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Equipment Discussions >> Refractors

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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Viewing sessions with my Istar127mm achro .
      #6020112 - 08/12/13 01:48 AM

Hi all , Brian here from Darwin Austraila , glad to be here .
This is a thread to lighten up the feelings going on here about Istar , the good the bad and the ugly .

The good , I built my Istar 127mm achro from an awesome lense sourced from Istar , very nice lense at a great price .

The bad , I built it during last years wet season so I could not test it for a few months ,, Grrrr that's tough ! .

The ugly , nothing at all , but I got ya guys though didn't I ?

I have had a few great sessions with good friends and their refractors 100mm -150mm synta achros a C8 and an 127mm f7.5 Triplet.
All were like waiting wolves for me to finish the build , and the weather to clear , now both are done we have had a few sessions , cold beer's and great fun testing these scopes against one another .
I wont go into the ins and outs on this as I have seen here that kind of discussions causes distain amongst certian ( un-named) people here .

This thread is to hopefully go above all that jazz and talk about the good times we all have had when out under the night sky , good scopes and great company .
Leave your snobbery at home , please?.

And my Istar is certainly different , draw you own conclusions and please contribute in a positive way .
Enjoy the few photos and I hope there will be many more posted by fellow refractor lovers , and thank you very much .

Brian.

Edited by beanerds (08/12/13 02:16 AM)


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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6020114 - 08/12/13 01:49 AM

I dropped photos down to 700x600 and still to large for the start , so here goes now .
Brian.


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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6020121 - 08/12/13 01:54 AM Attachment (134 downloads)

one more time ?

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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6020123 - 08/12/13 01:56 AM Attachment (115 downloads)

another , The white scope is my Istar 127mm f8 achromat .

Edited by beanerds (08/12/13 02:04 AM)


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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6020125 - 08/12/13 01:59 AM Attachment (65 downloads)

one more

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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6020130 - 08/12/13 02:01 AM Attachment (69 downloads)

Couple more , this my old mate Peter , he owns this nice 150mm SW f8 .

Edited by beanerds (08/12/13 02:05 AM)


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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6020138 - 08/12/13 02:10 AM Attachment (56 downloads)

We were out til 3am this night looking at southern delights , comparing views , having a ball using our scopes , eg. looking thru them , using and enjoying them , not looking at them as the old saying goes .
Brian.


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tonyt
professor emeritus


Reged: 09/02/09

Loc: Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6020159 - 08/12/13 02:42 AM

Istar do make a nice looking scope but I think your white one with silver highlight is right up there Brian. The 150mm f/10 I had for a bit had nice optics but was a little longer and heavier than I wanted to handle. Once they prove their version of the chromacorr a shorter scope combined with the correction might be attractive.

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T1R2
Carpal Tunnel


Reged: 06/11/13

Loc: NeverWhere, 35*N
Re: Viewing sessions with my Istar127mm achro . new [Re: tonyt]
      #6020177 - 08/12/13 03:28 AM

That's a good lookin white tube on that scope, nice

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Niklo
professor emeritus


Reged: 03/29/13

Loc: Bavaria
Re: Viewing sessions with my Istar127mm achro . new [Re: T1R2]
      #6020198 - 08/12/13 03:55 AM

Hi Brian,
so you build your own refractor with the Istar lenses? It looks indeed very nice. Do you have a build report or some pictures of your building steps?
Clear skies,
Roland


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James Ling
sage
*****

Reged: 09/18/10

Loc: Singapore
Re: Viewing sessions with my Istar127mm achro . new [Re: Niklo]
      #6020245 - 08/12/13 06:25 AM

Hi Brian....

I always envy you having a nice home , whereby you can enjoy with your Istar , whenever weather permits....

Whereas I am staying in a high-rise building , with a very limited West viewing, as such need to dismantle my equipment, bring it outside to an open area, setup and dismantle again after the viewing session..., then bring it back home, and mount it back.....

And I also cannot be like you , by purchasing the lens cell...from Istar.....and build the whole OTA....

Hope to see more report from you soon .....

Regards

James Ling


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Messyone
professor emeritus


Reged: 05/02/12

Loc: Down Under
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6020254 - 08/12/13 06:32 AM

Said it before ...Nice scope...can't beat a white frac on a wooden tripod.... classic scopes are for looking at too.
Cheers mate,
Matt


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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: Niklo]
      #6020277 - 08/12/13 07:09 AM

Thanks Roland , if you are interested just google 'Istar scope club' , you don't have to be a member to read the threads , just go to 'Istar ATM' then open 'Istar 127mm f8 retro fit' that me and there are 3 pages of my build there for all to see with photos , remarks and all that .
Enjoy .
Go for it you wont be disappointed .
Brian.
Quote:

Hi Brian,
so you build your own refractor with the Istar lenses? It looks indeed very nice. Do you have a build report or some pictures of your building steps?
Clear skies,
Roland




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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6021611 - 08/12/13 08:43 PM

Thanks James , PM'd you .
Brian.


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James Ling
sage
*****

Reged: 09/18/10

Loc: Singapore
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6021777 - 08/12/13 09:59 PM

Hi Brian...

Just reply you this morning.... Coz my network hang yesterday ....

And as you have mentioned about your 'Darwin Astro Group', and its regular activities...., I am very sure we are able to hear from you , your Istar's field report soon....since the weather now is getting better...

Regards

James Ling


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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: James Ling]
      #6026083 - 08/14/13 10:08 PM Attachment (63 downloads)

Here is the moon at 3rd quarter shot taken at prime focus , 1000mm using my Sony Alpha 200 DSLR , zero work except the sizeing to fit it here .
The views thru my 14mm TV Radian mimic this well , every one that's looked thru my 127mm comment on the contrast and lack of CA , and the inky black space around the moon .
Brian.


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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6026170 - 08/14/13 11:11 PM Attachment (61 downloads)

Here is probably the 'Acid' test for any refractor lense ever made , a rooftop taken in full sun with the above gear , raw shot again .
you will be hard pressed to se any CA in this photo , this was the first shot I ever took with this combo , the roof top is 500 metres up the street .

When viewing thru this lovely Istar achromat the views are the same .

Brian.


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James Ling
sage
*****

Reged: 09/18/10

Loc: Singapore
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6026565 - 08/15/13 06:47 AM Attachment (41 downloads)

Hi Brian....

looks like your ISTAR achro is performing better than my WO88ED , in terms of the colour correction....

And so happen I am enjoying my WO88ED with my friends last night at the 1st quarter moon, I can still recall mine still have a slight CA, and I even took a photo shot but is badly taken....so better not show it here....

Regards

james Ling


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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: James Ling]
      #6028206 - 08/15/13 10:55 PM

Thanks James , looks like you and your friends are having a great time , looking at the moon , I take it ? .
Brian.


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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6028217 - 08/15/13 11:03 PM Attachment (54 downloads)

James,
Here are a few of my mates getting ready for a nights viewing at one of our dark sky nights here in Darwin .
Good people , good viewing , that's what its all about .
Brian.


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Kunama
professor emeritus


Reged: 10/22/12

Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6028436 - 08/16/13 02:02 AM

All you need now Brian is to remove the Saxon script from the OTA and get an Istar sticker on it instead.

I am still waiting for Dan Crawford to finish my focuser for my 80mm f15 refractor (the brass cell one), then I can start on the Carton 80mmF15.
The Takahashi has been gathering dust due to clouds, wedding and housemoving getting in the way.

After I finish the two 80mmf15 scopes I will start on the 4"F12-F15 Steampunk to go onto my Gaunt Eq mount. You can never have too many refractors. (Having said that, I also have started drawing up for a 12.5" F6 Dob-Newt.)


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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: Kunama]
      #6030106 - 08/16/13 11:38 PM

Ha ha , Matt , but I like the 'Saxon ' sticker .
the weather here is great , I will be out tonight shooting the moon at 2000mm fl with my Istar and 2x TV Powermate , looking forward to it .
Also waiting for a report on the 3 inch .
Brian.

Edited by beanerds (08/16/13 11:40 PM)


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James Ling
sage
*****

Reged: 09/18/10

Loc: Singapore
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6030178 - 08/17/13 12:27 AM

Hi Brian....

Hope you have a good weather for your photo shoot.....

While I will be traveling over to our army club house, for my astro friend's planned astro talk and side walk event.....

And of course, my 8" ISTAR be there........and I will see how well it is going to perform on the 11 days old moon and giant gas planet Saturn....

REgards

James Ling


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James Ling
sage
*****

Reged: 09/18/10

Loc: Singapore
Re: Viewing sessions with my Istar127mm achro . new [Re: James Ling]
      #6033915 - 08/19/13 02:44 AM Attachment (47 downloads)

Hi Brian....

How is your last weekend for your photo shoot????

Over here in my army club house, i am enjoying it with groups of people that I never met them before.....

And it seems that I am enjoying spending an hour to set up my 8" ISTAR , just for 3 hrs of the event, then spending another hour to dismantle and load back into my car.....
All these didn't consider time at my home side for the loading and unloading for before and after the event...

As for me, I think enjoying this hobby is more important, by bringing the fun to all people who are interested, and showing them something they have not seen in their life.

This photo shows me setting my 8" ISTAR up for the 11 days old moon, while group of people gathers around me, waiting for the session to begin....

Regards

James Ling


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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6039552 - 08/22/13 03:44 AM

Cool photo James , I love your scope mate .

I forgot to mention this , I live 100 metres from 2 shopping complexes in the centre of a city of 40,000 so the light pollution here is horrendous at home , this is where this shot was taken from , my front deck .
Awsome contrast , this scope .

I had a family around the other night for a look at the moon and Saturn before it goes and I will post a few more photos when I down load them .

Brian.
Quote:

Here is the moon at 3rd quarter shot taken at prime focus , 1000mm using my Sony Alpha 200 DSLR , zero work except the sizeing to fit it here .
The views thru my 14mm TV Radian mimic this well , every one that's looked thru my 127mm comment on the contrast and lack of CA , and the inky black space around the moon .
Brian.




Edited by beanerds (08/22/13 03:47 AM)


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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6048767 - 08/27/13 12:52 PM Attachment (45 downloads)

Hi all just got in from another moon session , damn she is so beautiful in the Istar 127mm achromat and 12mm Radian , same image scale as these 2 photos I took , Prime , Sony DSLR , and TV 2x Power mate at 2000mm .

As always , raw photos only sized for CN site .
Enjoy and please comment .
Brian.


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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6048770 - 08/27/13 12:55 PM Attachment (46 downloads)

And another at ISO 800 , 1/320th a second .
The last was ISO 400 , 1 400th a second .
Zero CA in my eyes .
Brian.


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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6065579 - 09/06/13 04:32 AM

Dark sky night tomorrow night with our club here at Darwin , I will try a few deep sky shots and if all is good I will post them here for all to see .
Warts and all .

Brian.


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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6068602 - 09/07/13 09:55 PM Attachment (25 downloads)

As promised here are a few shots from last night
Brian.


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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6068606 - 09/07/13 09:57 PM Attachment (19 downloads)

The big Dob boys setting up a , 20 and 22 inch .
Brian.


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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6068608 - 09/07/13 09:58 PM Attachment (23 downloads)

And another .
Brian.


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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6068611 - 09/07/13 10:01 PM Attachment (44 downloads)

One more showing the lack of CA in my Istar 127mm f8 Achromat !!! .
This is Venus , raw , only zoomed in a bit and sized for CN's , you would not get a better achro in my opinion .
Please comment .
Venus is almost pure white ! impressive bit of glass , this Istar .
Brian.


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James Ling
sage
*****

Reged: 09/18/10

Loc: Singapore
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6070767 - 09/09/13 07:07 AM

Hi Brian...

While you have enjoyed the nice outing session with your Darwin club....
Over here, we have heavy downpour and even flooding,for the past few weeks.....
And I hope to have my 8" ISTAR out again for side walk , in coming two weeks time, which is our traditional Chinese Moon Cake festival, or else will be one month later at a planned oversea star gazing session in Malaysia....

REgards

James Ling


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Niklo
professor emeritus


Reged: 03/29/13

Loc: Bavaria
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6071010 - 09/09/13 10:46 AM

Hi,
it's great that your Istar 127 shows very little CA although I don't understand it. Normally even a 4" f/15 has a small color fringe around planets like Jupiter and Venus.
You have a 5" f/8 that should normally show more CA than a 4" f/8 ... At what magnification do you see a purple fringe around Jupiter?
If you don't see a color fringe around Jupiter than they sold you an ED 5" f/8 instead of an 5" f/8 achromat
Kind regards,
Roland


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sg80
super member


Reged: 07/29/07

Re: Viewing sessions with my Istar127mm achro . new [Re: Niklo]
      #6072216 - 09/09/13 10:11 PM

I see color fringe in your photo but for a 127mm f8 it does not seem to be that bad.Venus is tough. your shots of the moon are very nice.I like what I see from Istar.

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stevew
Now I've done it


Reged: 03/03/06

Loc: British Columbia Canada
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6072241 - 09/09/13 10:27 PM

Brian, Good shot of Venus, hard to believe its only an achromat.
Does Venus show about the same color correction visually?

Steve


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David PavlichAdministrator
Transmographied
*****

Reged: 05/18/05

Loc: Mandeville, LA USA
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6072263 - 09/09/13 10:38 PM

My monitor shows some purple.

David


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stevew
Now I've done it


Reged: 03/03/06

Loc: British Columbia Canada
Re: Viewing sessions with my Istar127mm achro . new [Re: David Pavlich]
      #6072337 - 09/09/13 11:16 PM

Quote:

My monitor shows some purple.

David



Mine does too, but in the image it's quite well controlled for a 5 inch F-8 achromat.


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Niklo
professor emeritus


Reged: 03/29/13

Loc: Bavaria
Re: Viewing sessions with my Istar127mm achro . new [Re: stevew]
      #6072587 - 09/10/13 04:20 AM

Quote:

Quote:

My monitor shows some purple.

David



Mine does too, but in the image it's quite well controlled for a 5 inch F-8 achromat.



Yes, it shows purple, but so little that it's hard to believe for a 5" f/8 achromat. Venus should show a little purple in much longer refractors that should theoretically have a much better color correction. I'm curious to hear how is the color correction in the ocular at which magnification compared to the photos.
Clear skies,
Roland


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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: Niklo]
      #6074205 - 09/11/13 12:04 AM Attachment (16 downloads)

HI all , and thanks for the comments .
My 127mm does start to show CA at about 150x on Jupiter and even that's very faint and the detail seen is awesome ! , it shows zero on Saturn even at 230x .

Venus is very similar to the photo at about 100x and it gets a little worse as expected at 150-200x , but still nowhere as bad as a C102HD I used to own , the purple is very faint and close in to the planet , and hey guys , Steve and David , come on Guys , its a 127mm f8 Achromat what do you expect ?? .
This shot equates to about 90x thru the eyepiece .

Roland the CA in my scope is there as I said but its very well supressed , Jupiter is really good even at 200x plus , it compares very well to a NG 127mm triplet I owned a while ago , yes the triplet was better controlled but the views are the same , eg. the same amount of detail seen was the same in both scopes .

I think its just the quality of the Istar lense , hand finished and all and the coatings are very , very nice .

Oh yes , a little colour does not bother me in the slightest , if I want a totally colour free refractor like view , I grab my Takahashi M210 .

Brian.


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Niklo
professor emeritus


Reged: 03/29/13

Loc: Bavaria
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6074314 - 09/11/13 02:02 AM

Hi Brian,
so the CA is better controlled than in the old C102HD? Do you own one of the new very cheap Synta 4" f/10? They should have a better controll of the CA, too but probably they are still not reaching your 127 f/8? That would be an interesting test to compare them. With normal glass sorts it should be the other way round a 4" f/10 should have much less CA than a 5" f/8.
Istar seems to use special glass that has very little CA (it would be interesting to let you refractor be tested but that's probably too much work). So just be happy to have an extraordinary good achromat and enjoy it
Cheers,
Roland


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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: Niklo]
      #6074421 - 09/11/13 05:41 AM

Thanks Roland , I had my C102 back in the late 90's on an EQ3 mount , it was good but I think the coating technology of today is much better and not to mention ( as I said ) the final figuring of my Istar 127mm f8 does make a difference .

On the testing , hell yes ! I am in Australia so I will let mine and everyone's eyes and brain that looks thru it be the testers ,,,
No negative comments yet , even a TelVue 127 owner was impressed , He asked if my Istar was a triplet , high praise indeed .
I wont be selling mine any time soon , I built it .

Brian.

Edited by beanerds (09/11/13 05:48 AM)


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RGM
scholastic sledgehammer
*****

Reged: 09/15/03

Loc: Burks Falls, Ontario, Canada
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6074534 - 09/11/13 08:03 AM

Brian, nice photo of Venus. I am also happy with the colour control of my Istar scope. I have a Fringe Killer and Lumicon minus violet filter on my filter wheel, but hardly use them. I just do not notice much, if any, improvement. Small amounts of CA are there in out of focus tests, but once the object is focused, CA is very minor on brighter objects.

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Niklo
professor emeritus


Reged: 03/29/13

Loc: Bavaria
Re: Viewing sessions with my Istar127mm achro . new [Re: RGM]
      #6074572 - 09/11/13 08:40 AM


Quote:

Brian, nice photo of Venus. I am also happy with the colour control of my Istar scope. I have a Fringe Killer and Lumicon minus violet filter on my filter wheel, but hardly use them. I just do not notice much, if any, improvement. Small amounts of CA are there in out of focus tests, but once the object is focused, CA is very minor on brighter objects.



Hi Bob,
you have a 5" f/12 so the CA is even less than in the 5" f/8. Istar seems to do a very good job.
The Venus picture is very nice. Could one of you Istar refractor owners take a photo of Jupiter? That should probably be a very nice picture with a lot of details.
Clear skies,
Roland


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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: RGM]
      #6074582 - 09/11/13 08:45 AM Attachment (28 downloads)

Bob I hear you mate , its the new generation of Achromats happening here I think . .
They are very good , Imagine paying $350 for a perfect 127mm objective , in a cell ,,, even 7 years ago ??? .

Here is a way over exposed moon shot , where ? is the CA that some people call the end all and be all in a refractor lense ???, I bet a few will see some on their moniters ?? .

Brian.

Thanks Istar , again .

Edited by beanerds (09/11/13 08:47 AM)


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David PavlichAdministrator
Transmographied
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Reged: 05/18/05

Loc: Mandeville, LA USA
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6074624 - 09/11/13 09:12 AM

Quote:

.

and hey guys , Steve and David , come on Guys , its a 127mm f8 Achromat what do you expect ?? .





The only reason I commented on the purple fringing is because you posted this:

"One more showing the lack of CA in my Istar 127mm f8 Achromat !!!"

I took that to mean that there was no CA. Had you said how little fringing or the tiny amount of fringing or some such thing, I would have agreed and never made a comment. However, I assumed that you meant there was no fringing. In fact, the picture doesn't look bad.

David


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Gord
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Re: Viewing sessions with my Istar127mm achro . new [Re: David Pavlich]
      #6074675 - 09/11/13 09:44 AM

Hi Brian,

I believe this image was taken afocally, and it looks to fairly low power given the whole moon is showing and it's small. Most likely you are seeing the objective is being stopped down by the exit pupil being much larger than the camera lens/diaphragm and so it's effectively making the objective a much longer F-ratio than normal, which of course improves all aberrations.

There has been a very detailed discussion of this lately on the ATM forum. The afocal images are only reliable under certain conditions (very high power to keep the exit pupil of the EP small), and a lot of cases of people posting images this has not been the case.

Clear skies,


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Niklo
professor emeritus


Reged: 03/29/13

Loc: Bavaria
Re: Viewing sessions with my Istar127mm achro . new [Re: David Pavlich]
      #6075491 - 09/11/13 04:32 PM

Quote:

Quote:

.

and hey guys , Steve and David , come on Guys , its a 127mm f8 Achromat what do you expect ?? .





The only reason I commented on the purple fringing is because you posted this:

"One more showing the lack of CA in my Istar 127mm f8 Achromat !!!"

I took that to mean that there was no CA. Had you said how little fringing or the tiny amount of fringing or some such thing, I would have agreed and never made a comment. However, I assumed that you meant there was no fringing. In fact, the picture doesn't look bad.

David



Hi,
the lack of something does not mean that it is completely missing, does it?
In fact it seems that this 5" f/8 shows very little CA for a 5" f/8 achromat refractors (at least at the photos).
I'm really impressed about that little color fringes seen on the photos. Well done with a good 5" f/8 achromat
If I had a wish free I would ask for a Jupiter photo with this achromat.
Cheers,
Roland

Edited by Niklo (09/11/13 04:35 PM)


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David PavlichAdministrator
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Re: Viewing sessions with my Istar127mm achro . new [Re: Gord]
      #6075817 - 09/11/13 08:39 PM

Quote:

Hi Brian,

I believe this image was taken afocally, and it looks to fairly low power given the whole moon is showing and it's small. Most likely you are seeing the objective is being stopped down by the exit pupil being much larger than the camera lens/diaphragm and so it's effectively making the objective a much longer F-ratio than normal, which of course improves all aberrations.

There has been a very detailed discussion of this lately on the ATM forum. The afocal images are only reliable under certain conditions (very high power to keep the exit pupil of the EP small), and a lot of cases of people posting images this has not been the case.

Clear skies,




Interesting observation, Gord. That leads me to ask if the image of Venus is prime focus or afocal?

David


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tubehead999
scholastic sledgehammer
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Reged: 11/25/08

Loc: Kennesaw, GA
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6076054 - 09/11/13 11:04 PM

Yeah, there is a little obvious CA, at least on my monitor, but , what is important , is if it makes you happy?

Hey, it is an achro,...achromats aren't magical......it is all about the physics...

My story;
I had an ISTAR 100/1200 one time, it was "alright".
Little over 1/4 wave, I paid 300 for the objective in cell with shipping.
I sold it for 200 shipped, what I figured it was actually worth.
I bought off the web site , which had an objective with a test report of 1/6th or close as an advertisement of the quality of the objective I was to receive.
Yes, I was disappointed that what I received was not what was advertised.
Was the objective I bought a "good" objective? Yes, I believe so.
Was it a "killer ' objective? No
Can one see the difference between a measured wavefront of 1/4 and 1/6th at the eyepiece? Yes.
Was I about to send it back and complain because I didn't get what I expected to receive?

No, because I don't have the time to play those kind of games. My curiosity has been satisfied.

I sold it with full disclosure of the interferometry report. I am sure the new owner is enjoying the glass and he got a "deal".

Another observer and I actually did a compare between the ISTAR 100/1200, the Carton 100/1300 and a Jaegers 103/1575. All in home-brew OTAs. Simple compare..Saturn. The Jaegars won.

Draw your own conclusions.


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stevew
Now I've done it


Reged: 03/03/06

Loc: British Columbia Canada
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6076120 - 09/11/13 11:49 PM

Quote:


Steve and David , come on Guys , its a 127mm f8 Achromat what do you expect ?? .
This shot equates to about 90x thru the eyepiece .


Brian.



Bri, the image of Venus, and the Moon look great for color correction! Very impressive for an Achromat.
Congratulations on a fine refractor.
I hope you get many years of enjoyment out of it.

Steve


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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: David Pavlich]
      #6076245 - 09/12/13 01:25 AM

Sony A200 DSLR straight in the focuser at the native 1000mm fl of the telescope , sized for CN's ( from 1.07mb to 128kb ) , zoomed in and cropped by windows media centre , that's it .
Brian.
Quote:

Quote:

Hi Brian,

I believe this image was taken afocally, and it looks to fairly low power given the whole moon is showing and it's small. Most likely you are seeing the objective is being stopped down by the exit pupil being much larger than the camera lens/diaphragm and so it's effectively making the objective a much longer F-ratio than normal, which of course improves all aberrations.

There has been a very detailed discussion of this lately on the ATM forum. The afocal images are only reliable under certain conditions (very high power to keep the exit pupil of the EP small), and a lot of cases of people posting images this has not been the case.

Clear skies,




Interesting observation, Gord. That leads me to ask if the image of Venus is prime focus or afocal?

David




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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: stevew]
      #6076249 - 09/12/13 01:30 AM

Thanks Steve , I like the way my Istar performs , well above the $360 I payed for it , I cant be happier with it .
Brian.
Quote:

Quote:


Steve and David , come on Guys , its a 127mm f8 Achromat what do you expect ?? .
This shot equates to about 90x thru the eyepiece .


Brian.



Bri, the image of Venus, and the Moon look great for color correction! Very impressive for an Achromat.
Congratulations on a fine refractor.
I hope you get many years of enjoyment out of it.

Steve




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Niklo
professor emeritus


Reged: 03/29/13

Loc: Bavaria
Re: Viewing sessions with my Istar127mm achro . new [Re: tubehead999]
      #6076377 - 09/12/13 05:54 AM

Quote:

Yeah, there is a little obvious CA, at least on my monitor, but , what is important , is if it makes you happy?

Hey, it is an achro,...achromats aren't magical......it is all about the physics...

My story;
I had an ISTAR 100/1200 one time, it was "alright".
Little over 1/4 wave, I paid 300 for the objective in cell with shipping.
I sold it for 200 shipped, what I figured it was actually worth.
I bought off the web site , which had an objective with a test report of 1/6th or close as an advertisement of the quality of the objective I was to receive.
Yes, I was disappointed that what I received was not what was advertised.
Was the objective I bought a "good" objective? Yes, I believe so.
Was it a "killer ' objective? No
Can one see the difference between a measured wavefront of 1/4 and 1/6th at the eyepiece? Yes.
Was I about to send it back and complain because I didn't get what I expected to receive?

No, because I don't have the time to play those kind of games. My curiosity has been satisfied.

I sold it with full disclosure of the interferometry report. I am sure the new owner is enjoying the glass and he got a "deal".

Another observer and I actually did a compare between the ISTAR 100/1200, the Carton 100/1300 and a Jaegers 103/1575. All in home-brew OTAs. Simple compare..Saturn. The Jaegars won.

Draw your own conclusions.



Thank you for your report. It's a pity that the objective wasn't 1/6 wavelength. You probably had bad luck
How was the CA comparing the Istar 100/1200 with the Carton 100/1300?
Saturn isn't a perfect object for comparing the CA but better than no comparison
Clear skies,
Roland


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Jon Isaacs
Postmaster
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Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Viewing sessions with my Istar127mm achro . new [Re: stevew]
      #6076393 - 09/12/13 06:26 AM

Quote:

Brian, Good shot of Venus, hard to believe its only an achromat.
Does Venus show about the same color correction visually?

Steve




When I view Venus in a reflector (or color free refractor) against a dark sky, I normally see the blue and red-orange edges that are the result of the atmospheric refraction. I would expect to see that in this image as well but I am not seeing it.

Jon Isaacs

Edited by Jon Isaacs (09/12/13 06:27 AM)


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star dropModerator
contra contrail
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Reged: 02/02/08

Loc: Snow Plop, WNY
Re: Viewing sessions with my Istar127mm achro . new [Re: Jon Isaacs]
      #6076881 - 09/12/13 12:17 PM

When I zoomed in on the Venus image it looks like the bottom of the purple fringe has a very slight reddish tint.

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Jon Isaacs
Postmaster
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Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Viewing sessions with my Istar127mm achro . new [Re: star drop]
      #6077549 - 09/12/13 06:11 PM

Quote:

When I zoomed in on the Venus image it looks like the bottom of the purple fringe has a very slight reddish tint.




When I zoomed in, I saw the purple fringe, didn't see any red, it might be there. What makes Venus extra challenging for an achromat is that there is blue-violet, orange-red thing going on underneath the existing chromatic aberration. So if you filter the purple, you filter the atmospheric refraction too.

Jon


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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: Jon Isaacs]
      #6077690 - 09/12/13 08:42 PM

Thanks for your observations and comments guys I do appreaciate them , yes it has a tiny amount of CA and venus was getting fairly low down in the mirk ( 40*) but as many people and I said its very , very good for a 127mm f8 achromat .
I will try for a Jupiter shot over the weekend and post one or two up for your appraisal .

Thanks ,
Brian.


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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Viewing sessions with my Istar127mm achro . new [Re: beanerds]
      #6081567 - 09/15/13 06:05 AM Attachment (11 downloads)

Could not get Jupiter this weekend , morning clouds ,both mornings but I will try again in the morning (Monday) .
Here is the 'Acid" test I use on any telescope again in-case anyone has forgotten , full sun on a white roof .
Brian.


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