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Equipment Discussions >> Binoviewers

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nemesis256
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Reged: 01/26/12

having problems and not impressed with binoviewer
      #5610990 - 01/07/13 09:53 PM

I recently started using binoviewers from Siebert Optics. I've been testing with Jupiter, M42, some open clusters, as well as the sun with h alpha viewing. In all cases, I've been having problems with getting the focus (diopter) correct and merging the images. And when I do get a decent view, it's still not that impressive. It just doesn't seem as sharp as it should be, and the diopter adjustment is way too subtle, making it difficult to find the right spot.

Is there also a trick to making images merge? Changing the distance between the two eyes helps, but this is also difficult to find the right positioning. Once in a while the image doesn't merge vertically, which I have no idea how to fix.

Any hints?


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avenger
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Reged: 01/08/08

Loc: USA
Re: having problems and not impressed with binoviewer new [Re: nemesis256]
      #5611022 - 01/07/13 10:18 PM

Why not call Harry and let him know what's going on with the binoviewer. He will take care of it even if you bought it second hand.

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GlennLeDrew
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Re: having problems and not impressed with binoviewer new [Re: avenger]
      #5611301 - 01/08/13 01:55 AM

I'm increasingly inclined to think that all binoviewers should be supplied with a comparator for the checking of collimation. The number of threads posted here in which difficulty with image merging is mentioned is just plain alarming. Are binoviewers often shipped as defective, or are many customers simply not capable of using them properly? A device which could unambiguously differentiate between the two cases would be useful...

In this specific case, might I ask what focal length eyepiece is being used? Binoviewer mis-collimation scales linearly as the inverse of the eyepiece focal length. Halve the eyepiece focal length, and the image divergence doubles.


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Jawaid I. Abbasi
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Re: having problems and not impressed with binoviewer new [Re: GlennLeDrew]
      #5611384 - 01/08/13 05:53 AM

I definitely agree with Glenn. Also, make sure that IPD sets properly and test with "Blink test" . Relax your eyes and try to use the smooth barrel eyepieces to see if they fully seated properly.

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nemesis256
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Reged: 01/26/12

Re: having problems and not impressed with binoviewer new [Re: Jawaid I. Abbasi]
      #5611426 - 01/08/13 07:05 AM

I'm using 18mm Meade HD60. I would have liked to use 25mm but the FOV of those are bigger than the 22mm binoviewer allows. I wasn't able to see the hard edge of the eyepiece with the 25mm.

Edited by nemesis256 (01/08/13 07:17 AM)


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johnnyha
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Re: having problems and not impressed with binoviewer new [Re: nemesis256]
      #5611444 - 01/08/13 07:29 AM

Try rotating the eyepieces to find better collimation. Give it a little time, experiment some more - it could definitely be worth it - if you do get them to work binoviewers are truly amazing. Siebert guarantees collimation so you can always send them back to Harry for inspection.

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mich_al
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Re: having problems and not impressed with binoviewer new [Re: johnnyha]
      #5611557 - 01/08/13 09:12 AM

The merging issue is one of the things that, so far, has kept me from buying a set of binoviewers. I have one eye that is much weaker than the other (20/200). All is well with binoculars but binoviewers is an unknown and spending $800-$1600 to find out is unappealing.

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Eddgie
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Re: having problems and not impressed with binoviewer new [Re: nemesis256]
      #5611569 - 01/08/13 09:20 AM

Can I ask you about your configuration?

What kind of scope, what kind of diagonal?

Here is what I do.

First, I turn the diopters all the way in and insert the eyepeices to ensure that they can fully bottom in the eyepeice holder on the binoviewer. This is because if they don't then if you turn the diopter in, the eyepeice can bottom in the barrel and stop moving. You're turning away, but the eyepeice isn't moving anymore.

Assuming that this test does not indicate a problem, the next step is to turn both diopters the same number of turns up, and usually about half way.

In other words, if they have a rotation of 10 full turns, I try to get the both turned almost exactly 5 full turns so they are both as close as possible to being in the center of their range of travel.

The next step is best done during the daytime, but you can do it at night if you wish.

With the telescope aimed at a sharp glint off of a distant car bumber or tail light (the reflectors often make tiny Airy disks) or a star at night, rack your focuser out. If it is an SCT, turn the knob clockwise past best focus.

Now, using the right eye and the right eye only, rack in the focuser very slowly until the right eye comes into as sharp a focus as you can get. Approach slowly. Once you get to the point of best focus, stop. Even if you go very slightly past this point, just stop. Your eye can accomdate a bit of missed focus if you overshoot by moving the focuser inward (counterclockwise motion in an SCT).

Now, open the left eye and close the right eye, and look at the glint. If it is not in focus, it will be necessary to adjust the left diopter.

But first, loosen the collet and slide the eyepiece out rather than use the diopter. This is just to see if you are inside or outside of focus.

If sliding the eyepeice allows you to reach focus, then put the eyepiece back in and raise it using the collet PAST best focus. Do not approach final focus using outward movement of the focuser knob or clockwise motion of the SCT focuser. Go PAST best focus.

Now, use the diopter to approach fine focus using inward focuser movement, or counter clockwise knob movement of an SCT. Once again, slowly approach best focus, and if you very slightly overshoot, don't worry about it because your eye can accomdate some over-travel.

Now, your diopters are set. When you open both eyes, your eyes should be able to easily visually accomdate a tiny amount of mis-focus if you overshoot from the inward/CCW focuser motion.

If when you slipped the eyepice, it was determined that you were outside of focus, the put it back in and screw the diaopter inward until best focus or a very slight overshoot.

Now, once the diopter is set, you hopefully won't have to mess with it again, but if you do, focus the right side using ONLY the telescope, then using the trick above to quickly determine which way the dipoter needs to go (slipping the eyepiece) and reposition the diopter to get it outside of focus so that when you approach with the diopter for fine focus, you are moving inward or using CCW motion of the SCT knob.

Also, when you put the eyepieces into the barrel, push down on them to ensure they are not canted and are fully seated against the diopter shoulder. If they are not square, they can shift when you tighten the holder so that you don't hit your prefocused position.

And as others mentioned, if you can't merge, check your IPD and try loosening, turning, and re-tightening each eyepiece. But my bet is that the eyepieces are not sitting square. Self Centering dipters are suppose to do this for us, but even in the Mark V, I feel that sometimes it doesn't quite get the eyepiece perfectly aligned.

And a lot of eyepeices today have wierd tapers or undercuts, which again, the self centring is supposed to manage, but I am not so sure.

Again, it would be helpful to know your configuration. If you are using an MCT or SCT with too much back focus, you could be loosing aperture and greatly increasing your magnification, which could cause issues, or you could be just using much higher magnification than you are used to, so that seeing or other factors are influencing the view more.

But focusing can be tedious until you get a method that works for you.

And my feeling is that it is far better to only use the focuser for one eyepeice and match the other eyepeice to the first one using the diopter.

And once you get a method estabilished, you will be able to hit focus quickly.


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dcoyle
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Reged: 10/11/05

Loc: Turbulent but dark skies, N.M.
Re: having problems and not impressed with binoviewer new [Re: Jawaid I. Abbasi]
      #5611780 - 01/08/13 11:29 AM

Hey, Jawaid,

Could you elaborate on how you use the blink test to zone in your binoviewers?

Thanks,

Dan


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Jeff B
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Re: having problems and not impressed with binoviewer new [Re: dcoyle]
      #5612150 - 01/08/13 03:16 PM

Also, watch out for eyepieces with undercuts as they can become cocked relative to each other even in binos with self-centering diopters.

Also, also, there can be eyepiece to eyepiece variation in the mechanical construction of the eyepieces such that the optical train may not be exactly centered in the barrel.

Both can make it difficult to focus and merge images.


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nemesis256
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Reged: 01/26/12

Re: having problems and not impressed with binoviewer new [Re: Jeff B]
      #5612522 - 01/08/13 06:57 PM

Thanks for the detailed instructions, Eddgie! That's mostly what I was attempting to do, except for sliding out the eyepiece. The difference the diopter makes is so subtle, it still sounds hard to do! Hopefully I'll get a chance tonight to try it out. By the way, when you say "collet" do you mean the ring that tightens the eyepiece?

The binoviewer I got was the $200 model (22mm), apparently slightly better than the cheap chinese models. There's no way to lock the diopter or tightening ring, and even after tightening, the eyepieces can move around a bit. My night time scope is Celestron 6SE, and my solar scope is Solarmax 60 with BF10. Both setups using 18MM Meade HD60 eyepieces.

I called Harry and explained my problems, and he told me that he stopped selling the cheap model I purchased, because too many people were having problems with them. He then tried selling me his $500 model (being able to return the binoviewer I have), which I'm not sure I want to do. I also asked if I could just return it and the corrector lenses for the solar scope, in case I give up on binoviewing, but he basically said no.

Annoying...


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bhuloka
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Reged: 03/06/12

Loc: Maryland, USA
Re: having problems and not impressed with binoviewer new [Re: nemesis256]
      #5613002 - 01/09/13 12:34 AM

Hi Nemesis256.
I just yesterday had first light with my new Siebert Black Night binoviewers. 5 hours of testing. Again tonight I had 2 hours. No problems whatsoever merging. Good clear views. Easy diopter adjustment. I've never used binos before, but these worked quite easily. So if you do choose to get the better binos, I would guess you'll be satisfied. I got mine with the 1.3x-2.0x-2.7x multimag OCA corrector, and a pair of Siebert Ultra 24 mm eyepieces. I also got the 13 mm ultras. Everything works well in my 16" f/4.5 Dob. I wonder if those 24 mm EP's might help with your problem. They are quite nice; at least as nice as my Explore Scientific 82* EP's. Much lighter weight, too.


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Eddgie
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Re: having problems and not impressed with binoviewer new [Re: nemesis256]
      #5613309 - 01/09/13 08:50 AM

I am very sorry to hear about your problems.

I think though this calls into question whether it is "Binoviewers" that you don't like, or the specific binoviwer you have.

At any rate, I can understand your frustration. No offense against Siebert intended, but this is often the case of small mom and pop kind of vendors. They lack the resources to provide the in depth, no questions asked kind of return polich that larger firms offer.

As to what you should do, I would persue him and ask him "Tune" the parts of the binoviewer that are giving you so much trouble. If he won't return it, perhaps you can prevail upon him to fix it. Maybe it is a simple fix for someone like him.

And if he refuses, then once we have that info (and please be fair) then others can use that information to make their own decisions regarding who to do business with.

The Binoviewer market is not a big market, and Siebert has a niche that I think needs to be served because he provides a lot of innovations, but if he wants to serve that market, then he needs to step up and serve it well.

Ask him to fix them.


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avenger
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Reged: 01/08/08

Loc: USA
Re: having problems and not impressed with binoviewer new [Re: Eddgie]
      #5613705 - 01/09/13 01:10 PM

Quote:

I am very sorry to hear about your problems.

I think though this calls into question whether it is "Binoviewers" that you don't like, or the specific binoviwer you have.

At any rate, I can understand your frustration. No offense against Siebert intended, but this is often the case of small mom and pop kind of vendors. They lack the resources to provide the in depth, no questions asked kind of return polich that larger firms offer.

As to what you should do, I would persue him and ask him "Tune" the parts of the binoviewer that are giving you so much trouble. If he won't return it, perhaps you can prevail upon him to fix it. Maybe it is a simple fix for someone like him.

And if he refuses, then once we have that info (and please be fair) then others can use that information to make their own decisions regarding who to do business with.

The Binoviewer market is not a big market, and Siebert has a niche that I think needs to be served because he provides a lot of innovations, but if he wants to serve that market, then he needs to step up and serve it well.

Ask him to fix them.




Siebert does give up to 60 days to return the product which in IMO is very good. On Siebert's website, they do give the $200 bino an alignment warranty of 2 years.


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Grandpa Jim
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Loc: GREAT AMERICAN DESERT
Re: having problems and not impressed with binoviewer new [Re: avenger]
      #5614285 - 01/09/13 06:55 PM

I have found Harry Siebert very nice to work with......although I had to give up my "BN-25" order due to financial issues with the VA, he went out of his way to be helpful and answer any and all of my questions.
He is quite plain about being a "Mom & Pop" operation, and he does take care of his bottom line, but who can blame him?
He is always willing to answer questions and do what he can.


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TGModerator
Pooh-Bah


Reged: 11/02/06

Loc: Latitude 47
Re: having problems and not impressed with binoviewer new [Re: avenger]
      #5614408 - 01/09/13 07:57 PM

Quote:

Why not call Harry and let him know what's going on with the binoviewer. He will take care of it even if you bought it second hand.




His charge is something like $30 to clean/collimate them and $20 ship. Turnaround is a few weeks.

Tanveer.


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ErikB
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Reged: 02/05/06

Loc: Central Arizona
Re: having problems and not impressed with binoviewer new [Re: TG]
      #5614749 - 01/10/13 12:11 AM

While the 22 mm units are stated to be "out of stock", his website still retains the information that describes difference between two different 22 mm bino's he used to carry. The first option is a unit with 60 days satisfaction and 2 years alignment guarantee for $199. The second option has 30 days satisfaction guarantee and no alignment guarantee for $149. So the buyer had the option of paying $50 up front for multiple alignments if needed, or pay $50 later for each instance of alignment. I see that as a well disclosed and fair choice. BTW I have his 25 mm unit and it works really well, including with 24mm Pan's and also with short ep's like 7.4 mm Plossl's.

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killdabuddha
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Re: having problems and not impressed with binoviewer new [Re: ErikB]
      #5616555 - 01/11/13 12:41 AM

Quote:

So the buyer had the option of paying $50 up front for multiple alignments if needed, or pay $50 later for each instance of alignment. I see that as a well disclosed and fair choice.




Yeah, we like Harry too, and nobody expects him to eat that. And I know yer not suggestin that. What you will get, tho, is the most reasonable and hopeful solution to a case of caveat emptor(?), if you decide you wanna keep them.


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nemesis256
member


Reged: 01/26/12

Re: having problems and not impressed with binoviewer new [Re: killdabuddha]
      #5618110 - 01/11/13 10:13 PM

Had another try with binoviewers and DSO observing. Focusing and merging was better this time, but I'm still not impressed. Images are too dim with my 6" scope (plus observing from a white zone) and I think I'm done trying on DSOs. I'll still attempt observing the sun and moon with them, although the forecast is showing clouds until Wednesday, so it may be a while.

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Eddgie
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Re: having problems and not impressed with binoviewer new [Re: nemesis256]
      #5618702 - 01/12/13 09:56 AM

What diagonal are you using?

If you are using a 2" diagonal, your telescope could be working at reduced aperture.

Even with a Baader Maxbright diagonal on my Mark V binoviewers, my C5 is only working at about 122mm.

For SCTs, when a binoviewer is used, the mirror must be moved very far forward.

This causes two things... First, the power is likely much higher than you realize, so the exit pupil is much smaller than you may think.

Next, if the mirror gets to far forward, the baffles may cut into the light cone reduceing the aperture of the scope.

If you want to know how to test for this, let me know.

The binoviewer does indeed cause the image to dim a bit, but it should not be severe. My first binoviewers did cause severe dimming and this is when I figured out that my scope was loosing a lot of aperture.

I changed to a system with a very short light path and it made a huge difference.

So, what kind of diagonal are you useing? And again, if you want to measure the apeture, let me know and I will tell you how to do it.

Edited by Eddgie (01/12/13 10:20 AM)


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Eddgie
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Re: having problems and not impressed with binoviewer new [Re: Eddgie]
      #5618740 - 01/12/13 10:20 AM

My previous post was edited. I had said my C15 was working at reduced aperture.

Should have read my C5. Apologies. Edited to correct.


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nemesis256
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Reged: 01/26/12

Re: having problems and not impressed with binoviewer new [Re: Eddgie]
      #5618747 - 01/12/13 10:27 AM

The diagonal is the one that came with my 6SE. So it's 1.25 inches

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Eddgie
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Re: having problems and not impressed with binoviewer new [Re: nemesis256]
      #5618767 - 01/12/13 10:37 AM

Ok.

Might still be intereseting to measure the aperture.

There is no doubt that binoviewing dims the image in my own experience, but adjusting for the higher magnification in an SCT, the dimming has not been severe except at high powers (for me)

And I suspect that some of this is the case for you as well. The lowest power you are probably getting is much higher than you are used to working with.

And if you read my post about the 40mm Plossls, you can see that I too regret some of the light loss. I am thinking about changing from 24mm Hyperions to a 28mm Pentax XL set to try to get a little brightness back.

Or maybe a pair of 32mm Plossls.

If you are using wide field eyepeices, try picking up the cheapest, lowest power plossl pair you can use with the clear aperture you have in the Binos to get some of the brightness back.


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orion61

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Loc: Birthplace James T Kirk
Re: having problems and not impressed with binoviewer new [Re: GlennLeDrew]
      #5618948 - 01/12/13 12:11 PM

Quote:

I'm increasingly inclined to think that all binoviewers should be supplied with a comparator for the checking of collimation. The number of threads posted here in which difficulty with image merging is mentioned is just plain alarming. Are binoviewers often shipped as defective, or are many customers simply not capable of using them properly? A device which could unambiguously differentiate between the two cases would be useful...

In this specific case, might I ask what focal length eyepiece is being used? Binoviewer mis-collimation scales linearly as the inverse of the eyepiece focal length. Halve the eyepiece focal length, and the image divergence doubles.



AMEN and Plus 1 for that Glen.
There are few of us with perfect Ocular Alignment, the majority have at least some Esophoria Exophoria \Esotrophia, or Esotrophia.
In extreme instances the common term people use is a
"Cast eye"
I sold a brand new Binoviewer and had nothing but complaints about it untill I bought it back. I still have it and it works perfectly.
Some of the less expensive models are good at one interocular distance and off at a larger or smaller one.
Then we have to figure in for the eyepieces and how close to optical center they were made to. I have seen up to 1 Diopter difference.
I wish they would make Binoviewers with a small adjustment on one eye built in to tweek it to individuals. Upown In/Out


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nemesis256
member


Reged: 01/26/12

Re: having problems and not impressed with binoviewer new [Re: Eddgie]
      #5619228 - 01/12/13 03:01 PM

Quote:

Might still be intereseting to measure the aperture.



How would I do that? Is it complicated?


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johnnyha
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Reged: 11/12/06

Loc: Sherman Oaks, CA
Re: having problems and not impressed with binoviewer new [Re: orion61]
      #5619470 - 01/12/13 05:16 PM

The new Denkmeier Bino27 is collimatible, looks like a real winner.

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Eddgie
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Re: having problems and not impressed with binoviewer new [Re: nemesis256]
      #5620435 - 01/13/13 10:17 AM

No, not complicated.

You need a good ruler and a bright light source like a laser or single emitter LED flashlight.

Then next time you observe, at the end of the session, use your binoviewer to focus on a bright star.

After focusing, do not touch the focuser until you complete the test. Of course you can do the test the next day or the next week, but don't touch the focuser until after you have done the test. You can remove the binoviewer if you like. It is not needed for the test. The only important thing is to not touch the focuser.

When you are ready to do the test, put your mount as scope near a wall and face the telescope to the wall as square as you can get it. The distance is not critical, but keep it close as you can but still reach between the scope and the wall.

Use a mid-power eyepeice (not critical as to which kind or focal length, but a smaller eye lens makes it easier to hit the center of the focal plane). If you have a laser collimator, this is even better. The eyepecie can be put in the diagonal or directly into the visual back. Makes no difference.

Now, hold your laser or light source about a foot or so (not critical) above the eyepiece and shine it in. It will take a bit of fiddling, but when the light source is perfectly aligned to the optical axis, you will see the image of your aperture projected on to the wall.

You might need and assistant, but now you only need to take your ruler and measure across at the widest part.

This measurment will tell you the effective aperture of the system.

I usually put a little piece of tape on either side so that I can mark with a pencil on the tape while holding the light source. Then, when I have marked both sides, I can use both hands to measure.

Easy test, and you get a very accurate reading of your aperture.

I do not know if your scope will have any aperture loss or not, but I know my C5 does, and this is using a light path that is about 200mm (2" SCT adapter, Maxbright prism diagonal, Mark V binoviewer).

The light collection of a C5 is only about 18.5 square inches (adjusted for secondary obstruction).

Even a 5mm light loss will bring the total light collection down to about 17 square inches. This by itself is almost a 10% loss of brightness. Barely enough to notice, but it all adds up. Combined with the brightness loss of the binoviewrs, you get a dimmer view.

But I am not at all sure that you are loosing any apeture, so this is just a data point for future posters to know.

But it also explains why I went to a bigger aperture binoveiwer. I needed some of those lower powers to get back some exit pupil to make the views brighter. For me, it was not so much true field as it was image brightness.

I am even considering going to 32mm Plossls over the 24mm Hyperions.

Binoviewers for me have been a constant evolution. Forcing me to try a lot of diffent things and accept a lot of limitations. I love them for planets, but still not 100% sold for deep sky.


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nemesis256
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Reged: 01/26/12

Re: having problems and not impressed with binoviewer new [Re: Eddgie]
      #5621482 - 01/13/13 07:24 PM

So I did the test, using an 18mm eyepiece, the same ones I use for binoviewing. I take it from your instructions that I was supposed to make measurements without the binoviewers. So I focused without the binoviewer (for comparison), measured, focused with the binoviewer, but then removed it and used only the eyepiece, and measured again. Both measurements were around 150mm, which is the aperture of my scope. Then I measured with the binoviewer for curiosity, and the measurement was 140mm, about 1 cm less. Does this tell us anything? Is the loss of aperture from the 22mm binoviewer?

Oh, btw, I focused on a far away light, not on a star. I'm pretty sure the focus was close to infinity anyway, since the light was already mostly in focus from the last time I used my scope.

Edited by nemesis256 (01/13/13 07:33 PM)


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Eddgie
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Re: having problems and not impressed with binoviewer new [Re: nemesis256]
      #5622024 - 01/14/13 01:13 AM

It doesn't matter if you use the binoviewers or not as long as you don't change the focuser.

As for not being at true infinity, it might make a little difference. Once the system is in in aperture loss, even a small movement of the focuser can make a difference.

The point was to try to determine if aperture loss is contributing to your dim view. 3 Or 4 millimeters will go unnoticed, but 10mm is enought to dim the view.

I know that this was the case the first time I used a 2" based binoviewer in my C14. The aperture was cut down quite a bit.

This is why keeping the back focus as short as possible is important in most SCTs.

So, now you have dimming from the binoviewer (always) and perhaps some dimming due to some aperture loss.

I would repeat the test the next time you have the scope at true infinity focus though.. My bet is that you see a slight increase in aperture. Again, when you are in the aperture loss configuration, a millimeter of mirror movement translates to a couple of millimeters of aperture loss.

You know how to check it now.

Binoviewers are complicated. If you have followed my posts in the past, you would see that I think keeping the light path as short as possible is one of the great keys to getting the best performance while using binoviewers. This is why I am such a fan of the Baader approach.

I see that Siebert is now offering a similar diagona/bino interface.


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GlennLeDrew
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Re: having problems and not impressed with binoviewer new [Re: Eddgie]
      #5622633 - 01/14/13 12:56 PM

When doing the flashlight test for aperture, it's actually very important to keep the configuration unchanged after setting the focus. If a binoviewer was installed, leave it in place. Here's why...

When the instrument is focused with the BV installed, the physical location of the focal surface is moved farther back. If you remove the BV, your eyepiece's field stop will be now located *inside* the focus. Not good.

The flashlight aperture test is simply 'raytracing' the system in reverse. The telescope forms an image of a star as a point in the plane if the eyepiece field stop. Shining a flashlight into the eyepiece (from a distance of no less than about 10 eyepiece focal lengths) forms a tiny image of the light in the plane of the field stop. This acts like the image of a star, but now shining through the system in reverse.

As long as the image of the light is located at the scope's focal surface, one can rely on the envelope of light passing backwards through the system being identical to the envelope accepted from a distant point target and being brought to focus.

If you set the focus with a BV installed, and then remove it so that the eyepiece is now inside the focus as set and hence closer to the OTA's back end, the light source image is located artificially closer to the objective, and an angularly wider light cone can pass through, thus very potentially leading to an artificially too-large working aperture.

Bottom line: For best accuracy, always leave the full system intact as it was when setting the focus.


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Eddgie
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Re: having problems and not impressed with binoviewer new [Re: GlennLeDrew]
      #5622691 - 01/14/13 01:29 PM

Thanks for the correction to my instructions. I did not think it mattered.

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gcfboulder
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Re: having problems and not impressed with binoviewer new [Re: Eddgie]
      #5643608 - 01/25/13 11:55 PM

My Siebert BN25 works quite well with my C8 and my 2" Stellarvue diagonal. But now you have me wondering if I should try it with a 1.25" diagonal. But the only 1.25" diagonal I have is the cheapie one that came with the scope, so I don't think that would be a good test.

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faackanders2
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Re: having problems and not impressed with binoviewer new [Re: nemesis256]
      #5644118 - 01/26/13 10:29 AM

Is it a proble with not having enough infocus at the limit all the way; or not having enough outfocus at the limit all the way out?

Higher powers are always less clear than lower powers, just like a single eyepiece.

Did you focus each individual eye to their sharpest point, pulling out eyepiece if more outfocus needed?

Did you mover IPD in and out to ensure you get on clear outer circle edge?

If you did all the above, and used your lowest power eyepieces, and you still can't merge (but others can) then you are just not fit for binoviewers. If others can't get it to merge either after doing all the above steps, then there is someting wrong with the collimation (or you are using too high a power eyepieces, since images in both eyes must be less than 10% difference to get brain to merge, and the less they are different the less likely you will bet tired or headaches since your brain doesn't have to work so hard to get both eyes to merge.


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EdZ
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Re: having problems and not impressed with binoviewer new [Re: faackanders2]
      #5644198 - 01/26/13 11:10 AM

C6 witth diagonal and binoviewer is operating at about a reduced aperture of 118-120mmm.

Extensive testing notes in the SCT forum for C5, C6 annd C8 showing aperture tests aand plotttiing operating focal length
http://www.cloudynights.com/ubbthreads/showthreaded.php/Cat/0/Number/5102760/...

also, C6 with binoviewer is operating nearr F=1800, so F=1800 and D=120 (my setup) = approx f/15.

Not surprised you're not impressed with image. that is FAR outside the operating design range of the 6" SCT mirror.

For operating focal length see
http://www.cloudynights.com/ubbthreads/showthreaded.php/Cat/0/Number/5092859/...


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EdZ
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Re: having problems and not impressed with binoviewer new [Re: EdZ]
      #5644213 - 01/26/13 11:19 AM

a C5 with standard diagonal and binoviiewer is operating near F=1700. That's f/13.6 before even taking into consideration the aperture losss. I don't recall, but I'm thinking aperture is cut down to about 100mm, so operating foocal ratio is near f/17.

Regardless what you read and hear elsewhere, because of the vast change in operating focal length and the dramatic reduction in aperture, small SCT scopes were not designed to be used with binoviewers. Can you do it? Sure, you can do anything.

edz


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faackanders2
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Re: having problems and not impressed with binoviewer new [Re: EdZ]
      #5644509 - 01/26/13 02:32 PM

Ed, i don't have an SCT but would the "starsweeper OCS" help or worsen the SCT binoviewer issue. I have always been entrigued with the starsweepers low power, but disapointed it would not work for Newtonians,

Ken


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EdZ
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Re: having problems and not impressed with binoviewer new [Re: faackanders2]
      #5644579 - 01/26/13 03:09 PM

Quote:

Ed, i don't have an SCT but would the "starsweeper OCS" help or worsen the SCT binoviewer issue. I have always been entrigued with the starsweepers low power, but disapointed it would not work for Newtonians,

Ken




As you will note by reading the results of the testing done in the thread refferencced above, the startsweeeper worsens thhe situation.

It does reduce the effective power at the end of the train, but what a reducer does is causes the need to move the mirror such that it substantially reduces the operating aperture. Using a star sweeper reducer results in a 6" SCT operating at less than 4".


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faackanders2
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Re: having problems and not impressed with binoviewer new [Re: EdZ]
      #5644602 - 01/26/13 03:26 PM

Quote:

Quote:

Ed, i don't have an SCT but would the "starsweeper OCS" help or worsen the SCT binoviewer issue. I have always been entrigued with the starsweepers low power, but disapointed it would not work for Newtonians,

Ken




As you will note by reading the results of the testing done in the thread refferencced above, the startsweeeper worsens thhe situation.

It does reduce the effective power at the end of the train, but what a reducer does is causes the need to move the mirror such that it substantially reduces the operating aperture. Using a star sweeper reducer results in a 6" SCT operating at less than 4".




Thanks for the simple explanation. No wonder why SCT owners want to binoview with the mirror as far back as posible.

Would it be possible to design an SCT with a focuser that moves the eyepiece in and out keeping the mirror at the ideal focal length position? If this was optimized for binoviewing, would it also work for single eyepiece mide (with 3" less effective focal length? If so there may be SCT binoviewing customer demand.

Ken


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EdZ
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Re: having problems and not impressed with binoviewer new [Re: faackanders2]
      #5645562 - 01/27/13 07:38 AM

Quote:

Would it be possible to design an SCT with a focuser that moves the eyepiece




But, by design thatt is nnot how an SCT works. It is unfortunate that many people who own SCTs really do not understand how an SCT works. Very few really understand that the operating focal length of an SCT changes for every configuration you put on the back end of it. It even changes according to the eyepieces you use. The act of focusing an SCT changes the operating focal length, so it's slightly different for every eyepiece.

f/10 is nothhing more than nominal. There is actually only one single position when an SCT is actually operating at f/10, and particularly for the small SCTs that is NOT the normal operating focal length.

I addded an SCT focuser onto the back end of myy C6. It allowed the mirror too stay fix and allowed me to focus by moving the eyepiece. But it added so much length to the back endd of the C6 that it significantly reduced the aperture, by a lot. I considered it a poor option and quit using it.

If you want to get the most out of an SCT, keep the length of the accessories behind the backplate as short as possible. A diagonal plus binoviewer, especially if using a reducer, is about the worsst configuration you can put on the back end of a small SCT. It doesn't have as big an effect on the large SCTs 8" and over. But on the small SCTs, it has a huge detrimental effect. For more info, I'd suggest reading the entire thread i linked to above.

FWIW, after several years of options, I've returned to using my 6" SCT with nothing more than a 1.25" diagonal.


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Eddgie
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Re: having problems and not impressed with binoviewer new [Re: EdZ]
      #5646208 - 01/27/13 02:54 PM

This is why I was such a big fan of the Baader Maxbright and Baader T2 Prism diagoanl.

This setup offers the absolute shortest light path that I know of.

When I went from the 2" based Denkmeier Supersystem to the Maxbrights, the differecnce in performance was huge.

I had estimated that the C14 was working at around 11 inches of aperture with the Supersystem low power arm in place. The effect on the image was profound. It was far far to much to attribute to bino induced brightness loss alone.

I have since went to a Mark V, but I kept the Baader standard prism because it still offers the shortest possible light path.

Even in the C5, I measured 122mm of apeture with the Mark V and the Baader Prism. That is not bad at all.

Keeping the back focus down on any SCT is a good idea.

And like you, I went back to 1.25" diagonals on my C5 quite a while ago.

I also continue to see people say that using a 2" diagonal behind a focal reducer doesn't harm anything.

How can that not see the loss of aperture? It is so o glaring that the view is dimmer than it should be at exit pupils they are using!


Small SCTs and MCTs are much better performers with the 1.25" diagonals they were shipped with.

Binoviewers are going to cause apeture loss I think in all C5s and C6s. I don't think there is a configuration that one can use to avoid it, though I think I could come close with the Baader short SCT adapter (10mm) but that makes it hard to turn the diagonal. Might be OK for an Alt-ax situation though...


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faackanders2
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Re: having problems and not impressed with binoviewer new [Re: Eddgie]
      #5646437 - 01/27/13 04:53 PM

What about if they designed and optimized an SCT with a 2" diagonal for since eypieces, and a shorter 1.25" diagonal for binoviewers. This would reduce the increase in focal length for the binoviewer.

P.S. I can clearly see that if I ever get an SCT, my binoviewer will not work as well as it does on my 17.5" f4.1 Newtonian Dob.


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GlennLeDrew
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Re: having problems and not impressed with binoviewer new [Re: faackanders2]
      #5646631 - 01/27/13 06:31 PM

An SCT could be designed so that the nominal location for the focus is farther outside the back end. But to do this does require a somewhat larger secondary mirror.

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