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Pages: 1 Erik Bakker Carpal Tunnel Reged: 08/10/06 Loc: The Netherlands, Europe Lowest power to split Albireo: 8x?       #5311827 - 07/10/12 06:59 PM Edit   Reply   Quote Quick Reply   Last night I resolved Albireo with my tripod mounted Swarovski Habicht 8x30W. It was a nice clean split with the two components and their golden and blue colors beautifully seen. And my lowest power yet to achieve that. Could not believe my eyes. Usually I use a scope with 18x and preferably more to split this double. What is the lowest power you have used in which instrument to positively split Albireo? Look forward to your reports! Post Extras:       azure1961p Postmaster Reged: 01/17/09 Loc: USA Re: Lowest power to split Albireo: 8x? [Re: Erik Bakker]       #5312202 - 07/10/12 11:00 PM Edit   Reply   Quote Quick Reply   Erik, The thing Ived read [forgive me if Im saying nothing new] is that binos in the 7x50ish category can split or show duplicity down to 14". Im guessing thats a Dawes kinda looking split and Albireo was more of a Rayleigh looking split through your binoculars. I must give this pair a try now with my Nikon 8x42s!! Interestingly, using Spica as a comparison star I was a little shocked to see Saturn actually appearing ellipsoidal. Youve posted on low power bino viewing before and that actually gave me interest to try Saturn. When time allows Ill see if I can nail Albireo. Love your spirit Erik! Pete Post Extras:       RLTYS Post Laureate Reged: 12/18/04 Loc: New York (Long Island) Re: Lowest power to split Albireo: 8x? [Re: Erik Bakker]       #5312449 - 07/11/12 06:01 AM Edit   Reply   Quote Quick Reply   I've split Albireo with 10x50's. Rich (RLTYS) Post Extras:       brianb11213 Postmaster Reged: 02/25/09 Loc: 55.215N 6.554W Re: Lowest power to split Albireo: 8x? [Re: RLTYS]       #5312468 - 07/11/12 06:57 AM Edit   Reply   Quote Quick Reply   I'm not sure there is any point in trying to establish a "record" as peoples' eyes vary considerably in capability, mostly depending on how hard & how often you exercise them i.e. training. If it's any help, I find Albireo obviously double in a 8 x 50 finder, and split without too much difficulty with a 6 x 30 finder, but not with my 4x20 binoculars. I would prefer a much higher optical power - of the order of x30 to x50 and at least 3" / 80mm aperture - to bring out the beautiful colours. Post Extras:       Erik Bakker Carpal Tunnel Reged: 08/10/06 Loc: The Netherlands, Europe Re: Lowest power to split Albireo: 8x? [Re: brianb11213]       #5312992 - 07/11/12 05:08 PM Edit   Reply   Quote Quick Reply   At these low powers, not only the quality of the optics is important, it's also our own eyes that play tricks with us. In the 8x30, operating at a little less than 4mm exit pupil, I clearly see Albireo as separated. In my 8x50 with a bit over 6mm, my eyes astigmatism worsen the star images to the point that I am balancing on the verge of separating it. Enter the 2x booster for 16x, and I am rewarded with a beautiful view of the 2 pinpoint components with huge dark space between them. So in this case, it's not the binos' optics, but my own "optics" that limit the separation. Presuming good sky conditions, optics and eyesight, I suspect 6x to be the lower limit of separation, probably with at least 25 or even 20mm of aperture. But maybe that's just dreaming ...... To make sure I don't miss the lower limit, I'll try with my 3x12 mono under good conditions and see what happens Edited by Erik Bakker (07/12/12 01:05 PM) Post Extras:       Jon Isaacs Postmaster Reged: 06/16/04 Loc: San Diego and Boulevard, CA Re: Lowest power to split Albireo: 8x? [Re: Erik Bakker]       #5313202 - 07/11/12 07:02 PM Edit   Reply   Quote Quick Reply   A few thoughts and comments: I have seen Albireo as a double in my 6x30 finder, finders are good for this because they represent a stable platform. The Rayleigh criteria, the size of the airy disk, is: 5.45*in/D Albireo is about 35 arc-seconds so this suggests that a 4.5 mm aperture would be capable of splitting Albireo... Your eye opens this far. But the eye cannot see an airy disk with a 4.5 mm exit pupil and in any event it cannot resolve 35mm arc-seconds. In general, a 1mm exit pupil is good and at least 3 arc-minutes of separation is good, more would be better... 3 arc-minute/35arc-seconds = 6X 4.5mm/6x = 0.75mm exit pupil. Seems reasonable... They are unequal so a bit more magnification maybe necessary... It might be that stopping down my 6x30 finder to something closer to a 6x10 or even smaller might provide the best low power views. Jon Post Extras:       Simoes Pedro sage Reged: 02/03/09 Re: Lowest power to split Albireo: 8x? [Re: Jon Isaacs]       #5313967 - 07/12/12 09:37 AM Edit   Reply   Quote Quick Reply   It should easily split when the apparent separation is 4 arcmin or larger. This holds for equally bright pairs. Since Albireo separation is 34.5 arcsec. This translates to about 7x. This is consisting with splitting Rayleigh equal doubles at 0.5 exit pupil. The lower limit for apparent separation is somewhere between 2 and 4 arcmin. From the comfortable 4' of aparent separation, one can go down with positive results as long as the exit pupil lies within the 3 to 4 mm range which is optimal for visual acuity. This means, for instance, that a 4x16 binoculars could split Albireo, but a 4x24 is unlikely. Post Extras:       brianb11213 Postmaster Reged: 02/25/09 Loc: 55.215N 6.554W Re: Lowest power to split Albireo: 8x? [Re: Simoes Pedro]       #5314034 - 07/12/12 10:29 AM Edit   Reply   Quote Quick Reply   Quote: 4x16 binoculars could split Albireo, but a 4x24 is unlikely. I rather suspect that "low light" resolution loss would be a factor here. The fainter component will be only two or three magnitudes above the threshold in a 16mm instrument (even with a perfectly dark sky) & this will affect visibility as much if not more than any extra eye aberrations in an instrument with a larger exit pupil. Of course if your eyes have significant astigmatism this should be corrected with spectacles, contact lenses or Dioptrix before attempting this sort of observation. As I said above, I failed with my 4x20 binoculars (which are fairly good optically though they don't have modern multicoated optics, which may allow more scatter); my eyes are pretty good at this sort of thing (I can split epsilon Lyrae easily with no help other than spectacles to correct my short sight, if the sky is dark) but I don't think it's beyond the bounds of possibility that someone with a good dark sky and a very good quality 4x instrument could split Albireo. Irrespective of aperture, but I would expect more than 20mm to work better than less than 20mm. Post Extras:       blb Post Laureate Reged: 11/25/05 Loc: Piedmont NC Re: Lowest power to split Albireo: 8x? [Re: brianb11213]       #5314093 - 07/12/12 11:06 AM Edit   Reply   Quote Quick Reply   Quote: It should easily split when the apparent separation is 4 arcmin or larger. This holds for equally bright pairs. Since Albireo separation is 34.5 arcsec. This translates to about 7x. This is consisting with splitting Rayleigh equal doubles at 0.5 exit pupil. If you have good astigma free eyes. Different people have different quality eyesight. If all had great vision this would be true. Post Extras:       Erik Bakker Carpal Tunnel Reged: 08/10/06 Loc: The Netherlands, Europe Re: Lowest power to split Albireo: 8x? [Re: blb]       #5317604 - 07/14/12 02:46 PM Edit   Reply   Quote Quick Reply   I tried Albireo last night with my Zeiss 3x12B mono. Conditions were OK, not great. I was nowhere near splitting Albireo with the 3x12. Based on what I saw, I presume we need at least 6x and 20mm to be successful, probably more. Post Extras:       Ed D Carpal Tunnel Reged: 04/30/10 Loc: Sunny South Florida Re: Lowest power to split Albireo: 8x? [Re: Erik Bakker]       #5318103 - 07/14/12 09:36 PM Edit   Reply   Quote Quick Reply   Erik, I have been enjoying views of Albireo with my 8x56 binoculars hand-held, as well as mounted either on a monopod or photo tripod. It is a definite split and the colors are wonderful, just as you describe. Ed D Post Extras:       Pages: 1

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