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Post by Deleted on Nov 27, 2014 14:45:50 GMT
i know ed apos would be 100% better. but in a refractor isnt ed is it still useable for video ?? i was looking at old post somewhere.. from like 2006 and 7. lots of none ed's used.
how bad is it ? if not ed for video ?
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Post by Deleted on Nov 27, 2014 18:48:07 GMT
i know ed apos would be 100% better. but in a refractor isnt ed is it still useable for video ?? i was looking at old post somewhere.. from like 2006 and 7. lots of none ed's used. how bad is it ? if not ed for video ? Any telescope achromat, semi apo, full apo will work for video. The most visible difference will be the sharpness and shape of the stars, with an apo they will be pin point, less so with a non apo. Using an IR/UV blocking filter will help reduce the slightly out of focus IR 'light; which causes star 'bloat'. Note 35mm camera lenses with a C mount adapter will work for video, also C mount video zoom lenses offer some very useful observing and many are not expensive to buy. Use an IR/UV blocker if a mono video camera to obtain accurate colour rendition. Pentax M42 screw thread camera lenses are very low cost S/H and are excellent optics at any focal length. Remember a 'standard focal length lens for a 1/2" CCD is approx 8-12 mm, so any 35mm camera lens over this, which most are, will all act as telephoto lenses. A cheap 300, 400 mm Pentax screw fitting lens of any make becomes a telescope with a C mount adaptor. Check out my websites for some examples & ideas. Here are a few of my optics used for video astronomy. picasaweb.google.com/109921669020426367250/VideoAstronomy1988Present?authuser=0&feat=directlinkpicasaweb.google.com/109921669020426367250/CameraLensesAdaptersForAstroUseASmallSelection?authuser=0&feat=directlinkClear skies...Shevill
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Post by Deleted on Nov 27, 2014 20:14:16 GMT
yeah i made a adapter for cam olyumpa cam lens to the c mount for the sammie.. i asked as i see a few 5 to 6inch refractors for a fair price. and thinking i might like to try one but not 100% sure yet on that. i have a 5 inch newt. that i need to try out on video.
when i 1st started with video. i did try it but not knowing anything.. things didnt go good.. now i know still next to nothing lol .. i might give her another go .. i have the C8 also. so not sure with that one yet also.
we moved to winter. so i think ill move downunder for the warm weather. lol winter slows me down a lot.
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Post by Dragon Man on Nov 28, 2014 10:48:37 GMT
Phil, ED's are used and yes there is a difference between them and full Apo's and plain old Achromats. Some people either don't notice, or don't care, but when you see them side by side the difference is noticable. The Non-Apo (Achro) will display blobby stars and Violet fringing and Chromatic Abberations around brighter objects. Semi-Apo (ED) will show sharper stars and no false colour around bright objects. A full-on Apo will have even sharper stars, but not really noticable from an ED until doing serious Astrophotography. Here is an example using some of my screen grabs using both ED (Semi-Apo) and Achromat (non-Apo) This first one shows how the stars get blobby with an Achro compared to the sharp stars in the ED, and also notice that detail in the galaxy is blurred in the Achro. This next image shows Chromatic Aberration from an Achromat: This one gives an example of the Vioet fringing around the brighter stars: Another example of violet fringing: and another: Compared to using an ED or Apo: Don't let me discourage you from using the much cheaper Achromat scopes. They still do a fine job, and for less than half the price to the same size scopes. The Achro I used for most of my Achro work is a wopping big 6 inch f/5 achromat that cost only $800 new (the achro used in the above photos). An ED in 6 inches is about $3000 plus. A full Apo in 6 inch is around $12,000 plus. But thankfully, a remarkable little ED hit the market years ago and instantly became a hit with Astrophotographers, and they work fantastic for Video. The ED80 and they can be found for around $500 - $600 new. My ED80 is what I use now 99.9% of the time, and I know many others do too. They just work great, especially when used with a Focal Reducer (as seen in my photos above of the ED80 pics). But if you come across a good price on a big aperture short focal length Achro, grab it
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Post by Deleted on Nov 28, 2014 17:47:10 GMT
thank you Dman.. yes i have the ed80apo. it does a sweet job for sure. but wasnt 100% sure how bad a none edapo would be. i belt a wedge for the nexstar mount. the C8 seems a hair heavy in this config. but i belt the wedge to be lil taller then normal. so i could fit the ed80 on it. so ill stick with the ed80 and have to wait for the warmer weather .. heres the wedge i made. it seems ok so far. as in fit and holds up the c8 with no issue. so we shall see.. cheers phil
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Post by Deleted on Nov 28, 2014 19:07:41 GMT
yeah i made a adapter for cam olyumpa cam lens to the c mount for the sammie.. i asked as i see a few 5 to 6inch refractors for a fair price. and thinking i might like to try one but not 100% sure yet on that. i have a 5 inch newt. that i need to try out on video. when i 1st started with video. i did try it but not knowing anything.. things didnt go good.. now i know still next to nothing lol .. i might give her another go .. i have the C8 also. so not sure with that one yet also. we moved to winter. so i think ill move downunder for the warm weather. lol winter slows me down a lot. Hi, You will get sharper images from any reflector because all colours /wavelengths come to the same focus, unlike light passing through an achromat lens. However, at f/10 and the narrow field of view makes them less suitable for wider views unless you use a focal reducer in the system, which is what many people do. The mount tracking also is less forgiving at these longer focal ratios so with extended exposure times, oval stars are common unless very well polar aligned. I also have a 6" f/8 Sky Watcher refractor which I often use for video, a minus violet filter in the nosepiece helps reduce the slight fringing one gets with an achromat. Showing the general public astro images in real time through any sort of lens/telescope to them is mind blowing, they do not see the minor imperfections that the experience user gets bothered about. Video astronomy, like any other methods using camera, monitor, and or computer equipment does have a learning curve with trial and error being the key. At least with video you have a real images on screen that lets you see what happens as you make camera adjustments. Play around with your 5" Newtonian and C8 if they are on an EQ tracking mount.
Clear skies... Shevill
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Post by Deleted on Nov 28, 2014 19:43:33 GMT
i know ed apos would be 100% better. but in a refractor isnt ed is it still useable for video ?? i was looking at old post somewhere.. from like 2006 and 7. lots of none ed's used. how bad is it ? if not ed for video ? Hi, I think people gets a bit confused with telescope types and what is suitable for video astronomy. Many people start out with the telescope they have, often an achromat refractor. Unless you are an expert or very experienced video enthusiast, the difference in image quality between the many telescope options available today are a far cry from the old day of very average f/15 3" refractors. I have a bog standard 80 mm f/5 which gets used for video quite often and only me knows he subtle differences between my cheap scope and one costing 10 times the price.
You need to be very keen and have deep pockets for fully apochromatic 2 or 3 element telescopes, and for video observing unlike imaging, is the huge extra cost worth it, personally I doubt it, and not the way I would advise a beginner to start off. Also buy an anti fringing or yellow 1.25" EP filter to put in front of the camera nose-piece. This will reduce the fringing. An IR/UV filter if not fitted to the camera, is a good idea, using one will give more accurate colours & tighter stars.
See this link with a setup I used recently for a project. picasaweb.google.com/109921669020426367250/BinoCamSomethingNew?authuser=0&feat=directlink
Don't get all hung up on theory either, do a search and see what others are using and have started with at entry level, obviously a semi apo, or ED as they are often called are excellent but at a much higher price.
Clear skies...Shevill
PS, if you are worried about purple fringing then use a reflector, a small Newtonian or an SCT with a focal reducer is as sharp as you will get and colour fringe free, unless you are addicted to refractors!!
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Post by davy on Nov 28, 2014 20:56:57 GMT
Well said shevill..totally agree cut your teeth on a cheap scope cheap camera...see if it's what you like and are happy doing..I think we are the poor relations to astrophotography in some eyes, we strip and modify cameras and blend them to our kit ect..why because it is an exoensive hobby if you jump in the deep end..top notch equipment aint cheap and to my knowledge we dont have any millionaire members on the forum so we bat for the little guy and give good advice on what to start with and help you grow your equipment and skills so you can help the next wee guy that wants to video the night sky
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Post by Deleted on Dec 7, 2014 9:53:32 GMT
I have a celestron 102 refractor which I never use except for keeping an eye on the magpie nests in the nearby oak trees . I will give my new Micro ex a go at some DSO's. If it is acceptable I may even post my first image. Paul
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Post by Dragon Man on Dec 7, 2014 10:37:46 GMT
Paul, what is the focal ratio of your Celestron 102? I see they come in f/6.5 (660mm fl) and f/9.8 (1000mm fl). The shorter the focal length the better
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Post by Deleted on Dec 7, 2014 11:16:28 GMT
Ken ,it is 6.5. I guess a focal reducer is still worthwhile. I have an Orion 2" 0.8 focal reducer for it. I bought that when I didn't know what a focal reducer was.. I just need to sort out the right connections. The biggest problem might be the accuracy of the goto with all that weight. Maybe I should stick to the 0.5 reducer. When these clouds disappear ,I will give it a go Paul
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Post by Dragon Man on Dec 7, 2014 12:06:21 GMT
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Post by scopesnc on Dec 7, 2014 12:52:45 GMT
Ken
What I have found ( no expert here ) is no matter the type refractor one uses , a camera like the Mallincam is going to show false color around the brighter stars, planets and some star bloat is going to happen. I have seen it even on the best triplets out there. I have no real reason as to why, but video cameras seem to be able to show that C A when nothing else will. I also am no expert and never really cared much , but stars seem to bloat more in reflector type OTA's than refractors when using video also. I think that may be due to the mirrors involved.
To me any set up one can afford , that makes you happy with the results is all one needs. No theory about any set up is ever going to top that. It is the bottom line. I try to always keep that in mind when I see other set ups and listen to people talk about equipment.
Good job explaining the ED non ED information. What a lot of great information. Thanks Ken, well done.
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