Joined June 2012: Location, Ottawa, Ontario
Mes télescopes et jumelles:
150mm F5 Newt on EQ5, 127mm Mak Cass on AZ4
Oberwerk BT70-45 and 15X70 SkyMasters
Quote:Jupiter was amazing in the Newt. It was noticeably brighter and the edge of the bands were sharper and more defined on average than in the Mak.
First and foremost observing love: naked eye.
Last but not least, telescopes.
And I sometimes dabble with cameras.
Happy owner of--
A Mag 1, 12.5 inch Porta Ball
A Dual Axis Equatorial Platform
A PST Double Stack
Quote:Bill, that's exactly the issue, the sharpness would come and go, but when it was there it was great. Dimmer than the 150, but still great. I'm pretty sure that I still had thermal issues with the scope while the open tube Newt had reached equilibrium.Eric
Orlando, Florida, 81° W, 28.5° N, Joined: 8/27/11
CGEM, C8, C11, AT72ED, NexStar 5SE
Orion Starshoot Pro V2 Color, NexImage 5 / ASI120MC Planetary imagers
My photos: http://astrobin.com/users/Steve/
8"GSO dob, EQ platform, a case full of EPs
ALL my posts should be considered as opinions shaped by MY experiences and understanding of the facts.
My eyepieces are made from the waste product of exploding stars.
10XTi 102XLT ST80A(2" Focuser); President, Eypieces Anonymous, Denver Chapter (Hello, I'm an eyepiece junky, what's your excuse?)
DAS Dark Site
NexStar 8SE; Stellarvue SVR90T; Celestron 102GT; Orion ST80 Orion 9x63, Oberwerk 15x70 binos
And there they still stood, obscurely commemorating man's triumph over time and matter and the triumph of time and matter over man. -- Aldous Huxley, on the Mayan stelae at the Quirigua ruins
Quote:I suspect that the tendency for detail to pop in and out probably has to do with ones eyes trying to maintain focus within the shorter in-focus zone of the very fast primary mirror of the Maksutov as mentioned above. Anyway, that makes sense to me.
Quote:Since the OP is about aperture, I don't want to take this too far off track, but lately I've become interested in the benefits of the increased depth of focus provided by true long focal ratios
Quote:I have also read that smaller scopes are less susceptible to seeing effects.
Quote:I suspect that the tendency for detail to pop in and out probably has to do with ones eyes trying to maintain focus within the shorter in-focus zone of the very fast primary mirror of the Maksutov as mentioned above.
There is also a very interesting discussion on star test energy distribution (achromats have more energy in central maxima of airy disc, less in diffraction rings), which seems to favor achromats, and the impact of switching from photopic to mesoptic vision (impairs achromat's Strehl more than apo's).
Quote: I do recall that the Mak showed textbook perfect diffraction rings around both components of Epsilon Lyrae at 200x. My thoughts here center more around the behavior of a camera lens. Stopping down the lens increases the f-ratio, which creates a greater depth of focus. Somehow, I think the physics would have to be the same for a lens in both applications, and it only makes sense that the focus zone of a faster lens would be less that that of a slower lens.
Quote:I will have to backtrack a bit and correct myself. I mentioned in a previous post that both systems I was comparing were f/15. That is not correct. One was a 4" refractor and the other was a 5" Mak. Both systems had focal lengths of 60". Thus, the Mak was a little faster system overall. Anyway, I'm going to duck out of this discussion as I'm probably in over my head.Bill