akhael
Junior Member
Posts: 18
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Post by akhael on Jan 31, 2015 11:57:38 GMT -5
Hi everybody, so here is my thread about the building of an 100mm F12 refractor. The lens is due to arrive in the next few days so I began working on the TCR-like structure : Here is a close up of the intermediate baffling parts : At the bottom the piece for the focuser and just above for the lens cell. The thin parts are aluminium/resin sandwich called Dybond (3mm thick). The thick parts are PVC plastic 10 mm thick. They were all CNC cut. They are painted matte black and drying right now. I will assemble everything with screws tomorrow. To be continued...
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Post by bn1777 on Feb 2, 2015 4:57:07 GMT -5
looking good ! a very professional job so far , I will follow this build with interest . Brian.
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rgm
Full Member
Posts: 65
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Post by rgm on Feb 2, 2015 8:00:29 GMT -5
Very professional looking. Keep sending us pictures. Any idea what focuser you will be using?
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akhael
Junior Member
Posts: 18
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Post by akhael on Feb 2, 2015 9:03:52 GMT -5
Hi and thank you for your kind words. Now that the black paint is dry, it doesn't look so professional under close inspection !!! I had to struggle with dust and cat's hair ! As for the focuser I am using a TS 2" crayford. Here it is on its plate with the end corrector of the "tube" under it : To be attached with push-pull screws, so I will be able to collimate on this end too... The good news is the lens arrived this morning at the post office. Hopefully I will be able to get it tomorrow. First light by the end of the week, if weather is on my side ! To be continued…
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akhael
Junior Member
Posts: 18
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Post by akhael on Feb 3, 2015 6:27:29 GMT -5
Lens is home ! And it's a thing of beauty ! Very light-weight : 0,85 kg Very well coated, from most angles you could think there's no glass in the cell ! Now back to work to get it assembled to the "tube". To be continued…
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akhael
Junior Member
Posts: 18
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Post by akhael on Feb 5, 2015 4:40:48 GMT -5
So the structure is assembled : Weight of the strucure with focuser : 2 kg (4 lbs), with lens and dew shield under 3.5 kg (7 lbs) Last night was first light, but with extreme conditions : no collimation yet (but alignment seemed pretty good), temperature below 0°C, strong wing, fog in the valley below, a veil of high altitude clouds and full moon ! Nevertheless, I was able to point at a few targets to see how it worked. First is I was only able to use my never used before UO 40mm konig ! I will have to shorten the bars by 4 cm to achieve focus with my other eyepieces. I need only 0.5 to 1 cm to achieve focus but I want to have some margin since I plan to use my bino… I will post a photo of the finished OTA tomorrow. To be continued…
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akhael
Junior Member
Posts: 18
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Post by akhael on Feb 6, 2015 3:26:18 GMT -5
So here are two quick shots of the completed scope on its mount (old heavy duty Gitzo mount, weight 7 lbs) : I still have to figure how to fix the dew shield as for now it's just holding directly on the lens cell with foam pads… As I don't want it to constrain the lens I have to add some little brackets to srew it on… I was able to collimate the refractor yesterday in a few minutes (I have push-pull screws on both ends, focuser side and lens side). I will shorten the tube tonight after work and wait for the clouds to go… To be continued…
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akhael
Junior Member
Posts: 18
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Post by akhael on Feb 10, 2015 5:52:12 GMT -5
So yesterday was official first first light ! At lunch time I did a quick session on the sun and yesterday night a 2 hours run on the stars and Jupiter. Temperature was 3°C, a light wind was blowing. Transparency was pretty good but seeing not so as I discovered when pointing Jupiter. First target was Orion nebula with the 40mm UO Konig (30x). The whole sword fitted in the field of view and the details in the nebula were very fine. At first glance I was struck by the sharpness. I then did a few clusters going up to 85x. No CA visible yet, except on the brightest star and you had to look for it and move your eye off axis (my 85x eyepiece is a 14mm 73° Clavé that I suspect adds CA, since it shows more CA than my 11mm Nagler). Now on to Jupiter. In the 11mm Nagler (109x) there is a little CA, a red line on one side and a blue/violet halo (less than the width of the planet) on the other. Again it is more obvious when off axis, on axis it is very discreet. The disc itself is white with the 2 main belts orange. One pole is light brown. When turbulence holes happenned details began to show. The satellites are obviously not stars. Near the end of the session a black spot appeared on one side of the planet. I was able to follow its course on the globe for half an hour. I assume it was Europa's shadow as I found the satellite was in transit one hour later. I tried my ES 6.7mm (179x), but the image was very soft and "boiling" due to poor seeing. So far I am very happy with the refractor even if it's far from perfect, mechanically wise. The length makes it a bit shaky on the mount when focusing, but it's OK. The structure itself is not stiff enough as I discovered that when I swing the OTA 90° on one side the collimation goes off a little (4-5mm), but again it's OK since I don't have to when observing. Good thing is the overall weight : I can lift it and go outside with one hand, that's grab'n'go ! The sky will be clear tonight again, so I hope I'll have better conditions for Jupiter. As a side note on CA, I use a combination of WO VR-1 with a 85a Light blue (to lower the light yellow cast of VR-1). It works very well here on short focal EP here : CA was nowhere to be found and Jupiter's color was very neutral, just a little warmer ("coffee" taint).
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akhael
Junior Member
Posts: 18
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Post by akhael on Feb 11, 2015 4:06:26 GMT -5
Yesterday night was better in seeing (6/10) than the night before (3/10) so I spent an hour and a half on the giant gas planet. Transparency was still very good as usual above my place. Oh my oh my oh my ! WOW ! I plugged the bino into the refractor and began observing with a pair of 11mm Naglers T6 (109x). The views were better without the filters mentioned on my previous post, more tiny details could be seen. CA was less than the previous night and not bothering since it was very discreet, in fact after a few minutes I just forgot about it. The light being split in half by the bino could explain this maybe : less bright light, less CA ? The border of the planet was still rippling at times but in the gaps when air was calm a wealth of details was showing. One of the better view of Jupiter I have ever had ! I have a 12" dobson with a very fine primary (hand corrected for a super-smooth surface), but the seeing often prevents steady images in it at my place. On a side note I have never looked through an APO and I am mainly a deep sky guy. Only once could I achieve a better view but without the bino and its 3D effect it was not that memorable. After a while I plugged in a pair of 9mm UO orthos to achieve a magnification of 133x. The view was still very sharp. In fact I could have gone farther in magnification but I don't have a second ES6.7mm (my shortest EP) for the bino. Now I have to plan the purchase of a new pair of orthos in the 5-6mm focal range. I know it will get used ! Here is a picture of Jupiter I photoshoped to try to render the vision, it's not perfect of course as tiny details that the eyes can see are difficult to render with pixels this size : So to sum it up : THANK YOU ISTAR ! I am really enjoying this scope, great stuff you're providing !
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Post by marcello on Feb 11, 2015 6:34:13 GMT -5
Hi Chris,
it looks really a great job, and so light!
I'm glad you had such good views.
Did you have any chance to look at Venus?
I'm trying to do a scope with the same optics (as you have seen in my post, thanks for your reply there) using a tube, but your post makes me think I could change idea and do it as you.
Just a question: are the three stakes in aluminium as well?
Thanks Marcello
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akhael
Junior Member
Posts: 18
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Post by akhael on Feb 11, 2015 8:13:01 GMT -5
Hi Marcello, yes the stakes are aluminium square tubes. Section is 15x15 mm. I have not had a chance to look at Venus yet. It's low on the horizon behind the trees when I get home... But I will try, and Mars also which is just above Venus. I will report the results here… Chris
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Post by marcello on Feb 11, 2015 8:27:16 GMT -5
Thanks Chris,
I will follow your updates
Marcello
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