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How much strehl difference is actually detectable?

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#176 CHASLX200

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Posted 06 May 2021 - 06:14 PM

The full resolving potential of any 14-inch telescope is never realized because of seeing in the "vast majority  of locations". Only in the best seeing did the C14 tie the other scopes. Otherwise the seeing, even when good, limited the C14"s resolving potential and with the "lesser quality" of the optics that proved to be the difference.  Most backyards do not have really excellent seeing so the comparison in different seeing should be of value to many. And it is also "one reason" why a high quality optic is desirable.

 

In really excellent seeing, a high quality optic will do 80x per-inch on Saturn. 

 

Roland Christen of Astro-Physics took his 10" Mak to the WSP and used over 800x to resolve the 325 mile wide Encke Gap on Saturn. That type of observation is why many seek high quality optics. Of course, one can enjoy astronomy with scopes of lesser quality. 

 

Bob

Great optics and great seeing = crazy high powers. I push all my scopes to the max every chance i get. Bad scopes show how bad they really are as in the case of my dud C14 that was total mush.


 

#177 CHASLX200

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Posted 06 May 2021 - 06:20 PM

Agree and thus my snide comment ie. how many actually view at those ridiculous high powers or how often ? I would think not too many too often so that aspect is really meaningless save for a few ...... !

I do all the time in bigger scopes over 10" for 700x. I don't even get warmed up at 350x and really never could see much detail on the planets with a small disk at 350x and below. I have bad eyes and need a big image. But i do have some of the best seeing one can wish for living right on the gulf in FL.  So a super good 10" scope can do 600x, a 8" 500x and a good 6" refactor can do 450x.  I have used 1150x with my 14.5" Zambuto scopes and 15" OMI scope.  So if you don't have my seeing then you would never understand.


 

#178 LDW47

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Posted 06 May 2021 - 06:42 PM

I do all the time in bigger scopes over 10" for 700x. I don't even get warmed up at 350x and really never could see much detail on the planets with a small disk at 350x and below. I have bad eyes and need a big image. But i do have some of the best seeing one can wish for living right on the gulf in FL.  So a super good 10" scope can do 600x, a 8" 500x and a good 6" refactor can do 450x.  I have used 1150x with my 14.5" Zambuto scopes and 15" OMI scope.  So if you don't have my seeing then you would never understand.

I have Bortle 1, SQM-L 22.0 most times all spring, summer and early fall, thats good enough fo me ! And for you I am happy you do get those great views at high power, you are indeed a lucky astronomer !


 

#179 CHASLX200

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Posted 06 May 2021 - 06:59 PM

I don't do deep sky. So dark skies are not needed and FL does not have dark skies anyways.


 

#180 barbie

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Posted 06 May 2021 - 08:41 PM

Not many do i am sure or have the seeing. But even at 400x a better mirror will show.

Under my skies, it's 150x-200x!! 


 

#181 Joe1950

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Posted 06 May 2021 - 08:46 PM

You’re a skilled observer, Barbie! Ohio isn’t easy, nor is New Jersey. But I know you’ve put in a lot of time ‘behind the eyepiece!’


Edited by Joe1950, 06 May 2021 - 08:46 PM.

 

#182 LDW47

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Posted 06 May 2021 - 09:08 PM

 

Those who continuously brag about their scopes 

And how perfect the optics are

Always besting this & better than that,

Those are skilled shoppers & money spenders.

They are common & loud.

Move on from them.

     

Those who work at observing

And trading their eyes to see fleeting detail

Even with a modest & imperfect instrument,

Those are skilled observers & astronomers.

They are rare & soft spoken.

Learn from them.

 

I agree wholeheartedly, this can apply to many ........ !


 

#183 Asbytec

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Posted 06 May 2021 - 09:10 PM

So if you don't have my seeing then you would never understand.


Great seeing is a real eyeopener. Literally. Imagine those once in a lifetime steady nights happening weekly.

Edited by Asbytec, 06 May 2021 - 09:14 PM.

 

#184 barbie

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Posted 06 May 2021 - 09:17 PM

You’re a skilled observer, Barbie! Ohio isn’t easy, nor is New Jersey. But I know you’ve put in a lot of time ‘behind the eyepiece!’

Thanks Joe!! Yes, we here in the northeast and great lakes regions spend a lifetime behind the telescope!!


 

#185 Joe1950

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Posted 06 May 2021 - 09:54 PM

I agree wholeheartedly, this can apply to many ........ !

 

Thanks LDW47.

 

In writing that I really don’t want to be judgmental or critical of what others do, how they spend their money or what’s most important to them. If getting a top of the line scope is what makes one happy, then I say that’s great. I probably would do the same if I had the means. shrug.gif 

 

I just get upset seeing arguments about what is better and what’s not, but I guess that’s just part and parcel of interacting with others.

 

One thing I’ve become acutely aware of over the last year with the horrible events is that we all need something enjoyable or comforting to focus on aside from the harsh realities we face. Without that it becomes very difficult to do anything.

 

So whatever you do to keep busy and occupied, observe, build/test scopes, buy scopes, eyepieces etc., collect vintage stuff, take photos, garden, read, watch tv or movies... whatever it is, make a point to enjoy it.

 

thanks, joe


 

#186 timmbottoni

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Posted 06 May 2021 - 09:56 PM

Fascinating post and discussion!  Thanks, I have learned a bunch reading the replies


 

#187 CHASLX200

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Posted 07 May 2021 - 05:55 AM

Under my skies, it's 150x-200x!! 

I think many don't buy i can use such crazy powers and i would love anyone to come on down and a take look at the planets in my seeing at 600x+.

 

It's not like every nite is super steady as i sure have my share of so so nites that you can't use over 300x.  But get a big Zambuto or top notch mirror in super steady seeing and it will shock you. 


 

#188 barbie

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Posted 07 May 2021 - 06:11 AM

Thanks LDW47.

 

In writing that I really don’t want to be judgmental or critical of what others do, how they spend their money or what’s most important to them. If getting a top of the line scope is what makes one happy, then I say that’s great. I probably would do the same if I had the means. shrug.gif

 

I just get upset seeing arguments about what is better and what’s not, but I guess that’s just part and parcel of interacting with others.

 

One thing I’ve become acutely aware of over the last year with the horrible events is that we all need something enjoyable or comforting to focus on aside from the harsh realities we face. Without that it becomes very difficult to do anything.

 

So whatever you do to keep busy and occupied, observe, build/test scopes, buy scopes, eyepieces etc., collect vintage stuff, take photos, garden, read, watch tv or movies... whatever it is, make a point to enjoy it.

 

thanks, joe

Well said Joe!!

waytogo.gif


 

#189 bobhen

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Posted 07 May 2021 - 06:18 AM

 

Those who continuously brag about their scopes 

And how perfect the optics are,

Always besting this & beating that.

They are intent on having only the best.

They are common & loud.

Be skeptical of their claims.

     

Those who work at observing

And training their eyes to see fleeting detail,

Even with a modest & imperfect instrument.

They are skilled observers & astronomers.

They are rare & soft spoken.

Learn from their experience.

 

Do you think that a person with a high quality telescope means that just by owning such an telescope means they do not work at observing?

 

Do you think that a person with a high quality telescope might, through years of experience and observing and owning lesser telescopes, have learned that high quality optics deliver more?

 

Do you think a person who owns high quality telescope means that they are not skilled?

 

Do you think that a person after years of observing and working his or her way up to owning a high quality telescope has nothing to teach a newcomer?

 

Would all TEC, CFF, Takahashi, Astro-Physics, Questar, LZOS, Tele Vue and other high end brand owners all be, as you define them, common loud, braggarts?

 

Can you post specific examples where people who own a high quality telescopes are bragging about owning such telescopes and are putting down the owners of lesser telescopes?

 

Bob


 

#190 CHASLX200

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Posted 07 May 2021 - 06:22 AM

I call a scope as i see it or see thru it i should say. If it's mush i say so and if it's freaky sharp i say so. I have had dud in every kind of scope and many winners.


 

#191 t.r.

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Posted 07 May 2021 - 06:23 AM

Fascinating post and discussion! Thanks, I have learned a bunch reading the replies

I usually learn a lot more about human psychology than about telescope optics in these forums.
 

#192 LDW47

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Posted 07 May 2021 - 07:44 AM

Do you think that a person with a high quality telescope means that just by owning such an telescope means they do not work at observing?

 

Do you think that a person with a high quality telescope might, through years of experience and observing and owning lesser telescopes, have learned that high quality optics deliver more?

 

Do you think a person who owns high quality telescope means that they are not skilled?

 

Do you think that a person after years of observing and working his or her way up to owning a high quality telescope has nothing to teach a newcomer?

 

Would all TEC, CFF, Takahashi, Astro-Physics, Questar, LZOS, Tele Vue and other high end brand owners all be, as you define them, common loud, braggarts?

 

Can you post specific examples where people who own a high quality telescopes are bragging about owning such telescopes and are putting down the owners of lesser telescopes?

 

Bob

You said it and I am sure not going to argue with you ! As my old gramma used to say ‘ read and take heed ‘ and gramma knew best !


Edited by LDW47, 07 May 2021 - 07:46 AM.

 

#193 Galicapernistein

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Posted 07 May 2021 - 08:07 AM

If the only thing I had to look forward to while observing was NOT seeing chromatic aberration, I think I would give up the hobby. 


 

#194 noisejammer

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Posted 07 May 2021 - 08:36 AM

Ok people, please tone it down.

 

The topic is about detecting changes in Strehl ratio, not whether people with nice scopes have antisocial personalities.


 

#195 LDW47

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Posted 07 May 2021 - 09:06 AM

I usually learn a lot more about human psychology than about telescope optics in these forums.

Completely correct !


 

#196 Joe1950

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Posted 07 May 2021 - 10:55 AM

Do you think that a person with a high quality telescope means that just by owning such an telescope means they do not work at observing?

 

Do you think that a person with a high quality telescope might, through years of experience and observing and owning lesser telescopes, have learned that high quality optics deliver more?

 

Do you think a person who owns high quality telescope means that they are not skilled?

 

Do you think that a person after years of observing and working his or her way up to owning a high quality telescope has nothing to teach a newcomer?

 

Would all TEC, CFF, Takahashi, Astro-Physics, Questar, LZOS, Tele Vue and other high end brand owners all be, as you define them, common loud, braggarts?

 

Can you post specific examples where people who own a high quality telescopes are bragging about owning such telescopes and are putting down the owners of lesser telescopes?

 

Bob

 

Bob. Do you know what I think of your post and all your other confrontational posts?

77E2068F-9CF4-4BAA-85D0-C4946C66D68B.gif

 

I’M PERMITTED AN OPINION JUST AS YOU ARE, PAL! The mod is correct that this thread has gone way off course, due to continuous argumentative statements. 

 

Do you think your opinion is the only valid one?

I didn’t say any of those things Bob! You are trying to continue the argument!

Don’t accuse me of saying something I did not say Bob.


 

#197 Joe1950

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Posted 07 May 2021 - 11:02 AM

The post has been deleted, Bob. Not for you, but out of respect to the moderator and TOS!

Your acidic nature and posts mean nothing to me. They only serve to inflame the conversation.

If you had read the post you would understand I was speaking of braggarts who look down on what others have. Nothing to do with those who have expensive equipment!

And yes, I can give specific examples.  Very specific examples. But I’ll not play your juvenile game of inciting an argument.


Edited by Joe1950, 07 May 2021 - 11:42 AM.

 

#198 bobhen

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Posted 07 May 2021 - 11:40 AM

Bob. Do you know what I think of your post and all your other confrontational posts?

attachicon.gif77E2068F-9CF4-4BAA-85D0-C4946C66D68B.gif

 

 

I don't care.

 

Bob


Edited by bobhen, 07 May 2021 - 11:42 AM.

 

#199 peleuba

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Posted 07 May 2021 - 12:01 PM

Ok people, please tone it down.

 

The topic is about detecting changes in Strehl ratio, not whether people with nice scopes have antisocial personalities.

 

Indeed.  

 

Maybe there is something to this...  Maybe we're anti-social because we're out alone using our high-end, better-then-yours telescopes?  More seriously, I have never seen anyone overtly "brag" about a telescope in a manner which made another member feel inferior.  I have seen - many times - the opposite occur.  Where folks who have modest equipment will bait those that have boutique brand stuff into defending why they laid the cash out for such high-end equipment.  Some of the very same member(s) participating in this thread are guilty of this.  

 

In any event, I posted a comment early on about a direct comparison between my TEC160FL, which is an honest 1/8 wave optic and an AP155EDF that is at least (per A-P) .984 Strehl and 1/10 wave PtV.  I could detect a difference in the the star test, as could a friend.  The A-P was the better scope.  It put slightly less light into the diffraction ring(s) and has less "junk" floating around in the diffraction rings.   This was only noticeable in the star test at very high power.  I will say that to me, the TEC seemed to have slightly better color correction. 

 

Anyway, based on the lack of commentary on what I wrote, perhaps no one is really interested in real world experiences trying to address the OP's question.


Edited by peleuba, 07 May 2021 - 12:02 PM.

 

#200 LDW47

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Posted 07 May 2021 - 12:16 PM

Bob. Do you know what I think of your post and all your other confrontational posts?

attachicon.gif77E2068F-9CF4-4BAA-85D0-C4946C66D68B.gif

 

I’M PERMITTED AN OPINION JUST AS YOU ARE, PAL! The mod is correct that this thread has gone way off course, due to continuous argumentative statements. 

 

Do you think your opinion is the only valid one?

I didn’t say any of those things Bob! You are trying to continue the argument!

Don’t accuse me of saying something I did not say Bob.

Give up, it won’t sink in !


 


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