aolo
Junior Member
Posts: 10
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Post by aolo on Mar 7, 2012 21:58:50 GMT -5
Ok,
I'm getting closer to deciding on my next purchase but still throwing around ideas.
I do like to Binoview though, but this is a secondary consideration.
I'm thinking of a 7" f/10 R30. I think this means:
A 7" scope with 1800 mm F/L operating @ f/13? If I Stop stop it down to 6" I'm operating at 6"@ f/15? If I Stop it down to 5" I'm operating @ f/18? Is this correct?
Are there any other Rxx that I might want to consider?
How much would a 7" f/10 R30 OTA weigh?
Thanks
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Post by jamesling1000 on Mar 7, 2012 22:51:08 GMT -5
Hi Aolo.
7" with the FL 1800mm , should be quite close to my 8" 1800mm...
Mine is 45 lbs for the bare OTA, so the 7" could be close or around 40 lbs...
And with those accessories like mine mounted onto the bare OTA, you will be surprised that it is around 60 lbs... same as mine... Coz mine does not even come with a dew shield...., which I think all Istar new scopes should come with dew shield....
REgards
James Ling
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aolo
Junior Member
Posts: 10
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Post by aolo on Mar 7, 2012 23:23:02 GMT -5
I think I saw your video on youtube. Love to see some more video of your 8" when you get a chance to through some more up. That was you right?
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Post by jamesling1000 on Mar 7, 2012 23:54:06 GMT -5
Hi Aolo. Yes. I am the one in the utube....... In fact, in South East Asia region, due to our smaller build, no one will acquire any refractor , bigger than 6". And it really recreate some interest in our local astronomy when I decided to bring this 8" ISTAR into my country..... You can see from this photo attachment, my Istar does not come with any dew shield.... I hope to show more of these big achro to all those who are interested , through sidewalks and even videos or photos etc... Regards James Ling Attachments:
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aolo
Junior Member
Posts: 10
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Post by aolo on Mar 9, 2012 16:25:27 GMT -5
What was the make of the 6" refractor in your video?
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Post by jamesling1000 on Mar 11, 2012 1:57:19 GMT -5
What was the make of the 6" refractor in your video? Hi Aolo. Are you referring to this utube video? There are 2 refractors in this video shot by my friend when my newly purchased ISTAR 8" F8.8 arrives during the weekend. The 1st part of the video shows how big and massive is the ISTAR 8" F8.8 set up on a losmandy G11 mount.... And you must get prepared , when you purchased your 7" FL1800mm .... Is much tougher both in setting up and transportation than the C14. The 2nd part shows another smaller 6" APO triplet refractor belonging to another of my friend whereby we do a comparison on the 1st light of this ISTAR 8" big achro. It's a TMB-designed 152mm (6") f/8 APM/LZOS Triplet Apochromat OTA For plantetary performance , against this 6" triplet, I will say the ISTAR Phantom CFT 152-8 CaF2 Fluorite Triplet super APO refractor, will be the one that can match or performed better... And everyone know there is a very wide gap on the price for both scopes. For my 8" achro, although I could not see the difference in the details on the surface of Jupiter on the night shootout between the 2 scopes , powering up above 400X, when the seeing condition is so excellent...., I am sure if u go for 7" F1800mm with R30 and even later RAYYCOR 6, the performance could be closer to APO..... REgards James Ling |
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aolo
Junior Member
Posts: 10
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Post by aolo on Mar 11, 2012 11:59:23 GMT -5
You are probably right I have a Nexstar 11 that I do not consider a challange to setup, and had 8" Mak-Newt that was 45 lbs that was just to much for the Atlas mount. 40 lb on a 6' tube + tube is managable if the longest level arm is not longer than 3.5' . CA is a concern though if the 7" performs at f/13, that why I would like to stop it down to 6" f/15. Hopefully Ales will answer my questions when he gets a chance.
I'm thinking of a 7" f/10 R30. I think this means:
A 7" scope with 1800 mm F/L operating @ f/13? If I Stop stop it down to 6" I'm operating at 6"@ f/15? If I Stop it down to 5" I'm operating @ f/18? Is this correct?
Are there any other Rxx that I might want to consider?
How much would a 7" f/10 R30 OTA weigh?
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Post by jamesling1000 on Mar 13, 2012 6:13:26 GMT -5
Hi Aolo.
I used to think on masking down the aperture , to reduce the CA, but after I did it to my 8" Istar, to 6" opening, I think I better leave it at full aperture....
From my own experience of using the 8" Istar, yes, the CA , on the moon is like a greenish stripe over the edge of the moon...
You do not notice the difference when you masked it down to 6", which is f12.
But for the 7" F10 R30, you should already see a smaller greenish stripe ......then my 8"......Or smaller than my Celstron C6R F8, which also has a smaller greenish stripe.
For surface details, such as Jupiter and Saturn, the CA doesn't really bother at all......, not like those from C6R F5 which I have seen it........
Regards
james Ling
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aolo
Junior Member
Posts: 10
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Post by aolo on Mar 15, 2012 15:35:21 GMT -5
Thanks James, I appricate your input. Gonna start a thread called "Ask James".  |
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Post by jamesling1000 on Mar 15, 2012 21:10:10 GMT -5
Thanks James, I appricate your input. Gonna start a thread called "Ask James". Hi Aolo. Pls don't say that......, as i am still considered very inexperience on using the refractor....... Although I have owned a few refractors, which are achromat, and has never been happy with it, and that is why I moved towards mirrors, and after I heard about Istar name, I just want to give it another shot to go back to lens..... And is from here , then I start to realized a lot on CA and advantages of long FL... Ales and Mike , and even many others , in this club, are very knowledgeable and many years of experience with their refractor(s).. Hi all. it will be nice in this forum, that you will share your valuable experiences, whether is visual or photo, whereas I very much like to tell to everyone what I have seen with the ISTAR I am having now..... Coz there is no point for me to tell people about my C14 and 10" Mewlon.... as there are many other people , especially in CN talked a lot on these mirror or compound scope.... REgards james Ling |
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Post by tonybegg on Jun 18, 2012 21:31:35 GMT -5
James. Just want to say I am enjoying everything you post. I love that you do outreach in the middle of a light polluted city (my patio has 10 full Moons worth - measured - of streetlight). I am also sorely tempted by the 8 inch f/8.8 achromat because it has a lot of light gathering power, even though 6 inch f/15 makes more sense for an achromat because of CA. But I have high hopes of the Raycorr mitigating CA. I only have an Explore Scientific 5 inch f/7.5 APO, and have a low cost 8 inch Ritchey-Chretien on order it seems like forever, so am wondering whether to switch to the 8 inch refractor even though it makes no sense at all other than high contrast and light gathering power and romance. But I love your posts and your willingness to outreach with a cumbersome set-up. If I get the 8 inch I would try to take it to star parties too.
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Post by jamesling1000 on Jun 19, 2012 20:45:30 GMT -5
Hi Tony......
Have seen lately some members like you start posting in this forum, and is very encouraging that other members will also start to post their query, doubts and their experienced, even not related to ISTAR scopes.....
I believe anyone who happens to access to ISTARSCOPECLUB, like myself one and a half years ago..., very much like to know the news and latest products from ISTAR, as well as field reports from members , like myself, who acquires the ISTAR scope....
I can see you and few other members are really keen to acquire bigger aperture ISTAR scope, and like myself waiting for the RAYCORR to hit the market before end of this year....., or hopefully early next year, for my 8" F9....
Hi All....
Again taking this opportunity to express my satisfaction on using the 8" F9 ISTAR for the past one year 9 months......
ISTAR optics quality is definitely not same as those mass produced products like my current 150F8 refractor from a very mass market producer....which image breakdowns around 200x......
And that is also the reason I found out that the 8" cannot be going lower than F9, if you want to use for planetary use....
Unless you are going for the R30 version.....
In fact for 8" F9 to perform so well, definitely ISTAR cannot figure them like those mass market producer for their 6" doublet....
And my 8" F8 has really proved itself able to reach above 400X on planetary objects, although I never seen with more than 500X, and the image still remains sharp and crisp.....(my next eye piece is 2.5mm, too far apart from my current 4mm ep, at 450X)
There are many more things I can experienced with this 8" F9 ISTAR, especially on the meade focal reducer that I mentioned in another forum....which can made my ISTAR from F9 to F6.....
And I am going to continue with the experimenting during these 2 weekends, as the moon is falling over my western side of my house viewing side....
Regards
James Ling
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