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Post by Deleted on Jul 23, 2017 22:18:27 GMT
Hello everybody, Just looking for some advise on a nagging issue I've got with my current scope set up. For the past year I've been using a 8" Celestron Evolution scope and a Revolution R2 imager. For the most part, once I figured out some of the basic function settings of the camera, I started to get some pretty cool images of the planets, star clusters, nebulae, etc. I think my biggest problem is that I'm not getting the accuracy I need when using the 3-star alignment method to configure the scope's go-to system. When I'm observing through regular eyepieces, I get the targets centered close enough to be seen in a 40mm or even 25mm eyepiece. I might have to make a few adjustments, but it's usually within the field of view when my scope slews to the next object using the go-to system. My problems seem to arise when switching to the R2 imager as I can never seem to get the target image I want within the camera field of view without putzing around with the scopes hand controller to try to center my target in the camera's view. So I guess I'm looking for tips in getting more accurate when calibrating the scope's go-to system. Would switching out the scope's crappy red dot finder help at all with accuracy? I seemed to have a bit easier time before my go-to scope days when I had a slightly magnified finder scope with crosshairs. A saw Celestrons 9X50 illuminated scope online (see link) but I thought that would be way too bulky, and, frankly too much power for what I would need it to do. But I did like the idea of a right angle corrected image so that I don't have to contort my neck/head into an impossible posture just trying to get any given object into the crosshairs. Another part of me is thinking that a new finder scope really wouldn't do much and I just have to do a better job getting targets dead center in my eyepiece before committing them during the 3-star alignment. Any advise you might have would be much appreciated before I decide on buying any additional equipment. Thanks!
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Post by howie1 on Jul 23, 2017 22:35:41 GMT
Hey Marty, the answer lies in when you say with the 3 star you get the targets centered close enough to be seen in 40mm or 25mm eyepiece. The R2 sensor diagonal measurement is only 5mm or so ... so it is like putting a 5mm eyepiece into your scope. IE 5 times more magnification than putting in your 25mm eyepiece. Or to put it yet another way, 5 times narrower field of view than your 25mm eyepiece. So your gotos have to be really spot on to 'find it' with the (5mm like) camera.
Hope you get what I put up above.
Anyway, on to how to make that goto better ... most mounts including your celestron have a "Sync" process. I think that is actually what Celestron call it so check the manual out in detail and you should find it in there. Sync'ing allows you to slew to a bright star in the constellation where your target object is so being bright it is visible in any finder be it red dot, or 50mm finder, or laser. You centre it when the 'Sync" routine tells you to. Once done it makes the accuracy of that constellations objects much, much tighter than it originally was. So once done, slew to your small/dim object and the go to should be much better able to put it into the FOV of the R2 camera.
Cheers Howie
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Post by ChrisV on Jul 24, 2017 0:37:42 GMT
Also. Are only using the red dot finder for the alignment ? You need to centre it with the RDF, then the image from the 224 camera.
Do the 2star alignment with all 3 (or is it 4) calibration stars And use focal reduction. I used to use a C8 with the 1st version of the RI - it really needed the 0.5x focal reduction otherwise very difficult with the small fov.
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Post by Deleted on Jul 24, 2017 4:50:30 GMT
Hey Marty, the answer lies in when you say with the 3 star you get the targets centered close enough to be seen in 40mm or 25mm eyepiece. The R2 sensor diagonal measurement is only 5mm or so ... so it is like putting a 5mm eyepiece into your scope. IE 5 times more magnification than putting in your 25mm eyepiece. Or to put it yet another way, 5 times narrower field of view than your 25mm eyepiece. So your gotos have to be really spot on to 'find it' with the (5mm like) camera. Hope you get what I put up above. Anyway, on to how to make that goto better ... most mounts including your celestron have a "Sync" process. I think that is actually what Celestron call it so check the manual out in detail and you should find it in there. Sync'ing allows you to slew to a bright star in the constellation where your target object is so being bright it is visible in any finder be it red dot, or 50mm finder, or laser. You centre it when the 'Sync" routine tells you to. Once done it makes the accuracy of that constellations objects much, much tighter than it originally was. So once done, slew to your small/dim object and the go to should be much better able to put it into the FOV of the R2 camera. Cheers Howie Howie, Yes, that made a lot of sense. It got me thinking that perhaps I should try calibrating the scope's goto system while using a 10mm eyepiece and a 2x Barlow to truly center the object. That would more closely simulate what the R2 is going to see when I swap it in for the eyepieces. I think the sync process that you're describing sounds like a much more precise process when it comes to browsing a particular constellation. The calibration process I've been using is done linking my iPad with SkySafari Pro to the scope's wifi signal. It has me picking three bright star objects anywhere in the sky and then controlling the scope via iPad wirelessly. My problem, I suppose, comes from me just ballparking a centered object through a 40mm eyepiece and entering it in as centered when it really isn't dead center. That would account for me seeing a whole lot of nothing trying to use the R2 at times. To be honest I got the R2 mostly for my 5-year old son and his cousins (all under 10) who often lack the touch and patience for viewing objects via an eyepiece. This way I could have them gather around the R2's monitor and they could all see cool things at the same time without having to take turns at the eyepiece. But as I got a bit more of a experience with the R2 I began to see it as a pretty good tool for astrophotography (that would be my next endeavor). But before I get into that, I wanted to get a bit more accurate with alignment of the goto system. Thanks again for your help. Marty
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Post by Deleted on Jul 24, 2017 5:10:29 GMT
Also. Are only using the red dot finder for the alignment ? You need to centre it with the RDF, then the image from the 224 camera. Do the 2star alignment with all 3 (or is it 4) calibration stars And use focal reduction. I used to use a C8 with the 1st version of the RI - it really needed the 0.5x focal reduction otherwise very difficult with the small fov. Hi Chris, No, I'm using the finder to get the bright star objects within the field of view of my eyepieces. I just didn't realize that the R2 is essentially a digital version of a 5mm eyepiece. I had been using a 40mm to "center" the bright star objects in my attempts at centering the scope. I just find the RDF a bit tricky since the dot itself obscures some of the bright objects that I'm trying to lock onto. Plus, some of these objects are high in the sky making it difficult to crouch under the scope and try to get a bead on objects. I do have the 0.5x focal reducer that came with the R2. I've just been less apt to use it since I usually use the R2 to display planets. Also I've found that the R2 with the long snout AND the focal reducer attached butt right up against the mirror on my star diagonal and I'm afraid that over time this contact might damage my star diagonal. You lost me on the reference to a 224 camera. Did you mean R2? Anyhow, thanks for your patience with a newbie and thanks for your help. Marty
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Post by ChrisV on Jul 24, 2017 5:41:45 GMT
The RDF might be a bit tricky for alignment as it has no magnfiication. So even when centred on the RDF it might not be in view with your camera. The C8 has a really small fov with that camera, especially if you dont have focal reduction. So use a focal reducer for DSOs - the C8 can handle a lot of reduction with a 224-based camera. I usually used a meade f3.3 - made it really fast and gave a reasonable fov.
224 - sorry. I meant the zwo asi224. Its much flatter than the RI camera with the 224 sensor. I see that you need the diagonal to get enough clearance from the base of the evo mount. I didn't have that problem as I've only used EQ mounts
We are all newbies. The one thing I've continually found is that I continually find there's so much I don't know ... continually!
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Post by davy on Jul 24, 2017 6:27:04 GMT
When I started, I had the same issues,, trying to focus a Samsung scb2000,, what I used was a flip mirror, I could leave my camera fitted and use a 25mm ep to check my view, then swap it with a 6mm EP to help focus the camera
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Post by davy on Jul 24, 2017 6:31:57 GMT
The trusty old scb with a flip mirror
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Post by howie1 on Jul 24, 2017 7:11:27 GMT
...... It has me picking three bright star objects anywhere in the sky and then controlling the scope via iPad wirelessly. My problem, I suppose, comes from me just ballparking a centered object through a 40mm eyepiece and entering it in as centered when it really isn't dead center. That would account for me seeing a whole lot of nothing trying to use the R2 at times. Errr no. Even if you absolutely dead centered your alignment stars, the GoTo's would still have some errors. It's an unfortunate result of the combination of gears, motor pulses, and the software which has to do some freaky calculations to it's internal star map whenever you do an alignment. The "sync" function is done totally separate to the alignment process, and is specifically designed to help you find stuff in those areas of the sky where you have done a goto, but due those gear/motor/calc errors you cannot see the object. If you slewed to an object and its in the FOV of your R2 then you wouldnt do a "sync" on it. Read the manual. Cos what I said is true ... no matter how good an alignment you did there are always going to be goto's which are not in the FOV. The "Sync" will help save you heaps of frustration. Cheers
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Post by howie1 on Jul 24, 2017 7:17:48 GMT
Oh yeah ... nearly forgot ... a simple trick in centering more precisely with your 40mm or your 25mm eyepiece is simply to defocus the star so it becomes a big round blob. Much easier to centre a big round blob in the FOV. Your eye can easily judge the annulus around the edge of that big round blob to the FOV as offset to one side or the other.
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Post by howie1 on Jul 24, 2017 7:38:03 GMT
I just find the RDF a bit tricky since the dot itself obscures some of the bright objects that I'm trying to lock onto. Plus, some of these objects are high in the sky making it difficult to crouch under the scope and try to get a bead on objects. Join an astronomy club so you can legally buy a laser finder. Looks like a thick pen but with nice straight edges. Hold it by hand against the tube and with its edge up against the finder 'foot' plate which is screwed to your evolution ... and just standing there beside the scope you will see up in the sky where its pointing. There's heaps of specialised laser finder 'holder's which will mount in your tubes finder shoe if you wish. And for your kids, you can stand and point out the stuff in the sky where you are about to go 'see'. Just dont let them get hold of it ... eyesight is a precious thing. The astro club might cost you 20 or 30 bucks but you'll meet some interesting folk. And get good tips. If there's no local astro club then email one ... they wont knock you back even if you are way out in the sticks ... they like cash!! The laser will cost you $20 off eBay or $60 off celestron or whoever still carries them. Why join the club ... well the local coppers sometimes see them and freak out about you trying to shine on airplanes and bring them down by blinding the pilots n such. If they visit (a) they will see your scope (b) you can show them your paid up membership receipt (print it out) and (c) with your words about being responsible astronomy etc etc they will most likely then ask you to show them some stuff too!
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Post by davy on Jul 24, 2017 9:41:26 GMT
I just find the RDF a bit tricky since the dot itself obscures some of the bright objects that I'm trying to lock onto. Plus, some of these objects are high in the sky making it difficult to crouch under the scope and try to get a bead on objects. Join an astronomy club so you can legally buy a laser finder. Looks like a thick pen but with nice straight edges. Hold it by hand against the tube and with its edge up against the finder 'foot' plate which is screwed to your evolution ... and just standing there beside the scope you will see up in the sky where its pointing. There's heaps of specialised laser finder 'holder's which will mount in your tubes finder shoe if you wish. And for your kids, you can stand and point out the stuff in the sky where you are about to go 'see'. Just dont let them get hold of it ... eyesight is a precious thing. The astro club might cost you 20 or 30 bucks but you'll meet some interesting folk. And get good tips. If there's no local astro club then email one ... they wont knock you back even if you are way out in the sticks ... they like cash!! The laser will cost you $20 off eBay or $60 off celestron or whoever still carries them. Why join the club ... well the local coppers sometimes see them and freak out about you trying to shine on airplanes and bring them down by blinding the pilots n such. If they visit (a) they will see your scope (b) you can show them your paid up membership receipt (print it out) and (c) with your words about being responsible astronomy etc etc they will most likely then ask you to show them some stuff too! Or just send me 20 to 30 bucks and I'll give you advice ,,lol,😂
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Post by Dragon Man on Jul 24, 2017 14:25:38 GMT
Marty, I have to ask: Why are you using eyepieces to do your alignment? I always use the camera for my 3 star alignment. If you want to observe with the camera, use it for the alignment too.
The chances of the exact centre of an Eyepiece FOV and the exact centre of the cameras FOV being the same is slim.
I do absolute Polar Alignment, use a camera for 3 star alignment, and even then the Gotos can be slightly off. But because I align using the camera, the object is just on the edge of the FOV at worst. But often near or at centre. As Howie has mentioned, the mechanical aspects (gears, motors, etc) prevent perfect Goto's every time. But they are usually close.
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elpajare
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Post by elpajare on Jul 24, 2017 16:23:54 GMT
I use the same procedure as Ken. I have had a lot of problems finding stars and objects too.....until now. Use a metallic finder with TWO brackets, SIX screws and LED illumination (with a diagonal if you need it) and use the camera to center stars not the ocular. I use a finder like this: www.astroshop.eu/explore-scientific-8x50-illuminated-finder-scope/p,51986
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Post by Deleted on Jul 24, 2017 23:06:47 GMT
Marty, I have to ask: Why are you using eyepieces to do your alignment? I always use the camera for my 3 star alignment. If you want to observe with the camera, use it for the alignment too. The chances of the exact centre of an Eyepiece FOV and the exact centre of the cameras FOV being the same is slim. I do absolute Polar Alignment, use a camera for 3 star alignment, and even then the Gotos can be slightly off. But because I align using the camera, the object is just on the edge of the FOV at worst. But often near or at centre. As Howie has mentioned, the mechanical aspects (gears, motors, etc) prevent perfect Goto's every time. But they are usually close. If it were just me viewing, I'd prefer using eyepieces. I just like the optical quality and the lack of a mess of wires hanging from the back end of my scope. I got the R2 primarily as a way to display things on a monitor for my son and his young cousins so they didn't have to jockey for eyepiece time and mostly since they lack the knack for seeing things properly through an eyepiece (especially at higher magnification). But as I've used the camera a bit more lately simply because I can see things that the eyepieces simply can't see. Typically I go out there first, set up the scope, align it, view a few test targets through eyepieces and then the stampede of kids come. That's when I usually switch to the R2. Then, when the crowd thins, I go back to the eyepieces. Just as an aside, I'd like to thank you for the alternative wiring that you rigged up for the Revolution Imager on YouTube. Once I got the replacement wires it did cut down a bit on the Borg-like mess of wires protruding from the back of the scope.
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Post by Deleted on Jul 24, 2017 23:11:45 GMT
Join an astronomy club so you can legally buy a laser finder. Looks like a thick pen but with nice straight edges. Hold it by hand against the tube and with its edge up against the finder 'foot' plate which is screwed to your evolution ... and just standing there beside the scope you will see up in the sky where its pointing. There's heaps of specialised laser finder 'holder's which will mount in your tubes finder shoe if you wish. And for your kids, you can stand and point out the stuff in the sky where you are about to go 'see'. Just dont let them get hold of it ... eyesight is a precious thing. The astro club might cost you 20 or 30 bucks but you'll meet some interesting folk. And get good tips. If there's no local astro club then email one ... they wont knock you back even if you are way out in the sticks ... they like cash!! The laser will cost you $20 off eBay or $60 off celestron or whoever still carries them. Why join the club ... well the local coppers sometimes see them and freak out about you trying to shine on airplanes and bring them down by blinding the pilots n such. If they visit (a) they will see your scope (b) you can show them your paid up membership receipt (print it out) and (c) with your words about being responsible astronomy etc etc they will most likely then ask you to show them some stuff too! I do indeed have a GLP. Got it years ago before they were, em, weaponized. But I had never thought of using it on a bracket as an alternative to the RDF. I had mostly used it as originally intended, to point out the general spot that we were looking at, or to help people spot the ISS or other satellites as they passed over. So, thanks for the suggestion. That gives me more options.
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Post by Deleted on Jul 24, 2017 23:14:53 GMT
Oh yeah ... nearly forgot ... a simple trick in centering more precisely with your 40mm or your 25mm eyepiece is simply to defocus the star so it becomes a big round blob. Much easier to centre a big round blob in the FOV. Your eye can easily judge the annulus around the edge of that big round blob to the FOV as offset to one side or the other. Great tip! Thank you! I would have never thought of that.
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Post by Deleted on Jul 24, 2017 23:20:14 GMT
The trusty old scb with a flip mirror Another great idea. Thanks!
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Post by Dragon Man on Jul 25, 2017 10:37:26 GMT
Just as an aside, I'd like to thank you for the alternative wiring that you rigged up for the Revolution Imager on YouTube. Once I got the replacement wires it did cut down a bit on the Borg-like mess of wires protruding from the back of the scope. Your very welcome. It's pleasing to know that people watch my videos and get something out of them Makes it worthwhile making them
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robrj
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Post by robrj on Jul 25, 2017 17:35:00 GMT
Have you ever tried "Precise Goto"? It works great and is built into the Celestron mount. It's not documented in the manual that comes with the scope but it should be there.
You get to it with your "Menu" key instead of using the "Deep Sky" key. You'll be presented with a list of 5 brighter stars near the object of interest. They're usually bright enough to be seen with a red dot finder. Put the scope on the star using the finder then center it in the camera. Then press "Enter". The scope will slew to the object and usually put it in the camera's field of view. The menu key on my 130SLT is the #7.
Here's a video tutorial of it:
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