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Posts Made By: Alexis Cousein

October 19, 2007 08:56 AM Forum: Reflectors

Re: need some help again 80mm asrto vs 102mm

Posted By Alexis Cousein
victor truglio said:

i am trying to choose between the astro-tech 80mm triplet or
the astro-tech 102 doublet

Sounds like the wrong forum to me...this is the reflectors forum.

January 18, 2007 11:34 AM Forum: Eyepieces

Which 2" wide field to use with my new xt12i?

Posted By Alexis Cousein
Casey Whalen said:

Hello all,

I'm probably going to be purchasing a Intelliscope xt12 and will currently only have enough money for 1 wide-angle 2" eyepiece. I have only been using 1.25" eyepieces and have never bought or used a wide-angle eyepiece. I was wondering if anyone can suggest a great 2" wide-angle ep for a decent price? I think the most i'd be willing to spend is around $200.

Orion Stratus (if they get any -- the presence of the 2" versions is on and of their web page) or Baader Scopos. They're not Naglers but they're quite good for the money (I prefer the 30mm to the 35mm).

If you have slightly more money and a patience, wait for the TMB Paragon 30mm (which was rumoured to be planned for the next few months); I think the Paragon 40mm is a bit of a stretch in an f/5 scope (with an exit pupil of 8mm, you'll see the shadow of the secondary fairly soon when defocusing), but it does give you *the* widest field of view you can get in a 2" eyepiece (with the caveat your scope might not be illuminating the outer portion that well).

February 6, 2007 02:27 PM Forum: Beginning Astronomy?

Resolution Question

Posted By Alexis Cousein
The theoretical resolution for infinite contrast objects would be that of a larger scope, but only in one dimension if you used only two holes. Tough luck.

If you make four holes, you have just invented the newtonian with four extremely thick curved spider vanes and a large central obstruction - the theoretical resolution limit may seem interesting, but you're likely to throw enough energy into the diffraction rings for the scope to really not perform very well visually (especially if you want to look at low contrast features on anything).

Use an infinity of 3" apertures arranged at the edge, and you have the 20" aperture with a 14" central obstruction (with very much the same consequences).

The question is: what do you want to do with the aperture?

To fully understand the performance, you should look at the Modulation Transfer Function across all frequencies, not just the fixed "resolution", and you'll see that you can't obscure a sizeable portion of the aperture's area with complete impunity.

February 27, 2007 08:56 AM Forum: Beginning Astronomy?

Telescope for low temperatures

Posted By Alexis Cousein
Depends on where she stores the scope. She does probably not want a large scope, and certainly not a closed tube Mak or SCT.

The problem with a refractor is that you want a mount. A lot of GEMs (certainly cheap ones with Syntaglue) will become hard to use.

The first thing she probably wants is little electronics. A small Dob, stored close to ambient temperatures?

She'll definitely want a Crayford focuser rather than a rack and pinion focuser; probably not a dual speed one either (the Vernier reducer can also cause trouble).

February 27, 2007 09:05 AM Forum: Equipment Talk

Prism diagonals

Posted By Alexis Cousein
matt elliott said:

Does anyone know if these are self collimating?

No, they're not (at least no any more than mirror diagonals. If they don't reflect the centre line of one barrel onto the centre line of the other, they're miscollimated, be they prism or mirror diagonals.

If you want it to be well collimated, the optical design is the least of your worries. Quality (of the mechanical design and the assembly) is.

March 12, 2007 11:10 AM Forum: Eyepieces

Which one to get?

Posted By Alexis Cousein
Let's suppose that having gaining some experience with the 26mm, I feel that I want an EP bewteen the 26 and the 17.
I won't humour you; I have a 26T5 and 16T5 and I don't feel I need anything in between wink.

The cheapest solution to your "problem" would be to sell the 17T4, get a 20T5 and get something shorter than 17mm (like a 13T6 or even 12T4 if you want more eye relief), but I have a feeling they couldn't pry the 17T4 from your cold, dead fingers.

March 21, 2007 07:59 PM Forum: Eyepieces

No more using the initials or names for ?

Posted By Alexis Cousein
Body Odor, in this case, is full of Male Bovine Excrement (if indeed he has asked anyone to refrain from using his name in discussions - we've only heard second hand reports).

A trademark is just that. It does not magically bestow copyright onto the owner of the trademark and its reach does not extend to mere mortals discussing a subject without selling anything, and it certainly doesn't prevent people from using the name for critical examination and discussion or even parodies (not even copyright does).

A *logo* does have copyright protection, though you can still make a parody (but the parody should better be clear).

March 22, 2007 07:50 AM Forum: Eyepieces

No more using the initials or names for ?

Posted By Alexis Cousein
Please refrain from using their real names of initials or I will be forced to delete the post. smile

Does this forum software have a word filter? On some other fora, you could arrange for a certain letter combination to be translated to Body Odour automagically wink.

May 4, 2007 07:16 AM Forum: Eyepieces

Orion Q70 32mm

Posted By Alexis Cousein
James Powell said:

Could anyone please let me know how the Orion Q70 32mm eyepiece perofrms in fast scopes. I am using an 10" F5 dob.

I purchased an Eclipse 32mm 2" eyepiece from Agena but the performance was no better than the GSO 2" 30mm eyepiece that came with my telescope so I have returned it.

The Q70 (which is identical to the Agena SWA) and the 30mm GSO Superview are amongst the better cheapie wide fields - if you're not satisfied with them, all you can do is purchase a premium eyepiece. One thing you could do is wait a few months and hope the 30mm TMB Paragon will be available on time.

September 20, 2007 12:14 AM Forum: Reflectors

Orion Optics of UK, Experiences?

Posted By Alexis Cousein
Mark Jordan said:

Hello,

And thanks in advance for any input! I have been considering a possible OTA upgrade from my humble Orion SVP 8" Newtonian. Not really even an aperture increase, just a little better optics in the tube.

No need to go through TS if you're in the States.

http://www.orionoptics.co.uk/

Nothing to do with Orion US.

Yes, their "1/6th lambda" optics are quite good, and so are their Hilux coatings. A couple of people I observe with have some (with a Zygo interferometer report, but also the star tests and views to back up the performance claimed on it).

The optics are their strong point.


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