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Post by shannon on Jun 26, 2019 20:39:07 GMT
Hi, all. This is my first real post. I have become intrigued with the idea of video astronomy, and hope to acquire equipment and get started soon. I have spent a fair amount of time reading, trying to decide on my initial equipment purchases. My goals are to use my gear for live or near-live viewing. I am interested in viewing nearly anything in the night sky, but DSOs would be my greatest interest. Really, I'll just be happy to see whatever is out there! I would like for my equipment to be pretty light, and I would like for my monetary investment to initially be modest. If I enjoy myself and gain sufficient skill, I can invest in more expensive equipment at a later date. With that in mind, here is what I am thinking:
Telescope: 80 or 90 mm achromatic refractor (with the appropriate filters). I'm considering the Meade Infinity 90 AZ. It is a 600 mm F/6.7 scope. I figure with a 0.5 focal reducer and a 2x Barlow, it should offer some versatility and decent views. The OTA weighs 4 pounds, so wouldn't need a humongous mount. The mount that is supplied would be handy for terrestrial use or a quick peek at the moon, too! I have also considered the Celestron Omni XLT 102 AZ refractor, and the Celestron AstroMaster 80 mm refractor. The Omni 102 gives more aperture but is bulkier, and the AstroMaster is lighter and faster, but the Meade 90 mm seems a good compromise.
Mount: Given the light weights of the scopes I'm considering, I'm looking at the Explore Scientific iExos-100 EQ mount and the iOptron Cube Pro AZ mount. The iExos has a slightly higher weight capacity, but the iOptron includes GPS and doesn't require messing with polar alignment. I'm hoping that, for live viewing, field rotation won't be a huge issue, and can be mitigated somewhat through software.
Camera: Right now, the ZWO ASI224 looks like a good choice. I have a laptop and a Microsoft Surface, either of which could run the necessary software. From all I can gather from reading, this seems to be a fairly versatile camera.
So, what do you think? Meade Infinity 90 AZ plus iOptron CubePro plus ASI224 looks like my working target. What suggestions would you make? Any big pitfalls I'm not seeing?
Thanks for your insight!
Shannon
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Post by howie1 on Jun 27, 2019 2:00:59 GMT
Congrats, that's a great "recipe" for getting into VA. IE A 224 sensored camera on an Alt Az mount with a low'ish F ratio refractor combined with a reducer and barlow. Tried and proven to work. I always forget this but Dragonman (Ken) on this forum knows a cheap yellow filter (I think it was) which does a great job at curing the achromat color fringing.
On it being the tried and proven "recipe" then IMHO do not try to save money on other IMX224 sensor cameras from other (cheaper) brands. Invariably the software to control and stack will be different. The software has a big learning curve! You will have to seek help for how to use it! ZWO cameras use SharpCap which has heaps of users and there are forums with some help files on how to use it as a beginner. IMO there's very little help if using other software.
Derotation .... yes software will derotate each frame in a stack overlaying pixel for equivalent pixel in successive frames. But if you shoot too long exposures so every frame has star trailing, no amount of stacking will sharpen the stars as every frame contains star trails. When you are shooting short enough that every frame has sharp stars, then every frame will have sharp stars in slightly different positions (due to field rotation). So stacking will derotate each and every frame and the final image is a stack of sharp stars ... as every frame had sharp stars.
I'd suggest noting down the Alt and Az and (sharp stars - no trailing) single exposure time for objects when you start using your new kit. The aim being to get a table/chart of the longest exp time for that part of the sky (As different Alts and Az have different degrees of field rotation). So in future when you go out you can save heaps of time! That's the benefit of doing this table creation ... IE you are then able to goto some new target object you've never done before, then use the mounts menu to find its position, then lookup the alt and az on your table of max exp times possible and bobs your uncle! Set it and start stacking right from the first frame.
Cheers
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Post by Dragon Man on Jun 27, 2019 12:20:59 GMT
I always forget this but Dragonman (Ken) on this forum knows a cheap yellow filter (I think it was) which does a great job at curing the achromat color fringing. Good choices Shannon. Yes Howie, that was me who did a thread about conquering the problem of Violet Fringing and Chromatic Aberration in Achromats for Video work. You were 'almost' correct. The Yellow filters work great on CCD sensors, but the 224 has a CMOS sensor which the yellow filters don't work well, BUT! a Minus Violet Filter or a UHC Filter does the same corrections with CMOS This was tested again just this week when one of our club members was using his new 120 f/5 Achromat and when he went to Trifid Nebula the stars had enormous Violet haloes. I didn't have any spare Minus Violet Filters for him to use so I gave him a Yellow to try (knowing it wouldn't work well, but it was a great chance to show him what works and what doesn't). The Yellow didn't work (because he was using a CMOS 224 camera) but when I gave him a UHC filter (Link: www.astronomik.com/en/visual-filters/uhc-filter.html ) to use it completely cleaned up the stars, and the colour balance of the Nebula itself. Note: You will still need to use an IR cut filter. Here's my thread on it (mainly concentrated on Yellow filters used with CCD sensors but with a footnote about CMOS: astrovideoforum.proboards.com/thread/1079/using-achromats-video
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Post by shannon on Jun 27, 2019 17:47:55 GMT
Thank you, Howie and Ken! I appreciate the advice.
Now, I just have to save my pennies for a little while!
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Post by shannon on Jun 28, 2019 15:31:07 GMT
Analysis paralysis is a terrible thing (you should see me trying to decide on which guitar string to buy).
I am now considering the Orion StarSeeker 130mm Newtonian scope (630 focal length, F/5). It gives more aperture and avoids chromatic aberration. I don't mind collimating periodically. It comes with a GoTO mount that seems to get good reviews. I have sent an email to Orion asking if it has sufficient focus travel.
Assuming it has sufficient focus travel, is there any reason this scope wouldn't be okay?
Shannon
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Post by Dragon Man on Jun 28, 2019 18:32:18 GMT
Shannon, you may find with such a small aperture Fast Newtonian that you may need a Field Flattener. Coma-like curvature in these scopes is horrendous. Also, you may discover that it won't reach focus with a Focal Reducer. That's the main hassle with Newtonians. Look into if it will reach focus with a 0.5x focal reducer. Most won't. Some can be used with a Negative adaptor. But give it a try. The small sensor in a 224 camera might not need a field flattener as it only uses the small portion of the centre of the optics. The Coma effect is in the outer third of the FOV. Also be aware that when you do use a Focal Reducer in a Newtonian that the Petzval field curvature becomes increasingly worse. The shorter the Focal length the worse the curvature becomes. Don't let me put you off, there's Happy times ahead
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Post by shannon on Jun 28, 2019 20:12:38 GMT
Thanks for the information. It does not discourage me, and it is exactly the kind of experienced know-how I was hoping for!
Shannon
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Post by davy.... Shirva.. on Jun 28, 2019 20:20:26 GMT
Hi Shannon. I've left the guys to give you advice on what equipment you have looked at. And the guys are spot on as usual.. First thing about video astronomy is ,, it's completely nut's We go against the grain,, lol.
What we do,, can and is done in many different ways and techniques. You can go full video and be a visual astronomer,, just looking at near live or live views without recording images. To be fair most like a keepsake of a great night and do a capture,, I used to lol but now like just pottering around.
Equipment wise,, every body has there favourite piece of kit,, Starting off with the mount,, Buy the best you can and use two thirds of your budget on it... Skimp on it at your peril.. What type... Stick to what is tried and trusted.. for me, my advice an heq5 pro..I wish I had this from day one but I was piss poor and recovering from a messy divorce,, lol.. is there any other kind π
Heq5 solid bit of kit..and minimum I would recommend,, get that or its big brother eq6 if you know Astronomy is what you want to do,, if you want to get out again,, this mount holds its money.
Az or eq,, az has came a long way,, but for versatility,,eq all the way,, my personal views,, I have both and eq is my recommendation if you are thinking big rig, twin scopes,, multiple camera's ect Az on big scopes,, grand and a half jobs ok,, couple of hundred pounds one,, limited for upgrading.
Scopes. No one scope does it all we say,,. Years ago,, but with changes in camera technology not much in it. What I would say is,,let what you wish to capture be the benchmark. Everyone has or gets aperture fever,, think it started off by telescope manufacturers,, this one gathers 20% more light than this one,, next one gathers , x , more and so on. And it's true,, to a point. Lots of us use small fast refractors ,, because video doesn't require massive scopes,, were speed merchants that want a big field of view,, it can be a trade off at times,, but will come down to personal taste on the view you like. Look at images,, determine what you like,, see what equipment was used to capture it,, and hopefully it wasn't done from a total dark zone that you will never see in your puff.
That's where add on equipment like filters become very very useful π.
Camera.. identify a scope ,then use simulation software to determine what view you will get with a camera,, bit more research... Then ask folk what they think.. and the pieces of the puzzle comes together.
Me,, several scopes Skywatcher explorer 200pds Skywatcher evostar ed80 pro with 0.85 flatner/reducer
Mounts Heq5 pro,, with Skywatcher WiFi adapter Still to fit Rowan belt mod π Eq3 pro Az gti Star adventurer Eq2 with simple clock drive
Camera's Canon Eos 600d. X2 Canon Eos 450d modded Canon Eos 4000d Zwo Asian 178 MC Watec 902h analogue cameras Samsung mooded CCTV cameras,,, a few π Three laptops 10 miles of cables π.
Ps,, Disregard all of above,, experiment π it's part of the fun Davy
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Post by shannon on Jun 29, 2019 23:59:19 GMT
Shannon, you may find with such a small aperture Fast Newtonian that you may need a Field Flattener. Coma-like curvature in these scopes is horrendous. Also, you may discover that it won't reach focus with a Focal Reducer. That's the main hassle with Newtonians. Look into if it will reach focus with a 0.5x focal reducer. Most won't. Some can be used with a Negative adaptor. But give it a try. The small sensor in a 224 camera might not need a field flattener as it only uses the small portion of the centre of the optics. The Coma effect is in the outer third of the FOV. Also be aware that when you do use a Focal Reducer in a Newtonian that the Petzval field curvature becomes increasingly worse. The shorter the Focal length the worse the curvature becomes. Don't let me put you off, there's Happy times ahead The folks at Orion answered an email and said I might indeed have trouble focusing with that scope. What about scopes labeled as βastrographsβ? Astronomics sells a 6 in 610mm f/4 that is fairly light weight, and is apparently designed for use with cameras. www.astronomics.com/astro-tech-6-f-4-imaging-newtonian-optical-tube.html?___SID=U . Would a scope such as this offer any significant advantages over the 90mm achromatic refractor I have been considering, other than avoiding CA? Would it even need a focal reducer?
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Post by davy.... Shirva.. on Jun 30, 2019 3:01:16 GMT
Looks a good price and a decent scope and you can achieve focus, definitely gives you options, CA tough one,, I had a Skywatcher 102mm refractor and a lot of folk wrote the CA was bad,, me I didn't think it was a big issue,, maybe I got a good one lol, I got great views with it,, I bought the Skywatcher evostar ed80 pro with the 0.85 Skywatcher matched focal reducer flatner and bang for buck I don't think you can go wrong with this scope,,I upgraded the focuser and it made it even better,, brilliant scope and that to my Skywatcher explorer 8' Newtonian,, cover's all I could want... By looks of things I think two scopes are the way to go for you,, starting off I would go for the Newtonian first,, think I detected aperture fever lol
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Post by Dragon Man on Jun 30, 2019 7:10:46 GMT
Yes Shannon, an Astrograph is a telescope designed for use with cameras. It will alleviate most of the problems.
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Post by shannon on Jul 1, 2019 2:56:47 GMT
Davy, I agree that I will wind up a two-scope guy. I don't want to spend a ton of money, and it appears that spending a ton isn't necessary. I also gather that huge aperture isn't a huge consideration when doing video astronomy.
So now, I'm thinking about something like a Celestron C90 (1250mm f/13 Mak) for lunar and planets. Since Jupiter, Saturn, Mars, etc are small and bright, I figure I don't need a fast scope and the small FOV would be an advantage. Then, something like a short tube 80mm refractor. With a focal reducer and a 2x Barlow, that should be versatile for DSOs. I could pick the appropriate scope for whatever I wanted to view on a particular night, and I shouldn't need a humongous mount.
Birthday's in August, so maybe I can get started soon ...
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Post by davy.... Shirva.. on Jul 1, 2019 6:25:26 GMT
I observed Jupiter when I first got into Astronomy with my etx80 I had its built in Barlow on and another x2 Barlow,, it was a struggle,, granted I never had a camera on it,, for me I would want a bigger aperture and slow scope to do planets,, A mak may be the way to go,, but keep looking at images and equipment to narrow down what you like best
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