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Thread: What scope should i buy for deepsky imaging?

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    Default Re: What scope should i buy for deepsky imaging?



    Thanks you answered some of the questions i will be having when i buy my new setup..
    Skyquest XT6, Skyquest XT12I

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    Default Re: What scope should i buy for deepsky imaging?

    Hi folks,

    Nice to see some activity here. Sorry for all the typo's I make. Some more things cross my mind to mention, I hope may be useful.

    If you are comfortable with collimation, and I mean presicse collimation -folded optics like the newt's, R/C's, and Cat's are fine scopes, and if you are after getting some detail in truely remote objects like most galaxies, (and the smaller planetary and globs in our own galaxy) they (larger mirrored scopes) are the only game in town unless you are wealthy or have a large pile of 'extra' money. By detail I mean that it will occupy the majority (over 50%) of your image area. I cannot stress enough - when it comes to collimation, what was 'good enough' for visual might not be good enough for imaging - this depends on how critical you are. Collimation is not a black art. Whatever scope you have has it's drill you must learn. Once learned, you just dial in when necessary. I've owned some scopes somewhat immune to needing recollimation, others that were fairly sensitive and needed more frequently - it was/is all in the cells and spiders or what have you. There are or may be some tweaks you might need to consider to firm up the various parts to not move even a fraction of a mm once collimated, but that is part of the fun of owning them. So summing up, nothing to fear, but if you move the OTA frequently and it's 'sensitive', keep that in mind. You will be in the twilight with your collimation tools 'dialing it in'... or getting questionable sub exposures that may not be 'fixable'.

    Another thing is focusing and focusers - this on any optic. For imaging you NEED a great focuser. What makes one great vs. good? Part ofm it depends on the speed of you optics and the critical focus region. Faster the optic, the more that tightens up. Dual speed is pretty essential. So think hard that you want a focuser that has absolutely no 'slop' or 'play' for your imager. Next is that because a great focuser has no slop or play that it will hold your imager rock solid in the focal plane while your scope tracks over the sky at different angles. If the focuser cannot do this - you'll be tossing subs again. Maybe the critical thig to take away from what I mean here is that the focuser needs to tote your imager, (and DO NOT forget you will need a coma corrector, maybe a reducer flattener, nearly all need something for curvature) and the larger the load, the more robust it will need to be. It is a common 'needed' upgrade to some of the less expensive folded optics, especially the Newt's. MoonLite and FeatherTouch make great focusers. Don't feel cheated if you need to get one, there is a reason the less expensive scopes are less expensive - they have to cut a coner here or there, the great thing IMO is that there is so much available today to use - it is a great time for us Lots of folks selling into the market like these folks and many others.

    Learning imaging. For a minute let's forget calibration and processing and concentrate on getting 'keeper' sub exposures. Not sure how to introduce the concept, but there is an ideal scope for any object, and most objects are different. A small galaxy, a large nebula... what is a great scope for one isn't for the other. A great scope for galaxies. A great scope for large nebula. If you have only one imaging scope you will have to settle. Neither will be bad for both in a sense. The galaxy scope will be good for nebula detal (maybe just a part of the overall), the widefield nebula will be good for widefield galaxies (though maybe little detail in them). This might seem trivial, just get two scopes A short widefield for nebula and a large apeture for galaxies. Use one for imaging and one for tracking. So the conversation moves to mounting two scopes. You might see these thing called 3-point rings for mounting your smaller guidescope piggyback. Stay away from them. Get solid rings. Your guidescope does not need to be exactly centered on the object. My piggyback setups have always been as rigidly mounted as possible.

    What you say? All I can offer for proof is this and many others images.

    At the heart of this is "think system". No particular component is more important in a well thought out system, that they all work together without pushing the limits is all that matters. This is true tooth to tail - from the imager used and the focuser it is on (do not make the mistake of thinking same not true for you guidescope) to the mount that is pointing and tracking it all. Details everwhere, all matter. I'd say if you want to spend large (in a comparative sense) do it on your mount, it is the possibly most critical 'component' in the system that going larger and better than you think you need makes sense. Skimping on the mount you will become an expert at 'trying to image', and I think that sends many folks packing or becoming tweaking experts while loosing major chunks of what may be rare clear sky imaging time. I want to add that you tripod or pier is just as important, the old construction addage... "build a good foundation before you build the structure".

    I'm not saying you won't need to learn your gear in ways you never imagined - you will. You can have a very decent setup and have the autoguiding screwed up and... This business of pointing at things a zillion miles away iand it not drifting -even one pixel - is not for the faint of heart, and possibly more true for those with little to no patience. Don't be cavalier about any of it starting with your initial choices - there is no system to beat here. If you start making spreadsheets of details in the respective components and your head hurt's... good! If you think the imaging side of the hobby is 'spendy' or 'expensive' to jump into, that is nothing compared to if you need to buy things two or three times! to get it right. From my woodworking... "Sheesh -I don't know what is wrong here, I've cut this thing three times and it's still to small!"

    So think 'well balanced system', whatever your requirements. You WILL get sub exposures that are 'keepers'. And it wont be by accident or 'this time it worked'. It will be consistent, reliable.... that is once you understand and dial in autoguiding and the imporatnce of good Polar Alignment. again... not visual good, imaging good.

    Then the pendulum swings! you can start learning about processing and post processing Here I just want to emphasize again... tweaking poor images in post processing is IMO a time waster. You want to learn how to process good data - it's a different animal. Getting to where you reliably get useable sub exposures, even with good gear choices - takes some patience, but it's well rewarded.

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