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Barn door or Orion Min-EQ?

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#1 Dilligas

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Posted 02 March 2009 - 11:49 PM

Hello,

I am stuck in making a decision between building a barn door (Scotch) mount or buying an Orion Min-EQ with EQ-1M motor drive. I have been into astronomy since Mr. Halley's comet came around last, into photography since about 2000, and finally ready to take a step up from wide-field images on a static tripod. I would like to keep the cost of a tracking mount near or under $100 (here in the US). If increasing my budget to $300 will make such a difference that the barn door/Min-EQ images will look bad hand sketches compared to the Hubble-like images that a $300 mount could offer, I might consider it (or if there is something else that I haven't considered that would make the $300 setup more than three times better). I would expect a huge difference in performance to justify the added cost at this point though. I just have read so many things (both good and bad) about both of these solutions, that I just don't know which will be easier to use and/or provide the best results for the limited cost.

What I have to work with already... I have a Canon XSi (450D) with the 18-55 f/3.5-5.6 IS, 50 f/1.8, 70-300 f/4.0-5.6 IS currently. I have been considering the addition of a few primes to my bag (Sigma 30 f/1.4 and a Canon 100 f/2). I also have a Manfrotto 055XProB with 322RC2 head (to which either mount would likely be attached) and various flashes, etc. lying around. I primarily shoot landscapes, museums, etc. for my hobby and am the semi-official photographer at my church (just shot a new church directory, weddings for those that can't afford a pro, and so on). That is why some of my choices probably look a little schizophrenic. I don't mind picking up equipment if I can help others with it, but to spend $1000+ (and I expect to have eyes roll with me saying that while talking astrophotography) on purely hobby-related images, well, that I have a hard time doing at this point.

Now, what I want to do with it... I would like to tackle some of the larger and/or brighter deep sky objects (Orion Nebula, Andromeda galaxy). I would like to take planetary photos (i.e. catching the Galilean moons, resolving the crescent on Venus, etc.) and nicer pics of comets than I have personally be able to do up to this point. I do not plan on adding a telescope to this mount or to ever try taking photos through a telescope. I just want to use camera lenses and my DSLR attached to a mount.

The construction aspects of the barn door do not bother me as I am pretty handy with such things, but I like the motor control of the Min-EQ (with EQ-1M). I am not that skilled at trying to build my own motor drive for the barn door as all of these that I have seen require building circuits (definitely not my strong point there). It looks like the barn door would possibly be easier to mount and align a polar finder scope to, but the Min-EQ is already designed for proper balancing, etc. to hopefully make the tracking smoother. There are just too many pro's and cons for me to sort out without getting some firsthand information from those that have used one or both of these mounts. So, I would greatly appreciate any information that you can give in comparing/contrasting the strengths and weaknesses of these two mounts to help me in my decision. Thanks.

#2 NeoDinian

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Posted 03 March 2009 - 12:21 AM

I'd build a Barn-door...

If anything, just for the feeling of pride you get from making something with your own 2 hands. :)

If you feel you want something more, I would personally go with the SVP rather than the EQ1... It will do MUCH better with the larger lenses you have, as well as already owning a mount, you can add an OTA later. The advantage of the SVP over the EQ2 is the addition of the Polar scope, which makes aligning MUCH easier. :)

#3 John Noble

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Posted 03 March 2009 - 12:08 PM

I have a Min-EQ with tracking motor, and I'd say it's OK for shorter focal length (50mm or so) 35mm SLR lenses, but that's about it. I've seen some nice widefield images made with this combination, so it can be done.

#4 MtnGoat

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Posted 03 March 2009 - 05:50 PM

Keep your eyes out for, and pick up an old 4504 Meade Starfinder 4.5" reflector by prowling Craigslist in your nearest major metro area. I see one or two every month usually. If it's more than $100, keep your powder dry, another will be along. will work great and have Autostar for 100 bucks, sometimes as little as fifty.


Don't use the OTA, and redo the motor mounts, check the worm tension, and get the bearings tight.

it's no precision mount, but does decent 30 second subs at 500mm and should do far better with the average SLR lens and camera on it. I'm sure it will be at least as good as the options you are already showing.

here's my thread on what I did with the 4504 frankenscope

Below is M1, Crab Nebula, shot with 30 30 second subs with a Short tube 90 and that very mount.

Attached Files



#5 Dilligas

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Posted 03 March 2009 - 11:55 PM

Thanks for the replies. I have been asking around on photography-themed boards on this question for a while now, and (thankfully) someone finally pointed me to Cloudy Nights. I'm getting the impression that the Min-EQ isn't really what I'm looking for (which is disappointing, but I had somewhat expected it -- too good to be true). Can anyone tell me how it (the Min-EQ) would have compared to a simple barn door mount? Is it (the barn door) similar, better, worse than the cheap-o equatorial mount? In other words, would it handle what I am wanting to do better than the Min-EQ or is it just cheaper?

MtnGoat, I will keep an eye on Craigslist, but I am not really close to any major metropolitan area (Kansas City is a couple hours away - good for the skies, but bad for the used market) which makes it a bit more difficult to find things and see them in person before handing over money. I will keep an eye out though, as a deal too good to be true might come along.

NeoDinian, am I right that the SVP is the SkyView Pro from Orion? If so, do you know if there is much difference between this and the Skywatcher EQ5 Pro? They're both nearly the same price with the Skywatcher being the newer model in the lineup (according to the website).

As I dig through old posts, I am reluctantly realizing that I may end up having to spend more than my $100 target budget on this unless I am underestimating what I can accomplish with a barn door mount and my longer lenses. I may just have to give up on the idea altogether if it will just be that expensive (doing the math: SVP = $380 + single-axis drive = $85 + polar alignment scope = $52 == $517 + s/h >> what I hoped that I would need to spend). Maybe I can talk myself into that at some point in the future, but with the economy the way it is and the fact that so many people spend their nights under the stars because they have no home to go to, it just makes it hard for me to put that much money into a hobby (as I seriously doubt that I will ever make a dime off of any of my astrophotos). (And sorry if that dipped into politics...I don't know exactly where that line is on this board.)

Thanks for the first-hand experience with the Min-EQ John. Can you tell me where the problem came from on the longer lenses? Was it too much weight for the mount to track properly (binding of the gears, etc.), too hard to get an accurate enough polar alignment, other issue that I haven't thought of yet?

Thanks again for all the replies, and I would love to hear from others that have used one or both of these mounts, or have suggestions for other options that I just haven't run across yet. Keep 'em coming...

#6 gordianknot

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Posted 04 March 2009 - 05:12 AM

Here's my 2 cents worth:
1. The Min-EQ isn't a great mount for a wide variety of reasons, though it's fabulous buy. It has a reasonably low weight capacity (though might be enough for your needs), hard to point precisely, not great gears, and the "tripod" or lack thereof is really bad simple because its so small. It's practically impossible to find a stable enough piece of outdoor furniture to place the thing on, even for visual observing, much less imaging. The EQ-1 is the same mount, but on the world's crummiest full size tripod. Personally, I built my own tripod for the min-EQ out of wood which is very sturdy. The head is still pretty bad, but at least it's sturdily mounted. Others have tried photo tripod legs, but in my testing, that's quite unstable. If you get a motor, get the EQ1-M drive, not the Astrotrac!
2. It's hard to compare barn door trackers since they are all home built. One could potentially build a very nice barn door tracker that would knock the socks off the EQ-1/Min-Eq but I think a run of the mill one would be at best of comparable quality.
3. If you really want to do imaging, I'd save up for a either a computerized Celestron CG-5 (aka ASGT) or Meade LXD-75. They can probably be had for < $500 or so used ($600 new), but will give you much better results. The CG-5, EQ-5 goto, and SVP goto are virtually identical, but CG-5 has been cheaper recently and IMO is a little nicer.

#7 Dilligas

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Posted 04 March 2009 - 09:55 AM

gornianknot, do you have any suggestions about the CG-5 (knock-off?) on ebay? I have read a few posts saying to stay far away from anything on ebay, but I was wondering if you knew anything good/bad about these? Thanks.

#8 MtnGoat

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Posted 04 March 2009 - 01:52 PM

true, the worst part of the low end mounts is the horrible tripods. the reason I'm getting decent results is the cheap pier I did for it, which is plenty solid at the scale of these small mounts. this is visible in the thread I linked to. $10 worth of 4" PVC, $20 worth of concrete, a couple hours in the yard and you're done. Oh, and some scrap plywood to make pier plates.

I just pull the OTA and leave the mount after imaging, after all I have the polar nice and dialed. Cover it with a trash bag and then a fresh tarp, then wrap it up with some rope. Works fine. I replace the inner bag every few months and it stays dry in there. It wintered our insane snow storms and heavy rain this year no problem.

On this pier with the worms adjusted properly and redone mounts, the GOTO accuracy is fine. 100 tooth gears on this mount are not too bad, and as long as you do the drive training I'm perfectly satisfied with the goto performance. It is consistently in FOV of a 9mm eyepiece on the short tube, and nearly always the target is in frame of my imager.

#9 gordianknot

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Posted 04 March 2009 - 02:36 PM

Having never used or even seen one of the CG-5 clones like the "CG-5 type Dual Motor Equatorial Telescope EQ Mount" currently on eBay, I can't really comment on them. Others on the board do however know something about them, so perhaps one of them can chime in.

#10 Patrick

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Posted 04 March 2009 - 10:23 PM

Hi Dilligas and Welcome to CN!

I spent a great deal of time researching the pros and cons of building a barn door tracker vs buying the Mini-EQ. I ended up buying the Mini-EQ and I'm not sorry. :smirk:

First of all, the lens focal lengths you will be able to use with either mount will be pretty much the same...somewhere around 100mm max for 1 minute exposures, 50mm for 2-3 minute exposures and so forth. Secondly, the Mini-EQ can be mounted on a medium to heavy duty photo tripod using the threads on the bottom of the mount...not exactly 3/8 thread but close enough to work. Thirdly, because the Mini-EQ is an equatorial mount, there's no need to resort to curved screws or fancy electronics to eliminate tangent error. Lastly, you can balance each lense/camera combination with the counterweights.

You can see my setup and a more in-depth discussion of the Mini-EQ HERE. I even went so far as to record the periodic error of the mount which is near the bottom of the thread.

If you want to use longer focal lengths you will need a beefier mount. The Celestron CG5-GT is a great deal right now at $600 for a full goto setup...you could even put a telescope on it if you wanted to. :grin: It's a very capable mount for astrophotography.

Another possible mount is the AstroTrac. If you already have a decent photo tripod and a good geared head mount you're all set. It costs more than the CG5-GT but it's very portable.

Clear Skies!

Patrick

#11 Dilligas

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Posted 05 March 2009 - 08:34 AM

Thank you Patrick (both for the welcome and the advice)! I see that I am not alone in this quest for economy. I believe that I am correct in that the length of exposure is inversely proportional to the focal length of the lens. If so, this would mean decent photos at 300mm for 20 s or so exposures, correct? If I went with the Min-EQ, I had planned on mounting it to my Manfrotto tripod. Since the threads on the Min-EQ are the metric equivalent to 3/8", I didn't know if it would be a good idea to make an adapter plate so that I didn't chew up the threads on my mount. Have you had any problems with that?

I'm torn right now between staying cheap and looking for an additional summer job (I'm a college professor in a somewhat poor state) so that I can afford a mount to last me for whatever my hobby might someday grow into. (I hate these kinds of decisions!) Thanks again for all the advice, and please keep it coming... =}

#12 Patrick

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Posted 05 March 2009 - 09:58 AM

Since the threads on the Min-EQ are the metric equivalent to 3/8", I didn't know if it would be a good idea to make an adapter plate so that I didn't chew up the threads on my mount. Have you had any problems with that?



No, I haven't had a problem with that. What I've noticed is that the threads seem a little loose until you get down to the very end where the mount tightens up against the base. At that point, it seems very secure, but at the same time, the threads can back off fairly quickly as well. Like I said, it's not a perfect fit, but it works if you're careful.

I'm torn right now between staying cheap and looking for an additional summer job (I'm a college professor in a somewhat poor state) so that I can afford a mount to last me for whatever my hobby might someday grow into. (I hate these kinds of decisions!)



Astrophotography is one of the more intense fields of photography requiring a lot of discipline and knowledge...knowledge not just in cameras and equipment, but also in astronomy, computers, and image processing. There's a long learning curve with the equipment part maybe being the less important part, perhaps. With a mini-eq setup, you can spend most of your time on learning the astronomy you'll need, the foundamentals of imaging techniques, and then the post processing of your images. As you grow and want to increase your focal lengths to capture smaller and dimmer objects, then you'll have a foundation to build on with a larger setup with more functionality and capability. The mini-eq is a great place to start. If you can master it, you'll do well!

Also, keep in mind that there are other expenses in astrophotography aside from the mount. For instance, post-processing software (some are free, other programs are not), camera control devices (multi-image exposure control...you'll want to take many short images), perhaps modding your DSLR camera to replace the IR filter....believe the list goes on.

The book on CD recommended above by Jerry Lodriguss (A Guide to Astrophotography) is a great place to start. Some of his 'getting started' material is available on line under his Catching the Light website. Even though Jerry disses the Mini-EQ, he gives a lot of good info.

Kind regards!

Patrick

#13 Dilligas

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Posted 05 March 2009 - 02:45 PM

Patrick, Jerry Lodriguss' site is one that I have already dug through many times now. He is also one of the most vocal critics of the Min-EQ that I have run across as well (not to say that there haven't been others).

Actually, the software side of things doesn't really scare me that much (maybe it should, but it doesn't so far). I am pretty capable in Photoshop and even had to write some of my own image analysis programs while working on my PhD (not astronomical however). I have also been starhopping my way around with a decent pair of binoculars (that came after I finally realized how bad my first 60mm Tasco refractor was) since the mid-1980's. Saying that, I know how easy some objects are to find and how difficult others are to spot. I actually like the challenge of finding the objects, and I anticipate that I will enjoy the post processing as well. Part of what concerns me is the "everything in between" of astrophotography. I realize that it would be a miracle if I took a decent photo the first night (week/month/etc.) out with a tracking mount regardless of whether it cost $100, $1000, or $10,000. It is going to take time, patience, and perseverance to get it right, but I do want to have the hope that I will not outgrow the mount I get too quickly. That being said, I am really looking forward to doing a majority of wide field (18-50mm on a 1.6x crop factor camera) shots with the occasional small comet that I would like to have fill my frame or time-lapse of the Galilean moons (that might be asking too much, but it would be cool to try). It would be reassuring to know that I could do more with it later if I wanted, but again, I am struggling with the cost associated with a desire to occasionally push the envelope vs. keeping it simple.

Basically, I am torn between the inexpensive route to just take a step up from what I have already attempted and trying to match the capabilities of my camera/lenses to the mount. There is no sense in going for a better mount than my camera can handle, and I don't foresee ever getting out of the "consumer line" of Canon cameras (Rebel/40D/50D/etc.). Some of the information that I have looked for and have yet to find (and may not even be put together in such a format) would be how long of an exposure a given Messier Object (say M31 for my example) would take to get a result (depth) that was equivalent to [posted picture]. Then, to have a list of the variety of mounts (EQ1, EQ2, etc.) to say how long you could track an object at a given focal length (and aperture) with reasonable accuracy (and I realize that would vary from person to person). You were able to provide me that last bit of data on the Min-EQ/EQ1 mount (and I thank you again for that). However, if I were to choose to set my sights a little higher, I am once again feeling a bit lost as to how high? I have had CG-5's recommended as sufficient to match my 300mm lenses, but I have had others recommend EQ3 mounts and a good match for the performance of my lenses.

On a personal note, It is such a relief to have an actual conversation with people who have actually used these mounts and offer helpful advice. Some of the photography-oriented boards I posted on before would get 1 or 2 replies recommending their $1500 or $2000 rig in lieu of a barn door mount and then never follow up. I am still mining as much data as I can from old posts on these forums as I can on these subjects, but it is proving a bit difficult to draw comparisons when the term "quality" is so variable between individual expectations.

#14 Patrick

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Posted 05 March 2009 - 04:48 PM

Basically, I am torn between the inexpensive route to just take a step up from what I have already attempted and trying to match the capabilities of my camera/lenses to the mount.



The reality with astrophotography is that for focal lengths 200mm and up you are going to need a stable and accurate mount. The mini-eq is really best suited for 100mm and less and that means 24mm to 50mm are more optimal. At 50mm, Jupiter is a bright star and the moons will probably be indistinct.

The CG5-GT mount is the least expensive mount you can get that will carry a nice range of focal length scopes. If you get into autoguiding, there's no reason you couldn't shoot long exposures with 1000mm focal length scopes as well as using the mount for wide field imaging with just the camera sitting on it.

There is no sense in going for a better mount than my camera can handle, and I don't foresee ever getting out of the "consumer line" of Canon cameras (Rebel/40D/50D/etc.).



If you've spent any time at all in the DSLR forum below, you'll soon realize the DSLR cameras you're speaking of are NOT THE WEAK LEAK in astrophotography! You can do a lot of serious imaging with a common DSLR.

how long of an exposure a given Messier Object (say M31 for my example) would take to get a result (depth) that was equivalent to [posted picture].



I don't see your picture, but here is a photo of Andromeda (M31) taken at 320mm focal length and comprised of 60 x 1 minute exposures. The mount was a CG5-GT mount...just for reference. The camera was a Canon 30D. The lense was an Astronomy Technologies 66mm APO refractor. A 300mm Canon lense would be more than adequate as well.

I have had others recommend EQ3 mounts and a good match for the performance of my lenses.




At 300mm and above, I would not want to be using an EQ3 mount. Wide field imaging is one thing and the EQ3 would be fine for that, but once you get into longer focal length imaging, you wlll really want to autoguide. The EQ3 doesn't have that capability. Another feature that is very useful for imaging is goto. I took this shot of the North American Nebula without actually ever seeing it in my telescope. I had to take an image just to verify that it was there. The goto on the CG5-GT mount put the nebula dead center in the field of view. In addition, some objects may require multiple nights of imaging to get enough data. Having a goto scope can really be helpful there.

That's why I say that the CG5-GT mount with full goto and autoguiding, and capable of holding a wide range of instruments is such a great deal at only $600.

Patrick

#15 Dilligas

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Posted 05 March 2009 - 06:09 PM

The reality with astrophotography is that for focal lengths 200mm and up you are going to need a stable and accurate mount. The mini-eq is really best suited for 100mm and less and that means 24mm to 50mm are more optimal. At 50mm, Jupiter is a bright star and the moons will probably be indistinct.


At 300mm, some rough calculations show that Jupiter should vary between 10-15 pixels in diameter on my camera. That is why I held out a bit of hope at this longer focal length that I might pick the moons up, but so far, I have never bothered to try to catch them on a fixed tripod.

The CG5-GT mount is the least expensive mount you can get that will carry a nice range of focal length scopes. If you get into autoguiding, there's no reason you couldn't shoot long exposures with 1000mm focal length scopes as well as using the mount for wide field imaging with just the camera sitting on it.


Looking back through my last post, it sounds as though I am being dense, but a lot of that was trying to post in a limited amount of time between classes and thinking that I was being clearer than I was.

There is no sense in going for a better mount than my camera can handle, and I don't foresee ever getting out of the "consumer line" of Canon cameras (Rebel/40D/50D/etc.).



If you've spent any time at all in the DSLR forum below, you'll soon realize the DSLR cameras you're speaking of are NOT THE WEAK LEAK in astrophotography! You can do a lot of serious imaging with a common DSLR.


You're absolutely right on that one. I have been spending my time mainly in the mounts, beginner's corner. etc. and not (it appears) enough time in other areas. I may have just enough knowledge on the DSLR capacity front to be dangerous, and I will try to spread my time around a little more evenly in the forums. There is so much in just basic knowledge in this new area, that I want to get "up to speed" as quickly as possible.

how long of an exposure a given Messier Object (say M31 for my example) would take to get a result (depth) that was equivalent to [posted picture].



I don't see your picture, but here is a photo of Andromeda (M31) taken at 320mm focal length and comprised of 60 x 1 minute exposures. The mount was a CG5-GT mount...just for reference. The camera was a Canon 30D. The lense was an Astronomy Technologies 66mm APO refractor. A 300mm Canon lense would be more than adequate as well.


There wasn't actually a picture posted there, but it was intended to show that "perfect" source of distilled information that would help make my decision easier. (Yes, I know that isn't much of a testament to my willingness to be patient in this process.) However, once again, your pic at an approx. 300mm equivalent is visually what I am hoping to produce (which may mean summer school for me - but at least I could keep reminding myself what I would get for my efforts =} ).

At 300mm and above, ... you wlll really want to autoguide. ... Another feature that is very useful for imaging is goto. I took this shot of the North American Nebula without actually ever seeing it in my telescope. I had to take an image just to verify that it was there. The goto on the CG5-GT mount put the nebula dead center in the field of view. In addition, some objects may require multiple nights of imaging to get enough data. Having a goto scope can really be helpful there.


Your last statement there really struck me. I have spent time doing wide-field short exposures, star trails and jumping around with binoculars, and I really hadn't thought through the issues associated with trying to image dimmer objects in a narrow field of view. Starhopping is going to let me down in this, isn't it?

That's why I say that the CG5-GT mount with full goto and autoguiding, and capable of holding a wide range of instruments is such a great deal at only $600.

Patrick


Ah, more research to do... Usually my SO is ready for me to go ahead and make whatever purchase I am considering by the time I am done kicking tires, so I know that I can get irritating while trying to make up my mine and apologize for that and thank you for your patience with me through this process. =}

#16 MtnGoat

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Posted 05 March 2009 - 06:25 PM

This is why I recommend getting your feet wet with a little work on a Clist mount for $100 bucks, then you can experiment until such time as the $600 bucks shows up. Good gear is great stuff...gear that works OK and you can actually afford, is good too. I've been in the finances hole before as we all have, and me, I'd rather have something in hand and get some results than dream about what is much better but I can't afford.

#17 Dilligas

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Posted 05 March 2009 - 09:38 PM

Well, I have already picked up a cheap Celestron 6x finderscope to put on a barn door to help with polar alignment. This should tide me over until the money is available for a CG-5 (or if there is an even better deal that comes along).

Seeing more of what I want in quality (and sometimes having to extrapolate back to a focal length), it looks like I will want the heavier mount before it is all said and done. I have seen some very nice pics with inexpensive mounts, but if seeing some dust lanes in M31 will be possible with the more expensive mount, it is just too tempting. However, I should be able to keep myself busy for quite some time getting my feet wet with learning polar alignment, more image post-processing than I already have done, etc. with a barn door. In fact, depending on how it goes, I might even develop an astronomy course for our college and have the students build their own, but there I go again trying to put the cart in front of the horse... =}

#18 MtnGoat

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Posted 06 March 2009 - 01:11 PM

Any mount running properly will get the dust lanes, it's merely a matter of exposure time. Here's M31 from the cheapo mount with an ETX70 (350mm FL running 30 second subs) and a DSI-C I hadn't taken new dark frames with for quite a while.

The polar align wasn't quite nailed yet, light haze, and I oversharpened, but you get the idea.

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#19 iamjulian

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Posted 02 April 2009 - 09:53 AM

I'd vote for the self build barn door option. I was in a similar position to you but as I am only working with 30mm and 50mm lenses at the moment, perhaps the barn door is going to be more suited to that than your 300mm. Building the thing itself is as easy as pie once you have the measurements. The first built was ok but not great. The second build where I added a red dot finder for polar alignment was a big help and has allowed me 3 minute exposures without noticeable error. I am lucky to have relatively dark skies and I was picking up stars of magnitude 11 in a 3 minute exposure with a 30mm lens. I have no idea whether that is good but version one of my barn door only managed magnitude 9. For version 3 I have picked up a one meter threaded rod which I intend to curve.

The bottom line is I have had hours of fun making it. It has taught me quite a lot. And it has cost me the equivalent of about $50 ($40 of that for the red dot scope!) If the barn door doesn't work out for you then you have lost nothing.






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