Aces High Bulletin Board
General Forums => The O' Club => Topic started by: Tac on November 15, 2007, 09:29:40 AM
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I have had a Meade LXD55 AR6 refractor (6") for some time now but had not used it for more than moon-watching because the Autostar mount was not working properly.
Last night, to my personal humiliation, we found out it was working perfectly and the error had been mine (the cage section that rotates left/right was...backwards. sigh. no wonder the scope could never align, it was receiving signals from me telling it that south was north.. hahaha)
So.. 'first light' was good. Scope pointed nicely to the alignment stars, it centered Mars dead-on the center of a 6.5mm eyepiece while I had a 2X barlow on (i know bad choice, i just had to try it) so i was impressed with the autostar.
Now, being a retarded nooblet, I need some help with the optics and a lil' photography.
First off, even with my 2X barlow and the 6.5mm eyepiece Mars still was nothing more than a little red dot on the eyepiece. I thought the scope could at least show you the planet.
I see a red dot half the size of this guy's picture:
(http://members.aol.com/petealway/Mars-March-14-82.jpg)
I know nothing of optics so i'd like to ask you guys what I need to get to see something decent with the scope. I know most astrophotos out there are the result of CCD cameras crunching 100+ pics into one and using digital magnification to make the pretty pic
(http://k53.pbase.com/u32/jayseejay/upload/21100664.Mars090703Web.jpg)
My first guess is I need a better barlow (i see some 4X ones out there) or such.
I have a 10mpixel 'pocket' digital camera and a 6mpixel digital that uses optical lenses (not an SLR but similar) and I'll be getting the adaptor for both to slap on the scope. But before I can use the cameras I need to be able to see something decent with the naked eye I think. Or maybe ill just buy http://www.amazon.com/Meade-Deep-Imager-AutoStar-Suite/dp/B0006FRYSK/ref=pd_bbs_sr_1/103-0626835-9445431?ie=UTF8&s=electronics&qid=1195140356&sr=8-1 or http://www.amazon.com/Celestron-NexImage-Solar-System-Imager/dp/B0002X5Q72/ref=pd_bbs_3/103-0626835-9445431?ie=UTF8&s=electronics&qid=1195140356&sr=8-3
to do the job. hopefully it can work to take a few mediocre nebulae pics.
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TAC,
The rule of thumb for “useful” magnification under normal seeing conditions is about 50x per inch of aperture. For your scope that’s about a limiting magnification of 300x. In rare, perfect seeing conditions you might be able to go higher. On many nights, you won’t be able to even use 300x. You can magnify past that but it just gets blurrier with no additional information.
Your AR6 has a focal of 1219mm. with a 6.5mm eyepiece that’s 187.5x mag. With a 2x Barlow that’s 375x mag. So you are already pushing the practical magnification limit of your scope. To use higher magnification, you’d need more aperture or really, really good seeing conditions.
Mars is a tough object. It’s pretty small. Sometimes the surface is obscured by sand storms. Even at its closer approach this year (24 Dec), it’s still going to be pretty small. With a webcam (like a toucam plus Registax software) you can get some decent picture that you can enhance and enlarged. You can eek out more information from a processed wecam image that you could have seen from the eyepiece.
BTW, for planetary imaging, you are MUCH better off with a webcam type imager than a digital camera. You want to be able to catpure hundreds of sub second frames and filter out the ones blurred by atmosphere with software. That way you can stack and enhance the frames (maybe 2 frames out of every 10) that momentarily capture a bit of steady air.
Regards,
Wab
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Wabbit,
What's a good model for planet hunting? I've been surfing Amazon and checking the Meade's and other models. I know I want the computer/planet tracking stuff, but what else should i look for if I hope to take pictures?
The price range seems pretty huge so I thought I'd run it past ya
Can a good model be had for $400-500?
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Originally posted by LePaul
Wabbit,
What's a good model for planet hunting? I've been surfing Amazon and checking the Meade's and other models. I know I want the computer/planet tracking stuff, but what else should i look for if I hope to take pictures?
The price range seems pretty huge so I thought I'd run it past ya
Can a good model be had for $400-500?
Hmmm. I can only tell you what I'd get. There are so many options and so many variables to consider. You'll have to weigh yourself.
400-500$ might not be possible. However, if you are mainly wanting to do solar, lunar, planetary imaging then you want a wedge mounted, eletric drive scope but it doesn't necessarily need to be computerized. Those are mainly naked eye objects and they won't be hard to spot visually and just point the scope at them. This option allows you to find some less expensive, older used scopes that aren't computerized. If it were me, on balance, I'd go with an older, used, pre-computerized 8" SCT , with wedge and drive.
Like this (http://cgi.ebay.com/MEADE-2080-TELESCOPE-8-SCHMIDT-CASSEGRAIN_W0QQitemZ160179014803QQihZ006QQcategoryZ74929QQssPageNameZWDVWQQrdZ1QQcmdZViewItem)
(You might also check out Atromart.com)
You'll probably then want something like a Toucam webcam with adapter (~$130), Registax (Free), capture software like K3CCD or similar (shareware $?), Laptop , a good 2x barlow, a front-end mylar solar filter, eyepieces.
With that you could do enough visual, solar, lunar, planetary observing/imaging to keep you busy for years.
The computerized scopes come into usefulness when you are trying to find small, dark fuzzies like galaxies and dim nebulas. You can find those manually, people did for decades. For planetary stuff it’s not that useful. You do want an electric drive, but you don’t need computerized Go-To. That can save you some money.
Note: I used to lean slightly more towards refractors for causal users because they require less maintenance being a sealed system. But you can get more inches aperture per dollar with a reflector. And in the end, aperture is king. The main thing you have to do with a reflector is learn to align (collimate) the mirrors every so often. But it’s REALLY not that difficult.
Let me know if I can help further.
Regards,
Wab
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Some more data points for your consideration.
http://uplink.space.com/postlist.php?Cat=&Board=askastronomer
Post pics when you get it going...
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Also, here is a older discussion of some of the variables for you to consider:
linky (http://forums.hitechcreations.com/forums/showthread.php?s=&threadid=78275&highlight=telescope)
Wab
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AKWabbit, have you taken any images of Comet 17P/Holmes yet? I'm curious to see what kind of image your setup can get of this very interesting phenomenon.
I meant to get some prime focus pics through my 4" Meade but only had time to use my telephoto lens on the camera. Even so, it's clearly visible:
Canon 20D f/5 10.00s ISO 800 70-300@70mm
(http://i45.photobucket.com/albums/f93/hawk_fw/Night%20Pics/Comet17P-Holmes_Small.jpg)
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Wab,
Im a total noob when it comes to this and I dont really understand the eyepiece/magnification math yet.
I guess my concern is that no matter what I do the only thing ill ever see through the eyepiece when pointing at mars or jupiter/saturn is a little dot that I can hardly see any features through. :(
as for the camera... well, i really would like to spend more time taking pics of a nebula than a planet so I was looking at something that would let me do both.
What would you suggest I can get thats not so expensive?
I only have:
LXD55 mount (autostar 1 GOTO)
AR6 tube
Eyepieces that came with meade anniversary kit:
2X barlow
6.4mm
9.7mm
12.4mm
15mm
20mm
26mm
32mm
40mm
Blue/Red/Green/Lunar filter
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Holmes' been dimming pretty quick these last few days...
An interesting bit about it: Its halo of dust is now bigger in volume than the Sun. (http://www.ifa.hawaii.edu/faculty/jewitt/holmes.html)
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Originally posted by Tac
I guess my concern is that no matter what I do the only thing ill ever see through the eyepiece when pointing at mars or jupiter/saturn is a little dot that I can hardly see any features through. :(
I think you'll be surprised at how much better viewing Jupiter and Saturn are then Mars. Mars is pretty small.
That's a pretty nice setup you have there. With the right camera, you could get some nice results.
If you want to see something no one alive has ever seen before and likely never will again, check
out Comet 17P/Holmes (http://cometography.com/pcomets/017p.html).
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Originally posted by Tac
Wab,
Im a total noob when it comes to this and I dont really understand the eyepiece/magnification math yet.
.......
The eyepiece/ focal length math is simple. The resulting magnification is equal to the focal length of the Primary component (i.e. you front lens) divided by the focal length of your eyepiece. So looking up the focal length of your scope I saw it was 1219mm. You said you were using a 6.5mm focal length eyepiece. So that’s 1219 / 6.5 = ~187.5x. If you slapped on a 2x Barlow it simply multiplies the magnification so a 2x Barlow would make it 187.5 x 2 = 375x. So with your objective lens, 6.5mm eyepiece, with 2x Barlow you are getting 375x magnification.
As I said, Mars is a tough object even in my 12” LX200. Your view of Jupiter (best next June) or Saturn (best next Feb) will be much more impressive. I bet it does great on the moon (might consider getting a minus violet filter) and with the proper solar filter would be great on sunspots.
As for a camera that does great for both planets and deep sky stuff, that’s a difficult thing to achieve. It’s like designing a plane that is as fast as a FW190 but has the low speed maneuverability of a SpitV. If you can get a reasonably priced adapter for the camera you already have, I’d start with that. You just have to realistically understand your limitations. At first, it’s fun just to get any image at all. As you get more experience you and decide it’s something you want to stick with, you can always upgrade your equipment later. Sunspots (with a proper filter), and lunar shots are what I suggest you start with. They are big bright objects that are good to cut your teeth on. You can start getting reasonably pleasing results right off the bat.
Regards,
Wab
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Relative scales of planets as seen from Earth right now (Uranus is closer than Neptune 19:30 IIRC), with the moon on the left, magnification is 400x.
(http://farm3.static.flickr.com/2151/2035388152_c7cf275699_o.jpg)
Below Mars are Mercury, Uranus, and Neptune.
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Originally posted by ChickenHawk
AKWabbit, have you taken any images of Comet 17P/Holmes yet? I'm curious to see what kind of image your setup can get of this very interesting phenomenon.
[/IMG]
CHickenHawk,
Wow thats a cool shot. Yeah, Holmes is all the buzz now. I've been so busy last 2 months, I've hardly touched the scope. I mght get to take a peak this weekend.
I'm hoping I'll get a lot of sky time come Dec. December is pretty much going to be devoted to Mars. I want to get at least 1 really decent shot. This is the best approach we're going to get for the next 16 years. :(
Regards,
Wab
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Hehe while we're at it, another cool pic: Daylight picture of the moon's and venus' crescents next to each other (http://apod.nasa.gov/apod/ap061030.html).
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Originally posted by moot
Hehe while we're at it, another cool pic: Daylight picture of the moon's and venus' crescents next to each other (http://apod.nasa.gov/apod/ap061030.html).
Now THATS a nice one.
Wab
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Tac or anyone else here, I have an interest in space, I got a telescope about 3 years ago, The one I have is this one telescope (http://www.amazon.com/Galileo-FS-90-Mount-Reflector-Telescope/dp/B0009HNH3G). I've used it a few times but I've had a hard time understanding just how to use it to see the things I want too. It has an eye piece that turns to different settings, and it has these attachments that I have no idea how to use, 1 is called a "1.5X Erecting Eyepiece" and the other is "3X Barlow", so you guys seem to know quite a bit about telescopes so I was hoping that someone could give me some pointers on how to use it properly. I'd like to use it to see one of the planets, like the rings of Saturn, Jupiter, or Mars. So I'd really appreciate it if someone could give me some tips, thanks.
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Check http://www.astronomics.com for good deals on scopes & such. They've got a 10" Dob by Celestron for $500. Not bad considering it lists for $1,000. The majority of their stock is Orion (low-price scopes) and Celestron (medium price), with a good stock of Meade (higher-end). Though if you want to build your own from the optical tube up, you could start out with a Takahashi reflector. Make sure someone has smelling salts handy; Takahashi prices might make you pass out.
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Flakbait [Delta6]
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Boy the Meade DS-2102MAK 4" go-to Maksutov-Cassegrain looks great for the money.
Thanks for the link, Flak.
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Originally posted by LePaul
Boy the Meade DS-2102MAK 4" go-to Maksutov-Cassegrain looks great for the money.
Thanks for the link, Flak.
That looks like a fun little scope, but I would mention thats only 4" of aperture. And since its a Mak it also has a central obstruction for the secondary mirror so its not even a clear 4" of aperture like a refractor.
Resolution is directly proportional to aperture. So the image scale and possible magnification of that scope would be pretty limited. If you notice they only list it as recomended for lunar and terrestrial photograhy. I assume because it doesn't have enough resolution for the smaller planets. And with less than 4" of aperture, deep sky observing would be very challenging.
That doesn't mean you CAN'T take a picture of Saturn or Jupiter with it, but your result would be limited.
Still, if you just want a beginner scope to throw out on the patio for a quick peek, it looks like a fun scope.
$0.02,
Wab
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Originally posted by trax1
Tac or anyone else here, I have an interest in space, I got a telescope about 3 years ago, The one I have is this one
Trax1,
For beginner observers or photographers I always suggest starting with the Moon. It would be hard not to be able to find the Moon. Its big, its bright, it has a huge amount of high contrast features. It gives you something easy to find and look at while you learn about using your equipment. You can figure out how to control an position your scope, how to track an object, learn what eyepieces work best, how much magnification you can get away with, how to focus. There are a lot of interesting features to find and learn about on the Moon. More than people usually think. Checkout LPOD.Org and look for their Lunar 100 list. That should keep you busy for a while.
You might also check these out:
1 (http://www.opticsplanet.net/telescope-faq.html)
2 (http://www.opticsplanet.net/dozen-telescope-observing-tips.html)
3 (http://www.astronomical.org/portal/modules/wfsection/index.php?category=3)
If you have a specific question, I'll try and answer it.
Regards,
Wab
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Thanks, these sites look like they're gonna be very helpful. Do you know much about telescopes? I mean do you think the one I have is powerful enough to see the rings on Saturn?
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Originally posted by AKWabbit
That looks like a fun little scope, but I would mention thats only 4" of aperture. And since its a Mak it also has a central obstruction for the secondary mirror so its not even a clear 4" of aperture like a refractor.
Resolution is directly proportional to aperture. So the image scale and possible magnification of that scope would be pretty limited. If you notice they only list it as recomended for lunar and terrestrial photograhy. I assume because it doesn't have enough resolution for the smaller planets. And with less than 4" of aperture, deep sky observing would be very challenging.
As the owner of a 4" scope, I can say that AKWabbit is giving you good advice. Had I known all this years ago, I would not have spent hundreds of dollars on the scope I did.
If I could convince the wife to let me get another scope, I'd get the biggest aperture I could afford.
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Originally posted by trax1
Thanks, these sites look like they're gonna be very helpful. Do you know much about telescopes? I mean do you think the one I have is powerful enough to see the rings on Saturn?
The scope you have is a pretty modest aperture but you should be able to see the rings of Saturn fine. The image won't be large. But you should be able to clearly see them.
I would use your zoom eye piece (the one with different settings). You'll want to start out at its lowest magnification. (what do the markings say? is it 8-16mm or 100x to 50x?) Get it focused and then start zooming in the magnifications a bit at a time and refocus each time. At some point you'll see that you've reached a point of diminishing return where the magnification isn't worth the extra blurriness. Then back it off just a bit. You might get all the way down to the 8mm setting. Frankly, I wouldn't bother with your barlow lens.
Your biggest problem is going to be able to find and track Saturn. Learn you constellations a bit and look at Astronomy or Sky and Telescope magizine for that month and see when Saturn is going to be up. (I think around Feb its going to be closest to Earth this year)
Again, I start on the Moon to learn how to point your scope and track to keep a feature in view for several minutes. You need to learn how to align your finder scope with the main scope so you can get close with that before going to the eyepiece.
The particular type of mount you have is going to make it a challenge to keep it in view at high magnification but it can be done.
Regards,
Wab
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Posted this in another thread on space pictures a while back.
Seemed like a pretty interesting project
Making an Astro Cam from a Webcam (http://www.youtube.com/watch?v=H1auTp6qJcM)
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my head hurts.
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Okay, Tac, take a look at this place: http://www.sjaa.net/beginner.html They have more info than you can shake a stick at, and generally explain things very well. Especially read the Advice to Beginners from the Company Seven site, and the How to Pick a 'Scope from Astronomics site. Warning The Company Seven link on the above page is LONG, but packed with great info.
LePaul, you're welcome!
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Flakbait [Delta6]
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Originally posted by ChickenHawk
As the owner of a 4" scope, I can say that AKWabbit is giving you good advice. Had I known all this years ago, I would not have spent hundreds of dollars on the scope I did.
If I could convince the wife to let me get another scope, I'd get the biggest aperture I could afford.
Wabbit and Chickenhawk (this sounds like a Looney Tunes episode!)...
Good points, I'll keep shopping. My last scope was a beginner one with wing nuts for tracking. For $100 more, I couldve had motorized tracking. So I appreciate you saving me some hassles from the get go!
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One other question..what CCDs do you like? I've reading a lot about the Meade's on that site. Im noticing a lot of monochrome?
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Originally posted by LePaul
One other question..what CCDs do you like? I've reading a lot about the Meade's on that site. Im noticing a lot of monochrome?
Well, that's another complicated question. :)
It again depends a lot on your intended purpose, as well as your level of seriousness.
Basically let's divide it into two camps. Cameras optimized for Solar, Lunar, and Planetary photography; and cameras optimized for dim dark fuzzies like Nebula, Galaxies, and star clusters, etc. For short let's call these genre Planetary and Deep Sky respectively.
For planetary cameras, you need something to help you beat the blurring effect of the undulation atmosphere. Imagine looking at a perfect photograph of a planet that is sitting on the bottom of a swimming pool with kids making waves at the other end. The waves will be constantly shifting, blurring, and distorting the picture your trying to look at. This is very like trying to look at a planet through our planets thick atmosphere. On a longer exposure, the undulations and distortions average together during the exposure and create a blurred result. What you want to be able to do is take an exposure of a fraction of a second to catch a moment in between the waves when the image is undistorted. The problem is this short exposure is going to cause the image to be very grainy and noisy. However, if you take hundreds or thousands of short exposures and use software (Registax) to sort thru them and find the sharpest ones and "stack" them. This stacking increases the signal to noise ratio enough hide the grainyness.
So you want an inherently low noise camera that can take 10-60 frames a second for possible several minutes. There are some high end cameras for this purpose like the Lumenera Skynyx models. Very nice. Very pricey. However amateurs have found they can get really excellent results with modified consumer webcams (a favorite is the Phillips Toucam). They have been modified by unscrewing the built in front lens and screwing in an adapter that lets you insert the camera like an eyepiece (See scopetronix.com is one source). You'll capture the 2-5 minute AVI's to a laptop or desktop and later use freeware like Registax to do the magic of sorting and stacking. There are also models like Meade's LPI and I think Celestron has one. I have an LPI. Its not bad. Has some really nice software. But It doesn't do as well as my old Toucam in my opinion.
I also have a monochrome Skynyx. Its VERY sweet. It dang well ought to be for the price!
There issue between monochrome and color is mainly due to two factors. 1. Monochrome ccd chips tend to be a bit more light sensitive. 2. because of the way a color chip must fit detectors for all 3 colors in the same realestate, the same size chip can have ~30% less pixels (resolution). To get optimal performance, some people choose to go with monochrome chip for the resolution and take three sets of images using different colored filters (RGB) and combine later with software. I wouldn¡¦t go this route originally. It's a pain. For your fist camera, I would go with a color model.
Next, Deep Sky....
Wab
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That's some excellent information
I thank you for taking the time to share.
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Sorry for the late response. I got side-tracked.
Deep Sky is all about collecting LOTS of photons. The type of objects you are photographing like nebulas and galaxies are already kinda soft and fuzzy by nature so atmospheric distortion is not so much of an issue. Here you are basically wanting long exposures with low noise.
In the past this was the domain of expensive, dedicated astronomical CCD cameras. These are still top dog, but they are also top dollar. However, like the amateur webcam revolution for planetary photography changed the equation, amateurs have found they can get results that rival the astronomical CCD’s with consumer level digital SLR’s. Camera like the Canon 10d, 20d, Digital Rebel can produce amazing results. As good as the best astronomical CCD? No. But pretty darn good. (Examples: http://ca.geocities.com/bradydjohnson@rogers.com/M42andFriends.htm http://ca.geocities.com/bradydjohnson@rogers.com/M31_76ED_300D.htm ) They cost less than the dedicated CCD’s, and they can be used for normal daytime photography (unlike astronomical CCD’s).
There are other tools like the Meade DSI and others. They are a kind of lower end option but can be a good place to start.
But if you already have a digital SLR or were thinking of getting one for regular daytime photography, THAT would be the way I’d go. (SLR being the key here. The front lens needs to be detachable.) Something like the Canon Digital Rebel would be a great choice.
A couple of things to consider. You will need an equatorial mount. A wedge mount or German Equatorial (I prefer wedge). You will need to learn to pretty accurately polar align. Not trivial, but you can learn how. The tracking criteria are much higher for deep sky photography as compared to planetary. As planetary photography’s main challenge is beating the atmospheric turbulence. For deep sky, the main challenges are tracking error, image noise, and gathering enough exposure time. (Both types share the problems of focusing but that’s a WHOLE ‘nother discussion thread!)
Back in the old film days, there was a useful limit to how long you could expose film. This was due to the background radiation of the sky starting to “fog” the film. This limited how much light you could gather on a target before the fogging effect outweighed the benefit of additional exposure. This was called reciprocal failure. Digital photography has the beautiful property that it is not subject to reciprocal failure like film. There is no real limit to how long you can gather light on a digital image. The image just keeps building information.
However, long exposures do face the problem of tracking errors. Polar alignments are seldom perfect. Worm gears have minute flaws that cause the drive rate to vary slightly over time. Machined parts are imperfect so that the axis of the mount and scope are not perfectly orthogonal. All these things will contribute to causing the image of a star to slightly trail and smear across a frame of a long exposure. You can attach a second scope to the main one and target a nearby star at high magnification and correct for the errors real-time, but you would still have to deal with the issue of field rotation and it’s tedious.
But digital imaging has another beautiful property. The image responds in a linear fashion to exposure time unlike a film that responds logarithmically. What this means is that with film if you exposed for 10 minutes to get a certain level of detail, you might have to expose for another 10 minutes just to get 20% more information. When combined with the problem of reciprocal failure, it presented a real problem. Digital imaging on the other hand, responds in a linear manner. 20 minutes gathers twice the information as 10 minutes, etc. AND it doesn’t have to worry about reciprocal failure so there is no limit other that tracking. However, the image can be broken out into separate exposures and stacked later with software. 10 exposures at 1 minute each can be stacked to produce an image that is essentially the same as if it had been a single 10 minute exposure. This is important because the amount of tracking error that will accumulate during 1 minute exposure is a lot less than what will accumulate during a 10 minute exposure. Not only that, but there are a LOT of things that can go wrong during a 10 minute exposure. Image carefully guiding during a 10 minute exposure only to have an airplane fly across the view in the last 30 seconds. Now you have a nice ugly light streak right across you image! If I had been taking 10 exposures at 1 minute each, I would just keep and stack the other 9 and toss the last one. Of course you also need software for all this. I use ImagesPlus, some people use IRIS, or even Photoshop. There are others I’m sure.
So to wrap up, if it were me, I would get a good digital SLR that I could use for both astrophotography and normal daytime photography. I would get at least an 8” SCT with wedge mount (10” is better. 12” is upper end of what would be portable). Either just electric drive or computerized depending on your budget.
If you didn’t want to drop that much, then you might start out with something like the Meade DSI as an entry level camera. I don’t own one, but I don’t remember seeing any horror stories (You’ll need to research that one. A good source might be CloudyNights.Com).
Of course, if you are rich and money is no object, there are some dedicated astronomical CCD’s that are truly phenomenal. (See SBIG, but you can easily drop 10 large)
One side note. You might notice I keep mentioning the 8” SCT. There are a couple of reasons I think that is a great choice. Anything smaller and you would find it too limiting very soon IMHO. Larger scope increase in weight and cost exponentially. The 8” SCT is SOOO popular that it is manufactured in truly prolific numbers. Because of economies of scale, that makes the 8” SCT far and away the best performance/cost ratio out there. That’s my $0.02.
Clear Skies,
Wab