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Istar 8" F/6

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#51 The Ardent

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Posted 16 August 2014 - 02:03 PM

We must be like ants to you.



#52 drollere

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Posted 16 August 2014 - 04:14 PM

Ralph, James said that the view between 180X-300x were good even in a bad sky  But you say that this scope isn't capable of such power.

Since you had real doubts about the capability of this scope why didn't you push the magnification yourself to find out.

I wonder what James would say right now?

 

Credibility, Credibility, it's all about Credibility.

 

i can't agree, really. pretty much everything you read in CN about specific equipment or equipment choices ("shoot outs") is unreliable as the basis of purchase decisions, for four reasons:

 

1. happy face.

2. "i was driving drunk on marketing fumes."

3. amateur instrument testing skills (for example, failure to star test the optics/collimation).

4. YMMV (and it almost always does).

 

what's wrong with all that? this is a recreational forum, not a professional one, and nothing you get here should be construed as professional advice. "credibility" and recreation just don't mix.

 

i pointed out why i find a review more informative. but i wouldn't trust ralph's opinion that "i will love the scope" as far as i could throw him. much less, throw the scope.

 

then what's informative about ralph's review? PURPLE; also, not the best choice for planetary/lunar, also that he considers it "the cheapest way to get 8 inches"; also, it's basically an RFT. the fact that he admires it greatly is only an inducement to get more information.



#53 jrbarnett

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Posted 16 August 2014 - 06:06 PM

 

Thanks Ralph.

 

That's precisely what I would expect for such a large, fast achromat.  Be prepared, however, to be nailed to the cross of big, fast achro fanboism.

 

Witness my martyring over telling it like it was with respect to the Astrotelescopes 152mm f/5.9 an another thread:

 

http://www.cloudynig...scopes-152-f59/

 

Use scopes for what they do well.  Figure out what a scope does not do well, and do not do those things.  Seems pretty simple.  If you want to have or have to have just one scope, be sure it's a scope whose strengths play into your observing preferences.  No amount of wishful thinking of rabid slavish faith will magically transform the scope into something that the science mandates it cannot be.

 

Excellent, unbiased, report.  It doesn't scare me in the least, either.  It's be a great RFT or comet sweeper I suspect.

 

- Jim


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#54 De Lorme

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Posted 17 August 2014 - 12:03 AM

Ralph did not push the magnification from 180 to 300 himself .  If your going to say that something is bad you have at least evaluate it yourself.

 

The reason I'm buying this scope is because I cannot afford a G11.  This is was my second choice of getting a 8" refractor.

 

I knew that this scope was not designed for planets but rather for nebulas, galaxies and clusters.  Planets are at the bottom for me.

But there are ways to improve the view of planets by using  a Baader 495 Longpass filter.

 

All this was brought on by Ralph giving his strong review which I thought was not credible because Ralph did not actually look through

the Istar 8"f/6 Comet Hunter at magnifications between 180 and 300 to find the QUALITY of this LENS. 

 

Karl has a Cas member who has a APM 7.1 F/6 who has pushed his refractor well over 300 power with good views. 

I expect the views with this 8"f/6 will be great.  Many people have said that Istar lens are very very good.

Why should they lie?  It's the people who are the real critics.  They know when a lens is not up to par just by it's performance. 

 

I said this in the beginning that this was my second choice but was looking to make a second best as best as I can.

 

Ralph started this, why don't you go ask Ralph if he discussed his evaluation of the 8"F6 with James?

 

Why don't you go ask James just how bad the color was on planets and how high he could go to resolve globulars?

 

I know why you won't because he won't tell you in the terms that you want him to; Scientific and very detailed.

 

Well that's not James and you should not expect him to be.  What he said is what he meant. Why can't you just believe him.?

 

Remember some of us are not as demanding on what we have, were just grateful for what we do have.

 

De Lorme



#55 stevew

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Posted 17 August 2014 - 02:42 AM

 

 

Thanks Ralph.

 

That's precisely what I would expect for such a large, fast achromat.  Be prepared, however, to be nailed to the cross of big, fast achro fanboism.

 

Witness my martyring over telling it like it was with respect to the Astrotelescopes 152mm f/5.9 an another thread:

 

http://www.cloudynig...scopes-152-f59/

 

.

 

- Jim

 

Sorry but I don't get that.... No one should be crucifying anyone for reporting a truthful criticism about a piece of equipment. 

Your doing them a favor by telling them what to expect in real world performance, rather than letting them fanaticize over the glossy pictures in the adds. 

It's the reports of unrealistic descriptions and observations that do us a disservice.

 

No one would buy a Toyota Corolla to drive in the Indy 500,

so why would anyone expect a rich field telescope to perform as something it was not designed to do.

A few years back I bought my kids an old Coulter 8 inch F4.5, and it's certainly not a planetary telescope, but that's not what I bought it for. I bought it because it was easy for them to use, and it has enough aperture for them to easily find deep sky objects and learn the sky, and it excels at that.

It doesn't have a great mirror but they have had countless nights of enjoyment with it sweeping the Milkyway, and observing deep sky objects at low and medium powers.


Edited by stevew, 17 August 2014 - 03:46 AM.


#56 stevew

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Posted 17 August 2014 - 02:50 AM

 

I knew that this scope was not designed for planets but rather for nebulas, galaxies and clusters.  Planets are at the bottom for me.

I'm sure it will have jaw dropping views of nebula's and clusters from dark skies.

M31 should be outstanding.

Please post some pictures when you receive it.

 

Steve



#57 De Lorme

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Posted 17 August 2014 - 09:46 AM

Tell me Steve does Karl know what he's talking about when he refers to his friend having viewed through the APM 7.1" going well over 300 power? 

It's the optical quality that allows fairly high powers{250 plus} to happen.  I didn't here Ralph say anything about Istar's optical quality did you? 

Just the theoretical limits what a 8" f/6 should/can do.  I'm not expecting 400 plus but maybe up to 325 because of the quality of Istar's lens.

The people looking through Istar's lens are not scientist but just people with different back grounds saying that Istar's lens give great views.

 

Why is it there is not a direct assault upon the APM 7.1 f/6 review?  Is it that APM is of known quality and they would look stupid in doing so.

 

Nobody here has actually looked at Istars lenses or have said maybe we should listen to those that have and learn from their non-scientific

point of view.  They just keep saying the quality of the views will be low or good but very limited on what the Istar lens can provide without

actually saying the word Istar.  Is their an underlying bias toward Istar?  I'm going to listen to the people who have actually used them.

Even though they may not say the lens is great in scientific terms they do say Istar lens provide great views.

Remember it's the people who are the real critics and who should be listened to first not the scientist.

Because they have to live with what they bought with their hard earned MONEY.

Hum, Money; could that be part of this equation? Just wondering.

 

Is Istar reaching the level of APM and others?

 

Now I'm tired of this.  Lets move on to something more interesting like how I can optimize the Comet Hunter to get the best

views with whatever filters{nebulas,  galaxies, light pollution}would be useful. 

 

Lets don't argue, Lets have fun,  De Lorme


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#58 astroneil

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Posted 17 August 2014 - 09:58 AM

Hey De Lorme,

 

I hear ya.

 

If I were you, when you do finally get your 'scope, don't share it here in the CN refractor forum.

 

They don't deserve to read what you have to say about it, because they're already blind.

 

Regards,

 

Neil. ;)


Edited by astroneil, 17 August 2014 - 10:01 AM.


#59 BillP

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Posted 17 August 2014 - 02:01 PM

Is their an underlying bias toward Istar?  I'm going to listen to the people who have actually used them.

 

De Lorme,

 

IMO no.  No manufacturer bias.  Something else...

 

IMO all reviews and all opinions are correct.  The reason this is, is that each person is giving their review or their opinion, based on their experience and their likes and dislikes.  Talk to a person who loves refractors and they are not so praising of SCTs.  Similarly, talk to folks who love the best color correction and they are not so praising of instruments that show color.  So no foul, no harm, everyone is being honest from their perspective on things.  Realizing this, one can find the truth in all reviews and opinions.  So it is actually more important to first assess where the reviewer is coming from first, because if you don't you might mistakenly assess their input as being relevant to where you might be coming from.  So important to keep apples with apples and oranges with oranges.  So an 8" f/6 Achromat is going to show lots of color, and in its original configuration is not going to be so good on some targets.  *If* you are the type of observer who is happy with masking the aperture smaller and adding CA filters to get the performance to more color free, then it is a good choice for you and how you observe.  But not everyone is like that.  Why important to understand the reviewer or commented first as from their context in things, their opinions (harsh or generous) may be entirely correct even though seemingly at odd with each other.

 

Looking forward to your reviews when you get your new toy :)



#60 jrbarnett

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Posted 17 August 2014 - 02:04 PM

Yes Ralph it's true that Istar says it's maximum magnification is 51x but he also states that people are going well over that into the 300-400 magnification

range with great views.  The color is as one perceives the color.  The longpass makes stars pinpoints of light ,craters and mountain ranges really stand out.

Have to think a bit when I see such conflicting views.  Perhaps your expecting to much from a $3500 telescope.  What does APM charge for there

big 8"?  It's way beyond what I can afford. De Lorme 

De Lorme, I wouldn't worry.  This scope will be AWESOME at what it's good at doing both "deep" and "wide".  That combination is achievable only with the marriage of aperture and speed.  Contrast will be better in such scenarios than similarly spec'ed obstructed scopes (like the ubiquitous 8" f/6 solid tube Newt), though the latter will behave similarly in the "deep and wide" arena and cost a bit less.

 

Enjoy the scope for its strengths.  Don't fret over what it cannot do.  By all means experiment with filtration too.  That's what I'm doing with the 6" f/5.9.  However, I haven't found a filter yet that eliminates all of the ills of secondary spectrum in that scope on brighter stars and planets.  Put another way, the scope with a #8 yellow or minus violet filter cannot touch a 6" Newt or 5" ED doublet or triplet on such targets, but it can still provide an enjoyable observing experience on them.

 

And on the low power sweeping front, you're in good company.  Comet hunter and famous amateur Leslie C. Peltier used a 6" f/8 for his observations.  I don't think he worried about what other designs or prescriptions might have done better.  Instead he used his particular tool for the tasks for which it performed best.

 

If you want to get the most out of this deep sky wide field machine, I'd look into a decent ultra-wide field, well-corrected eyepiece.  Something like a 30mm ES 82 or 20mm ES 100 would be good choices.

 

Lastly, I'd ignore advice that you not share your user experiences here.  This is the best place to do so, since this is not a brand-tied fanboi forum populated by a handful of the faithful, but rather a forum actively reviewed by thousands of experienced amateurs who've generally learned what equipment works best for them the hard way.  In my view that's really the only way.  The other school first decides what its belief will be (i.e., this particular telescope design and prescription is THE BEST) and then sets out to defend that belief at all costs.  For them, it's not about the activity of astronomy but rather the need to be part of a sect and enjoy the self-righteousness that comes with imagined persecution.  :whistle:

 

You seem rather normal to me.  I think you fit perfectly here with the mainstream.  :winky: 

 

Regards,

 

Jim


Edited by jrbarnett, 17 August 2014 - 02:17 PM.


#61 stevew

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Posted 17 August 2014 - 02:10 PM

Tell me Steve does Karl know what he's talking about when he refers to his friend having viewed through the APM 7.1" going well over 300 power? 

It's the optical quality that allows fairly high powers{250 plus} to happen.  I didn't here Ralph say anything about Istar's optical quality did you? 

Just the theoretical limits what a 8" f/6 should/can do.  I'm not expecting 400 plus but maybe up to 325 because of the quality of Istar's lens.

The people looking through Istar's lens are not scientist but just people with different back grounds saying that Istar's lens give great views.

 

Why is it there is not a direct assault upon the APM 7.1 f/6 review?  Is it that APM is of known quality and they would look stupid in doing so.

 

Nobody here has actually looked at Istars lenses or have said maybe we should listen to those that have and learn from their non-scientific

point of view.  They just keep saying the quality of the views will be low or good but very limited on what the Istar lens can provide without

actually saying the word Istar.  Is their an underlying bias toward Istar?  I'm going to listen to the people who have actually used them.

Even though they may not say the lens is great in scientific terms they do say Istar lens provide great views.

Remember it's the people who are the real critics and who should be listened to first not the scientist.

Because they have to live with what they bought with their hard earned MONEY.

Hum, Money; could that be part of this equation? Just wondering.

 

Is Istar reaching the level of APM and others?

 

Now I'm tired of this.  Lets move on to something more interesting like how I can optimize the Comet Hunter to get the best

views with whatever filters{nebulas,  galaxies, light pollution}would be useful. 

 

Lets don't argue, Lets have fun,  De Lorme

I'm not arguing with anyone. I'm sure your Istar will meet your expectations, and will be a wonderful scope.

The couple of Istar telescopes I have seen seem to be extremely well built.

In fact I just sent them an e-mail enquiring about a n 8 inch R30 F-9.

The lure of a big refractor is hard to resist, especially at the comparatively low prices offered by Istar


Edited by stevew, 17 August 2014 - 02:15 PM.


#62 De Lorme

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Posted 17 August 2014 - 06:05 PM

This big 8 won't be able to go as deep as I would like but I'm sure it will be better than my CR6".  It wasn't that I don't understand or did not  want the F/9 but I just didn't have the money. Even if I had sold the PVS7 the credit card payment for both would at times been difficult. So I decided it's better to have a good B than no 8"  and be grateful.  If it wasn't for Istar reducing the weight on the Comet Hunter I would probably never have one. 

 

The PVS7 is a back up for my light polluted skies.  I would rather use just the eyepiece to but plan B{at times} is better than barely seeing whatever.

 

I'm really excited to here my wife say WOW again. Now that's fun! LOL

 

I once had a Baader Nebula Filter but sold it to by a DGM, because in remembering I thought I liked the DGM better but after selling it to fund

the 8079 HP{yes this is signs of crazy but I'm sure you understand LOL LOL}  I'm mow thinking the Baader is better because it allows more stars through.

To me the stars give M42 more context but just my personal opinion.

 

What do you guys like?   Clear Skies, De Lorme



#63 stevew

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Posted 17 August 2014 - 10:13 PM

I don't know that much about C/A filters. Iv'e got a Lumicon Minus Violet that seems to work well enough.

But I think you should consider a good light pollution filter such as a UHC, or an Orion Ultrablock.

I bet the Veil nebula with an OIII filter in your 8 inch would be spectacular.

 

Steve



#64 Dakota1

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Posted 17 August 2014 - 10:46 PM

The OIII works great on the Veil nebula and other nebulas with my ES AR152.  My favorite with this scope is the 495 longpass filter

to control what CA I do have.  Thanks

---------------------

Bill



#65 De Lorme

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Posted 18 August 2014 - 12:25 AM

Hi Bill, Steve,  When using the PVS7 I use the Baader 610 longpass for a light pollution/noise filter.  On Baaders website they said if you combine their IR/UV filter with the 610 it makes a cheap but effective nebula filter. I've haven't used them together since the weather has been so bad but look

forward to trying them out.  

 

Steve because of the light pollution I don't think I'll see  the Veil nebula, through the eyepiece{hope I'm wrong} but I'm confident I will with the PVS7.

I would prefer a black sky to but the PVS7 is a good alternative when your faced seeing nothing.

M42 looked good with the Baader nebula filter maybe I can find another used one. 

 

De Lorme



#66 aa6ww

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Posted 18 August 2014 - 01:11 AM

Even without filtering, the veil was visible last night with the big 180mm APM F/6 achromat, my only achromat. Using a Lumicon OIII filter in my 41 Panoptic at 26x and 2.6 deg actual field of view. all 3 segments of the view jumps out at you, the western arch, the central filaments, and the eastern arch. Despite the large field of view using the 41 Pan Optic, all 3 segments of the veil were not visible all at one time, though it was close. My Celestron 150R 6" F/5, I recently sold, was capable of just barely capturing all three segments of the veil in one field of view however.
  

 

Ralph in Sac





 

I don't know that much about C/A filters. Iv'e got a Lumicon Minus Violet that seems to work well enough.
But I think you should consider a good light pollution filter such as a UHC, or an Orion Ultrablock.
I bet the Veil nebula with an OIII filter in your 8 inch would be spectacular.
 
Steve


Edited by aa6ww, 18 August 2014 - 11:58 AM.


#67 aa6ww

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Posted 18 August 2014 - 01:23 AM

Locate 52 Cygni in Cygnus and see if you can detect that eastern portion of the Veil, also called the Witch's Broom Nebula, NGC 6960.

The Witch's broom passes right though that bright star, which is naked eye visible. Without dark skies, you'd need a UHC or OIII filter. Its nearly transparent, so you have to stare in the eyepeice, sometimes for minutes to see it. Use a wide field low power eyepiece.

http://www.feraphoto...lo/Ngc6960.html

It's be gray and nearly transparent, not red like the attached photo. Its very whispy, like a floating veil, you can actually look right at it and not see if, if you rush at it.


.. Ralph


Hi Bill, Steve,  When using the PVS7 I use the Baader 610 longpass for a light pollution/noise filter.  On Baaders website they said if you combine their IR/UV filter with the 610 it makes a cheap but effective nebula filter. I've haven't used them together since the weather has been so bad but look
forward to trying them out.  
 
Steve because of the light pollution I don't think I'll see  the Veil nebula, through the eyepiece{hope I'm wrong} but I'm confident I will with the PVS7.
I would prefer a black sky to but the PVS7 is a good alternative when your faced seeing nothing.
M42 looked good with the Baader nebula filter maybe I can find another used one. 
 
De Lorme



#68 drollere

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Posted 19 August 2014 - 01:46 PM

IMO all reviews and all opinions are correct.  The reason this is, is that each person is giving their review or their opinion, based on their experience and their likes and dislikes.  Talk to a person who loves refractors and they are not so praising of SCTs.  Similarly, talk to folks who love the best color correction and they are not so praising of instruments that show color.  So no foul, no harm, everyone is being honest from their perspective on things.  Realizing this, one can find the truth in all reviews and opinions.  So it is actually more important to first assess where the reviewer is coming from first, because if you don't you might mistakenly assess their input as being relevant to where you might be coming from.  So important to keep apples with apples and oranges with oranges.  So an 8" f/6 Achromat is going to show lots of color, and in its original configuration is not going to be so good on some targets. *If* you are the type of observer who is happy with masking the aperture smaller and adding CA filters to get the performance to more color free, then it is a good choice for you and how you observe. But not everyone is like that.

in my experience you need to spit the difference between bill's and jim's contributions.

 

on the one hand there are the personal observer factors that are the foundation of your evaluation. if you wear eyeglasses then you will emphasize eye relief in eyepieces. some people seem not to mind chromatic aberration, other people can't stand it. most people seem to ignore "kidney bean" aberration, i detest it. to jim's comment, i agree that you really only learn all this stuff through serial ownership or attending lots of star parties and using lots of equipment.

 

the other factors raised by jim are the expectations you have for what the scope can do in relation to how you intend to use it. and i think the subtext is that you need to distinguish between a "compromise" instrument like an SCT that can do most anything pretty well and a targeted instrument like a "comet hunter" that is meant to be superb in a specific way. that's a wide, deep instrument and double stars or planets are just not wide, deep targets. if those things look good after manipulation with filters or eyepieces then that's great. but if they don't look as good as they might through a similar aperture SCT, then your expectations rather than the telescope would be the source of your disappointment.

 

both points mark the line between a testimonial and an instrument review. the testimonial just enthuses about what a great scope it is ... but you can't really imagine yourself at the eyepiece, or judge the reliability of the witness. an instrument review actually tests the scope in many different ways, on many different targets, and explicitly describes the visual evidence and (ideally) compares the scope to other equipment in the same class. you can almost feel that you're using the scope yourself and won't be surprised by its performance (unless pleasantly) when you actually do.

 

the distinction between testimonial and review is sometimes not clear in what CN users choose to post, but i think it's useful to keep in mind when you try to use comments here to guide your purchase decisions.



#69 galaxyman

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Posted 19 August 2014 - 10:17 PM

That is why Bruce when I do a review of a scope, it's an actual observing post at the eyepiece of many objects, sometimes on multiple nights. Also having a number of other experienced observers with a variety of scopes to compare with.

 

A restricted review can be positive, but I like to read variety and quantity which some reviews lack.

 

The instrument in question can be more than a "comet sweeper" if the quality of the optics is similar to say the APM 7.1" f/6 in CAS or what seems the one Ralph owns. 

 

 

 

Karl
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#70 De Lorme

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Posted 19 August 2014 - 11:11 PM

Drollere,    The are quit a few variables as to why a person would buy a scope. For example Cost,  ease of use, what the scope would show you are just a few that come to mind.  Although not completely 100% percent fool proof the reviews at least gives information on quality of build and what they see through

the lens giving a comparison to other similar and un-similar telescopes.  In so doing the reader can ask questions that are relevant to his needs at the moment or in the future.

In reading a review, asking a person to articulate in terms that are relevant to what the reader is accustomed to and expecting him to give the

information that he DESERVES is expecting more than what the reviewr is required to give.

While it would be nice to get the answer in the way that's more easily understood the reviewer only has the responsibility to

be honest, telling the truth with as much accuracy as he can.  But he has the right to be what he is and nobody should expect more then

what a reviewer can give

A person can always ask questions and there are other people who can contribute{interpret} what a reviewer

has said to get the answers that they need to make a purchase.  One of several reasons I bought the 8"f/6 is because what James said;

 

"I actually NOW use a Minus Violet filter aka " fringe killer"...I do have to say it brings another

dimension to how good this scope truly is, meaning; IT Kicks Some Serious BUTT, planetary and DEEP

SKY!!! I use all the Explore 100 degree eyepieces, down to the 5.5mm, nothing I look at gives off a

"marginal" view, more so it brings out more of what I look at, BS on the fringe aspect, If you haven't

looked through a 8 inch refractor, YOU have nothing to base your opinion on...Northern Cal has not had

decent skies, even last weekend we had to deal with smoke from a fire east of our location...all in

all, the 204 was exceptional, I spent a great deal of time resolving the Elephants trunk and the Iris

nebula but the skies wouldn't cooperate, but the quadrants we spectacular, pin point stars and vivid

dark space...MORE to follow!!"

 

Clear Skies,  De Lorme



#71 2244champ

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Posted 02 September 2014 - 05:03 PM

De Lorme, Do you have a delivery date? I'm anxious for your review. Very interested in this scope. Thanks, Doug



#72 De Lorme

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Posted 02 September 2014 - 07:30 PM

Hi Doug, I was told by Istar {through David at Highpoint Scientific that}it would be 4 to 6 weeks from date of order.
It's been exactly 4 weeks today. So presumably it will be just 2 more weeks. I e-mailed David last week
about an arrival date and he said he hadn't heard anything from Istar.

De Lorme

#73 Simoes Pedro

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Posted 03 September 2014 - 10:49 AM

Hi.

 

Even if this scope achieves a a focus shift of 1/2000 of the focal length, which would be an improved fraunhofer achromat, it is nowhere near being diffraction limited. The e-line to c-line shift would be exactly the same, even with the long pass filter on.

 

I can run OSLO EDU and post some spot diagrams. It would be interesting to check how good it would be with focus at d-line (587nm) and considering a visual spectrum between 500 and 632 (orange) nm.

 

On such a fast lens, spherical aberration will start to play an important role wide open

 

The scope should be a marvel on deep sky down to 2 mm exit or thereabouts (maybe).



#74 galaxyman

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Posted 03 September 2014 - 11:48 AM

Hi.

 

Even if this scope achieves a a focus shift of 1/2000 of the focal length, which would be an improved fraunhofer achromat, it is nowhere near being diffraction limited. The e-line to c-line shift would be exactly the same, even with the long pass filter on.

 

I can run OSLO EDU and post some spot diagrams. It would be interesting to check how good it would be with focus at d-line (587nm) and considering a visual spectrum between 500 and 632 (orange) nm.

 

On such a fast lens, spherical aberration will start to play an important role wide open

 

The scope should be a marvel on deep sky down to 2 mm exit or thereabouts (maybe).

We've gone through this weeks ago, and it's best to wait to read what De Lorme sees through the scope.

I'm betting the scope will perform well on DSO's (resolve globs, small planetaries and galaxies) using 200x plus magnifications.



Karl
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#75 Simoes Pedro

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Posted 03 September 2014 - 12:02 PM

I have just put a 8  inch f6 Fraunhofer achromat on OSLO and after optimization of the last surface for spherical aberration at d-line (587nm) got the following results.

 

Focus at d-line:

 

500nm 3.1 waves

520nm 1.0 waves

540nm 0.40 waves 

e-line (546nm) 0.35 waves

560nm 0.39 waves

580nm 0.15 waves

d-line (587nm) <1/20 waves

600 nm 0.42 waves

632nm 1.8 waves

C-line (656nm) 3.0 waves

 

 

Note that because spherical aberration is corrected for d-line, any focus shift from the d-line (for instance e-focus) yields terrible results, i.e. the doublet would have to be reoptimized for the e-line focus.

 

e-line optimized at e-line focus:

 

500nm 3.0 waves
520nm 1.1 waves
540nm 0.18 waves
e-line (546nm) <1/20 waves
560nm 0.11 waves
580nm 0.26 waves

d-line (587nm) 0.41 waves
600 nm 0.79 waves
632nm 2.2 waves
C-line (656nm) 3.5 waves

 

Apparently much better.

 

Recepies:

 

d-line optimized

R1 +730.8
R2 -438.48
R3 -442.13
R4 -1872

 

e-line optimzed:

 

R1 +730.8

R2 -438.48

R3 -442.13

R4 -1841

 

Spacing is 1.2 mm

 

8" f6 is just too fast, you need to control radius of curvature of last surface to less than 1%.








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