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Equipment Discussions >> Refractors

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pdxmoon
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SW 100: Will I notice Difference?
      #6171957 - 11/02/13 01:23 PM

Hi Astro Friends:

This past summer I jumped on the refractor bandwagon big time and I have been very happy with the Celestron ED80 and that super deal many of us got from OPT on the Celestron 102.

With holiday sales starting, the Skywatcher 100ED has dropped in price to $649, and I'm wondering the following:

Will I notice a difference in my planetary and lunar observing between the 100ED and the two scopes I already have, or

Should I just wait until the day I can add a 120ED? Unfortunately, with the SW120 ED comes the necessity of a new mount, and the SW100ED would probably work fine on my Polaris.

So, your opinions, please: enough of a difference in the 100ED to be noticeable, or simply an improvement in build (nicer focuser, etc.)

Edited by pdxmoon (11/02/13 01:41 PM)


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Mikefly
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Re: SW 100: Will I notice Difference? new [Re: pdxmoon]
      #6171991 - 11/02/13 01:39 PM

Well the first evident thing would be the negation of false color. Your images will also be more contrasy and snap into focus better. Having viewed through a 100ed for a while at a star party I can say that while your DSOs will be virtually identical the 100ed will have more contrast and the dual speed is a very nice thing to have.

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pdxmoon
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Re: SW 100: Will I notice Difference? new [Re: Mikefly]
      #6171993 - 11/02/13 01:41 PM

I have the dual speed on my AT72 and it's a dream. I assume you mean the added contrast of the ED100 will make lunar observing better (my principal target)?

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Mikefly
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Reged: 10/05/13

Re: SW 100: Will I notice Difference? new [Re: pdxmoon]
      #6172003 - 11/02/13 01:44 PM

Yes. You lose some contrast from CA since a few wavelengths of light are not entering your eye at the same point as the others. Of course it depends on how you look at it and if you can I'd suggest locating somewhere that you can have a look through one your self.

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BKBrown
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Re: SW 100: Will I notice Difference? new [Re: pdxmoon]
      #6172049 - 11/02/13 02:20 PM

On DSOs not really, on anything bright - absolutely! The reduced CA will improve lunar and planetary performance and can even help when splitting doubles. The SW100ED Pro is a great deal at the regular price, with the big discount it's a cosmic no-brainer in my book

Clear Skies,
Brian


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Eric63
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Reged: 06/16/12

Loc: Ottawa, Ontario
Re: SW 100: Will I notice Difference? new [Re: BKBrown]
      #6172121 - 11/02/13 03:15 PM

Not sure if the Ed100 will give you that much more on the moon. Luna is a very bright and high contrast object. I think what you want here is more aperture to get you more resolution and go deeper. I would think of getting a Newt, SCT or Mak for days where you want to go in deep and keep the ED80 for those grab and go days. A C6, for example, would ride nicely on your mount and give you enough aperture to make things more interesting, even during average seeing conditions. Yes some will tell you that it only has the contrast of a 4 refractor, but the moon has high contrast to start with, so this will be less critical. The extra resolution would nice. Otherwise you may want to hold out for the 120ED, especially since refractors are your favourite instruments. My two cents.

Good luck Thom
Eric


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pdxmoon
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Re: SW 100: Will I notice Difference? new [Re: Eric63]
      #6172215 - 11/02/13 04:20 PM

Hi Eric

By C6 I assume you mean this:?

C6


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jag767
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Re: SW 100: Will I notice Difference? new [Re: Eric63]
      #6172216 - 11/02/13 04:21 PM

I did exactly what you are thinking about, went from a 102gt to an orion ed100. I think it was most certainly worth it big improvement.

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pdxmoon
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Re: SW 100: Will I notice Difference? new [Re: jag767]
      #6172220 - 11/02/13 04:24 PM

Thank you. What do you usually observe? DSO or lunar/planetary? What changed for you with the new scope?

Thanks!


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Eric63
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Reged: 06/16/12

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Re: SW 100: Will I notice Difference? new [Re: pdxmoon]
      #6172221 - 11/02/13 04:24 PM

Yep, that's the one.

Eric


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pdxmoon
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Re: SW 100: Will I notice Difference? new [Re: Eric63]
      #6172229 - 11/02/13 04:29 PM

My Friend:

votre bon cur !

Thom


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jag767
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Re: SW 100: Will I notice Difference? new [Re: pdxmoon]
      #6172232 - 11/02/13 04:30 PM

Quote:

Thank you. What do you usually observe? DSO or lunar/planetary? What changed for you with the new scope?

Thanks!




I observe open clusters, globs, and dso's most, then planetary, and doubles least. There is a definite improvement in all of the above. I couldnt make out the adjoining galaxies to adromeda with the 102gt and i can with the ed100. Best analogy would be going from a lcd tv, to a top of the line 4k led tv. Same size, just a ton clearer.


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Eric63
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Re: SW 100: Will I notice Difference? new [Re: pdxmoon]
      #6172238 - 11/02/13 04:33 PM

C'est mon plaisir

Eric


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Eddgie
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Re: SW 100: Will I notice Difference? new [Re: pdxmoon]
      #6172321 - 11/02/13 05:30 PM

Yes, you will notice a difference.

Will it be worth $650?

Maybe, maybe not.

My advice? Save your money.

Sell all of these other scopes and stuff.

And go bigger.

Consider a 120ED type scope. If you really want a meaningful improvement, this is the way you should get it.

Changing from an f/10 achomat will of course make an improvement.

But here is the thing. Apeture gives you exit pupil.

A 100mm achromat is going to give you a dim image at 150x.

And guess what. So will a 100mm f/9 ED scope.

And exit pupil and image scale are your friends for planetary observing.

If you really want to improve your planetary observing, but retain all of the virtues of the refracting design (wide fields, no coma) then again, sell all your stuff and buy a telescope that is not only better, but is also bigger.

I know, the price is really nice, but I don't think you are going to pee your pants at the difference.

A 120ED scope though? Now you are talking.

Past this and it gets expensive fast, but the 120ED scopes were a tremendous value. They are still light and have a short enough package that they are not demanding to mount, and they will be much more capable planetary performers than a 100ED.

Do yourself a faver and take a step and a half ahead rather than a half step sideways.

And if you can't afford it now, then live with what you have until you can.


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Jon_Doh
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Re: SW 100: Will I notice Difference? new [Re: Eddgie]
      #6172328 - 11/02/13 05:37 PM

Plus the 120ED is at a reduced price right now. And comes with a carrying case, two inch dialectic diagonal, right angle viewfinder and two 1.25 eyepieces (5, 20mm).

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BillP
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Re: SW 100: Will I notice Difference? new [Re: pdxmoon]
      #6172370 - 11/02/13 06:11 PM

I would wait to afford the 120ED. However, if you are impatient then there is an Orion (Vixen) 120mm NeoAchromat for sale in the CN Classifieds with mount for $849. Reviews place it sharper than your 102 with about the same level of color correction,

Look at #7 - Link.


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magnus
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Re: SW 100: Will I notice Difference? new [Re: Eddgie]
      #6172383 - 11/02/13 06:25 PM

Eddgie!

Very wise & good thinking in my humble opinion.

Magnus 57N.

----------------------------
C80ED
MK66
C8
8"f/6 OOUK Newt
LS35HaDX

Edited by magnus (11/02/13 06:29 PM)


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saemark30
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Reged: 02/21/12

Re: SW 100: Will I notice Difference? new [Re: magnus]
      #6172448 - 11/02/13 07:18 PM

I would wait for the 120ED, the 100ED is too small for detailed planetary views.
There are also 6" achromats to consider.


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pdxmoon
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Re: SW 100: Will I notice Difference? new [Re: Eddgie]
      #6172516 - 11/02/13 07:59 PM

Yes, there's wisdom in this.

What would you use to mount. I prefer alt az and that's really what I'd want. The 120 is lighter than most, so the least hefty I can get away with.


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Eddgie
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Re: SW 100: Will I notice Difference? new [Re: pdxmoon]
      #6172653 - 11/02/13 09:42 PM

I am going to rant so forgive me.

I do not for the life of me understand how people can use an alt az mount for planetary observing.

Almost all scopes only perform at their full potential when the target is within a few arc minutes of the center of the field.

For reflectors, coma is the contrast killer if you let the planet get out of the center of the field by more than 5 or 6 arc minutes for a typical reflector. Beyond this and the image is no longer diffraction limited.

For refractors, it is field curvature. Once you let the target drift about 5 or 10 arc minutes out of the center of the field it is no longer at best focus.

For the highest resolution observing, it is really best to have the target at or near the center of the field.

And for planets, where you want to use high power, keeping the target centered is really important.

This allows you to relax and concentrate on the target.

Even today, using only 75x on my 110ED for solar white light, it was driving me mad to track (my motor drive is down for repair).

Just as I would get a few moments of steady seeing, I would be interrupted to re-center the target area. Seeing was coming and going and here I was taking my eye off the ball.

How maddening!

To me, if you are really serious about planets, you need a tracking mount.

You can get the CG4 for $275 brand new and shipped to your door.

This is not the most sturdy mount on the planet but is is not really much worse than a lot of Alt-Az mounts that cost $300.

I really mean this. For planets, I would rather have a mount that shakes when I focus it but has tracking than have a solid alt-az mount.

But that is me. I think I have done some really amazing planetary viewing, and I simply can't comprehend how people can eek the most challenging detail out of their scopes by being interrupted to move it every 30 seconds.

So, that is my take.

Sure, if you can afford a Cadillac mount like the GM-8, then that is great.

But my own advice is that if you really want to get the most detail out of a scope that is aimed at a planet, you need a good, comfortable observers chair and a tracking mount.

I think you can do some pretty good planetary observing with a good 120mm ED refractor (and I would not get the Vixen 120. It is not going to be in the same class as the 120ED scope).

But when you study optics, you quickly realize that most telescopes will perform at there very best when the target is kept very close to the center of the field.

And don't be fooled. Most refractors do defocus at the edge of the field, but as long as the star does not swell up to more than about 3 arc minutes of apparent field, we can't really tell that easily because in a coma free refractor, it remains a small dot.

But the planet will go out of focus and you can easily see it.

Sorry for the rant, but if you get a great planetary scope, get the most out of it with a tracking mount.

And later, get a good pair of binoviewers.

I have come to consider Binoviewers as far more important than the eyepieces you put in them.

These are all the opinions of an old man, but I have been doing serious planetary observing for a very long time now, and have had very great success I think.

And how people do serious planetary observing with an un-driven mount is beyond me.

Today, doing the sun without my motor was maddening. Every time I seemed to get a moment of perfect seeing, the detail seemed to be drifting close to the defocus point of the diffraction limited field of my scope. Maddening.

How do people do it???


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Eddgie
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Re: SW 100: Will I notice Difference? new [Re: Eddgie]
      #6172668 - 11/02/13 09:54 PM

I said CG4 in my previous post, but there are other inexpensive GEMs if money is tight. You can get used CG5 type mounts for less than $300 too.

A really decent Alt Az is going to cost double this by the time you stick a good tripod on it.

I am running my new 110ED (14 lbs with binoviewer and eyepiece) on a humble Polaris mount (though it does have a HAL 110 tripod).

Sure it shakes a little when I touch it, but once I let go it settle down.

And planetary observing is about waiting a lot of times.

You pick the power that you think will give you the best result for the best moments of seeing that are occurring, plug it in, sit, and wait.

Most people make the mistake of using a power that gives the best overall view for the average of the seeing, but I always select the power that is right for the few moments of more stable seeing that always occur.

It is during these fleeting seconds that you get your most challenging detail.

And if you are fussing with eyepieces or with re-positioning the mount, you miss it.

This is the key to getting the most out of your telescope for planetary observing. Push the power a little big over what seeing seems to limit you to, sit, and wait for it.

It almost always comes.

Big scopes are not supposed to do well in most seeing, but all of my best observations were done in less than excellent seeing using the above method.

Edited by Eddgie (11/02/13 09:55 PM)


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BillP
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Re: SW 100: Will I notice Difference? new [Re: saemark30]
      #6173840 - 11/03/13 02:20 PM Attachment (40 downloads)

Quote:

I would wait for the 120ED, the 100ED is too small for detailed planetary views.
There are also 6" achromats to consider.




IMO there is a bulk/mount consideration when moving between a 4" to 5" class instrument that is not trivial. As far as details comparitively in a 100 vs 120 I'm not so sure I would chanracterize it as so dramatic for planetary. It's a 20% gain in resolution, which is about the same as going from an 85mm to a 102mm. So if the OP wants to get a flavor of a difference in details between a 100 and 120, all they have to do is make an 85mm mask for thair Celestron 102, point it at Jupiter, and observe with and without the mask to get an idea of the relative difference in resolution.

And as far as details, a 4" can see quite a bit. Below is what I see *typically" on average with Jupiter - boundry details are etched when viewing, my sketching skills not good enough to represent this well however. Last week at about 4:30am I got a peek of Jupiter that was far better than this in my 4" APO as the atmosphere was very clear and stable. This is a binoviewer sketch and the 4" APO was mounted on a simple Vixen PORTA II. Eyepieces and bino were not exotic either.

Edited by BillP (11/03/13 02:32 PM)


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Eddgie
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Re: SW 100: Will I notice Difference? new [Re: BillP]
      #6174104 - 11/03/13 05:10 PM

Well, you may have addressed your post to saemark30, but perhaps you were responding to something I said.

And if that is the case, you have put a word in my mouth that I sure did not use.


seamark30 did not use the word "Dramatic" either.

Here is what I said:

Quote:

If you really want a meaningful improvement, this is the way you should get it.




The move from a 4" f/10 achomat to a 4" APO is going to yield perhaps a rather subtle improvement, but the move to a 120ED will yield an improvement that is much easier to see.

Dramatic is words I would use if he were gong to a 7" APO or a C14, or a 10" MCT or something.

Below that it is just a few small steps in meaningful improvement.

Once you get past 6", it gets big, or it gets expensive to get a "Dramatic" improvement.

So, just wanted to keep the record straight. I don't think I said "Dramatic" and I don't think saemark30 did either.


And I really could care less what the OP gets, but the proven road to better planetary performance is more and more good quality clear aperture.

Mounts, portability, seeing, cooling, and all that other stuff is secondary potential to the full potential of instrument you use.

If you start with a scope with limited capabilities you can never rise past those capabilities, and diffraction of the aperture is the ultimate limit.

Someone on another thread just chided me for the fact that my new 110ED was not going to be as good as his super apo 4" whatever for planets.

Yeah, right. Of course.

But that is why I have a 6" APO if I want to look at planets.

Good quality clear aperture is what you need for planets and the more, the better.

If one is worried about how big it is, then one has to be willing to settle for less.

Even Roland Christen uses a big MCT for planets.

Edited by Eddgie (11/03/13 05:38 PM)


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BillP
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Re: SW 100: Will I notice Difference? new [Re: Eddgie]
      #6174186 - 11/03/13 06:02 PM

I don't think we need to get wrapped up with individual words. That's just my interpretation of things. So simply replace dramatic with one you think correct. My post where I quoted Seamark30 was in response to 2 things, one being that a "100ED is too small for detailed planetary". So by inference from that quote, which is quite proper, if a 100 is too small and a 120 is fine, I would personally chanracterize the difference between going from too small to acceptable as a dramatic one relatively. So that is where dramatic comes from, all contained within interpretation of what I quoted. So if that particular word is bothering, then my apologies and simply put in another word you want that charaterizes a situation where one aperture is inadequate by being too small and the other aperture of 120 is adequate. I will keep that relative difference as being dramatic for my perspective on things.

But again, let's not get wrapped up in the single word. My inclusion of the sketch is to indicate that 100 is indeed not too small at all, not by a long shot And going larger means lots of things, like beefier mounts and more effor and longer cool downs and of course much more money. I am trying to keep my responses atuned to the spirit of the OPs starting post. Talking all those other larger aperture instruments is way afield I think since the OP is asking about 100 vs 120 differences. I, btw, do care what the OP gets as they are asking advice afterall specific to a narrow request of 100mm vs 120mm.

As far as starting with "limited" capabilities, well all scopes have limited abilities and larger ones certainly limit lots of abilities relative to readiness. Heck, I've had SCTs that were never ready for planetary all evening long! Just one of their limitations in certain environmental scenarios. As far as MCTs, well I would expect RC to use that and tout it because he makes them, it is marketing afterall!

Anyway, none of these are chides, just another opinion for the OPs to consider. I personally don't think 100mm is too small and find it rewarding as my sketch shows. Larger is always better in *some* terms, but always has its downsides as well. The magic is in striking the balance that best meets individual goals


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jag767
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Re: SW 100: Will I notice Difference? new [Re: BillP]
      #6174252 - 11/03/13 06:38 PM

I think for many ignorance is bliss. I love my ed100 and find it great for planetary viewing. That being said I have no viewing time through a larger refractor to compare it to.

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pdxmoon
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Re: SW 100: Will I notice Difference? new [Re: BillP]
      #6174253 - 11/03/13 06:38 PM

I appreciate both points of view, Ed's and Bill's. Ed obviously feels strongly about EQ mounts,etc., and his words have a lot of wisdom to them, and I am grateful he "ranted", as he said :-)

I also appreciate Bill's comments, and there's wisdom there too. Particularly the issues with mounting, and frankly, the way I prefer to observe--which is alt az. I like doing it that way. I find it relaxing to track the moon by hand.

I am also an incremental kind of guy. I like moving up slowly in the food chain, and not moving too quickly. It's just how I roll.

So, I believe it's very likely that both the mechanical aspects of the 100ED (i.e., the improved focus mechanism, better build) and the improvement in viewing--even if subtle, and the fact that I already have mounting I can use and that is easy for me to use, may win the day.

I'm still not entirely sure I'll do this, but I believe the chances are good I'd enjoy the 100ED if I did.

Thank you, everyone, for your thoughts.

T


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BillP
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Re: SW 100: Will I notice Difference? new [Re: pdxmoon]
      #6174316 - 11/03/13 07:16 PM

One of the things I enhoy about a smaller scope is the ability to move it between multiple less expensive mount plantforms. So the 102mm APO I have gets rotated around depending on my seasonal mood So I have an iOptron Minitower Pro for tracking, a Porta II Alt-Az for a light and easy solution, and also a CG4 for equatorial needs. I've had the 102 on the iOptron for the past few months and have just recently switched it to the Alt-Az to enjoy more rapid excursion capability, so basically a zero setup and work on this and light as a feather while still being stable enough.

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Nippon
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Re: SW 100: Will I notice Difference? new [Re: pdxmoon]
      #6174327 - 11/03/13 07:23 PM

I think the Celestron 8SE is at a $200 rebate. The mount is a little shaky but the gotos are accurate and it tracks. The 8" optics will crush the SW 100ed on planets and go much deeper for deep sky. Later you can buy a mount such as the Celestron AVX and have a solid set up for planetary viewing. I love my Vixen ED 103 S but it simply can't compete with my NexStar 8SE tube on anything but wide field. I used the 8 SE tube on it's goto alt/az for three years before I bought the AVX mount and it is a very competent set up. The AVX just added more stability and increased goto accuaracy.

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timps
sage


Reged: 02/24/13

Re: SW 100: Will I notice Difference? new [Re: BillP]
      #6174347 - 11/03/13 07:38 PM

Quote:

Quote:

I would wait for the 120ED, the 100ED is too small for detailed planetary views.
There are also 6" achromats to consider.




IMO there is a bulk/mount consideration when moving between a 4" to 5" class instrument that is not trivial. As far as details comparitively in a 100 vs 120 I'm not so sure I would chanracterize it as so dramatic for planetary. It's a 20% gain in resolution, which is about the same as going from an 85mm to a 102mm. So if the OP wants to get a flavor of a difference in details between a 100 and 120, all they have to do is make an 85mm mask for thair Celestron 102, point it at Jupiter, and observe with and without the mask to get an idea of the relative difference in resolution.

And as far as details, a 4" can see quite a bit. Below is what I see *typically" on average with Jupiter - boundry details are etched when viewing, my sketching skills not good enough to represent this well however. Last week at about 4:30am I got a peek of Jupiter that was far better than this in my 4" APO as the atmosphere was very clear and stable. This is a binoviewer sketch and the 4" APO was mounted on a simple Vixen PORTA II. Eyepieces and bino were not exotic either.




I am waiting for delivery of my TSA102 and am certainly not expecting to see Jupiter like that. I haven't even seen that much detail on Jupiter with a TOA130!


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BKBrown
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Re: SW 100: Will I notice Difference? new [Re: timps]
      #6174586 - 11/03/13 10:08 PM

Quote:

I am waiting for delivery of my TSA102 and am certainly not expecting to see Jupiter like that. I haven't even seen that much detail on Jupiter with a TOA130!




And yet the detail is there to see if you have the skill set down. I agree with BillP that a 4" ED/Apo is a very capable instrument for planetary viewing, my SW100ED has given me many splendid, memorable views of Jupiter, Saturn, and the Moon. What is more problematic is having the time, patience, and willingness to become a skilled planetary observer...that doesn't happen overnight, you have to work for it

Clear Skies,
Brian


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Eddgie
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Re: SW 100: Will I notice Difference? new [Re: pdxmoon]
      #6174721 - 11/04/13 12:06 AM

Enjoy your new scope. I am sure it will be excellent.

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Jon Isaacs
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Re: SW 100: Will I notice Difference? new [Re: Eddgie]
      #6174893 - 11/04/13 05:39 AM

Quote:

Almost all scopes only perform at their full potential when the target is within a few arc minutes of the center of the field.

For reflectors, coma is the contrast killer if you let the planet get out of the center of the field by more than 5 or 6 arc minutes for a typical reflector. Beyond this and the image is no longer diffraction limited.

For refractors, it is field curvature. Once you let the target drift about 5 or 10 arc minutes out of the center of the field it is no longer at best focus.




This is why people use coma correctors like the Paracorr when viewing with a Newtonian and realize that even at 100x, the field curvature of a 100mm F/9 is miniscule.

You know how to do the math... The depth of focus at F/9 is 0.0070 inches, the field curvature across a 12mm field of view (0.76 degrees = 45 arc-minutes) is only 0.0023 inches... the depth of focus is three times the field curvature across a field greater than the size of the moon.

In an 10 inch F/5 Newtonian fitted with a Paracorr, the "coma free field of view" is 0.65 degrees or 36 arc-minutes, again greater than the size of the moon...

As far a 120mm ED on a GEM being a better choice than a 100mm ED on an alt-az mount:

Both a relatively small scopes and the differences in the views, while noticeable, will be much more the same than they are different. That 20% increase in aperture provides somewhat finer contrast but not a great deal. To see a major difference, it takes a major difference in aperture. Either of these scopes can provide meaningful, enjoyable planetary viewing but neither will provide the best possible views that decent seeing will allow.

The major difference between a 120mm F/7.5 on a CG-5 class GEM and a 100mm F/9 (or even better F/7) on an alt-az is the portability, ease of use, ease of setup. The smaller scope qualifies as "grab and go" but the larger scope is no longer so easily managed and setup. In my experience, it takes about the same effort and time to setup a 10 inch Dob as it does a 120mm refractor on a equatorial mount.

This gets to the heart of why I (and maybe others) use hand tracked alt-az mounts. It comes down to getting the best image to the focal plane for the least amount of hassle. A good 10 inch will easily outperform a very good 5 inch..

Some people have more trouble than others hand tracking.. I enjoy it. It's that simple.

The right scope for you, the right scope for me, the other guy, that is what is important. They are all very likely quite different. In the final analysis, it's all about the actual experience. This is just a hobby we enjoy, nothing more..

Jon


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jag767
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Re: SW 100: Will I notice Difference? new [Re: Jon Isaacs]
      #6174900 - 11/04/13 05:53 AM

For me, there have been nights where i am so dead beat tired I just grab my 65mm and go out because I can literally carry my entire setup with one hand with ease. I got a 100ed over a 120 for 2 reasons. First reason was it no longer is a light scope easy to mount for those quick sessions (which most of mine are) to just pop outside on something like a porta II. Second is it would have eaten up too much of my budget right off the bat. In the used market and ed100 f9 can easily be found for 300 plus shipping without accessories, where as a 120 will be at least triple that.

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Eric63
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Re: SW 100: Will I notice Difference? new [Re: pdxmoon]
      #6174987 - 11/04/13 08:25 AM

I think you made a wise choice Thom, I have only heard amazing things about the 100Ed and this way you don't need a new mount. And like Jon said, the difference from 100 to 120 will not be that great, at least not $700 worth . Later on you can decide if you want to venture into the larger SCT or Newtonian world, but keeping aperture fever under control has its own merits too! This is something I keep struggling with. I read some nice threads about amazing views with larger instruments, but then I remember that the simplicity of the hobby is what keeps me observing. Going too large and complicated will just reduce the enjoyment for me.

Eric


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Stephen Strum
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Re: SW 100: Will I notice Difference? new [Re: jag767]
      #6175007 - 11/04/13 08:39 AM

My experiences are similar to the last couple of posts. Probably 90% of my observing sessions are less than 20 minutes long as a result of long work days, family, etc. I generally can't stay out more than that during the week and still get anything remotely close to 6 hours of sleep. So, small scopes, of whatever type, on an alt-az mount that can be taken out in one trip with everything attached make observing frequently a possibility. I can still get a 8" SCT out the door on an alt-az mount in one trip but it is awkward enough that SCTs <=6" get used more, and refractors over 4" exceed that limit quickly, and even 4" can be pushing it. Obviously it is nice to have a large scope available to use when you have the time, but if I was limited to just one scope it would probably be a 3-4" refractor simply because it would be used so much more frequently.

Similarly, I sold my only equatorial mount (that offered tracking) because it never got used. Partly because my yard has numerous trees and so observing different objects usually requires picking up and relocating the scope, and doing that frequently with an equatorial mount wasn't as fun. Plus, I also enjoy tracking objects by hand, even planets at high power. Manual tracking with an overloaded alt-az mount is hardly easy or fun, but when matched correctly and well balanced, it is easy to track at well over 200x with a little practice, at least for me. Also, for whatever reason, I prefer to see objects move rather than remain stationary. Now, if I was retired or otherwise had more time, or had a larger property that allowed me to put in a more or less permanent mount, then I would likely observe much differently. Luckily, we all have numerous options available and so with some trial and error most people can find the scope sizes and types and mounts that provide them the most enjoyable experience. Unfortunately, there is really no way to figure that out without actually living with a scope for a while since listening to various opinions and experiences all day long can't replace your own. Even trying a scope out at a star party can't replace actually trying to negotiate your kitchen, back door and steps with the thing. And, those best-for-me combinations will always be changing as your life changes. But, trying new things is half the fun of the hobby.


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Stephen Strum
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Re: SW 100: Will I notice Difference? new [Re: Stephen Strum]
      #6175016 - 11/04/13 08:50 AM

As a follow-up, scope choice I think often depends on whether an observer gets more enjoyment out of being able to see the greatest amount of detail possible when observing (when considering physical and financial constraints on that) or whether the observer simply wants to be able to get out an observe easily and frequently. For me, I'm not usually so concerned about that fact that I could have seen more detail on Jupiter or some other object if I had a scope a little bigger out with me. Most of my enjoyment simply comes from the relaxing experience of being outside observing the sky with whatever instrument I have. Now I suppose that view might change in 30 years after I've observed the same things countless times.

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Eric63
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Re: SW 100: Will I notice Difference? new [Re: Stephen Strum]
      #6175038 - 11/04/13 09:11 AM

I agree with you 100%. That's why I have recently returned to using binoculars. Just yesterday with 0 degree (32F) temperatures, I drove 5 minutes to a dark spot with my 15X70 Binoculars and a photo tripod to simply enjoy Auriga and Orion for only 20 minutes. I just loved how the objects were framed in the sky instead of trying to see the detail within them. A change of perspective is sometimes good

Eric


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pdxmoon
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Re: SW 100: Will I notice Difference? new [Re: Eric63]
      #6175226 - 11/04/13 11:05 AM

I do most of my observing in the summer months, because of the weather here in Portland, and because of my work schedule. In the winter I rarely get out, and when I do I have a 60mm Meade right outside my door just waiting for looks at the moon.

My 102GT is covered in the garage, so if the weather is mild and I can spend more than 10 minutes, I can open the garage and lift it into place in about 15 seconds. But mostly, it's the summer.

And here's another thing I've noticed about myself. Because of the deliciousness of the two speed focus on my AT72, I often reached for that, even over the ED80, sometimes. It is just such a pleasure to use. If I go for the ED100, I expect that because of the improvement in build, that alone will add to my pleasure.

I appreciate all your comments and ideas.

Edited by pdxmoon (11/04/13 11:06 AM)


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PeterR280
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Re: SW 100: Will I notice Difference? new [Re: pdxmoon]
      #6175325 - 11/04/13 12:09 PM

I find 100mm the best compromise between portability and visual performance for a grab and go setup. For ordinary seeing situations, a magnification of 150x or maybe a little bit higher is about all you can get. The 100mm will do just fine up to about 200X depending on optics. It is also noticably brighter thn an 80mm refractor.

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saemark30
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Re: SW 100: Will I notice Difference? new [Re: BillP]
      #6175347 - 11/04/13 12:19 PM

BillP,
Can you tell us the details of the drawing such as power, eyepieces, filters if any, and planet apparent size?

Jupiter can vary from 30 to 50 arc sec.
An exquisite Takahashi 4" can show detail on Jupiter.
Typically a 6" is the aperture to notice significant increase in detail as reported in literature from the last 100 yrs and ValeryD suggests 6"-7" apos.

A 5" can show some polar caps and dark regions on Mars at a close opposition.

I am now trying out 6" f/8 achromats. Forget the theory and just view. These scopes are amazingly sharp and contrasty.
When growing owning a 6" refractor was a pipe dream, now they are dead cheap. Right now its my favorite scope.


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Eddgie
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Re: SW 100: Will I notice Difference? new [Re: Jon Isaacs]
      #6175372 - 11/04/13 12:36 PM

It's really far more than just the field curvature of the telescope itself.

For example, let's say that someone has drank the coolaid and is using a 10mm orto in their telescope for planets.

Or a Plossl for that matter.

Assume an f/5 reflector.

On the image axis of either a plossl or a an ortho, the eyepeice is capable of focusing the spot from a star into a one arc minute of appearent field circle.

But by time a planet has drifted to 10 degrees off axis (less than half the way to the field stop of even a 40 degree AFOV Ortho), due to astigmatims, the spot will have expanded to 5 arc minutes.

Any curvature will of course expand the blur even further.

This means that for fast telecopes the eyepeice itself is no longer diffraction limted once the target or detail has drifted less than half way to the field stop.

By f/10, you would have to go to about 20 degrees off axis for this same amount of astigatism, but really this is far to much astigmatism to generate a sharp image.

And again this is at a flat field.

Now the combination of the telescope and eyepecie field curvature may make this better (or perhaps worse) but most eyepeices that are praised for planets have very small off axis angles where they will be diffraction limited.

I can see that the detail on the sun looses definition when it drifts outside of an image circle that I would judge to be about 20 arc minutes in diameter in most eyeepcies I have tried.

The most difficult detail that is visible when I hold the detail at the center of the field is not available to me if I let the detail drift outside of this circle.

And even at f/7 and 75x, the detail drifts from this circle very quickly.

I don't know how people cannot see this difference. It is crystal clear to me that I only get the full performnce of the telescope and eyepeice when I place the target at or near the exact center of the field.

I could refocus of course as the object drifts out of this small area, but that gets tedious.

So, for me, I can't see how people can miss this image degradtion.

I see much more detial when I place the target at the exact center of the field and focus on it and track it than if I allow it to drift away from center.

How can people not see that? It is glaring to me.

On the sun, the preumbra simply falls apart and turns into a soft blur if I let it get more than about apparent degress off to the side of the eyepiece center.

It was driving me crazy using my mount without the motors. As soon as the sunspot drifted a little away from center, I was loosing the detail that I was workning hard to see even with the target perfectly centered.

I just don'd understand how peopel could miss this level of damage.

And for this kind of observing, Naglers will of course have far less astigmatism, but in a fast dob, the coma will still kill the contrast on the most difficult detail.

Honestly, anyone that takes the time to really study the image hard will see that as the target drifts off of the optical axis in most scopes either the eyepciece fails (on a fast scope) or the scope itself contributes enough off axis aberration (field curvature or coma or whatever) to render the image less than diffraction limited.

It just escapes me how people can miss this!

But there was a recent thread... An individual using a binoviwer in his EdgeHD 8".

I had been going on and on about the ills of a lot of back focus when using binoviewers with the EdgeHD 8".

Over the space of a month, HowardK measured his apeture and discovered he was loosing about .5".


But it did not seem to bother him...

Until....

When he took the time to really make a serious comparison using the configureation that was causing the apeture loss to a configuration with much less apeture loss, he quickly discovered that there was a meaningful difference in performance.

He had to see it for himself, and once he did, he abandoned the configuration he was using.

If people look for this, they are going to see it.

With the detail are of intrest at the exact center of the field, find the most difficult feature possible.

Now, let the target drift towards the edge.

My bet is that for most observers, using most telecopes/eyepeciece combinations, they will no longer be able to see that detail before the area has drifted half way to the field stop.

At least that is the way it works in almost every telescoep I have used for planets. I only get the full capability of the instrument when I keep the target very near the center of the field.

I don't really care what other people use, but if they really want to get the most out of their telescopes, they will take this test.

And if they decide that they still don't mind the performcnae falloff, then they get to make their own choice.

But many are going to perhaps be surprised.

Thre is nothing like seeing it for yourself.

Ask HowardK. He is now a believer about back focus in the SCT. He proved it to himself.


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Eddgie
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Re: SW 100: Will I notice Difference? new [Re: Eddgie]
      #6175412 - 11/04/13 01:02 PM

And this.. The book Telescope Optics has a great example of what I am talking about.

On page 194, they show how varius telescope and eyepiece combinations perform.

They show the blur circle for each combinations with a one and five arc minute circle so you can see how much the image suffers.

Remember, the scotopic eye can resolve about 2 arc mintues of damage.

They also show how much visual accomdation would be required in diopters for the observer to keep the blur at best focus (though the image will never be better than the blur allows).

Only one/eyepeiece combination kept the blur contained very well, and that was a 100mm f/8 APO using a 13mm Nagler, and this was ongly good to 20 degrees off axis, or half the way to the field stop of the eyepecie.

Now imagine how quickly a planet is going to get half the way to the edge of a Nagler at 150x.

And this was the best case.

Anyone that has this book can quickly and easily see this for themselves and once seeing this, my bet is that the will quickly understand the point I am making.

But if they have a telescope, they can test it for themselves.

I don't really care what other people do, but if they want to get the absolute best planetary detail with their telescope, they should strive to keep the point of interests as close to the center of the field as possible.

Edited by Eddgie (11/04/13 01:05 PM)


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Eddgie
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Re: SW 100: Will I notice Difference? new [Re: Eddgie]
      #6175422 - 11/04/13 01:08 PM

And I know.. Someone will say "Oh it is just a book.. Just a theory.. Ray traces don't tell all that much."

We all make our own choices of what data to believe.

But telescope optics is such a well known area that all of this was figured out many decades ago.

I encourage more people to read about it. Fun topic.

But anyone that reads Section 16.7 of Telescope Optics and studies the chart on page 194 will quickly conclude that for best performnce, it is best to kee the target at or near the center of the field in most telescope/eyepeice combinations.

And for fast dob users, they will quikly conclude that if they want to let the target drift, they are beter off using a Nagler than an Ortho. They still get the coma from the instrument, but at least the eyepiece behaves.

Most simple designs are incapeble of performing well outside of a pretty narrow angle.

Edited by Eddgie (11/04/13 01:12 PM)


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Jon Isaacs
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Re: SW 100: Will I notice Difference? new [Re: Eddgie]
      #6175456 - 11/04/13 01:20 PM

Quote:

And for this kind of observing, Naglers will of course have far less astigmatism, but in a fast dob, the coma will still kill the contrast on the most difficult detail




Eddgie;

I just provided you with the coma free field of view of a 10 inch fitted with a Paracorr as being significantly larger than the moon. Yes, orthos and Plossls are not sharp off axis. So.. Naglers are.. those who view the planets and track by hand typically use Nagler class eyepieces and a Paracorr.

Is that so difficult to understand?

A telescope is a system, the mount, the scope, the eyepiece and the observer. Making them all work together is what it's about. Dob mounts are solid and stable. If hand tracking is part of the equation, then the scope, accessories and eyepieces need to be chosen wisely.

It's just that simple.

Jon


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BillP
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Re: SW 100: Will I notice Difference? new [Re: saemark30]
      #6175521 - 11/04/13 01:53 PM Attachment (27 downloads)

Quote:

BillP,
Can you tell us the details of the drawing such as power, eyepieces, filters if any, and planet apparent size?




That sketch, rendered in a smaller scale to show how it appeared in the AFOV is pictured below. That was at 2010 Jupiter opposition so one really didn't need much magnification to get a good view. I was only operating at 100x. For Mars, I am generally much higher and usually around 140x to 220x just depending. I rarely use filtration when observing and tend to prefer cool toned eyepieces over warmer tones, even for Jupiter because I tend to focus on the lowest contrast challenge features when observing and find they get obscured more easily with warmer toned eyepieces. If I can do bino-mode I do as 2 eyes always lets me perceive a bit more detail and contrast is perceived better as well. The image says the eyepieces were RKE but that is an error. They were actually the older Edmund 1-1/8" eyepieces which are non-symmtrical Plossls. These provide a sharper on-xis image than their successor the 28mm RKE. It's just slightly better, but the small gain is important to me since I'm always after challenge features for the scope.


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BillP
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Re: SW 100: Will I notice Difference? new [Re: saemark30]
      #6175546 - 11/04/13 02:04 PM Attachment (23 downloads)

Quote:

A 5" can show some polar caps and dark regions on Mars at a close opposition.




You don't need a 5" to see great detail on Mars. Polar caps are an easy catch and lots of surface details including limb haze, orthographic clouds over Olympus Mons, and other very delicate details - my sketches do not do justice to what I can see as my sketching skills are not that honed. Contrast performance is really important I find. As you can see in the sketch below, the difference between a complex design eyepiece and on the right the as pure as you can get singlet eyepiece is quite substantial. Even though the left sketch is at a higher magnification, when I do use EPs where the magnifications are equalized, the singlet always provides a higher contrast view that is easy to notice when comparing it to anything other than a premium-level standard Abbe or the like. The singlet is a ball or sphere lens eyepiece that was ATMed. Both good views but the home made ball EP can keep up and sometimes even exceed a ZAO as its contrast is unparalleled. Tracking mount required with the ball EP as the usable FOV is only about 10 degrees or less. Worth it though to me as it brings out lots of subtlties within the various Mares, not to mention how blazing stark white the polar caps and limb haze appear when using the Ball or ZAO.


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PeterR280
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Re: SW 100: Will I notice Difference? new [Re: BillP]
      #6175578 - 11/04/13 02:17 PM

I have seen polar caps on Moars with 4"

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saemark30
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Re: SW 100: Will I notice Difference? new [Re: PeterR280]
      #6175667 - 11/04/13 02:57 PM

Mars varies from 13 to 26 arc sec at opposition so I guess the instrument required must vary within that ratio too.

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t.r.
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Re: SW 100: Will I notice Difference? new [Re: saemark30]
      #6175714 - 11/04/13 03:17 PM

Quote:

A 5" can show some polar caps and dark regions on Mars at a close opposition...You don't need a 5" to see great detail on Mars.






I have read that 60mm is all that is needed to show some macro planetary detail on the usual targets of Mars, Jupiter and Saturn. I agree and indeed, many of us started planetary observing with a 60mm. Take a look here...

60mm

And here...

60mm too

To answer the OP's question...Will I notice a difference?...Well, I notice the difference when there is as little as 10mm increments in refractors until about 7". Is it "dramatic"? That is up to you! But rest assured the difference of just 10mm can be seen.





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saemark30
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Re: SW 100: Will I notice Difference? new [Re: t.r.]
      #6175784 - 11/04/13 04:02 PM

Yes but those sketches were made with a premium 4" APO.
The 100ED might have very difference Q&A.
In fact there was a triplet version of the 100ED that had problems with spherochromatism.
And apparently not all 60mm refractors are created equal. I never saw detail like those as the images were too faint by the time the magification was high enough.


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pdxmoon
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Re: SW 100: Will I notice Difference? new [Re: t.r.]
      #6175829 - 11/04/13 04:26 PM

I use a 60mm on the moon and planets all the time. Great for rocket fast 10 minute observing sessions!

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BKBrown
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Re: SW 100: Will I notice Difference? new [Re: saemark30]
      #6175951 - 11/04/13 05:41 PM

Quote:

Yes but those sketches were made with a premium 4" APO.
The 100ED might have very difference Q&A.
In fact there was a triplet version of the 100ED that had problems with spherochromatism.
And apparently not all 60mm refractors are created equal. I never saw detail like those as the images were too faint by the time the magification was high enough.




My SW100ED can detect those kinds of detail, and I have seen them on many occasions. BillP has a superb instrument in his TSA-102, and the Jupiter sketch (very nicely done Bill ) is quite representative of what an experienced planetary observer can pick out. That said, properly figured 100ED f/9 optics can pleasantly surprise you if you give them a chance...

Clear Skies,
Brian


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jag767
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Re: SW 100: Will I notice Difference? new [Re: t.r.]
      #6176236 - 11/04/13 08:31 PM

Quote:

Quote:

A 5" can show some polar caps and dark regions on Mars at a close opposition...You don't need a 5" to see great detail on Mars.






I have read that 60mm is all that is needed to show some macro planetary detail on the usual targets of Mars, Jupiter and Saturn. I agree and indeed, many of us started planetary observing with a 60mm. Take a look here...

60mm

And here...

60mm too

To answer the OP's question...Will I notice a difference?...Well, I notice the difference when there is as little as 10mm increments in refractors until about 7". Is it "dramatic"? That is up to you! But rest assured the difference of just 10mm can be seen.








I have to agree a lot can be seen with something so small. My 65mm nearly blew me off my feet the first time I looked at Jupiter with it. The level of detail was so far beyond what I had expected and in fact I had no intention of ever doing any planetary viewing with it. I just decided to take a peek on a whim, very very glad I did. I think a lot of people get caught up in the numbers with this hobby- something that is incredibly easy to do. The bottom line at least to me is if you put something in view, and seeing it makes you crack a smile, then it did the job!


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BillP
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Re: SW 100: Will I notice Difference? new [Re: BKBrown]
      #6176367 - 11/04/13 09:44 PM

Quote:

Quote:

Yes but those sketches were made with a premium 4" APO.
The 100ED might have very difference Q&A.
In fact there was a triplet version of the 100ED that had problems with spherochromatism.
And apparently not all 60mm refractors are created equal. I never saw detail like those as the images were too faint by the time the magification was high enough.




My SW100ED can detect those kinds of detail, and I have seen them on many occasions. BillP has a superb instrument in his TSA-102, and the Jupiter sketch (very nicely done Bill ) is quite representative of what an experienced planetary observer can pick out. That said, properly figured 100ED f/9 optics can pleasantly surprise you if you give them a chance...

Clear Skies,
Brian




And as you know (but others don't) I had an observing session with you with your 100 f/9 and my 102 f/8. The two were so darn close in their views on planetary, and no difference on other targets! That SW 100ED is optically very very good so quite a value. Put a Feathertouch or Moonlight focuser on it and....sweet!

The fun part of that evening though was placing multiple stacked Barlows under a 28mm RKE with your TEC140 and observing Saturn with eye relief in the neighbors yard

Edited by BillP (11/04/13 09:45 PM)


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BKBrown
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Re: SW 100: Will I notice Difference? new [Re: BillP]
      #6176627 - 11/05/13 12:05 AM Attachment (9 downloads)

Quote:

Quote:

Quote:

Yes but those sketches were made with a premium 4" APO.
The 100ED might have very difference Q&A.
In fact there was a triplet version of the 100ED that had problems with spherochromatism.
And apparently not all 60mm refractors are created equal. I never saw detail like those as the images were too faint by the time the magification was high enough.




My SW100ED can detect those kinds of detail, and I have seen them on many occasions. BillP has a superb instrument in his TSA-102, and the Jupiter sketch (very nicely done Bill ) is quite representative of what an experienced planetary observer can pick out. That said, properly figured 100ED f/9 optics can pleasantly surprise you if you give them a chance...

Clear Skies,
Brian




And as you know (but others don't) I had an observing session with you with your 100 f/9 and my 102 f/8. The two were so darn close in their views on planetary, and no difference on other targets! That SW 100ED is optically very very good so quite a value. Put a Feathertouch or Moonlight focuser on it and....sweet!

The fun part of that evening though was placing multiple stacked Barlows under a 28mm RKE with your TEC140 and observing Saturn with eye relief in the neighbors yard




I remember that session well Bill, that was also when you introduced me to ball EPs...a surprising revelation for me And yes, the Barlowed RKE 28mm experiment was a real treat! That was back before the observatory was built and Saturn was the star of the show, I would be more than willing to try it again as Jupiter approaches opposition...

Clear Skies,
Brian

Edited by BKBrown (11/05/13 03:15 PM)


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saemark30
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Re: SW 100: Will I notice Difference? new [Re: BKBrown]
      #6177264 - 11/05/13 12:08 PM

Where did you find the ball lenses and what size did you get?
I did try using doublets as eyepieces and the contrast was great for the 2005 Mars opposition.
I guess a long f/# 100mm refractor can show a lot of detail especially with a binoviewer and good seeing.
A larger scope will show the same detail with more contrast though.


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astrobug
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Re: SW 100: Will I notice Difference? new [Re: saemark30]
      #6177647 - 11/05/13 03:34 PM

Here's my $0.02:

I don't think you're going to see a huge difference in the view between the ED100 and ED120 for planetary work, assuming equal optical quality and seeing conditions. Yes, the image will be a little brighter in the 120 at the same magnification, but the theoretical difference in smallest observable details is only about 1/5 of an arc-second.

My experience supports this. I used to have a Burgess 1278 (125mm f/8 achromat). Despite the false color it was a fine planetary performer. I tried a bunch of different sized aperture masks, and frankly the planetary views at 150-200x were actually just a hair better at 100mm than they were at 110mm or full aperture (this is likely due to a slight reduction in chromatic aberration, while still having enough aperture to show fine details--Ronchi testing showed no edge problems at full aperture). Stopped down to 80mm, there was a much more obvious reduction in the amount of detail. (Interestingly the Burgess at 80mm outperformed my 80mm Skywatcher Equinox ED by a hair at the same magnification...but this could be attributed to differences in eyepieces/having to use a Barlow.)

So, in the end, for me, the extra aperture was basically just dead weight (I have other scopes for deep-sky viewing), but the difference between 80mm and 100mm was compelling, so I ended up picking up a Vixen ED100sf. So far, this seems to be a little bit better than the Burgess for planetary viewing (no noticeable loss in fine detail, and a cleaner view overall). The big pluses for me are the 2-speed focuser and lightweight OTA. I can mount the Vixen on my old-school Polaris for quick looks rather than having to use my Meade LXD-75 (which takes much more setup time).

All that said, on a night of very good seeing, I would want a larger instrument for planetary work. Considering this is the refractor forum, the ideal be an 8" or larger APO. Considering my bank account, I would have to be content with a similarly-sized Newtonian that has been optimized for planetary viewing: 8-12", focal ratio above f/6, tube flocked or baffled and extending well past the focuser, minimally obstructing secondary, curved-vane or wire spider, and fans on primary mirror to reach equilibrium faster.

To the OP: I live in Portland, OR, too, so if you'd like to try out an ED 100 variant before buying, feel free to PM me. (Though with the recent change in weather, we might not get a clear night before the sale ends ).

-Brett


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Sasa
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Re: SW 100: Will I notice Difference? new [Re: astrobug]
      #6177866 - 11/05/13 05:21 PM

My story is similar to Brett and Stephen. I was also considering buying either ED100 or ED120. Originally to complement my fairly good 250mm f/6.4 fully flocked Newton. Having that large telescope already I opted at the end for ED100. I wanted a telescope for quick sessions on light alt-az mount that would give me more optical power than my 80mm f/6 apochromat.

At the end I found out myself observing through 100mm refractor more and more. I was taking out the big dobson only occasionally, even if I knew that I would see more on DSO or planets with it. I did not care. What I saw on planets with this small telescope was good enough and still very interesting. (You can see my drawings on my web page, here for Jupiter

http://www-hep2.fzu.cz/~kupco/astro/sketches/obj/jupiter.html

here for Mars

http://www-hep2.fzu.cz/~kupco/astro/sketches/obj/mars.html )

With ED100 I was out every reasonably good night, most of them were nights when I would not bother to take the large dobson out. Finally, when I set up my dark-side observatory, I decided to sell the large Newton.

I think I did a right decision going with ED100 instead of ED120. I observed once with my friend's ED120 and it was clear that thermalization of ED120 was visibly slower. ED100 was providing crisp views of Saturn while ED120 was still a little bit mushy. Later I had also in my possession 130mm Vixen ED doublet with an excellent star test (it was supposed to be my main telescope for the dark-sky observatory, but it was replaced by Zeiss AS110 which I found at about the same time). In winter, it was almost unusable on planets without prior cooling. I remember one winter night when I started just to see Jupiter GRS after 30 minutes of being outside. With AS80/1200, I was done with drawing Jupiter in 20 minutes including Red Spot Junior...

Concerning the difference between 80mm, 100mm (and 130mm), the difference is clearly visible on first sight. However, with more time spent behind eyepiece, I'm not sure that it is indeed that large as it looks at the first sight. My experience on Jupiter, Saturn and Mars is that I record on my drawings very similar amount of detail. But I would say you need to work harder at 80mm to noticed them than in 100mm. Still of course I can find some details in 100mm which are not visible in 80mm.

Take for example this series of 3 Mars sketches made through 80mm, 100mm, and 250mm telescopes in 3 subsequent days (Mars diameter was about 9"):

http://www-hep2.fzu.cz/~kupco/astro/2012/2012_05_10/pic/orig/Mars_20120510_20...
http://www-hep2.fzu.cz/~kupco/astro/2012/2012_05_08/pic/orig/Mars_20120508_19...
http://www-hep2.fzu.cz/~kupco/astro/2012/2012_05_09/pic/orig/Mars_20120509_20...

The sketches look more similar than different.

On DSO objects, the difference between 80mm and 100mm is large. For example some galaxies start to reveal to my eyes some details in 100mm while in 80mm it is more about just seeing the galaxy (but still, here and there I run on unexpected surprises even in 80mm). And 130mm was another big step. At these sizes every centimeter counts. Already the difference between 11cm refractor AS110 and ED100 is clearly visible (for example on many globular clusters). But still I do not mind with what telescope I observe, being it just 63mm refractor or 250mm one. When I observe, I'm not bothered by thoughts what I would saw if I had larger telescope instead. I simply enjoy the view as it is.


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magnus
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Re: SW 100: Will I notice Difference? new [Re: Sasa]
      #6178031 - 11/05/13 07:12 PM

Sasa!

Thanks for an informative post and amazing drawings; 100ED must be the way to go if I want to have a larger refractor than my C80ED!

Magnus 57N.

------------------
C80ED
MK66
C8
8"f/6 OOUK Newt.
LS35HaDX


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jrbarnett
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Re: SW 100: Will I notice Difference? new [Re: pdxmoon]
      #6178078 - 11/05/13 07:43 PM

"Will I notice a difference in my planetary and lunar observing between the 100ED and the two scopes I already have,..."

Yes over the 80mm. Not likely compared to the 102mm.

"Should I just wait until the day I can add a 120ED?"

YES!

Sure, a new mount is kind of a drag, but look at it this way. Once you have that 40-45# payload class mount, you're good for anything from a tiny refractor to a mid-to-large SCT (10"-11"). Having a versatile mid-capacity mount is quite liberating, actually. Celesrton's CGEM is on sale currently for $1300; less than a 120ED OTA at current prices. And it'll work just fine with the OTAs you already have until you're ready to take the plunge and move up to a ~5" glass.

While I agree with Bill that an experienced observer with keen eyesight and a quality 4-incher can see quite a lot on bright targets like planets, to me for a refractor to achieve "do everything" status, it needs to be around 5-inches in aperture or larger.

I love 'em all, but I could comfortably observe for the rest of my days with a quality 5-incher. I can't say the same for a 4-incher, though.

Regards,

Jim


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Glen A W
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Re: SW 100: Will I notice Difference? new [Re: Eddgie]
      #6178259 - 11/05/13 09:49 PM

I had a 102 before since 1998, now the 100, on the same mount - a 1990 Vixen Regular Polaris. The 100 is far superior. On Jupiter, there is simply no comparison. Saturn, not so much difference, though maybe the 102 was a little brighter. On deep sky, not much difference, but the 100 is shorter and it helps with the field, a little. Also, the stars are just so pure, and pinpoint. Fields with bright stars look far better.

On the Moon - now that's a tough question. The 100 has far less color, but oddly, the 102 was better around the more full phases. Hard to explain why - maybe the CA made the white rings of highly-lit craters stand out, or maybe the 102 actually has slightly better contrast.

I have not used the 102 much since I got the 100. The 100 is a fine scope. The 102 is a very good scope for what I paid, and sharper than a razor blade, but the CA kept it from being what it could be. I can fit both in the same tube rings, though the diameter is not quite exactly the same. Keep in mind my 102 is an old one.

GW

Edited by Glen A W (11/05/13 09:50 PM)


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Glen A W
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Re: SW 100: Will I notice Difference? new [Re: Glen A W]
      #6178263 - 11/05/13 09:51 PM

I would also point out that the price of the 100 is incredible for what you get. When I was a kid, I could only dream of such a scope - it was totally out of reach, then. GW

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BillP
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Re: SW 100: Will I notice Difference? new [Re: jrbarnett]
      #6178830 - 11/06/13 09:21 AM

Quote:

I love 'em all, but I could comfortably observe for the rest of my days with a quality 5-incher. I can't say the same for a 4-incher, though.




Because these birthday things keep happening for me, I was wondering similar, if I will stay happy with a 4-incher until the end or if a larger is one day in order. But given the perceived boost in performance that happens with binoviewing, I'm considering just switching to that full time when too many birthdays have past. Plus I can never ever see myself with just one scope. So will always have a small 80mm or the like for daytime and occassional night time use or travel use, will always have the larger 4" APO, and will always have a larger light bucket for when those needs arise, like an 8". So given that an 8" is likely to forever be in the mix, hard for me to think about giving up the supreme convenience of a 4". Maybe compromise...a 115mm might me the perfect solution to the 4" or 5" puzzle


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saemark30
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Re: SW 100: Will I notice Difference? new [Re: BillP]
      #6179407 - 11/06/13 02:39 PM

If you like the 102mm then the 150mm f/8 achromat might be a good upgrade path. It has a big wow factor for me and the dream of a 6" within reach is here.
No CA problems, just a hairline for bight objects, though I haven't seen Jupiter or Venus.


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Mike4242
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Reged: 11/02/11

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Re: SW 100: Will I notice Difference? new [Re: saemark30]
      #6179451 - 11/06/13 03:04 PM

Quote:

I love 'em all, but I could comfortably observe for the rest of my days with a quality 5-incher.




I've found my own personal telescope Nirvana with my 127ED. To me it's the perfect balance of performance, portability, and maintenance.


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jrbarnett
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Re: SW 100: Will I notice Difference? new [Re: BillP]
      #6179532 - 11/06/13 03:55 PM

Bill, if I win the lottery I will buy you a TSA-120. I think that scope is the perfect solution, really. It's much lighter than the fatty TOAs, and only a little smaller than the TOA-130. As the years pile on here, too, I'm thinking of down-sizing to a TSA-120 myself as my big refractor, keeping only an 80mm of some sort for dual daytime, grab & go night time use and then a single mid-sized reflector (12-13") for my dark site deep sky stuff.

Loading and unloading and setting up and taking down is increasingly bringing out aches and pains. I think that's me telling me that bigger probably isn't better.

- Jim


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jrbarnett
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Re: SW 100: Will I notice Difference? new [Re: Mike4242]
      #6179535 - 11/06/13 03:56 PM

Same goes for you Mike. If I win the Lotto, so do you. TSA-120s all around.

- Jim


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NHRob
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Re: SW 100: Will I notice Difference? new [Re: jrbarnett]
      #6179540 - 11/06/13 04:01 PM

I'm there already. The TSA-120 is my choice to retire with. Unfortunately can't swing it just yet.

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snommisbor
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Re: SW 100: Will I notice Difference? new [Re: jrbarnett]
      #6179557 - 11/06/13 04:09 PM

Quote:

Same goes for you Mike. If I win the Lotto, so do you. TSA-120s all around.

- Jim




I just wanted to be on the record for participating on this thread in case Jim wins the lottery.


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Rutilus
Carpal Tunnel


Reged: 12/17/10

Re: SW 100: Will I notice Difference? new [Re: snommisbor]
      #6179600 - 11/06/13 04:38 PM Attachment (18 downloads)

Yes you can see quite a bit with a small scope, but I would rather go with a bigger aperture when it is available.
I had some good views of Mars with my TSA-102, but the next day my eyes did suffer after those small exit pupils.

Here is two drawings made with my 60mm refractor, at the time Mars was around 6 arc seconds in size.


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Mike4242
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Re: SW 100: Will I notice Difference? new [Re: Rutilus]
      #6179649 - 11/06/13 05:07 PM

Quote:

Same goes for you Mike. If I win the Lotto, so do you. TSA-120s all around.





Woohoo! You need be buying up some lottery tickets.


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pdxmoon
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Re: SW 100: Will I notice Difference? new [Re: snommisbor]
      #6179936 - 11/06/13 08:16 PM

Hey! I'm the OP! I get a 120 too!

Quote:

Quote:

Same goes for you Mike. If I win the Lotto, so do you. TSA-120s all around.

- Jim




I just wanted to be on the record for participating on this thread in case Jim wins the lottery.




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BillP
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Re: SW 100: Will I notice Difference? new [Re: jrbarnett]
      #6180563 - 11/07/13 09:09 AM

Quote:

Bill, if I win the lottery I will buy you a TSA-120.




I am adding this thread to my Favorites list


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jrbarnett
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Re: SW 100: Will I notice Difference? new [Re: BillP]
      #6180820 - 11/07/13 11:29 AM

See, with all this good Karma and collective psychic support, how can I miss? I think I'll start buying up multi-state Powerball tickets.

Oh, and if I win more than $100 million, you'll have to tell me what you all want yours mounted on.

- Jim


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SimonL
member


Reged: 09/17/07

Re: SW 100: Will I notice Difference? new [Re: jrbarnett]
      #6180892 - 11/07/13 12:04 PM

Yes the 100ED will be sharper and more contrasty.
I would add a good dob for deep sky views such as a 12" size with Zambuto mirror which is refractor like in performance.


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BillP
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Re: SW 100: Will I notice Difference? new [Re: jrbarnett]
      #6181389 - 11/07/13 04:22 PM

Quote:

Oh, and if I win more than $100 million, you'll have to tell me what you all want yours mounted on.




As long as we are dreaming, I'd probably opt for the current gen Super Half Hitch with tracking and all the other options and Super Tripod.


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BKBrown
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Re: SW 100: Will I notice Difference? new [Re: BillP]
      #6181487 - 11/07/13 05:14 PM

Quote:

Quote:

Oh, and if I win more than $100 million, you'll have to tell me what you all want yours mounted on.




As long as we are dreaming, I'd probably opt for the current gen Super Half Hitch with tracking and all the other options and Super Tripod.




Sweeeeet!

Clear Skies,
Brian


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Scott BeithAdministrator
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Re: SW 100: Will I notice Difference? new [Re: jrbarnett]
      #6181579 - 11/07/13 05:57 PM

Quote:

Same goes for you Mike. If I win the Lotto, so do you. TSA-120s all around.

- Jim




Dangerous words my friend!
You can give mine to someone else. I am fine in that range.
I do have dibs on your SV80S LOMO though...


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jrbarnett
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Reged: 02/28/06

Loc: Petaluma, CA
Re: SW 100: Will I notice Difference? new [Re: Scott Beith]
      #6181696 - 11/07/13 07:35 PM

LOL!

Tell you what Scott. If I end up biting on one of the made-to-order custom jobby SV80S LOMOs that Stellarvue is offering, I'll make you a deal on the old one that you simply can't refuse. I fixed it up. The dew shade is solid. The bent set screw has been replaced, and Starlight provided a free replacement knob due to the UV damage on the original. I did the best I could on the differentially fading paint on the tube and dew shade (likely because the saggy dew shade stayed retracted covering the tube). I used premium German acrylic polish with a high carnuba wax over it. It still has a few little love dents, though.

But the glass and focuser work well.

- Jim


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jag767
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Re: SW 100: Will I notice Difference? new [Re: jrbarnett]
      #6181706 - 11/07/13 07:39 PM

Quote:

See, with all this good Karma and collective psychic support, how can I miss? I think I'll start buying up multi-state Powerball tickets.

Oh, and if I win more than $100 million, you'll have to tell me what you all want yours mounted on.

- Jim




Thanks Oprah


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Scott BeithAdministrator
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Re: SW 100: Will I notice Difference? new [Re: jrbarnett]
      #6181855 - 11/07/13 09:16 PM

Quote:

LOL!

Tell you what Scott. If I end up biting on one of the made-to-order custom jobby SV80S LOMOs that Stellarvue is offering, I'll make you a deal on the old one that you simply can't refuse. I fixed it up. The dew shade is solid. The bent set screw has been replaced, and Starlight provided a free replacement knob due to the UV damage on the original. I did the best I could on the differentially fading paint on the tube and dew shade (likely because the saggy dew shade stayed retracted covering the tube). I used premium German acrylic polish with a high carnuba wax over it. It still has a few little love dents, though.

But the glass and focuser work well.

- Jim




Thanks sir!


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star dropModerator
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Re: SW 100: Will I notice Difference? new [Re: Scott Beith]
      #6181863 - 11/07/13 09:23 PM

And as we consider veering back to the original topic. Thank you, all!

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Scott BeithAdministrator
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Re: SW 100: Will I notice Difference? new [Re: star drop]
      #6181886 - 11/07/13 09:40 PM

Back on topic. Sorry about that.

While not the specific scopes mentioned by the OP, this report pits an 80mm achromat vs. an 80mm ED scope side by side. Same manufacturer and a minus violet filter was used on the achromat to sharpen the view.

Not 100 - 102mm but equal size and achromat vs. ED. I thought it might aid in this discussion...

http://www.cloudynights.com/item.php?item_id=1804


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