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bought an Arcturus Binoviewer & couldn’t be happier

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#26 Cali

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Posted 03 August 2019 - 02:20 PM

A sure way to get the focus spot on is to use a Bahtinov mask. Focus one eye (that is get the line centered) with the scope focuser, then do the same with the other using the diopter adjustment. The important thing is that the eyepieces are in proper focus relative to each other so even if you make further fine adjustments, they still track each other.

Can anyone recommend a durable Bahtinov Focusing Mask? I went on Amazon and there are a BaZillion masks listed. I would use it on an Orion Apex 127mm Maksutov-Cassegrain Telescope.

 

Thx!

 

Cal



#27 Joe1950

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Posted 03 August 2019 - 05:27 PM

Astronomics has a product called an Astrozap Focusing Cap. It’s a scope cap with a Bahtinov Mask built in. The quality looks very good.

 

The one I have uses three plastic screw and a rubber grommet on each. Somehow the screws come loose all the time and I have to look in the grass for it. Not ideal.


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#28 B 26354

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Posted 03 August 2019 - 05:30 PM

Hey, Cal!

 

I have this one for my ES102CF, and it's fairly stiff... so pretty durable, all-in-all. Haven't had any problems with the screws coming loose. For good measure, I keep it stored in a similarly-sized cardboard box from a Mediabridge audio cable.

 

https://www.amazon.c...r/dp/B07F7P53NJ


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#29 Joe1950

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Posted 03 August 2019 - 05:39 PM

That’s good too. Made better than the one I have. I’ll eventually replace the nylon ‘hardware’ with something better.



#30 Joe1950

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Posted 07 August 2019 - 04:22 PM

The Bahtinov Focusing Mask weighs 1.5 lbs? Must be substantial!

 

 

Here's a YouTube tutorial on using the mask if you need to watch. It may come with instructions. Astro Photographers use the mask quite a lot because imaging requires exact focus. But they are also used for visual, where people want to get the best focus without guessing.

 

With a binoviewer, pick a bright star, put the mask on and I do the following...

 

  1. Make sure there is adjustment room on each eyepiece with the Diopter knobs.
  2. Close your right eye, look only through the left and adjust the mask pattern for best focus, with the scopes main focuser knob.
  3. Close your left eye, look only though the right and adjust the mask pattern for best focus using the Diopter adjustment on the right eyepiece.

Now, your eyepieces are in correct relative focus. If you move on to the moon, due to various atmospheric reasons you may have to touch up the main focus to get it as sharp as possible. Same with planets, double stars, and so on. The important thing is that your eyepieces remain in best focus relative to each other, so if you do tweak the main focuser, you don't have to play with the Diopter adjustments.

 

If you change eyepieces, you'll have to do the whole thing over. However, if you keep the same eyepieces in and change the Barlow nosepiece to a different power, or use an external Barlow, the eyepiece relationship remains good.


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#31 Joe1950

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Posted 07 August 2019 - 06:32 PM

Here is an animation I quickly threw together showing about what you'll see when focusing and having the Bahtinov mask on the scope...

 

Using a bright star there will be fixed crossed lines extending outward.

 

There will also be a horizontal line crossing the Airy disk that moves up and down, as you focus.

 

Bahtanov focus ani.gif

 

When the horizontal line is centered between the crossed lines, the system is in focus. Very easy. Just make sure to use a bright star.

 

If the whole pattern is tilted, just rotate the mask.


Edited by Joe1950, 07 August 2019 - 08:16 PM.

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#32 EverlastingSky

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Posted 07 August 2019 - 07:56 PM

I once made a Bahtinov mask by printing one on stiff card. Then precisely cutting out all the slots with a blade on a cutting surface. I was curious to see the effect at the eyepiece...it worked well and was kinda cool...  but in time I just threw it away crazy.gif  Hmmm. Now I could actually use one for the binoviewer to see the focus difference between left and right eyepieces. Time to buy / make another one?

 

On another note, Joe1950, I like the animations you make waytogo.gif


Edited by EverlastingSky, 07 August 2019 - 07:59 PM.

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#33 Joe1950

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Posted 07 August 2019 - 08:27 PM

Thank you, Luke! My career job was as a graphic artist for a newspaper. I worked there for 46 years. During the last 20 or so everything was done on a computer and I had a lot of fun with the different software we had. Now I just have basic software but it still is enjoyable to do illustrations and animations.

 

Unfortunately, the internet changed the landscape for newspapers and they suffered. The last 10 years were not too enjoyable at all. Fortunately, I lasted until I could retire in 2013, a little early but workable. Since then I've worked as a cashier in a food store, a store rep at a home improvement store and the last 4 years as a crossing guard.

 

But this year I decided it was enough so I am fully retired now. I don't have endless money to spend but I still have fun with astronomy, ham radio, the computer and my great friend a maltese, Mo.

 

Best to you!

joe

 

 

BTW, some people find it easy enough to focus each individual eyepiece without using the mask, which is fine. The eyes give a little flexibility with this. For me, I can focus ok with my dominant right eye, but I have trouble with my left, so the mask helps. It just depends on what works best for you.


Edited by Joe1950, 07 August 2019 - 08:34 PM.

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#34 Glenn Graham

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Posted 09 August 2019 - 01:34 PM

After reading the glowing reviews I decided to jump in and get a pair of the Arcturus binoviewers. They arrived yesterday and I got my first view with them through a TV76 refractor (I will also be using them with my C11HD. Unfortunately, the view for each eye are not concentric. Now, I’ve had a number of binoculars used for observing with varying degrees of misalignment I can compensate for but I just can’t in this case. I did find the offset is not too far off when the barrels are flat (max separation of the eyepieces, too wide for me) but reducing the angle increases the offset dramatically.

 

So, I wouldn’t think of sending back an SCT or newt arriving out of collimation. Collimating is just part of ownership. Is that the case with binoviewers? Does this model provide accessible alignment screws or are things glued in place?

 

Here is the view down the common barrel when the angle is at max and min:

 

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#35 Joe1950

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Posted 09 August 2019 - 03:25 PM

They are collimated at the factory and the prisms are glued in place, Glenn. Most of the time, the problem with these budget viewers is with the eyepiece holders. BTW I have the same model and was looking to adjust collimation myself but fortunately did not.

 

First, if you have eyepieces without undercuts, they generally work better in these types of binoviewers. The problem is that the eyepieces are not centered properly or are tilted slightly in the holders. The undercuts add to the centering difficulty.

 

Anyway, what I would suggest to try first is to set your binoviewer in the scope and the right angle prism/mirror. Then place your eyepieces in the holders and only tighten the grabbing rings very, very lightly. Adjust them to just touch the eyepieces.

 

In fact, if you turned the scope upside-down, they would probably fall out.

 

Then adjust your IPD, and take a look.

 

That fixed things right up for me, and I hope it does for you. As I said I use eyepieces with no undercuts, but you may be okay, if you place them in the holders and keep them loose. Not loose to rattle around, but have the tightening ring just touch each eyepiece.

 

Tightening them to a normal tightness will almost always throw them off and make it impossible to merge the image.

 

Most say say that the difference between budget brands and the high priced kind are not in the optical quality but in the mechanical build, especially with the eyepiece holders.

 

Hope this helps, Glenn!

joe 


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#36 Glenn Graham

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Posted 09 August 2019 - 09:31 PM

Thanks Joe, I'll give that a try and report back.

 

-Glenn


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#37 Cali

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Posted 10 August 2019 - 06:47 PM

Thanks Joe, I'll give that a try and report back.

 

-Glenn

Product Description States, "Reflectors and short-focal length refractors may require the short 1.8x  barlow lens in order to achieve focus".

 

- Cal



#38 Joe1950

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Posted 10 August 2019 - 07:08 PM

He didn't mention a problem reaching focus, Cal. I think he had a problem merging the images.

 

With the Arcturus and like low cost BVrs, there is sometimes a problem with merging because the eyepieces don't center properly. Usually happens if they are adjusted too tightly in the holders.

 

Anyway, maybe Glenn will report back and hopefully had better results.


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#39 Cali

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Posted 10 August 2019 - 07:54 PM

He didn't mention a problem reaching focus, Cal. I think he had a problem merging the images.

 

With the Arcturus and like low cost BVrs, there is sometimes a problem with merging because the eyepieces don't center properly. Usually happens if they are adjusted too tightly in the holders.

 

Anyway, maybe Glenn will report back and hopefully had better results.

I just received mine and noticed I had to position my eyes a bit farther away from the lenses than I do with my binoculars.

 

Also, I'm using a Mak. The views are the best I've ever had. More on that later.

 

-Cal


Edited by Cali, 10 August 2019 - 07:55 PM.

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#40 Joe1950

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Posted 10 August 2019 - 09:19 PM

I just came observing the moon and Jupiter with the 127 Mak and binoviewer.

 

Since the Mak has such a long focal length and more focus travel, I can use it without any Barlow in the nosepiece. Don’t know if that’s better or not, but I was getting good image scale with a 15mm Plossls. Images were bright and detail was great.

 

Seeing was average and I could make out craterlets on Plato’s floor when it allowed. Copernicus and Clavius were sensational. 


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#41 Glenn Graham

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Posted 11 August 2019 - 04:08 PM

First, thanks to those that took the time to provide some advice!

 

Next, no problem with focus. With the TV76 I can bring it to focus without the barlow if used straight through (I actually needed to add a short extension tube). If used with the TV 2" mirror diagonal I do need to use the 1.8x barlow.

 

I tried the suggestion to loosen the eyepieces but no improvement. I'm using the eyepieces supplied with the binoviewer and they fit nicely with little to no lateral slop, so it really had no impact if tight or loose. However, this lead me to explore the eyepiece positioning a bit more and found that if I unscrew the helical focusers of both all the way out, focus the scope, and then fine-tune the focus from there I get a much closer match between the two views at a comfortable ocular spacing angle. While not perfect, I can accommodate the slight mismatch and get a reasonable view (Yay!).

 

Back when I was a kid (dark ages) I got really good at those random-dot stereo-gram posters so I am probably more flexible than many folks.

 

Finally, I see three sets of small screws inside each eyepiece holder. Can these be used to adjust any aspect of the alignment or eyepiece position?

 

Anyway, thanks again. Its been cloudy here since they arrived so I am waiting for my first opportunity to try them on planets/moon/Ha-sun. Eager to see what those views are like.

 

Cheers! 


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#42 Joe1950

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Posted 11 August 2019 - 06:04 PM

That’s a good question about the screws that hold the EP holder, Glenn. If they allowed some adjustment, that would be good, but I haven’t loosened the ones on mine for fear of throwing it off.

 

It’s a shame the loosening didn’t help. People who know binoviewers say that the mechanics of the eyepiece holders (and in some instances the prism size/FOV) are the main difference between a $200 viewer and a $1000+ viewer. If I had to spend that kind of coin, I’d be doing the pirate viewing again with an eye patch!

 

Sometimes tilting one side will line things up.  Not the ideal situation, but at least gets things merged.

 

Can you exchange the BVer you have? If not, you might check the screws and see if there is any play. Some trial and error and you might get them right on. Otherwise you might get a sample that is right on the money if you can exchange it.

 

I’ll tell ya, I’ve tried several times to use monovision to see if I could switch back (this on the moon and planets. Don’t have deep sky here) and it’s just not the same as the binoviewer. Maybe others have a different experience.

 

I’ve talked to several who have tried them and prefer monovision. And some who are totally sold on bino. 

 

Keep us informed, Glenn. I know once you get a good look at the moon, Jupiter or the sun in Ha, you’ll be amazed.



#43 Highpeaks

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Posted 11 August 2019 - 09:41 PM

Does anyone know what the IPD (inter pupillary distance) on the Arcturus Binos is? In the past they were 60 which is likely too high for kids to see through? Anyone have any experience with having their kids use them?



#44 Joe1950

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Posted 11 August 2019 - 09:56 PM

It's adjustable as you bring the halves together.With my scale, I measure 62mm minimum to 77mm maximum, approximately.

 

I was close. The spec sheet says 60mm minimum, 75mm maximum.


Edited by Joe1950, 11 August 2019 - 09:58 PM.

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#45 Cali

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Posted 11 August 2019 - 11:41 PM

Does anyone know what the IPD (inter pupillary distance) on the Arcturus Binos is? In the past they were 60 which is likely too high for kids to see through? Anyone have any experience with having their kids use them?

Joe1950 nailed it. Here is the spec sheet.

 

Aperture 22 mm
IPD Max 75 mm (2.95 in)
IPD Min 60 mm ( )
Prisms BAK-4
Optical Coatings Fully Multi-Coated
Weight (oz) 18 oz (510 g)
Product Dimensions
4.75" x 4.75" x 1.75"

Eye Relief:  22mm

Field of View:  48 degrees

Thread spec on the binoviewer body nosepiece side: 28.6mm


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#46 Joe1950

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Posted 12 August 2019 - 12:51 AM

Doesn’t happen often! grin.gif


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#47 Cali

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Posted 12 August 2019 - 03:18 AM

Doesn’t happen often! grin.gif

I know. I wanted to mark the occasion. (tee-hee)

 

- Cal


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#48 Highpeaks

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Posted 12 August 2019 - 08:17 AM

Thanks guys! So I’m assuming this may not be good for kids who generally have a lower IPD. On the other hand its a tempting package for what they offer. Just too bad they didn’t make the minimum IPD similar to other brands.


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#49 erin

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Posted 12 August 2019 - 12:44 PM

That is why I got the Orion BV's. My IPD is 56mm, and I'm a grown woman. Otherwise, I would have gotten the Arcturus.
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#50 Joe1950

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Posted 12 August 2019 - 01:04 PM

Didn’t know there was that kind of difference. Only 4mm, but IPD is very important.

 

Is that the Orion model that is red in color and adjusts laterally, Erin? Or the Orion that looks similar to the Arcturus, Celestron, etc?

 

The red model (don’t know the model name) is interesting. They claim no additional in focus movement is needed, or a Barlow type lens added to reach focus. The same model is sold in Europe for a little less and will ship to the US. Rather than bend them at a pivot point, you pull them apart to adjust the IPD. 

 

But I’ve never read any comments about them. None. And was wondering how they performed; not that I have plans to get them in the near future.




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