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Post by Viktor Z. on Aug 20, 2015 2:33:39 GMT -5
Has anyone used Chromacorr with Istar objectives? Thanks in advance for any input:)
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Post by jamesling1000 on Aug 20, 2015 19:48:29 GMT -5
Hi Viktor Z. Yes I am one of those that is using the Chromacorr with my 8" ISTAR F8.8 classic.... I purchased the Chromacorr II N version and it come with the mirror tilt adjustable diagonal and spacer that is machined to me focal length 8.8.. The following is the complete Chromacorr II assembly..  Regards James Ling |
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Post by jamesling1000 on Aug 20, 2015 20:10:16 GMT -5
The spacing is very important....if you have one to test it out... coz just a quarter turn between the chromacorr and the spacer (thread), you can immediately see the CA appearing.... You can see the difference during the day when you view a distant object , with and without the chromacorr, like the following photos which I tested it before I use it for my sidewalk.... Regards James Ling   |
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Post by jamesling1000 on Aug 20, 2015 20:29:36 GMT -5
The following photos of the moon are comparison made with and without the chromacorr II... Regards James Ling  |
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Post by Viktor Z. on Aug 21, 2015 21:05:59 GMT -5
Hi James:
Thank you very much for your posting. I also have the Chromacorr-II-N, and just unsure how to find the proper distance between the diagonal and the Chromacorr? Is the spacing sensitive to what type of eyepiece I use? Or I can just move the focuser itself to find a good alignment for different eyepieces? I also would like to avoid loose threads, because the thread should be tight, otherwise the diagonal with the device may easily fell on the ground. I guess a very exact spacer length is required, one that a machinist can make.
It is very interesting to see in your pictures how the Chromacorr sharpens the image and removes the blue halo from the head of the sculpture. I like all four of your Moon photos, even those without the Chromacorr, but the top two are clearly better images.
Regards,
Viktor
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Post by jamesling1000 on Aug 21, 2015 23:44:03 GMT -5
Hi Viktor Z. From your previous posting, u are having the 9" F8, which is 1800mm focal length... Which is exactly to my 8" F8.8 , also at 1800mm.. The measurement I took between the diagonal end and the chromacorr end is 41mm.. I suggest you made a threaded end with +/-5mm for the adjustment... What I did for myself is that after I tested it to the correct position, I put a scotch tape to hold it in place... Please take a closer look at the following photo which I made a connection attachment for my celestron 6" F8 at 1200mm focal length... Regards James Ling  |
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Post by jamesling1000 on Aug 21, 2015 23:51:30 GMT -5
Hi Viktor Z.
This is the utube video I have download this year, on Jupiter , which the 8" ISTAR is used with the Chromcorr II..
A video is just a video.... but when you view Jupiter physically with your own eyes, with the chromacorr II, when is setup properly, is a total difference experience....
Regards
James Ling
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Post by mikey cee on Aug 22, 2015 10:03:28 GMT -5
James your image looks like a reflector's video. Good shot! Yes I too have a Chromacor N which I have been using for over a month now. To me Jupiter looks like an apo image. Black sky right up to the limbs....absolutely no CA. The moon has an ever so slight thin blue edge just enough to tell it's not a reflector that I'm using. You really have to look for it. I guess with my 10" F/11 R30-R35 optics the Chromacor N does as good as your plain 8" F/8 optics do with a Chromacor II. Everyone should invest in what few chromacors that are left available huh??  Mike |
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Post by Viktor Z. on Aug 23, 2015 2:31:21 GMT -5
James, Mike: It is very encouraging that both types of Chromacorr N's work with your iStar achro and Rxx lens. It also tells me that the lens were made so well that N level correction is adequate. Thank you James for sharing your spacer distance for 1800 mm focal length. I will give a try having a spacer machined as per your recommendation, and hopefully this will work for me as well. I am thrilled by the opportunity that the performance of our otherwise excellent large achros and Rxx lens with the Chromacorr corrector become comparable to the unobtainably expensive 8-10" APO's. Yes, agreed, every achro owner should have a Chromacorr AND for an affordable price, not for those crazy prices of recent Chromacorrs! It's too bad nobody makes these anymore. Anyways, I will post my observations probably in October, when I'll have my telescope, the chromacorr and all my eyepieces with me again  Viktor |
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Post by francescot on Aug 23, 2015 4:27:43 GMT -5
Hi Viktor ! I have a chromacor II N :-) :-) I have almost finished my ISTAR 220-3300 CeF achromat PV/6, first light will be Tomorrow night , I am very excited, I will try to use the Chromacor with the big 22 cm at the proper distance: I will pst pictures very soon of the OTA, the chromacor and everything. I spoked with Valery Deryuzhin many times and I built a chromacor collimator wich will allow me to adjust the distance between the chromacor and the eyepiece baffle. YES , you're right, a big achro + chromacor means that you have a 90% apo performance .. at 10% of the price. Let's think about my 22 cm: a 9" APO Is listed at 29.000 $  *this* Is an achromat revolution, and ISTAR Is a forerunner, allowing us to have big lenses at good prices, please notice that having a 9" lens was unthinkable 5 -10 years ago. I am going to PM you, I studied a lot In this area :-) |
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Post by jamesling1000 on Aug 23, 2015 8:36:31 GMT -5
Hi All.... The ISTAR even without the chromacorr , is already very good..... and today I setup my 8" F8.8 ISTAR classic model with the Lunt solar wedge and the surface of the sun shows very nice sunspot details which I took the following photo shot....(hand hone)   And I also download a short video clip onto utube ...(hand phone) Regards James Ling |
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Post by Viktor Z. on Aug 23, 2015 16:07:57 GMT -5
Hi Francesco, I can't wait to hear more about your telescope building and the observing with your new giant 220/3300 refractor and Chromacorr combined! It must be fantastic! Absolutely you are right, this looks like the beginning of a big achromat revolution! We need a Chromacorr revolution too, Ales  Kind regards, Viktor |
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Post by dkahraman on Feb 13, 2023 11:12:33 GMT -5
Yes Ales we need an achromat and Chromacorr revolution. Valery informs me that his chromacorrs are easier to make for 220mm f/8 achromats. He will look for a spare chromacorr-I for my 220 mm f/15
Dan Kahraman
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Post by Ales - iStar Optical on Aug 14, 2023 18:55:47 GMT -5
Yes Ales we need an achromat and Chromacorr revolution. Valery informs me that his chromacorrs are easier to make for 220mm f/8 achromats. He will look for a spare chromacorr-I for my 220 mm f/15 Dan Kahraman Hello Dan, we are producing a really great quality 228mm F/7.7 Just check out the independent testing results on our website Istar-optical.com To pair such high quality achromatic doublet with Chromacor would really be awesome. If you can, talk to Valery, let's see if he would be willing to produce Chromacor for this particular iStar lens. 220mm is a serious aperture class and F/7.7 is fast enough imaging. This could really be something.... Shoot me a text message to 619-452-9820, lets see if Valery would be up for something like that... |
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Post by georgeionas on Aug 27, 2023 22:20:30 GMT -5
If Valery starts making Chromacors for 1800mm focal length scopes, I wonder if this chromacor could be used on the 204mm f/6 iStar achromatic lens with a different spacing - if so I'll be in for one.
George Ionas
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Mike
*this* Is an achromat revolution, and ISTAR Is a forerunner, allowing us to have big lenses at good prices, please notice that having a 9" lens was unthinkable 5 -10 years ago.
