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6" Apo vs. 6" Maksutov

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#201 wh48gs

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Posted 28 September 2009 - 08:08 PM

But the question was not about the relative merits of the optical physics of the types but an overall performance of the completed 'system' of Maksutov Cassegrain or apochromatic refractor, the subjective view looking through the system. This is why I said to argue numbers here is silly, no disrespect to Snell, Abbe, Fermat or anyone referring to them.



If the OP, as he states, knows the theory, his probable objective is to try to find out how much the theoretical advantage of an apo actually shows in the field use. But there's no need to argue numbers - they are as they are. And it is not silly to turn back to them whenever there is a disagreement in personal accounts - just because they provide the only objective measure.

Btw. the "theory" does include tracking down and quantifying fabrication, misalignment, thermally induced and other errors, effects of seeing and eyepiece/objective combined output. Each and every of those (and some others) is potentially important for the proper interpretation - and presentation - of a personal experience (view) through any given telescope.

This is not to say that every attempt at using numbers is necessarily a success. But it is not them to blame.

Vla

#202 SteveC

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Posted 30 September 2009 - 07:26 AM

Perhaps it is time to get back to the original question, to wit: "Could someone give me an impression of how a 6" Apo refractor would perform compared to a 6" Maksutov, particularly on planets?"

Assuming equal quality materials, design, and execution of design in the manufacturing process, the only entirely objective criterion (that is, the fact that one scope is obstructed and the other isn't) says that the the Apochromat will outperform the Maksutov in the area of contrast. Whether or not a viewer will notice the difference is a subjective judgment. Whether or not the considerable difference in cost between a 6 inch apochromat and a 6 inch Maksutov will be worth it to a particular consumer is also a subjective judgment.

Add in the objective fact that the apochromat will offer a wider field of view than a Maksutov and you get another subjective set of judgments that hinge on the value of a wide FOV to a planetary viewer.

In short, one cannot argue the physics, and there isn't much point in arguing the subjective experience.


Yes and No.

If there is an attempt to understand how universal the subjective experience is, then it is important to discuss/argue the subjective experience. I'm sure there are people whose subjective experiences mirror your own, and consequently, their subjective experiences carry more weight. There are posts reflecting more or less experience with either or both of the scopes in question and a certain amount of interpolated value can be found.

That's why people ask these sorts of questions. Heaven help the person who only gets one subjective response to a question.

#203 stanislas-jean

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Posted 04 October 2009 - 05:26 AM

Hi gents,
Fortunately, the diffraction has laws that may be predicted in term of the relation of resolution and contrasts.
Frankly it may be obserserved either an apo or a mct, it doesn't matter. The values given but the calculations can be discussed but not actually the fact of calculations.
The hypothesis that are taken into account are supposing something perfect like the quality and the homogenéity of the glasses, more critical on some aspects on refractors.
We could to speak a lot about, what it can be kept this is the fact that values are targets and the nearest approach to the calculated values can constitute the quality of the scope in cause.
On this forum we are not on this wave that apply for each scope.
What is discussed this is the comparison in term of perf between two kinds that are under the targets I spoke above.
And the better way is to calculate considering the diffraction laws. And at that stage we donot interfer with the notion of a sensor for observing (an eye, a ccd chip).
This is the next step.
THe graphs that was given before these post constitute in fact potentiallities that an aye or a ccd chip has to catch.
Viewing the problem under this angle this is quite different and free of subjectivities.
Now considering the properties of an eye (a standard one) and a ccd chip the global response in terms on contrast resolution capabilities give an answer, not subjective.
This global result can also verified on tests (not a ronchi, not an interfero, not contrast phase method, etc) but a test consisting to locate a target at a great distance and to observe these. These results shall confirm the calculations. What I did in this way confirmed the calculations even through seeing conditions (not bad) well characterised.
If this is not something is wrong somewhere (at least the caracterisation of the scope tested).
Stanislas


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