CONSIDERING A MEADE SYSTEM

[ASTRONOMO]

I have been to this Site several times before mostly an introduction but, tonight I'm interested in feedback. I have been away from Astronomy for 40 years now... but, we are ready to work in the Dark again. We are also a Photographer, so we want to purchase a System that will function with a large and somewhat heavy DSLR attached. We have been looking mostly at the Meade products and we like what we see. Their specifications and product construction appear to be aligned for those who are interested in high quality and good results. We have read many feedback and review reports, a very high majority are favorable. So after spending nearly three weeks reading, and asking questions on various sites, I have pretty much zeroed in on a system that I can afford and is expandable. The Meade LX80 Multi-Mount with the 8" SC tube looks like it will work for me. I would enjoy hearing from users of this type system, remarks, feedback and reviews are always welcome when one is interested in how a system works for others. Feel free to comment or share your experience with Meade products.

Ciao,

Don

[ollypenrice]

Just look around the deep sky imaging boards of this and the other forums. There are remarkably few SCT imagers posting pictures and of those who do most are, I would say, using Celestron.

DSLRs are, by the standards of astronomical CCD cameras, both slow and noisy. They are also uncooled and so are exposure-time limited by the build up of thermal noise. There is only one way to mitigate these limtations (other than by carrying out major mods to the camera) and that is to use fast focal ratio optics. The faster the better. In instruments like the Takahashi Epsilon (F2.8) we see very high quality DSLR images on occasion. Maurice Toet recently posted this one; http://www.dutchdeepsky.com/ic1396_sh2-129_130830.html

The F10 native FL of the SCTs is too slow for DSLRs. Personally I think it's too slow full stop. You can reduce them to the F6 to F7 range and that helps, but then you have to ask whether a decent refractor of comparable (or probably slightly shorter) focal length wouldn't in fact do better because of the superior optics. Would I swap a 5 inch semi-apo refractor for an 8 inch focally reduced SCT?  No.

Another DSLR issue is the superflous number of pixels they now offer. Fine for the daytime but the opposite of what we want for DS imaging. The longer the focal length the more absurd the pixels scale becomes, since it has you trying to resolve details way, way below what the seeing will allow and starving the pixels of light. Since a colour camera can't be binned 2x2 there is nothing you can do about this.

So in short I believe you'd be better served by a short FL instrument of a fast F ratio. Very fast F ratios bring diffiulties because they have shallow depths of field and require very fine collimation. Small refractors are the 'easy' compromise. Edit; You'll also need to be careful, if your camera has a full frame chip, that the optics you choose can cover it. Not many can do so, though they do exist.

As for mounts, I'd go for something with a proven track record. 

Olly    http://ollypenrice.smugmug.com/Other/Best-of-Les-Granges/22435624_WLMPTM#!i=2496491069&k=kb5hP7Q

[ASTRONOMO]

Greetings:

I believe that somewhere between your reply and my interest in Amateur Astronomy is where I will land. I completely understand your comments but do not find them applicable for that average Hobby Astronomer, your comments are much more in sync with very strict standards such as would be used by Professional Astronomers. We understand the variables associated with precision equipment and the results that can be gained with them but, for me, somewhere in the middle is where we will finally settle. I have worked my entire adult career in High Technology mostly System Engineering and we do not want to get that close with something we will play with several times a month, its just for fun not exact precision. Thanks for your reply and comments, we have done some further studying, since our post on Meade products and learned that Mead's financial status is not good or their standing as a company... so we will steer away from Meade and now we are looking at  Celestron, in a 8" tube with a Equatorial Heavy Duty Mount. We will chat again.

Ciao,

Don

[ollypenrice]

I think it's simpler than you make out, really. What's the perceived advantage of an SCT over a refractor? They can be had for the same price, so it's just a matter of matching optics to camera. The F reduced SCT will give you a longer focal length and similar F ratio but a shorter FL would better match your camera. There are other issues, like the imprecise focuser of the standard SCT. Aperture often seems important to people new to AP but, in isolation from other numbers, it isn't. I think people are often suspicious that with a small aperture you won't be able to get a good result. But a good look at the imaging boards will show that you can.

You're right about Meade. Be aware of the 2 levels of SCT from Celestron, the Edge and the standard. For AP the edge is much better but the reducer is costly. The standard one does need the 6.3 reducer flattener. It absolutely does, both for speed and flatness of field (and even with the reducer it isn't all that flat.)

Olly