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asaint
Carpal Tunnel
Reged: 04/25/03
Posts: 2021
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DMK USB 2.0 Camera
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Doug D.
Pooh-Bah
Reged: 08/23/05
Posts: 1327
Loc: Virginia
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Nice to have options - I just hope DMK doesn't plan to drop the firewire line now that they have introduced USB 2.0.
I mean, I understand it from a market perspective (just about every recent generation computer has USB 2.0) but from a purely performance-based perspective, I'd still prefer firewire for sustained throughput performance with devices like cameras.
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Refractors mostly.... solar and dark sky.
Charlottesville
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macastronomer
super member
Reged: 04/27/05
Posts: 135
Loc: Rochester, MN
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I highly doubt they would drop the firewire line of cameras. I really don't know why anybody would want the USB version over the firewire if they have a choice. I realize that a multitude of PC laptops don't have firewire but I also don't see why anybody would buy one of those when they have a choice.
I'm sure I will get people to debate me saying that USB 2 is as fast as firewire, but that is only the burst rate, sustained transfers don't compare. In addition, if you use the same bus (such as plugging in a mouse that happens to run on the same bus as your camera) you are crippled to the speed of the slowest device with USB —at least, that's my understanding of it.
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Macastronomer Group
MacAstronomer
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Doug D.
Pooh-Bah
Reged: 08/23/05
Posts: 1327
Loc: Virginia
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What can I say - I agree.
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Refractors mostly.... solar and dark sky.
Charlottesville
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Elektronkind
member
Reged: 06/10/07
Posts: 38
Loc: Silver Spring, MD
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If the product can perform to its stated spec with USB, then there's no need to prefer a firewire version over it.
Though if you're really concerned about buss contention (a valid concern), then it's pennies to go pick up a USB (or firewire) PCMCIA/ExpressCard32 card for your laptop in order to dedicate an entire buss to the device. This is what I do for my outboard sound recording interfaces which run the firewire buss in isochronous mode. Adding a non-isochronous device such as an external hard drive to the same buss can cause bad contention (this is on firewire mind you)
/dale
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Orion XT10i + Telerad
WO Megrez 90 APO
Astro-Physics Mach1GTO
WO EZTouch mount (AYO version)
TeleVue Nagler 3.5T6, 7T6, 22T4
Coronado PST (Hα)
Canon Digital Rebel XTi
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gatorengineer
professor emeritus
Reged: 02/28/05
Posts: 725
Loc: Hellertown, PA
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Would have been helpful to mention the price in the review.... Probably would save some folks the reading. A nice cottage industry of taking a $40 webcam repackaging it, and selling it for $700. Great work if you can get it.
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16" & 20" Dobs
4" Triplet Refractor
10" LX200R OTA
8"F20 Dall Kirkham
12.5" F3.5 Newt
CGE
Lots of binos---
Nikon 8x30, 10x35, Prostars,10W/18 x 70 astrolux; 10x50 Fujis. Collectors items 12x60 BLC, 10x80 Flaks, Gas Masks, US Mark 28, 30, 41, 43's
Telescopes Past - 8" Stf Mak, C8, Meade LX10-10", SN8, TAL150K, Orion 150MC, Jason 60mm refractor, ATM 6" F8, WO 110FLT, 92mm Off Axis Newt, Nikon 20x120 bino's, 15x110 Boarderguards, Kuhne Flaks
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iceman
Post Laureate
Reged: 03/07/04
Posts: 4353
Loc: Gosford, Australia
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I think the review could've gone a lot further, it really doesn't say anything about the camera and just provides one image. It's not really useful as a review of the camera, in my opinion.
The noise reduction really shouldn't be used at all - you're just going to be throwing potentially valuable data away. Any noise reduction should be done as a final step in post-processing, not be done at the time of capture.
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Mike
. mikesalway.com.au - Astronomy and Photography by Mike Salway
. IceInSpace - The Australian Amateur Astronomy Community
. My Bio | My Jupiter 2007 Gallery | My Image Gallery
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macastronomer
super member
Reged: 04/27/05
Posts: 135
Loc: Rochester, MN
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This isn't a $40 web cam repackaged. These cameras have less noise, are more light sensitive and can capture much faster (not to mention, depending on the model, chip size). As you know, the whole idea is to freeze those moments of clear seeing, and I've pushed mine past 60 frames / sec. If I pushed the Fire-i beyond 30, it would drop frames and freak out. I'm curious how many images you can push over USB in a sustained flow. I would bet it couldn't be done at the rates I've captured at, but I don't know. What I do know is that the firewire handles it without a sweat.
My previous webcam was a Fire-i (which cost me about $110) and last me about a year before it died, probably due to lots of dew filled nights and traveling in my equipment case. As for the DMK package, it's very nice—small and well built. Although I'm not going to try it, I could probably drive over it with my car and it would be unscathed. It's well sealed up and I doubt this camera is going to wear from my travels.
Between this camera and Astro IIDC, planetary imaging is just a blast. Due to it's sensitivity you can grab some deep space objects too.
If somebody wants to see what it can do, check out Alan Friedman's page (he's been imaging with these for a long time and has had way more steady sky opportunities than I) located here:
http://www.avertedimagination.com/latest_1.htm
All I can say is, "this camera is a lot of fun!"
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Macastronomer Group
MacAstronomer
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Gaz O'C
Pooh-Bah
Reged: 01/02/05
Posts: 1264
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At what point does the write speed of the hard drive become a factor? I mean, 60 FPS at that resolution is a lot of data to write without compression.
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14" f4.5 Dob
10" Meade SCT
180mm f15 Mak/Cass
127mm f12 Mak/Cass
150mm f5 refractor
ED100
EQ6 Skyscan
HEQ5
EQ2
http://stargazerslounge.co.uk/
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Doug D.
Pooh-Bah
Reged: 08/23/05
Posts: 1327
Loc: Virginia
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No question - the DMK's are great cameras and nothing at all like a repackaged WebCam. Point Grey Research also makes a great line of Firewire cameras (I own both a PGR and a DMK).
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Refractors mostly.... solar and dark sky.
Charlottesville
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Elektronkind
member
Reged: 06/10/07
Posts: 38
Loc: Silver Spring, MD
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Quote:
At what point does the write speed of the hard drive become a factor? I mean, 60 FPS at that resolution is a lot of data to write without compression.
60 frames/s at 640x480 and 8 bits per pixel is about a 18MB/s stream of data... well within the capabilities of any modern hard drive and bus. The fact that the data would be written out to disk in a sequential fashion helps well.
Considering 30fps is standard for television and the human eye requires around 15fps for persistence of vision to kick in, 60fps might be a bit useless for most purely visual applications.
/dale
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Orion XT10i + Telerad
WO Megrez 90 APO
Astro-Physics Mach1GTO
WO EZTouch mount (AYO version)
TeleVue Nagler 3.5T6, 7T6, 22T4
Coronado PST (Hα)
Canon Digital Rebel XTi
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macastronomer
super member
Reged: 04/27/05
Posts: 135
Loc: Rochester, MN
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You're right about the speed of visual work, but this branch of the hobby is quite different. If you've ever seen stop action footage, that's what planetary imaging is all about.
It's similar to looking at a stream of water from a faucet. It looks like a solid line of water. Then turn on a strobe light and you'll see individual droplets of water. If you take a fast enough image, you'll see that droplet of water.
When shooting a planet, the jet stream is acting like running water. If you take a 1 second shot, you've just imaged the planet through it and the refraction from it will blur everything. It's that split second between the "droplets" you have to catch. If you are at 30 frames per second, that's pretty good and you can get 1% of your shots to turn out good. However, in the same conditions, if you have a camera that can take shots twice as fast (and is more light sensitive and produces less noise), you can get 2x as many good frames to stack.
My experience so far—the sky is the biggest factor. A better sky is way more important than the camera. However, everything else being equal, these high end cameras can and will out perform their counterparts.
Good question on the hard drive write speed. The hard drives can handle it but some computers may struggle with bus issues. Firewire is superior to USB, but Windows users will have to run a patch as Microsoft hasn't optimized for Firewire (gee, I wonder why). I use an older Mac for field work (about 4 processor families ago) and it has no problems with this at all. I do recommend lots of RAM.
Don't get me wrong, I'm sure the USB version of this camera is fine and dandy—it's just that you could have one that is finer and dandier 
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Macastronomer Group
MacAstronomer
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ASTERON
sage
Reged: 11/24/07
Posts: 236
Loc: ISRAEL
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Hi MacAstronomer,
can you comment about the tradeof between frame rate and resolution in the 640X480 version and other higher resolution versions of the DMK.
Would choosing a higher chip resolution camera reduce the available frame rate over a USB 2.0 
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Meade 12" LX200R (GE mounted
100mm Astrotelescopes Achromat
WO 90mm Megrez "Fluorite" Doublet
WO 66mm (Petzval)
ETX125PE
Garret Optical 25X100 Binoculars
Lunt LS60THaDS BP1200/FT (pre-ordered)
Lunt LS60CaK BP1200/FT
Orion Atlas EQG Mount
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CCD-Labs
Vendor (CCD-Labs)
Reged: 12/16/06
Posts: 84
Loc: Wichita Ks.
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Depending on the mode of the transfer USB2.0 will have no problems in transfering this data. Isosynchronous transfer has a guaranteed transfer time period per frame. Bulk mode and Interupt mode have error checking and guaranteed bandwidth (timing on video is more important than the bandwidth).
Yes Firewire has been used much longer for video than USB2.0 and was basically made to transfer digital video, but with the use of Isosynchronous Transfer mode and well written drivers USB 2.0 can transfer with out the bursty nature of Bulk mode or bus contention one can have with Interupt mode.
Its best to not turn this into a Mac Vs. Windows debate as that is a mute point and that dog has been beaten to the point of nausea.
Everyone should be glad they have a choice now.
William
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CCD-Labs
Affordable Astro Imaging gear
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macastronomer
super member
Reged: 04/27/05
Posts: 135
Loc: Rochester, MN
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Sorry CCD-Labs, I don't intend it to be a battle of platforms. From my experience (especially with video) firewire has always outperformed USB. USB sometimes appears to have similar performance but often makes up for its shortcomings by caching and/or compressing. I have no experience regarding how well the DMK USB camera works. It does seem to be getting good reviews.
Asteron: I can't comfortably give advice regarding the higher res camera—firewire vs. USB, as I don't have experience with it. There is another factor regarding higher res. When you go to a higher res camera, you are generally getting a smaller pixel size. Each pixel is a well and a smaller well is getting less light (think of that pixel as a tiny telescope, the smaller the pixel, the smaller its aperture). Be sure to take that into consideration. A fast shutter speed will not help you if it doesn't capture enough light.
Here's some extended advice and rationale:
If you use a PC and it doesn't already have firewire, you should probably opt for a USB model. It's cheaper (as you won't need to buy a firewire card) and other software is going to behave as you'd expect. If you already have firewire support, don't give it a second thought, get the firewire model. Why? Because you will get people arguing that firewire is better than USB, but you'll never get people arguing that USB is better than firewire—and that alone speaks volumes.
Anybody interested in getting into this aspect of the hobby for the first time, I advise them to take the cheapest route first. Get a Unibrain Fire-i (for Mac) or a Philips ToUcam (for PC) and try it out. Watch the jet stream for steady seeing opportunities (the most important factor) and keep trying. If you are not adept with Photoshop (or similar tool), find somebody with a good understanding of sharpening and curves who can help you—it's simple but different than standard astro-imaging. If after all that you still enjoy it, dive into it with money in hand.
—maybe I should write an article for Cloudy Nights on the topic... there's so much more to say.
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Macastronomer Group
MacAstronomer
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Elektronkind
member
Reged: 06/10/07
Posts: 38
Loc: Silver Spring, MD
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Quote:
Sorry CCD-Labs, I don't intend it to be a battle of platforms. From my experience (especially with video) firewire has always outperformed USB. USB sometimes appears to have similar performance but often makes up for its shortcomings by caching and/or compressing.
Whoa, there. The USB protocol in either version 1.1 or 2.0 of its spec does not contain any provisions for caching or compression of payload over the wire. That is patently false and the caching bit doesn't even make sense in the context of USB. I've noticed (here and elsewhere) that people tend to toss out statements as fact vis a vis USB vs. Firewire without any real empirical evidence to back up one side or the other.
Many people involved in these arguments know just enough about either favored side to be dangerous and then tend to proffer them with arguments that are anecdotal at best. They see USB or Firewire as a abstracted "thingy" and don't pay attention to (or are not aware of) the finer variables that play into performance such as the chipsets involved, their drivers, end device USB bridge type, bus mode, bus contention, interrupt sharing and coalescing and so on and so forth. All these, plus others, play into overall device performance in either realm and regardless of the application.
A lot of times, people have arrived at dim opinions of either FW or USB because they had both a isochronous device such as a sound interface or video device plugged into the same bus that also serviced a non-isochronous device such as an external disk, mouse, keyboard or digital camera. When this happens you would be sure to have some contention which would seriously affect isochronous performance which would manifest itself in choppy video or dropped frames or pops and clicks in audio. Both USB and Firewire suffer from this.
The general rule is to be keenly aware of a particular device's bus requirements and for crying out loud, if you've invested in a $300+ camera, spend the extra $30 for a add-in USB or Firewire card to dedicate to that device - especially if it runs the bus in isochronous mode. This alone would cure a large percentage of instances where video performance is underwhelming.
Both USB 2.0 and Firewire can certainly make the cut for low-medium resolution video in terms of over the wire performance. No question about it. FW does have one advantage in that it provides higher voltage that can, on most systems, supply up up to 7W of power to end devices, making some devices powerable over the FW bus. USB can supply power over its bus as well, but don't expect more than 3 or 4W... not enough for even a 2.5" external hard drive.
Personally, I tend to favor Firewire because I'm a Mac-centric at my house and so it's there in both 400 and 800Mb flavors and it's easy to ensure that a FW bus has a device on it. Those USB ports on your laptop or desktop do not generally indicate a separate USB bus. It's typical to find that the keyboard and mouse and any integrated card readers also share the bus that port is on as well... often giving rise to the problems I described above.
/dale
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Orion XT10i + Telerad
WO Megrez 90 APO
Astro-Physics Mach1GTO
WO EZTouch mount (AYO version)
TeleVue Nagler 3.5T6, 7T6, 22T4
Coronado PST (Hα)
Canon Digital Rebel XTi
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mclewis1
Thread Killer
Reged: 02/25/06
Posts: 2452
Loc: Colorado
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According to a few of the camera vendors and from talking with friends getting a sustained 60fps requires a 7200 rpm drive so most notebooks with 4200 or 5400 rpm drives are not going to cut it. I also assume that nothing else should be using that ATA bus (2nd drive, DVD writer, etc.).
I goes without saying that to get maximum sustained transfer rates you'll also need a fairly quick cpu (assumes up to date buses) and free ram, but you should also turn off any virus checkers and background search indexers and such that will steal disk i/o. In general for this type of video capture you should also go through your PC and look for anything running in the background that's not necessary.
With USB you should be aware of any other devices on the bridge/internal hub that your camera's port is on. Checking the tech specs of your PC is worthwhile since not all ports that are physically next to each other are on the same bridge/hub. Ideally you'd want your camera to have access to all the available bus bandwidth.
While in general it used to be Mac=firewire and PC=USB things are changing. I just purchased a Dell Vostro 1500 notebook that had a 4 pin (non powered) firewire port. Interestingly all the initial docs on the product failed to mention this feature.
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Mark
C11, C6, APM/TMB115, and AT80ED
Tandem mount CGE and CG-5A, WO EZ-Touch and AT Voyager
25x100s, 8x56s, T-Mount Light, and Mark 1 eyeballs
Modded 350D, SPC900, Mallincam
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Gaz O'C
Pooh-Bah
Reged: 01/02/05
Posts: 1264
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That makes sense Mark I have a USB 2.0 Logictech Fusion that can runs 1280x960 @ 7.5 FPS, the internal drive on my laptop drops about 30% of the frames but none when I attach an external 7200 rpm drive. I'd guess these DMKs would need a similar setup up or a link to a desktop.
BTW I just ordered my DMK.....;)
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14" f4.5 Dob
10" Meade SCT
180mm f15 Mak/Cass
127mm f12 Mak/Cass
150mm f5 refractor
ED100
EQ6 Skyscan
HEQ5
EQ2
http://stargazerslounge.co.uk/
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macastronomer
super member
Reged: 04/27/05
Posts: 135
Loc: Rochester, MN
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ELECTRONKIND: Please read my post carefully before picking it apart. I wasn't strictly nitpicking USB, what I said (and what you quoted) was that from my experience, video devices can pull shenanigans to attain what their firewire counterparts can do natively. My experience may be outdated, but I have not yet seen a USB camcorder do what a firewire camcorder can do, such as convert analog to digital video on the fly while importing it in real time—now that takes some real sustained throughput. I don't have a recent model of camcorder with USB, but they all seem to have hard drives now days and it seems to use that as a caching mechanism (data is copied to the drive first and then send over USB). I also suspect that modern cameras are automatically compressing the data, which is how they get as much data stored on their little hard drives. It really doesn't take a rocket scientist to figure this out, a little experience and reading between the lines will do. I'd like to see some straight up testing! I also partly agree with you regarding running it on its own bus. For USB that is totally true. For firewire, I don't think that's necessary as long as the bandwidth isn't being consumed (in other words, don't be copying a bunch of data over the firewire bus while shooting with the camera). You should be able to hook up a DMK and a fast external firewire hard drive on the same bus and let'er rip. I'll be testing that very soon but I'm sure it will have no problems.
Just for some comparisons that have already been done, a quick google search shows this:
http://www.digit-life.com/articles/usb20vsfirewire/
(pan down to the graphs for a quick look)
or here:
http://www.usb-ware.com/firewire-vs-usb.htm
As a side note: a while back I tested a transfer of 50GB with both firewire 400 and 800. I don't recall the exact results but firewire 800 won by a good amount. I thought the hard drive would have been the bottleneck but apparently it wasn't.
MClewis1: Good point. I did opt for the faster drives in my systems (7200 on my G4) and it works great. As an option for people with slower drives in their laptops, with firewire you should be able to plug in an external firewire hard drive on the same bus and capture images at a high frame rate (as I said above, I'll be happy to test that). I would like to know what happens if you do that with USB—does anybody care to test that?
Gaz O'C: Congratz on your DMK camera! Between it and the Flea, I think they are the best cameras out there. I assume since you already have firewire that you got the firewire version?
The reason you're seeing more firewire on PCs lately is due to Apple's switch to Intel chips. The first Intel Macs didn't have firewire 800 because Intel didn't have a firewire 800 solution at the time. Now that they do, I would expect Intel to put it on their boards intended for PC laptops too.
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Macastronomer Group
MacAstronomer
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Gaz O'C
Pooh-Bah
Reged: 01/02/05
Posts: 1264
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Hi Mac,
I decided on the USB version, the Firewire camera entailed another power lead as the camera will be run from my laptop via a PCMIA card.
I'm a clumsy bugger and it just seemed one more thing to trip over on....
Gaz
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14" f4.5 Dob
10" Meade SCT
180mm f15 Mak/Cass
127mm f12 Mak/Cass
150mm f5 refractor
ED100
EQ6 Skyscan
HEQ5
EQ2
http://stargazerslounge.co.uk/
Edited by Gaz O'C (11/27/07 11:20 PM)
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