Equatorial Mounts For Budget Astrophotography? 85
Timoris writes "With the Perseids approaching rapidly, I am looking for a good beginner's motorized equatorial mount for astrophotography. I have seen a few for $150 to $200, but apparently the motor vibrations make for poor photographs. Orion makes good mounts, but are out of my price range ($350) and the motor is sold separately, adding to the price half over again. Does anyone have any good experience with any low- or mid-priced mounts?"
Astronomy Stackexchange (Score:2)
They're still looking for enough users to commit to open up the beta, but Stack Exchange (the folks behind Stack Overflow [stackoverflow.com], Server Fault [serverfault.com] and Super User [superuser.com]) have a proposal up for an question & answer astronomy site:
http://area51.stackexchange.com/proposals/51/astronomy [stackexchange.com]
barn door mount (Score:5, Informative)
It depends on how you are wanting to do your astrophotography. If it is a camera alone then you might consider making and/or getting a barn door mount.
http://en.wikipedia.org/wiki/Barn_door_tracker [wikipedia.org]
They are simple and work well.
If you are considering astrophotography through a telescope then you'll have to have some sort of eq mount for the scope and then the prices do rise. But since you seem to be interested in photographing the Perseids then I doubt this is the case. The wide field available with just a camera would be the way to go.
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Just a DSLR (Score:5, Insightful)
If you're on a tight budget, but want to capture the Perseids, put a DSLR on a standard tripod. Wide shots, say 18-55mm lens, you can expose for 30 seconds or so without noticing any earth rotation in your field. Take a bunch of exposures, and use a program like the free Deep Sky Stacker to align them into a final image with total exposure time equal to all the shots combines. I haven't taken any like this for meteor showers yet, but you can get some stunning shots of the Milky Way, and some of the bigger objects in the night sky. If you use a narrower field lens, like 100mm, then you might only get 10-15sec exposures, but just take several hundred and let the stacker program turn them into awesome.
If you want a motorized mount for astroimaging you get what you pay for.. A cheap one will have poor periodic error and vibration. I got a now discontinued LXD75, but due to the cheap plastic gears it's made with, I wish now I went with a more expensive EQ6 to get more accurate guiding.
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The above post is almost completely correct. However, even the cheapo equatorial drives should be ok for wide-field astrophotography with a 18-55mm lens. Their poor guiding will only start to show if you attempt to do zoomed shots on specific targets. So as long as you don't care about taking pictures through your telescope then this should be ok.
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Indeed, I agree with the parent and grand parent. For meteors you don't even need long exposure times, 30s is more than sufficient. Prepare to end up with hundreds of exposures without a meteor though... The meteors only last a fraction of a second, baring some exceptions. However, you do need the fastest lens you can get your hands on. I use my Canon 50mm f/1.4 for it, but stopped down to f/2.8 due to heavy optical aberations at any faster stop. This is just sufficient to get the brighter meteors (magnitud
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Agreement here. A standard DSLR lens will work fine on an inexpensive mount.
As with any mount, keep the vibrations to a minimum. Don't set it on a deck and have a dance.
If you want "star trails" with Perseids shooting through, then of course you need no tracking mount whatsoever.
Re:Just a DSLR (Score:4, Informative)
>like the free Deep Sky Stacker to align them into a final image with total exposure time equal to all the shots combines
This is excellent advice on getting a much improved image quality but do note that stacking images will not give you the same results as a single image using the combined stack times.
In other words, if each image in the stack is 20 seconds then 10 stacked images will not give you an equivalent of a 200 second exposure.
Stacking 10 images simply improves the image quality by removing hot pixels. The result, however, is still a 20 second exposure.
The single 200 second exposure image will contain fainter objects (and more noise) when compared to the stacked 20 second image.
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Stacking 10 images simply improves the image quality by removing hot pixels.
Where'd you get that idea from? Hot pixels are removed by taking dark frames at the same temperature as your exposures and subtracting them from your exposures before processing.
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While your flat field images improve (to a degree) your signal to noise ratio.
OK, it's crude approximation. but without doing a full statistical analysis, what you're going to get is a crude approximation.
Answering the original question : for meteor photogr
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I strongly second this. It produces far better wide shots images than buying a $3500.00 motorized mount because it can over the course of 36 images remove most of the imager noise.
It produces shots that will have others asking "How the heck did you get that shot?"
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Stuff like this makes me think that we're really missing some opportunities in amateur astronomy. Computers and software have the potential ability to revolutionize how much of it is done.
Why do you need an equatorial mount in the first place, when a computer can do the math to emulate this with an azimuthal mount? Why futz with calibration and guide scopes, when the computer can just analyze every shot from the main scope and calculate drift in near-realtime?
It seems like much of the equipment is optimiz
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You need an equatorial mount to deal with the field rotation you would normally get in an alt-az mount with long exposure photography. For people with computerized alt-az mounts, you can get an adjustable wedge that goes under the mount head that will align one axis with polaris and solve the field rotation issue; however wedges add weight to an already heavy mount (not to mention shifting the balance of everything upwards).
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Hadn't thought about that. However, if you take lots of short exposures and combine them, you could correct for the field rotation. At very high magnifications you could still get rotation during even a short exposure I guess.
Part of me wants to suggest just adding a third axis to the mount (rotation). I guess that would depend on the relative cost of building that motor. I suspect it might depend quite a bit on the weight supported by the mount - for a very heavy telescope it might be cheaper to rotate
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Because an azimuth mount is insanely hard to do right and get tracking properly.
With an equatorial mount you only have to control one axis of the motion of the instrument, and for lots of use that part is a simple clock motor run by sidereal 60+ hertz.
With an azimuth mount, you have to have variable speed motors on both the altitude, the azimuth, and the rotation of the telescope cage.
Worse the rotation rates for each depend on where the instrument is pointing, so you also have to have inputs for that.
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Worse the rotation rates for each depend on where the instrument is pointing, so you also have to have inputs for that.
Why?
Wouldn't it make more sense to just examine successive images taken from the scope, look for drift, and then correct for drift? Sure, the first 5 shots you take will be streaky, but it would very quickly learn.
Most likely any system controlling an azimuth mount would know where the scope is and where it wants to point anyway.
Sure, it would be useless except as part of a computer-automa
Re:Just a DSLR (Score:5, Informative)
Except that you would see the earth rotation a lot quicker than you apparently expect -- depending on where you are.
At 50mm, depending on your earth location, you would see star trails after 8.5 seconds (equator), or 25 seconds (30 degrees from celestial pole).
The rule of thumb is this:
Around 30 degrees from celestial pole: 1200 / focal length = max exposure time.
Around the equator: 400 / focal length = max exposure time.
I use 600, because that's what I found yielded the best "rule of thumb" for me, as compared to my location.
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So the best advise must be: move to the North Pole, shoot only straight ahead, avoid naughty elves and polar bears. :)
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I don't know if I'd trust that with an EOS7D+Battery grip or EOS 5D+battery grip.
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With my 7D on a tripod, EF-S 18-55mm f/3.5-5.6 lens, exposed for just 20 seconds star trails are very noticeable.
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30 seconds worth of rotation is more than you think. I've tried taking the typical star trails shot by stacking a bunch of 15 second exposures together. I got the star trail alright, but when you look close they're dashed lines. I can see the rotation during the 15 second exposures and then the darkness of the rotation during the 5 seconds that was occurring between exposures. My tails look like "-------".
Very tricky (Score:3, Informative)
I hope you are not intending on photographing a meteor from a telescope.
The most common thing to when photographing meteor showers is to point to the pole star and set your SLR (hopefully manual, film based on a tripod with a cable for the shutter) to a B setting and take a shot for a couple of hours. This produces really nice star trails and the occasional meteor.
If you are piggybacking the camera to a telescope you should not have any issues with the motor vibration, but you will need to beware of wind.
Save up your money and buy a Meade LX200, you can now get the older models (I personally think are better) for around 2000$US, combine that with a wedge and reticle eyepiece and you are ready to go. The thing really is a light bucket and something you will be happy with, with a little training you can even work out the periodic error correction with the scope so you can do astrophotography with the camera for the eyepiece.
If that is not satisfactory, build an adjustable wedge and buy a motor that rotates at 15 deg/hour and attach the motor to the top of the wedge with a camera on it.
Re: point to the pole star (Score:3, Funny)
Point to the pole star?
I'm in the southern hemisphere, you insensitive clod!
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He would point to the south pole star, you insensitive clod!
(if he can see it!) :-)
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I'm glad this topic came up as I have been researching telescopes for astrophotography but there seem to be relatively few in-depth reviews for telescopes like there are for SLR gear.
Why the LX200 rather than the Celestron C10-NGT? The Celestron may be longer/bulkier but you can get a larger objective (which in theory allows you to resolve higher magnitude (fainter) objects) for less money . Are the Meade's optics that much better? Which design would be better for making a mount to piggyback the camera (if
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You can get a first generation LX-200 (well generation 1.5, 18V drive and High Precision Pointing, not the flaky original 12V version) for a lot less than that, I paid $850 for a near mint condition 8 inch LX-200 about 5 years ago.
Hiss drive? Barn-door? EQ platform? (Score:5, Informative)
http://members.cox.net/tfangrow/hissdrive.html [cox.net]
Otherwise, barn door mounts:
http://www.mikeoates.org/mas/projects/scotch/ [mikeoates.org]
http://www.astunit.com/tonkinsastro/atm/projects/scotch.htm [astunit.com]
http://www.davetrott.com/DoubleArmBarnDoor.html [davetrott.com]
Equatorial platforms:
http://tech.groups.yahoo.com/group/eqplatforms/ [yahoo.com]
Lots of other links:
http://members.ziggo.nl/jhm.vangastel/Astronomy/links.htm [ziggo.nl]
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tough crowd...
diy (Score:2)
So what's the meteor shower go to do with this? (Score:1)
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Yeah, just what the title reads. I'm simply curious.
The Perseids are a meteor shower in the constellation of Perseus, leftover debris from the Comet Swift-Tutle that the earth plows through every year during it's wander about the sun.
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Re:So what's the meteor shower go to do with this? (Score:4, Informative)
http://www.medanku.com/wp-content/uploads/2009/08/perseid-meteor-shower.jpg [medanku.com]
instead of this:
http://celeb-news.net/wp-content/uploads/2009/08/meteor_shower_san_diego-8369.jpg [celeb-news.net]
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For some weird reason every time I go out at the time for Perseids and shoot the sky, I get a featureless gray picture. Damn you British weather!
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more detail needed (Score:1)
If you are trying to photograph deep sky objects through a mid sized telescope, I don't think you will find a mount in your budget range, unless you can get one used off of ebay or some such. The tabletop equatorial m
What kind of lens are you going to use? (Score:3, Informative)
I mean, for a meteor shower you would need a wide field, right? Probably under 150mm? Then small tracking errors such as minor vibrations would not really show up in the photo. I remember when I was in school, I was piggybacking on my manual equatorial mount telescope and I could manage crisp photos tracking manually - I doubt the inexpensive mounts are worse. ;)
I am assuming you have already tried fixed-mount photographing techniques for meteors, such as star-trail exposures or shooting repeatedly at exposures just before the stars start to trail (which of course depends on your lens & what dec. you are pointing at), and are considering advancing to something else. Otherwise try that first, budget astrophotography can start VERY cheap
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Oh, and a clarification for the people who are not familiar with meteor showers and photography: When we talk about a meteor shower associated with a constellation, e.g. Perseids, we don't mean you can just point a camera at Perseus and get the meteors. The meteors will cover most of the sky, appearing in a radial pattern that points outward from the area of Perseus and, in fact, the farther a meteor appears from the "origin" part of the sky, the longer its "tail" or visible path will be. So, you don't real
In that budget range just buy used commercial (Score:4, Interesting)
In that budget range, just buy a used commercial drive base from a broken small equatorial telescope like a Meade ETX-70 or ETX-90 that are typically sold in Wal-Mart at Chirstmas time. It is common to find them on ebay cheap with broken optical components. Another option is an old B&L 4000, the optics on most of these were junk, but they had a decent AC powered drive base, and since everyone knows the optics were junk, just ask google, they tend to sell cheap ($100 or so) on ebay.
Ike
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Many of the ETX's were offered in both a low end dumb equatorial mount version and a high end AltAz smart goto version I was talking about the cheap equatorials google ETX-90RA or ETX-70RA for an example.
I too wonder... (Score:2, Interesting)
I've been thinking about this for a while as I have built myself an 8" scope from the ground up, including the mount. And it all works well, except that it doesn't track. And everytime I look for a clock drive to put on there I end up only seeing options somewhere between $300-$30k. All I need is a big worm gear setup and a slow enough constant speed motor, but it seems gears are a lot more expensive than I think they should be. The weight of my scope is about 13lbs, with counterweights as it is now, closer
Tripod for showers! (Score:2, Informative)
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I remember seeing astrophotographs 30+ years ago that were made by amateurs with homemade gear, and those guys got breathtaking, amazing results. Seems like the state of the art has taken a giant step back since then, at least for amateurs who don't have unlimited budgets.
For Meteors? Just a tripod (Score:4, Interesting)
To shoot a meteor shower, you need nothing more than a tripod, a camera with a ~50mm lens, warm clothes and patience.
You don't want to take real long exposures to get meteors, too long and light pollution/sky glow will likely mess up your pictures.
Just point near the radiant (I try for framing a nice constellation nearby), and using a cable release take 20-30 second exposures while watching the area of sky that the camera sees. Most exposures obviously won't have meteors, but when you do catch one, take note of which exposure for later when you delete the (many) exposures that didn't have a meteor. When you do capture a meteor, start a new exposure because keeping the shutter open longer won't likely gain you anything.
If you're looking at doing further astrophotography beyond a meteor shower, then you will need some form of tracking. Making a barn-door tracker can be a cheap option to get started (YMMV, depending on how good you are at making stuff and your level of patience!).
As with the rest of astronomy, you can start out spending a bunch of money on stuff you don't really need or use, so it's always good to start cheap and see if you are really into it. If your interest holds, you will find a way to buy up.
craigslist (Score:2)
Capella? (Score:2, Interesting)
You can always try the Capella plans from the link below. I built it and it works fairly well. I find the friction required to get a proper static/stable lock on anything insufficient. Could be my implementation of the plans. I'm modifying the concept to use a couple of worm gears to stabilize everything. I've purchased some worm gears for garage door openers with 0.5" shafts. They are sturdy enough to keep a lock on an object. Probably not accurate enough to track an object over an extended period of time
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It seems to me that the screw is not the limiting factor in accuracy or even noise reduction. When you do machining you always have to make your moves from the same direction because the equipment has a certain amount of slop in it ("backlash") but the results can be amazingly accurate, far more accurate than the gear mesh tolerances of the actual machine. Therefore, if the screw is properly polished and coated with a lightweight grease (which will also help with damping!) it seems that preventing vibration
Here are a few tips (Score:2, Informative)
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Best off buying a mount UNLESS you happen to have access to a serious machine shop, THEN you can build some VERY nice mounts, but you probably would NOT be asking /., but looking on the ATM (Amateur Telescope Makers) list and sites dedicated to ATM(some HINTS there for anyone looking to build)
Remember some interesting things - with a SLOW turning device (and a drive IS), there is a debate RE Ball/roller bearings, and some sort of solid bearing (Bronze, PTFE, Molgice) - One will introduce periodic errors as
Is it just me... (Score:1)
Some tricks (Score:1)
Cheap mounts are mostly OK with vibration as long as you let it settle for a minute and don't have any wind (that's the killer). Otherwise they're OK for short shots (a couple of minutes). You are more likely to have a misalignment or having periodic errors on the gears. They won't matter for wide and short shots. You can still do reasonably good quality pictures within those scenarios.
If you are using an SLR, invest on an IR remote and before you start shooting use a dark cardboard to block the light, not
A motor mount is nice but for Perseids not needed (Score:2)
A motor mount is very nice but don't use your lack of one to not take photos of the perseids.
The best photos will be done with fairly wide-angle lenses and exposures of minutes and while some of the star field motion will be noticeable it will not be objectionable. The perseids will be bright streaks obviously different than the tiny little arcs executed by the stars.
Now, if you want to make dark-sky photos of small faint objects, with truly long exposures and much narrower fields of view, a motor mount is
Ob chdk link (Score:2)
If you're using a Canon cam, check out the Canon Hack Development Kit
http://chdk.wikia.com/ [wikia.com]
There are a couple of user scripts geared towards capturing things like meteor showers and lightning strikes, as well a lot of other useful tweaks. Opens up a lot of interesting features, like raw mode on low-end models.
buy used... (Score:2)
Because with this budget, a good equatorial mount with motors (like an EQ6) is really out of your budget.
You can try to find a EQ3-2 with RA motor, used, this is a good "small" mount.
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>Astronomy gear is grossly overpriced, IMO.
It's because Astronomy is such a lucrative profession, they have to keep the barriers to entry high. Too many people on that Astronomy gravy train wouldn't be good, right?
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The Orion mini EQ is a nice little mount for use with a camera, as long as you have a solid base to put it on (concrete picnic table, etc). You generally don't want to place it at ground level where someone could kick it. The only bad thing about it is the use is fairly limited to piggy back photography (or something like I bought my for, solar H alpha viewing with a double stacked PST) I have one of their older units with drive motors in my living room right now, I think I paid $35 for it used, at the ti
Motorized Equatorial Telescope mount free. (Score:1)
Title slightly misleading (Score:1)
At first I took this to be asking 'What are the best mountain ranges on the equator for astronomical observation?'
Arguably a more interesting question.
Don't use a mount! (Score:1)
When we photograph meteors for genuine data collection, we don't use a mount at all. We set up a ring of cameras with each covering several degrees of sky, and let them all take five or ten minute exposures. It's your best hope of catching a bright one and several faint ones. If you're using a decently short lens (50mm, 35mm), (a) you'll catch more meteors and (b) the star trails are less notable, or you won't care about them.
Remember, with meteors being an atmospheric phenomenon, you'll catch more closer t
Camera-only mount? (Score:2)
I know people who've had great success with the AstroTrac TT320X-AG mount. I've always wanted to try one myself, but at US$550.00 I think it's about three times the price it should be:
http://www.astrotrac.com/Default.aspx?p=tt320x-ag [astrotrac.com]