18 replies to this topic

[Reflector1234]

Hi everyone,

 

I recently purchased a used Binotron Supersystem with 21 mm eyepieces. Last night was the second time I used it under the stars. Both nights, I primarily observed Saturn and Jupiter. Seeing conditions were average, maybe a little above average.

 

I'm trying to figure out the best way to focus the system. Like everything, there's a learning curve. To help shorten the curve, I'm wondering if people would like to share their techniques and experience.

 

The system can reach focus in all my scopes. My trouble is getting both eyes focused and knowing that they are focused. With the planets, the system can be in perfect focus but planetary details can come in-and-out of focus due to seeing fluctuations, so I find it hard to know when my focus is optimal for the conditions.

 

My current strategy for focusing is to use the telescope focuser to reach coarse focus. Then, I close or cover my left eye while I focus the right eyepiece with the Binotron eyepiece focuser. Once the planet looks focused, I close or cover my right eye and focus the left eyepiece with the Binotron diopter focuser. Most of the time last night, I would be satisfied with the individual eyepiece focus, but disappointed with the focus of the two-eyed image, which showed less detail than the individual images. 

 

Now, there were a couple of moments when everything seemed well-adjusted and I had the impression of depth perception with Saturn or Jupiter. It was a very pleasing image, lots of detail to observe. Eventually, I would fiddle or fuss or change magnification with the power switch to see how far I could push the image. Then, I would struggle to get back to the focus I had. 

 

Is my problem that I am using a planet to judge individual eyepiece focus? 

 

Should I try focusing my right eye first, then adjusting the diopter focus for the left eyepiece with both eyes open until the view looks best?

 

Once I have the diopter accomodation set between eyepieces, is there any reason to touch the binoviewer individual eyepiece focusers again? Should I just use the telescope focuser for the rest of the night (unless I change eyepieces, of course), and avoid the back-and-forth right-eye-left-eye shenanigans?

 

What have you found that works for you?

[George Blahun Jr]

Although I don't own a Binotron, I usually set the focus for an eyepiece pair on a star.  Once the star is set, using the method you described, I find that planetary and lunar views are fine.  To substitute for a star, I sometimes use the moons of Jupiter or Saturn.  There's no real short cut to a learning curve and it sounds like you have things under control.

[Oddyse]

  I have the Denkmeier Binotron 27. Do all my setup in daytime viewing. Adjust focus for each eyepiece/eye, low-medium magnifcation, then leave it alone. Great views, always more detail with two eyes. Good focus can last for nights or even longer. I would expect trying to achieve perfect adjustment using nighttime celestial objects to be very difficult. Tennessee

Edited by Oddyse, 01 October 2023 - 01:18 PM.

[betacygni]

The moon is the easiest target to get exact focus on (or daytime). Stars or planets can be a bit harder to know exact focus as the details are less obvious. Once it’s set there is no reason to adjust it, as long as you are careful to not inadvertently rotate the diopter.

One other caution, squinting one eye closed has the potential to effect the focus of the open eye slightly. Rather than close one eye I just move the other eye away from the eyepiece.

Edited by betacygni, 01 October 2023 - 01:33 PM.

[MarMax]

I leave both eyes open and cover an eyepiece (usually the right) and adjust the focusuer as best I can. Then I cover the left eyepiece and use the diopter to adjust the focus on the right.

 

Doing the above seems to work the best for me in a area with a reasonable star field that also has some very dim stars. If the dim stars are such that you need to use averted vision to see them that's the best. I'll then fine tune each side with just the diopter so that the dim stars are visible averted.

[cahanc]

Does the Bino's from Denis L have a diopter on both barrels?

[MarMax]

Does the Bino's from Denis L have a diopter on both barrels?

Yes.

[betacygni]

Does the Bino's from Denis L have a diopter on both barrels?

You can actually install any type of eyepiece holders that use the T2 thread. He has offered different options, not sure the current ones. I went with Baader ultra short eyepiece holders to save on light path, which do not have diopter adjustment.

[Eddgie]

I would look very critically at the IPD and rotation of the binoviewer. Even small errors on rotation and IPD can cause your eyes to cross and if the image is not perfectly aligned to each retina, then you can't really get the full benefit of binocular summation. Your eyes will attempt to "cross" but this may be in imperfect solution. 

 

Otherwise, people have given you good options for focus. I usually focus the scope using my left eye (not using the binoviewer diopter at all) and then fine focus the right eye (my dominant eye) using the right binoviewer diopter. 

 

Again, my advice is to take great pains to ensure that your IPD adjustment is exact and that the binoviewer is rotated to perfectly line up to the angle of your eyes.  If you are on an GEM mount and the scope moves in both axis's, it is usually necessary to adjust rotation after every move because you are constantly changing your seating position. 

Edited by Eddgie, 03 October 2023 - 06:50 PM.

[Jeff B]

First, the Binotron is a great viewer, bright and sharp.  Congratulations.

 

Second, Eddgie's experiences basically match mine.  Getting the IPD for that eyepiece pair right and no tilt/rotation of your head and viewer will give you the most solid merging.

 

I also typically remove my head cover in the winter time when using bino-viewers as even a slight pressure, especially non-uniform pressure, above my eyebrows from a head cover can mess up my merging. 

 

Also, no more than one adult beverage (there's a fun thread here on that subject).

 

The other really, really, REALLY, important thing for me is to NAIL the focus for each eye.   When I do that, the experience becomes sublime and the bino-gods make visual love. 

 

Don't assume the optical path lengths between each side your fixed diopter viewer are the same.  They are not.  Ever.  Also, there can be subtle eyepiece to eyepiece variations.   My favorite target to nail focus for each eye is the moon as it has basically infinite detail and high contrast.  Next is Saturn, then a middle bright star.  I've multiple viewers with specific eyepiece pairs for each and once I find best focus for each eye, I lock the eyepiece positions down as best I can.   

 

Please take the time to get precise focus for each eye.  Plus don't be surprised or disappointed if you find one eye sharper than the other.  Still use both eyes!  Your bionic software knows this and corrects for it.

 

I and others have other tidbits as well.

 

Great thread.

 

Jeff

[Highburymark]

So do some observers refocus their binoviewer on a regular basis - or even every night? I’ve had five BV pairs over a period of a decade, and after adjusting them once after purchase, I don’t think I’ve touched the eyepiece focusers again more than once or twice. They’ve all kept focus beautifully so I just use the scope focuser.

[mikeDnight]

So do some observers refocus their binoviewer on a regular basis - or even every night? I’ve had five BV pairs over a period of a decade, and after adjusting them once after purchase, I don’t think I’ve touched the eyepiece focusers again more than once or twice. They’ve all kept focus beautifully so I just use the scope focuser.

I make sure I have critical focus each time I use my Baader BV's, as I will often change eyepieces during an observation. Once sharply focused they stay focused. However, I find I have to regularly adjust the focus of the scope itself, as the critical focus can be subtly lost as a planet, the Moon, or stellar target moves across the sky due to changing depth of atmosphere. Also local seeing can require an adjustment of focus, but the binoviewer itself remains unchanged. Hope this makes sense!

Edited by mikeDnight, 04 October 2023 - 01:41 PM.

[MarMax]

So do some observers refocus their binoviewer on a regular basis - or even every night? I’ve had five BV pairs over a period of a decade, and after adjusting them once after purchase, I don’t think I’ve touched the eyepiece focusers again more than once or twice. They’ve all kept focus beautifully so I just use the scope focuser.

To me it seems like my eyes change throughout the night. So when it seems like things are soft or not quite right I'll re-check focus and usually adjust a bit. I focus (re-focus) the same way as Eddgie, weak eye first (focus knob only), then diopter with the right. My left eye is usually the one changing and because it's a balance of both eyes it's worth while to check focus during a session.

 

And as Jeff B said, if any, only one adult beverage and hopefully a couple of hours before you plan to observe. I'm to the point where visual nights are zero adult beverages. And this is most important at higher magnifications. I had the best ever Double Double at 124x night before last (zero beverages). Conditions were equivalent the last night so I set up exactly the same, but following a triple IPA, and it was an awful quadruple quadruple.

[Highburymark]

But surely once the diopters have been adjusted satisfactorily for one pair of eyepieces, the binoviewer will remain focused for all eyepieces? And unless the diopters move in the middle of a session, all further focusing can be done by the telescope? That’s always been my presumption anyway.
I use my BVs hundreds of times a year (90% for solar ha), probably swapping eyepieces 3-4 times per session, and I’ve never needed to refocus the diopters. That also applies at night - the same binoviewers always appear pin sharp on the Moon.

[mikeDnight]

But surely once the diopters have been adjusted satisfactorily for one pair of eyepieces, the binoviewer will remain focused for all eyepieces? And unless the diopters move in the middle of a session, all further focusing can be done by the telescope? That’s always been my presumption anyway.
I use my BVs hundreds of times a year (90% for solar ha), probably swapping eyepieces 3-4 times per session, and I’ve never needed to refocus the diopters. That also applies at night - the same binoviewers always appear pin sharp on the Moon.

I suppose if you're eyepieces are all exactly parfocal you wouldn't need to touch the diopters. Mine are parfocal but not precisely so.  I can usually get away with just refocusing using the focuser, but i will often just tweak the diopter switches on the Maxbright ll's just to satisfy my curiosity. Doing so will often fractionally improve matters, I'm not sure why it would if the eyepieces were correctly focused in the first place. Perhaps my brain is a bit loose?!

[Reflector1234]

Lot's of good suggestions here, thanks everyone.

 

I had a session last night, looking at Saturn and Jupiter with the binos.

 

I started by focusing the left eye only using the telescope focuser. Then, I focused the right eye only using the diopter focuser. I am right-eye dominant. I had the best results (best-focused two-eyed image) when I did the individual eye focusing while keeping both eyes open. For example, when I focused the left eye, the right eye was open but covered by an eyepatch or the eyepiece cap was placed over the right eyepiece. It was a little awkward, but got better with practice. Even lightly closing one eye was noticeably inferior to focusing with both eyes open and relaxed.

 

After focusing each eye separately, I would look through the binoviewer with both eyes and finely tweak the focus on the left, then the right using the diopter adjustments while looking at the two-eyed image for signs of improvement on the moons. There was one moon of Saturn that was just barely visible near the planetary disc, which made it easy to see when my adjustments were in the right range. I also tried using a middle-brightness star, which worked well. I found this slight tweak (like less than +/- a quarter of a turn of the diopter focusers) made a small but noticeable improvement. Sometimes no diopter fine-tuning was needed, sometimes just one side needed a little tuning.

 

Getting the IPD and rotation right helped too. I realize now that I had the IPD too wide during the initial two sessions. Last night was much better. I used an observing chair to help get my head into a good, stable position. Getting all this ergonomics right also let me relax, which is when I was really able to settle into the view.

 

I felt like relaxing was really helpful in all of this. Relaxing my face, my eye, gazing into the distance, while adjusting focus. Trying not to "chase" the image with my eye and trying to let it come to me as I turned the knobs.

 

Thanks again for all the tips. Also, I had a laugh at myself when I read the suggestions to just leave the binos and eyepieces assembled between uses. I don't know why I felt I had to take the eyepieces out of the binos after every use. I can just put the caps on the optics and stow the whole assembly. The diopter adjustments should be pretty darn close to ideal right out of box.

[RAKing]

But surely once the diopters have been adjusted satisfactorily for one pair of eyepieces, the binoviewer will remain focused for all eyepieces? And unless the diopters move in the middle of a session, all further focusing can be done by the telescope? That’s always been my presumption anyway.
I use my BVs hundreds of times a year (90% for solar ha), probably swapping eyepieces 3-4 times per session, and I’ve never needed to refocus the diopters. That also applies at night - the same binoviewers always appear pin sharp on the Moon.

 

That is how my BV work, too.  I check the diopter adjustment every night and make adjustments as necessary due to fatigue, blood pressure, what I ate for dinner, and etc.  And if I check the diopter adjustment with my first pair of eyepieces, I shouldn't have to deal with the diopter adjusters the rest of the night.

 

BUT - the diopter adjustments on my Mark V BV are up there with the reverse ClickLock holders - and they don't have that beautiful little "nub" on them that Baader added to the MBII units.  So over the course of a night, the diopter adjustment could be moved accidentally a few times as I change eyepieces.  My Bad!   

 

So I will check again if I think I have bumped it out of place and readjust if necessary. 

 

Ron

[vicuna]

I would look very critically at the IPD and rotation of the binoviewer. 

 

 

Getting the IPD for that eyepiece pair right and no tilt/rotation of your head and viewer will give you the most solid merging.

 

 

 

Getting the IPD and rotation right helped too. I realize now that I had the IPD too wide during the initial two sessions. Last night was much better. I used an observing chair to help get my head into a good, stable position. Getting all this ergonomics right also let me relax, which is when I was really able to settle into the view.

 

 

how do you know when it's right? 

 

(I often share views with my wife so I can't really measure and lock it)

 

thank you for the tips everyone!

[Reflector1234]

how do you know when it's right? 

When adjusting the bino IPD, I will settle into a good viewing position, then close one eye to see if I can see the eyepiece field stop with the open eye. Then I’ll switch eyes and repeat. I try not to move my head at all while switching back and forth between individual eyes. Often, I’ll find that I can see the whole field stop in my right eye (dominant eye), but in the left eye I won’t be able to see, say, 10%-15% of the field. I’ll adjust the IPD, settle into position, then blink back and forth again and look for full field visibility. 
 

When the IPD is right, my eyes feel much more relaxed, so I use that as feedback as well. 
 

Hope that helps!