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Post by metro on Jan 6, 2019 6:27:52 GMT
I know many say for serious long exposure astrophotography as a rule of thumb you should have no more than 50% of the rated capacity of your mount loaded while shooting, this being scope, equipment AND counterweight.
Is there a rule of thumb number for video astronomy? What kind of weights are y'all running compared to your mounts max load number?
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Post by davy on Jan 6, 2019 10:23:39 GMT
Lol... I usually over do it.. I used to have a 200mm newt on an eq3 pro,, lit of folk said it could not be done,, I added a lot more weight to get perfect balance and never had legs extended,, worked fine in an enclosed garden with no cross wind.. Mounts are designed to a higher payload capacity than documentation says,, but it's safer to stick close to max payload
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Post by metro on Jan 6, 2019 11:20:14 GMT
And you were getting decent images as long as they were not extended exposures?
An 8 inch Newt is gonna be at least 16-17 lbs right? Add on camera and finder scope and you're pushing 20 + lbs. So you had way more than double the capacity?
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Post by Dragon Man on Jan 6, 2019 11:59:12 GMT
Metro, because Video Astronomy isn't as finicky or as demanding and temperamental as Astrophotography we can get away with a lot. Due to the super sensitive chips and shorter exposure times: there's no need for guiding, there's no need for absolute mount balance, there's no need for anti-vibration pads, there's no need to panic is someone (or some pet dog/cat) knocks the mount, there's no need for absolute clear skies, there's no need for stacking or post-processing, if a frame doesn't work, or look good, wait a few seconds and another one will be along, and Video Astronomy is fun. In all the years I did Astrophotography I would never refer to it as fun. Enjoyable sometimes. But never 'fun'. Video is 'FUN'. It's interactive. it's pretty much instant gratification.
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Post by howie1 on Jan 6, 2019 14:54:09 GMT
Metro, I've always run my HEQ5 PRO mount at or beyond its stated carrying capacity with an 8" F/5 metal Newt + heavy DSLR + right angle corrected finder scope. It wouldn't balance ... for years I ran it unbalanced. It was actually great unbalanced ... as I simply threw on the two weights right down at the very bottom of the CW bar ... and I was done. No fussing over balance! Very quick to setup. LOL!
EAA is not astrophotography. Those rules like 1/3rd of stated carrying capacity is all you should load don't apply IMO. I've seen newbies post help questions on other forums and they get told about arcsecs per pixel! Talk about blasting newbies with nonsensical info! Doing AP ... yes ... but short exposure EAA, heck no ... not useful info for EAA.
In defense of those other forums ... poor newbs asking what kit to buy usually get every type of camera, every type of scope, every type of mount suggested. So very confusing! But ... there's a reason for them hearing everything is what they should go get. The reason is actually every type of camera, and scope, and mount can actually be used for EAA. CN has a thread to post up photos of your EAA rig. And people have posted every single type of camera, OTA and mount. Some even use manual push-to Dobs for goodness sake! Kudo's to them! They are happy ... not NASA photo of the day! But they see much more than what they see visually through the scope. They see in color and ask why is that object that color? They are happy.
cheers
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Post by ChrisV on Jan 6, 2019 22:41:36 GMT
+1. Push it. What great do you have?
Edit. Forget that. Just noticed your other thread
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Post by metro on Jan 6, 2019 22:43:33 GMT
So it seems that it may be a fun kind of challenge to stretch exposure times and see what you can take them to.
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Post by howie1 on Jan 7, 2019 2:28:07 GMT
So it seems that it may be a fun kind of challenge to stretch exposure times and see what you can take them to. Exactly. Yes its fun trying. My overloaded, unbalanced, unguided kit has gone 2 minutes 30 secs without PA/tracking errors showing up. Trouble is ... doing EAA, I dont like waiting that long for frames! My fav sweet spot with my kit is single 30 sec frames. But I also like single 15 sec frames and even less if light polluted. I've used down to single 5 sec high gain/ISO for outreach. No problem with a 8" f/5 newt (My fav scope). Just noticed your scopes which you are interested in ... hmmm!?. Might make a short video helper for you. Pictures tell much more than words. Leave it with me and I'll try to get to it today/this evening ... cheers
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Post by metro on Jan 7, 2019 2:51:27 GMT
Thanks!! Yeah now that I'm not so concerned with weight the aperture fever I come down with has me thinking about the Orion 10 inch Newtonian Astrograph but I'll admit I may be getting a bit greedy there. The reason I was considering an 8" SCT over the 8" Newt AG is because it's shorter, lighter and I've heard sometimes Newts can get into awkward positions for viewing. Right now though I need to get acquainted with the new mount and practice polar alignments and learn the new Explore Scientific system.
Mark
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Post by howie1 on Jan 12, 2019 9:55:23 GMT
Hi metro ... here's the video on how to match camera with scope for EAA. SOrry it took a while to make. It's 30 minutes long but IMHO well worth the full viewing as it will enable to understand how it all works ... and more importantly WHY it works this way ... and why some of your camera and scope combinations MAY not work well. Cheers ...
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Post by metro on Jan 12, 2019 11:03:11 GMT
Thank you!! That was awesome! That vid should be pinned for beginners. I think I mentioned in another post that I am shying away from the Newtonian and leaning more towards the SCT because of size and weight and now all the more reason to do so. BUT, like you said, I am gonna take things slowly and master my equipment before I upgrade.
Again, thank you for taking the time to make that video and I'm sure many others down the road will appreciate it.
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Post by howie1 on Jan 12, 2019 13:12:49 GMT
Huh ? The SCT is a bad decision ... way too much magnification. The video stresses the best use of the RI R2 IMX224 camera with its reducer is on your Burgess 127mm F8 refractor. Try the FOV tool used and see for yourself. Cheers.
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Post by davy on Jan 12, 2019 21:03:44 GMT
Have to agree with Howie and it's on my personal taste,, I would go for a refractor ,, the skywatcher ed80 is a great scope not what we do,, and I can't fault mine,, I use it more than my skywatcher explorer 200pd and it is a great scope,, I would use the guide on the first light optics
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Post by metro on Jan 12, 2019 22:41:07 GMT
Oh yeah I am gonna use the Burgess but eventually I want to move up in aperture for observing and VA.
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Post by howie1 on Jan 13, 2019 0:29:25 GMT
Oh yeah I am gonna use the Burgess but eventually I want to move up in aperture for observing and VA. Ah, thanks metro for clearing that up. If you do go the SCT route in future, then be sure to get the one which accepts hyperstar. It will bring the f/10 down to f/2 for a nice wide field, and very fast exposures. As per that video, the wide field and fast exposures will (a) help find and centre targets when your GoTo's are not bang on, and (b) allow much faster exposures which helps you 'observe' more images during the evening. (also far less wait time if you show your family and friends or do any outreach). As per the video, just use the software to zoom in on small stuff. And again as per the video, take the hyperstar off and at f/10 you can do planets with the SCT native high magnification. And like you said, the larger aperture will be better if and when you stick eyepieces into the SCT to do visual observing. BTW, as usual there's multiple ways to skin a cat, and especially multiple ways to do EAA! LOL. So, some will tell you dont get the hyperstar but instead 'double stack' multiple reducers on the back of a normal/non hyperstar SCT. You can get down to f/3 or even f/2 this way ... that is true ... but you have to know what you are doing in order to combine them and not get aberations in the optics. You have to get them all at the correct distance apart. You have to get them nice and orthogonal or parallel lens or again you will get stuff like focus ok on one side of the image and not the other. Yes, it is able to be done ... but it a lot of hassle. And a lot of testing at night. So in the end you will spend several nights of clear skies testing and unscrewing and retesting before it all works nicely when double stacked. It is up to you to decide whether you want all that hassle, or just fork over the money for the hyperstar which will just screw on and bingo ... you are up and running at a guaranteed f/2. cheers
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Post by metro on Jan 13, 2019 1:34:51 GMT
So the Hyperstar at a thousand bucks will take the Nexstar 8SE down to f2 and the included focal reducer in the Revolution kit will take it down to f5. Will VA with the 8SE at f5 really be that tough? I guess I'm gonna have to do some studying on the simulator you mentioned.
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Post by howie1 on Jan 13, 2019 3:28:50 GMT
So the Hyperstar at a thousand bucks will take the Nexstar 8SE down to f2 and the included focal reducer in the Revolution kit will take it down to f5. Will VA with the 8SE at f5 really be that tough? I guess I'm gonna have to do some studying on the simulator you mentioned. I'll leave you to use that web FOV calculator to see the difference in how many targets you can 'see' at f/5 compared to at f/2. Have fun. The difference between f/5 and f/2 in exposure time is BIG though. As per the video it is not a linear scale. The rule of thumb is to divide the square of each number .... ie you are comparing f/5 with f/2 so 5x5 = 25 and 2x2=4 ... so 25/4 = about 6. So the exposure times at f/2 are 6 times faster than at f/5 to get the same image brightness. So at f/5 on some dim object you may be shooting at 20 seconds or more per frame. For the same object at f/2 you'll be shooting at 3 to 4 seconds per frame! Thus, if you are stacking 20 frames (say), you'll be waiting 400 seconds at f/5 to see a nice low noise image of the dim object ... but only 60 to 80 seconds at f/2 to see a nice low noise image of the same dim object. You may have to zoom in using the software zoom to get a more close up view of the object because the magnification is reduced at f/2 compared to f/5, but boy is the wait time shorter! And shorter means more targets in the night, and if doing outreach of showing your family and friends they don't get bored waiting 400 seconds to see it. cheers
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Post by howie1 on Jan 13, 2019 3:31:46 GMT
Also, like I said, you can double stack reducers and while that's a pain to get absolutely spot on aligned, and orthogonal etc, it is often done. Sometimes slight focus and other optical aberations dont bother a person. And it is cheaper than hyperstar. As I said up to you to decide if that might be a direction you go in the future ... and do a bit of DIY and double stack. cheers
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Post by metro on Jan 13, 2019 8:09:37 GMT
Well for now, seeing as I have more time than money and if I want a bit more aperture for observing I'll have to deal with 30 second exposures vs. 5. That is if I decide to pull the trigger on another scope. I'm still dialing in the new mount and have yet to even buy the camera setup so things may change. Who knows, maybe I'll go the opposite direction a get a small APO. I've always drooled over those little 80mm apos and the images they produce.
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Post by Dragon Man on Jan 13, 2019 9:15:22 GMT
I absolutely love using my ED80 for Video Astronomy.
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