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cirrus
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Highest practical binoviewer magnification new
      #1754898 - 08/03/07 12:48 AM

I was reading another post regarding how misalignment errors get amplified with magnification. Since this is the case, what is the highest magnification you have used with your binoviewer? Are they ok for relatively high power (200x-300x) planetary viewing?

cirrus


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Jim Rosenstock
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Re: Highest practical binoviewer magnification new [Re: cirrus]
      #1754904 - 08/03/07 12:53 AM

Quote:

I was reading another post regarding how misalignment errors get amplified with magnification. Since this is the case, what is the highest magnification you have used with your binoviewer? Are they ok for relatively high power (200x-300x) planetary viewing?





You betcha! Self-centering eyepiece holders are helpful, of course.

And 200X in binoviewers LOOKS like 300X, and 300X looks like 400X. Don't know why this is, but it's a very noticeable effect.

Illusion, perhaps, but it works!

Clear skies,

Jim

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suphotpu
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Re: Highest practical binoviewer magnification new [Re: Jim Rosenstock]
      #1754976 - 08/03/07 02:38 AM

I use Burgess BV with 20mm Binolite eyepiece on C8. It give me around 120X magnification (Because of the extra path lenght on the BV).

When I insert 2X Televue Barlow lens in BV nose piece. It look like 3X magnification so it is 360X. When the weather permit, I can use it on planet, no problem to merge the image.

I use it for Mars and Saturn opposition, the view is good when the weather permit.

Suphotu


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EdZ
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Re: Highest practical binoviewer magnification new [Re: suphotpu]
      #1755063 - 08/03/07 06:04 AM

A 20mm eyepiece in a binoviewer in a C8 is operating at close to 140x.

I know lot's of people describe the view thru binoviewers as making objects larger, as dscribed above where Jim R says 200x makes it look like 300x. I would consider that a gross exageration. Actually they don't really do this. So don't expect objects to simply grow because you look thru a binoviewer.

Granted some people are so impressed with binocular vision that to them the psycological affect of binocular viewing makes them think they see objects bigger. Frankly binoviewers are no different than binoculars from the viewpoint of this aspect. Do you see objects grow in size when you use binoculars? Just a thought.

Self centering diopters are convienient, but, if the binoviewer optical and mechanical axis is not adjusted precisely enough, they you will always be self-centering your eyepieces to an optical alignment that is slightly off.

My Stellervue B3 have about 10-12 arcseconds of misalignment. They have self-centering diopters. The self-centering works exactly as they are designed to do. Every single pair of eyepieces gets self-centered to show the 12 aecseconds of misalignment. Below 100x, it is not an issue. Above 150x it is annoying.

Self-centering diopter collets do not automatically center your eyepiecces to eliminate alignment issues. They center your eyepieces in the collets. If there are misalignment issues present in the optical system, they will show up consistently with every set of eyepieces.

If you have a pair of binoviewers with only 5-6 arcseconds misalignment, then you will probaably never even even notice this unless you make persistent attempts to measure it. If you have a binoviewer with 15-20 arcseconds misalignment, then you will probably never use them at anything over 100x without noticing you are having a difficult time merging the images.

edz

--------------------
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David E
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Re: Highest practical binoviewer magnification new [Re: Jim Rosenstock]
      #1755119 - 08/03/07 07:45 AM

Quote:

Quote:

I was reading another post regarding how misalignment errors get amplified with magnification. Since this is the case, what is the highest magnification you have used with your binoviewer? Are they ok for relatively high power (200x-300x) planetary viewing?





You betcha! Self-centering eyepiece holders are helpful, of course.

And 200X in binoviewers LOOKS like 300X, and 300X looks like 400X. Don't know why this is, but it's a very noticeable effect.

Illusion, perhaps, but it works!

Clear skies,

Jim




This is, as Ed has pointed out, just an illusion, like the summer Moon effect. But it's a positive one. I can actually see naked eye detail better with the Moon on the horizon than I can when it is away from the horizon. So this illusion works, at least for me.

The biggest advantage I think, is the fact that you are proccessing visual information with two eyes. If I may borrow a popular saying, using only one eyepiece is like "tieing half your brain behind your back." (And in this case, it doesn't make it fair.)

Like high power mono viewing, you are still limited by the aperture of the scope and the atmospheric conditions. But even with some unsteady air I find binoviewing rewarding around 150x. So far the most I have used with my Stellarvue BV1 binoviewers is 200x in my 102mm apo. But I use a muscle drive mount, so I'm not likely to buy eyepieces that get me any higher than that. 200x through binoviewers with a large enough scope is very rewarding when the air is steady and clear.

David E

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David E
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Danno2006
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Reged: 01/25/06
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Re: Highest practical binoviewer magnification new [Re: David E]
      #1755230 - 08/03/07 09:33 AM

I use the same power as when monocular viewing. Whatever the atmosphere supports is what I use. 200 - 250X with no issues. This is where planets start to get interesting.

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spencerj
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Reged: 11/17/04
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Re: Highest practical binoviewer magnification new [Re: Jim Rosenstock]
      #1755319 - 08/03/07 10:30 AM

Quote:


And 200X in binoviewers LOOKS like 300X, and 300X looks like 400X. Don't know why this is, but it's a very noticeable effect.

Illusion, perhaps, but it works!





I am with you Jim. I just picked up binoviewing in the Spring, and at first I was very confused by the magnification I was using. I was basing it on my experience with mono viewing and if pressed would have come up the the exact same numbers you did.

I know that I am not getting the resolution of the higher magnification, but I find it easier to pick out detail on what to me is a larger image. I even notice this with the AFOV of eyepieces. I rarely use a 50 degree AFOV eyepiece in "mono" mode, but in a binoviewer they are very comfortable. To me, the same eyepieces feel like they have a 60 degree AFOV.

I am sure this is an illusion, but for me it is very real and very beneficial.

--------------------
--Jason

"I am the victim of a series of accidents, as are we all." --Kurt Vonnegut Jr.

Intes MK66-DX (again)
TeleVue 102
10" Antares Dob
PST
90mm Orion Apex
Unistar Deluxe with Sky Commander XP4
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EdZ
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Re: Highest practical binoviewer magnification new [Re: spencerj]
      #1755350 - 08/03/07 10:57 AM

Quote:

at first I was very confused by the magnification I was using. I was basing it on my experience with mono viewing and if pressed would have come up the the exact same numbers you did.





My experience, based on actual measurements and from past discussions in this forum, is that most people do not know what magnification they are getting thru their binoviewers and, in every instance I can think of, the actual magnification was higher than they thought it was.

This error is compounded even more when people use SCTs for binoviewing, becasue very few people know the actual effective focal length of their SCT, few are aware that the focal length of an SCT changes with every single focus position and fewer still have ever tested their SCT to find out what the effective focal length is with a variety of eyepieces, let alone binoviewers.

edz

--------------------
Teach a kid something today. The feeling you'll get is one of life's greatest rewards.
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David E
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Re: Highest practical binoviewer magnification new [Re: EdZ]
      #1755413 - 08/03/07 11:43 AM

Quote:

Quote:

at first I was very confused by the magnification I was using. I was basing it on my experience with mono viewing and if pressed would have come up the the exact same numbers you did.





My experience, based on actual measurements and from past discussions in this forum, is that most people do not know what magnification they are getting thru their binoviewers and, in every instance I can think of, the actual magnification was higher than they thought it was.

This error is compounded even more when people use SCTs for binoviewing, becasue very few people know the actual effective focal length of their SCT, few are aware that the focal length of an SCT changes with every single focus position and fewer still have ever tested their SCT to find out what the effective focal length is with a variety of eyepieces, let alone binoviewers.

edz




In my case, I have an SV102ABV which has a removeable extension to make it bino-ready, so I was using no oca/s or barlow. I checked with Stellarvue to make sure the focal length does not change when using binoviewers this way. Still, I saw what I thought was larger images, on planets mainly. I got the idea to close one eye while viewing through the binos. Sure enough, the planet's image appeared to decrease in diameter when I closed one eye, proving that it was an optical illusion. Based on what you just said here, it looks like only a bino-ready refractor would potentially produce the same magnifications in both modes. Not a big deal really, except maybe when splitting doubles. Then it does help to know you are not over-estimating your magnification used.

David E

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John Miele
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Reged: 05/29/05
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Re: Highest practical binoviewer magnification new [Re: EdZ]
      #1755460 - 08/03/07 12:10 PM

Quote:


This error is compounded even more when people use SCTs for binoviewing, becasue very few people know the actual effective focal length of their SCT, few are aware that the focal length of an SCT changes with every single focus position and fewer still have ever tested their SCT to find out what the effective focal length is with a variety of eyepieces, let alone binoviewers.

edz




This is an excellent point and true. I have wanted to do this with my own C11. To find my true effective focal length, can I put in an EP and calculate the true field of view using the star drift method. Then using the published AFOV of the EP, work backwards and find the true magnification and then the focal length? Or is there an easier/better method?

Thanks.

John

--------------------
G11-GI w/ Ovision Worm
Edge 8 SCT
ST-402ME
QHY5-II/ST-80


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EdZ
Professor EdZ


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Re: Highest practical binoviewer magnification new [Re: John Miele]
      #1755569 - 08/03/07 12:57 PM

Well you can't ever use published Afov. Published Afov is almost always nominal and is usually 4% to 8% larger than actual. You need to actually measure the field stop and then drift time the eyepiece. That is the best way to do it. be sure to use a few eyepieces. It also helps if you have used some of those same eyepieces in a refractor of known focal length, so you can establish the the eyepiece focal lenth is accurate. For instance, the 21mm RKE is actually 21.5mm and the 28mm RKE is 28.7mm.

You want to insure you don't use an eyepiece that may be experiencing vignette.

edz

--------------------
Teach a kid something today. The feeling you'll get is one of life's greatest rewards.
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EdZ
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Re: Highest practical binoviewer magnification new [Re: EdZ]
      #1761435 - 08/06/07 01:18 PM

Quote:

My Stellervue B3 have about 10-12 arcseconds of misalignment. They have self-centering diopters. The self-centering works exactly as they are designed to do. Every single pair of eyepieces gets self-centered to show the 12 aecseconds of misalignment. Below 100x, it is not an issue. Above 150x it is annoying.

Self-centering diopter collets do not automatically center your eyepiecces to eliminate alignment issues. They center your eyepieces in the collets. If there are misalignment issues present in the optical system, they will show up consistently with every set of eyepieces.

If you have a pair of binoviewers with only 5-6 arcseconds misalignment, then you will probaably never even even notice this unless you make persistent attempts to measure it. If you have a binoviewer with 15-20 arcseconds misalignment, then you will probably never use them at anything over 100x without noticing you are having a difficult time merging the images.

edz




Thought I'd mention...

I was out last night for a while with my C8. I used a few mono eyepieces and I also used my Denk Big Easy. No adapter. With a pair of 18mm Tak LE in the Denk, I was right at 150x.

e1e2 Lyra was easily resolved. I noticed at this point that I needed to fine tune my focus. I commented about the focus of the Denk in another thread. This is the feature I like least about the Denk. Loosen, fiddle, tighten. Loosen, fiddle, tighten. IMO, a binoviewer without a twist focus diopter adjustment is a poor design. Other's may find this acceptable. I find this to be a design shortfall.

While viewing e1e2 Lyra, I also took special notice of the collimation. With a close double I was able to see that this Denk unit is collimated within about 3 to 4 arcseconds. Actually this is quite remarkable. The only reason I could notice it is the error is in the vertical. I could only see it very quickly as the images would snap together. Trying to keep the images separate with my eyes, they would still merge horizontally very quickly. But I could notice that one image slid over the other, but by not much more than the separation of the horizontal pair in the view and that's about 2.5 arcseconds.

M13 was outstanding, with strings of stars coming off the core in several directions. I counted about 50-60 stars resolved, mostly in the outer edges, but including some very bright points in the unresolved glowing core.

M11 was about the best I've ever seen it. I estimated about 150 stars resolved, but it was way too dense to count.

I captured a few more doubles and M71, M27 and M56. None were nearly as impressive as M11 or M13. I spent probably an hour viewing just those two targets.

an enjoyable night.

edz

--------------------
Teach a kid something today. The feeling you'll get is one of life's greatest rewards.
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b1gred
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Re: Highest practical binoviewer magnification new [Re: EdZ]
      #1761816 - 08/06/07 04:08 PM

Sounds like fun, Ed. I'm looking forward to our WUTS weekend and the DARK skies of SW Wyoming. I plan on really EXERCISING my BVs.

--------------------
"Dark Skies & Great Viewing"

RandyR / W0RDR
GPS 9.25 XLT/Sky Align /FeatherTouch
TV85 w/FeatherTouch





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Mike Harvey
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Re: Highest practical binoviewer magnification new [Re: b1gred]
      #1762835 - 08/07/07 12:15 AM

Seeing permitting, I regularly use 400X and up for planetary viewing with my 14.5" and Denk II's.
On one exceptional night I ran my 28" up to 2500X on a first-quarter moon!
No collimation problems at all.


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Paul G
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Re: Highest practical binoviewer magnification new [Re: Mike Harvey]
      #1763092 - 08/07/07 06:28 AM

In good seeing I max out in the 400-600x range, Baader MkV, no alignment problems.

--------------------
Gus

"Coffee leads men to trifle away their time, scald their chops, and spend their money, all for a little base, black, thick, nasty, bitter, stinking nauseous puddle water." ~The Women's Petition Against Coffee, 1674

If it ain't broke, fix it 'til it is.


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Joe Ogiba
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Re: Highest practical binoviewer magnification new [Re: Mike Harvey]
      #1763278 - 08/07/07 09:34 AM

Quote:

Seeing permitting, I regularly use 400X and up for planetary viewing with my 14.5" and Denk II's.
On one exceptional night I ran my 28" up to 2500X on a first-quarter moon!
No collimation problems at all.





--------------------
Pentax PF-80ED,Meade 102ED APO,Orion EON 72,120ST
Apex 127,C6 XLT,CR150,C9.25,XT10 ,Celestron Regal 100 F-ED, CT152
Zeiss 7x42 FL,Canon 10x42L IS WP,15x50 IS
12x36 IS II , Pentax 8x32 ED
Garrett Optical 28x110 HD-WP Signature Series
Oberwerk BT-80 45, Apogee RA-88-SA
Denk II Power x Switch binoviewer w/13mm Ethos, 20mm Pentax XW's, 20mm Widescan III's.
21mm Ethos,17mm Ethos, 22mm Nagler, 40mm Pentax XW, 14mm Pentax XL, 5.2mm Pentax XL, 8-24mm Pentax XL Zoom, 31mm Axiom LX
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warf
scholastic sledgehammer


Reged: 10/25/04
Posts: 817
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Re: Highest practical binoviewer magnification new [Re: b1gred]
      #1764090 - 08/07/07 04:33 PM

I have wanted to attend WUTS but always seem to have conflicts... back in the mid 80s I lived in Cheyenne and spent many weekends camping and fishing in the snowy range west of Laramie. At 9000+ feet in elevation and no lights you get some pretty amazing dark skies.

--------------------
Marsh
Celestron NS 11 GPS, Denk Standard Binoviewer, Pair of Denk 21 EP, Denk PowerSwitch Diagonal, Denk PST Corrector, Coronado PST Double Stacked, WO ZS80 Anniversary,Celestron 15x70 Binoculars


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b1gred
Enginerd


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Re: Highest practical binoviewer magnification [Re: warf]
      #1764989 - 08/08/07 12:07 AM

Ya, incredible. Just incredible...

--------------------
"Dark Skies & Great Viewing"

RandyR / W0RDR
GPS 9.25 XLT/Sky Align /FeatherTouch
TV85 w/FeatherTouch





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