some of the infamous laser eye correction problems (starbursts and flare at night on point sources) seem to come from people whose iris open up very wide.

Still there might be another issue but if it doesn't rotate with the bin it's difficult to pin it on the bin.

Masking is an interesting test. Or making artificial stars during the day (with your eye stopped down naturally).

Swapping the detector (i.e. the observer) might be another option. What does another viewer see?
 
It's a question of exit pupil. A 7x42 has a 6mm exit pupil, whereas an 8x32 has a 4mm exit pupil. The likelihood of imperfect human eyes showing aberrations (esp. astigmatism) increases as the exit pupil does. And a 6mm exit pupil is pretty wide open. That's why your smaller exit pupil bins look better- they have a smaller exit pupil. Many astronomers have a fine image up to a certain exit pupil, and then things get spiky once you go bigger than that. My spot is ~4mm. Sharp below that, spikes emerge above it.

I hate to say it, and when I first heard it I didn't believe it, but it's your eyes, mate. Try masking the 7x42's to test it out. Also- if the spikes don't rotate as you turn the bins, that's the classic sign.
 
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Now that you tell us your 8.5x42 EL gives sharp stars, I'm beginning to wonder about that Leica. It's hard to believe your eyes do so well up to 5mm, then suddenly turn to glop between 5 and 6mm.

Ron

Well, it would seem strange if my I didn't experience the same problem. I have astigmatism, worse in one eye than the other, but other than presbyopia, my eyes are okay (though I haven't been to the eye doctor for awhile, so I'll make that caveat).

But even when I did last see my eye doctor, I found that a 5mm exit pupil was the limit at which I can see pinpoint stars. Beyond that, I need glasses to correct my astigmatism.

At 6mm, bright stars "turn to glop" in my 8x50 Octarem (I've had others look though the bin, and the collimation is fine).

I also experience this with 7mm exit pupils (my pupils open that far, but the larger exit pupils of 6mm must cover more of my uneven corneal curvature, because no matter what bin I've tried 5mm is sharp, beyond that not.)

This could be coincidence or it may be what's going on with your Leica. Let a couple other people try the bin on the night sky and ask what they see.

If they see spiking too, then it's proof positive that the fault lies not in your eyes, but in the optics.

Brock
 
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It might just show that they also have level form of astigmatism. 6mm is really a big exit pupil for astronomy. I believe astigmatism is very common for human eyes at large exit pupils. Direct correlation, in fact.
 
Can I just say that of my binoculars, my Zeiss 8x56 which has a 7mm exit pupil has no starburst effects at all with stars.

My 10x42 Ultravid on the other hand has 4 point starbursts. The lines emanating from the stars are present as one line in one barrel and another in the other barrel. The axis is at almost 90 degrees to each other creating the 4 points (actually just two lines intersecting).

The lines actually move with rotation of the barrel showing its a bin characteristic rather than anything to do with my eyes.

I think that it's almost certainly a roof bin issue on these since the lines move with rotation and are almost 90 degrees apart (and varies with IPD adjustment of the barrels).

The lines are very thin and may be missed by casual view. It's an optical interface at the prism that is causing it since the spherical elements shouldn't cause this.

My new SEs are also perfect like the Zeiss 8x56 and are even more amazing in the edge sharpness department.
 
Interesting matter this!

Yes, I think it's possible that a larger exit pupil may show some flaw when smaller exit pupil shows a (more) pinpoint star. Also it's not sure that different configurations of same serie and brand have the same optical performance, neither at high-grades optics.
Because you Marley, mention that the 7x42 is outstanding during daytime I have hard to think it's faulty, however. No optics is perfect, and there are many contributing factors for the personal experience of optics. But I don't really know in your case. What I know is that smaller exit pupils more easily produces pinpoint stars than larger.

Regards, Patric
 
Those are diffraction spikes from the roof prism's roof edge. Each is perpendicular to the roof edge that is causing the diffraction spikes (one in each barrel with the prisms rotated 90 degrees to each other).

I think someone (on another thread) was saying that they never see this effect in "alpha" bins. That depends on the quality of the particular roof prism in the bin.

You will only see them with "bright" (i.e. intense and very small angular target e.g. a Minimaglite naked bulb in a darkened room or an artificial star) the rest of the time they just reduce the contrast a little.
 
Kevin,

My experience is that this, what I use to call "star-filter effect" is less noticable in higher class roofs than in cheaper ones. As well Nikon high-grade (8x20 I tried) and Swarovski show this effect when the light source will be enough bright (especially with a dark background). The only roof I have not ever noticed it is in Zeiss binoculars.

Some years ago I compared Leupold Katmai 6x32 with Zeiss Victory Flourite 7x42. Looking at daytime at cromed parts with sunreflexes the "spikes" appeared with Katmai 6x32, but not any visible spike with Victory FL 7x42.
When I compare my Katmai 6x32 with my Swarovski SLC 7x42 at nighttime this effect appears with both of them when I look at bright streetlights, though much less with SLC 7x42.
I never see any spike when look at stars with any of these glasses, however. Maybe at Venus, I don't remember if I tried.

Several years ago I had a Zeiss Classic 6x20 monocular (regret I sold it). That little monocular I used as well day and night-time, but never saw any noticable spike.
These my experiences make me to think that Zeiss is extraoordinary good when it comes to lack of spikes. I am not sure that Marley actually experiences these diffraction spikes.

Regards, Patric
 
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I agree that the diffraction spikes are more common in lower price products.

That's an interesting comment about Zeiss: the one brand of bins where I haven't seen this effect are Zeiss. I had extended my belief without any evidence to all the alpha bins after all the effect is related to scatter from the roof edge and the sharper it is the less the scatter so I assumed Swaro and Leica would be free of this issue. Apparently not.

I wonder if Zeiss aren't replying only on the sharpness but are doing something else too (optical coating perhaps?).

Or maybe they're just very very good at making roof prisms. They do have a lot of practice.

As I said a small quartz halogen flashlight with a naked filament at 4m or more shows the effect clearly in bins that have it (and you don't have to wait for the stars or streetlights). You can even do this test in-store when buying bins. It's also useful for picking up ghost images.

The worst bin I've seen with this was Nikon Monarch 8x42 viewing a mercury light in an REI store (there is a post on the forum). Big broad diffraction spikes. Yikes. That was bad. And it was the demo model.

I don't think these are Marley's issue either (the post where the images he sees don't rotate with the bin makes that clear). But it's interesting that alpha bins do suffer from them.
 
Would the type of roof prism utilized have any affect on this issue? The reason I ask is that it seems the Zeiss FLs are the model mentioned as not displaying this. Since they use the Abbe-Koenig prisms then is it possible that this particular roof prism design and not necessarily the quality level of the bin is what sets it apart?

I guess one could determine this by checking for it in the less expensive 8x40 ABK Conquest.
 
I don't see it on AK or SP roof prism bins from Zeiss (AK: full-size Victory, 7x42 FL; SP:8x32 FL and 8x30 Conquest and 8x20 Victory).

The only issue here is the roof edge assocated with the roof that does image reversion: both AK and SP roof prisms have that.
 
I hope we'll hear back from Marley on this. He didn't say how the spikes were oriented, so it might be the roof edge, or it could still be his eyes. The orientation would tell a lot, and the rotation test would tell a lot.

FWIW, my 8x42 Trinovid shows no spikes from the roof edge even on Venus, but more experienced observers than me have commented on sample-to-sample variation in this regard even among the top brands. My eyes are pretty good with the 5.2mm exit pupil. So despite its size, it's a fun binocular for stargazing. It split the wide components of Zeta Cancri just last night!

My big Fujinon 7x50 Porro makes tighter star images than that Leica, dazzling in a way, but the penalty for the 7mm exit pupil is a bit of spikiness on bright stars due to my eyes. That fine but low-powered Porro, and my not so mighty eyes, failed on this same double star split.
Ron
 
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