Posts Made By: Vahe Sahakian

Keith Lawson said:

I believe everyone has a dream instrument that is either beyond their bank account or is no longer made or a combination of other factors. So I ask: What is your dream scope and why? No professional observatories please.

Here is mine: A Questar 12. Optical and mechanical perfection! No GOTO but man what an instrument 8) As a lunar/planetary observer this would be an ultimate instrument. Now if I could have it and good seeing to match...

I remember that ad in Sky&Tel some years ago, for me it was love at the first sight, at the time Q-12 was also my dream scope.
I know a little more about Maks now, specially the ones to avoid at any cost and this one would be on the top of my list.
No harm in dreaming, but if you really like to have a 12” Mak your only practical choices are the Russian Maks, and they are good, you can get some that are optimized for high contrast performance with smallish co., excellent overall figure, reasonable cooling at least when compared to Q-12, much lighter and somewhat portable if you are in a good shape.

Vahe

Interesting question, only Roland can give you an answer on this.

On a related subject a long time ago TEC, during their Maksutov period, used to have a small setup, a vacuum chamber for doing in house coating, but I believe that the rig was sold and all coatings are outsourced.

I do recall a post on S.A.A. from Roland discussing the cost of coatings for his 10” Mak, both refractive and reflective surfaces, my memory is somewhat hazy on this but I recall a figure of $1500 for coating services per scope, obviously outsourced.

Vahe

Rod Mollise said:Is there less interest in binoviewers now? Were they just a fad? Or are they mainstream, with the current presence of _useable_ imports for (some of 'em) less than a hundred bucks. LOL

Dear Uncle,

For me the interest in binoviewers has not subsided at all, in fact I got hooked when AP first offered one in 1994, I have never looked back, today I use viewers ALL the time, no exceptions.
To me viewers are no longer a novelty, they are a must, but I am no longer interested in arguing their strengths and weaknesses over and over again.

My only advise to anyone considering one is to stay away from cheap models, buy a quality bino, or if it is just too expensive just do not buy one.

Vahe

david goldman said:the one scope that i know that has the best color correction ever seen by me is the Zeiss APQ.there is absolutely no bleeding over of false color[purple haze]on vega,and the design is also very well corrected in the deep red.the late Thomas Back sent me a Zemax print out showing spot diagrams at various wave lenghts inticating that fact.i also have other diagrams from him from the same program [which i do not understand]on the APQ and ap superplanetary as a comparison.

My understanding of APQ performance compared to other top apo’s is that APQ is optimized for best visual performance as opposed to some of the other top brands which offer extended coverage to better perform with CCD’s extended spectrum sensitivity.

Vahe

Larry Seguin said:Here's the question. I got into to binoviewing for less than two hundred bucks. What would I gain by going for one of the premium units? If I kick up the dough for Televue or Denk, what do I get that I don't got now? Interested in any comments!

Always be aware of the laws of diminishing returns when you upgrade just about anything, a binoviewer, an apo, a fancy eyepiece or even a car.

My suggestion is to continue using your low cost viewer, and if sometimes in the future you get a chance to look thru someones high end viewer that will be the time for you to decide if its worth moving up.

I started with two viewers, one Zeiss and the other Lomo, after a short while I decided to sell the Lomo as it was not even close to the Zeiss.

Vahe

I have a TEC6 and use it with Zeiss viewer (same as Baader from AP), I use it primarily with high power eyepieces on planets, when I ordered mine I specifically requested ample backfocus for binoviewing.
Perhaps you can contact Yuri with this question as he is most qualified to give you an answer.

Vahe

Not to de-rail the topic, but for those interested in this size refractor TEC has a new 110FL coming out soon, it’s a bit smaller than the 120TSA, although it is not a Super Apochromat but it is a TEC triplet fluorite and worthy of consideration.

Vahe

There will always be a trade off for the convenience that zooms offer. That said a high quality zoom will always outperform a medium grade prime (fixed focal length) eyepiece.

Just like photographic camera zoom lenses, zooms have a sweet spot where they offer their highest overall quality, this is generally somewhere in the middle of the zoom range, at the upper and lower extremes things go south, there will be no contest with high quality primes.

As we move into digital imaging era where photographic images are viewed on computer screen the quality takes a back seat and convenience rules.

The same is true when comparing a zoom with the top of the line eyepieces.

But, if you are happy with the performance, stay with the zooms.

Vahe

This is definitely not what you want to hear, but here are the facts;

Portable is hard to define, it varies from person to person, but using your stated benchmark of 4” refractor for size and portability, if I waned a portable instrument for Jupiter, something that that can do justice when it comes to showing the low contrast features of this planet, I would consider a cat, a 7” Mak Cass with small co or Mak Newtonian, the MC would be more portable.

With a 4” or smaller refractor, preferably an apo, the small exit pupil needed to achieve a decent power will add exit pupil’s diffraction effects & reduce the contrast to a point where the instrument will not produce much detail, perhaps with the exception of the two major equatorial belts.

I routinely use a 155 apo for Jupiter, that is when I am too tired to carry less portable but larger reflectors and the first thing that I notice is how limited the 155 aperture is for capturing difficult detail.

This is an argument that I always lose, those who view Jupiter with 4” apo’s tell me how wonderful and detailed the image is, I suppose that depends on your experience and the expectations, if what you see in a 4” refractor is good enough then you are in business, but once you get a taste of what is possible with a 6” refractor or equivalent Mak then perhaps you will give this a bit more thought.

Vahe

Jupiter at the eyepiece offers a huge and impressive disk compared to other planets, this makes it a very interesting object to view in any small telescope, even a 3.5” Questar will give you a spectacular view of this planet.

That is the easy part, now try to extract low contrast surface detail from this large disk and you will be faced with formidable challenges, this is where you will need aperture and IMHO a quality 6” is the starting point, not ideal, but just the starting point.

And also remember that whatever that you get will also be used for Mars and Saturn this coming season.

Vahe