XT10 classic with premium optics Tri-knob CR2 focuserCatseye + Glatter collimation toolsStarBlast 4.5" & 6"Round Table PlatformTV EPs
150mm MCT f/13, 31% CO
"People say I'm in denial. I disagree."
Quote:Anyway, I'm just wondering. I can't remember seeing an in focus diffraction ring before with any scope I have used and wondered if reflectors don't show these and they are only seen in refractors.
The corollary to the inverse proportionality with aperture is the inverse proportionality with exit pupil. No matter the aperture, the apparent size of the Fresnel pattern is the same at given exit pupil diameter. This is one reason why the exit pupil is a fundamentally important aspect of optics used afocally.
Quote:Jon,The fact that it's recognized that scopes (of equal quality, and neglecting atmospheric seeing) are all limited to the same magnification per unit aperture is the direct result of the Fresnel pattern subtending the same apparent angle at given exit pupil.
Quote:The corollary to the inverse proportionality with aperture is the inverse proportionality with exit pupil. No matter the aperture, the apparent size of the Fresnel pattern is the same at given exit pupil diameter. This is one reason why the exit pupil is a fundamentally important aspect of optics used afocally.
Astronomy educator/Sidewalk astronomer
Owner of Astronomy Delight franchise
18 inch f4.42 Dob on eq platform w ST120 f/5 finder
12 inch Zhumell Dob
8 inch f/6.9 home made Dob with Seevers optics
William Optics red 10th Anniversary 80mm FD
C8 XLT on Vixen GPDX
26lb eyepiece box
Cernan Space Center astronomer
Member of Northwest Suburban Astronomers
Quote: I observed the 0.49 arcsecond double zeta bootis
Quote:I've seen them many times through my 18 inch. Its sometimes easier to look at close doubles near the limit of resolution to confirm that the airy disks are indeed being seen. 2 nights ago I observed the 0.49 arcsecond double zeta bootis to see them as well as a few other close doubles.
Paul B. Jones http://www.astrobin.com/users/bunyon/
Quote:It's one thing to see a double (Zeta Bootis is one tight binary!) and another to photograph it. Since the image is so well resolved, I'd be interested in seeing how close together the stars can get before they appear as one.In 2021, I believe the separation will be less than 0.05", so some time between now and then the images will merge.Excellent shot.