Lunatiki
Pooh-Bah
Reged: 08/07/05
Posts: 1133
Loc: Amarillo, TX
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Larry Owens took these fine images. Used the same exact set up. Looks like the Lumenera people might want to consider lowering their prices.
web page
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Mars Watch
All images taken with:
Celestron NexStar 8i SCT
DBK 21AF04.AS
K3ccd/Registax4/PSP8
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Sean McDaniel
sage
Reged: 10/17/05
Posts: 425
Loc: ashburn, va
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i just saw the posting on the marsobservers list. i pre-ordered the usb2 dmk 21 today. apparently TIS is receiving an order for these on monday with another order coming shortly later. i feel real secure with my decsion now...not that i had the spare bucks for a sky-nyx.
now if i can find out what filters larry is using.
Edited by Sean McDaniel (10/10/07 09:11 PM)
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Lunatiki
Pooh-Bah
Reged: 08/07/05
Posts: 1133
Loc: Amarillo, TX
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I sure don't see $700.00 difference.
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Mars Watch
All images taken with:
Celestron NexStar 8i SCT
DBK 21AF04.AS
K3ccd/Registax4/PSP8
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Sean McDaniel
sage
Reged: 10/17/05
Posts: 425
Loc: ashburn, va
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i see a $700 savings.
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sean mcdaniel
ns11
toucam pro ii
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Lunatiki
Pooh-Bah
Reged: 08/07/05
Posts: 1133
Loc: Amarillo, TX
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I'm seriously considering ordering a DMK or another DBK, just to have as a back-up.
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Mars Watch
All images taken with:
Celestron NexStar 8i SCT
DBK 21AF04.AS
K3ccd/Registax4/PSP8
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Sean McDaniel
sage
Reged: 10/17/05
Posts: 425
Loc: ashburn, va
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joel, do you still have your toucam? i sold mine on amart to fund the dmk. just shipped it today but thinking i should have kept it.
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sean mcdaniel
ns11
toucam pro ii
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Lunatiki
Pooh-Bah
Reged: 08/07/05
Posts: 1133
Loc: Amarillo, TX
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I do still have it. I'm going to make it available to the local astronomy club for people who want to give it a try.
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Mars Watch
All images taken with:
Celestron NexStar 8i SCT
DBK 21AF04.AS
K3ccd/Registax4/PSP8
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Ron B[ee]
Tyro
Reged: 04/27/03
Posts: 4719
Loc: CA
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Thanks Joel for posting this very interesting comparison!
Can someone explain how the C14 operates at f/48 with the Skynyx and only at f/24 (like 1/2) with the DMK and yet the images have the same scale?
Thanks,
Ron B[ee]
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5-inch Tele Vue NP127 APO 
4-inch Tele Vue TV-102 APO 
8-inch f/6 Discovery PDHQ Dob 
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wes
scholastic sledgehammer
Reged: 11/13/03
Posts: 930
Loc: Oklahoma
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Hi Ron,
Most likely it’s the difference in pixel sizes between the cameras.
Wes Higgins
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Lunatiki
Pooh-Bah
Reged: 08/07/05
Posts: 1133
Loc: Amarillo, TX
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Larry said....
Well I took these comparison images, same scope, same filters, same glass (barlow) using extensions to get the same scale (different chip sizes) with both a DMK21AF04 and a Skynyx2-0M
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Mars Watch
All images taken with:
Celestron NexStar 8i SCT
DBK 21AF04.AS
K3ccd/Registax4/PSP8
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Ron B[ee]
Tyro
Reged: 04/27/03
Posts: 4719
Loc: CA
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Thanks Wes.
Wanting to learn more, may I ask another question. Does this mean then that smaller pixel size is better? For example, assuming we shoot the C14 at prime focus. The smaller pixel size will result in more pixel per sq area of the object. Thus in theory, the more pixel that covers the same area, the better the resolution in the image right?
Another question if I may  . But smaller pixel means smaller image scale which I now understand why f/48 versus f/24. Assume for the moment in the future we have a camera that is 1/4 the pixel size of the Skynyx today. Would that mean someone would have to pile on powermates/barlows at f/192 just to get the same image scale as the other camera? In other words, is there a limit to how small the pixel should be in order to be real-world practical?
Thanks,
Ron B[ee]
PS - Wes, I'm so glad you have a website now. I love going there to consult some features in great depth of details on your website 
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5-inch Tele Vue NP127 APO
4-inch Tele Vue TV-102 APO
8-inch f/6 Discovery PDHQ Dob
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Bird
Carpal Tunnel
Reged: 08/07/03
Posts: 2600
Loc: Canberra, Australia
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Ron, it's the other way around - smaller pixels make the image larger, increasing the effective image scale.
There's also the issue of noise, traditionally smaller pixels mean an increase in noise levels. Some cameras have a pixel size around 4.5 microns, which is about as small as you'd practically want to go.
The Toucam and DMK21AF04, and all other cameras using the sony ixc098bl sensor have a pixel size of 5.6 microns.
The Dragonfly2 / Dragonfly Express and some other SkyNyx models have pixel sizes of 7.4 microns.
The lowest noise / highest sensitivity camera that I personally have seen and used is the Dragonfly2 from www.ptgrey.com. I bought one last year, and it's the camera I used for the June 22 Jupiter image posted elsewhere.
cheers, Bird
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Deep Sky Optics 13.1" f/5.5 newtonian,
PGR Dragonfly Express, PGR Dragonfly 2
RedHat Linux + Coriander
http://www.acquerra.com.au/astro/
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novbabies
Postmaster
Reged: 06/05/05
Posts: 15678
Loc: Northern Georgia!
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....wow, great pix on the link page!
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Good Seeing!
Mark
Orion 12" XTi f/4.9
VERY old Edmund 6" f/8 reflector
Assorted binoculars
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Dobermann
member
Reged: 08/06/07
Posts: 71
Loc: Minsk, Belarus
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Quote:
The lowest noise / highest sensitivity camera that I personally have seen and used is the Dragonfly2 from www.ptgrey.com. I bought one last year, and it's the camera I used for the June 22 Jupiter image posted elsewhere.
cheers, Bird
Sorry for off-topic  . Anthony, is there any difference in sensivity and noise level between Dragonfly 2 and Dragonfly Express?
Thank you.
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Our team: Konstantin Morozov, Yuri Goryachko (Yuri_18),Mikhail Abgarian (Dobermann) .
http://objectstyle.org/astronominsk/index_en.htm
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iceman
Post Laureate
Reged: 03/07/04
Posts: 4219
Loc: Gosford, Australia
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Very interesting comparison, and bodes well for the little DMK. Sean came to a similar conclusion in his recent S&T review of the DMK.
For the price, it really is the best astronomy camera around.
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Mike
. My Bio | My Jupiter 2007 Gallery | My Image Gallery
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jonbosley
professor emeritus
Reged: 10/19/05
Posts: 506
Loc: Texas
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Sure looks like the DMK has it in this test - I was reading a write up on a new imager, which was hinting that firewire produces more noise then USB2. Has anyone heard of this before?
I guess a side by side test of a DMK firewire & a new DMK USB2 would shine light on it.
Jon
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C11 XLT Celestron
Atlas Goto Mount on Concrete Pier
WO 66 SD Doublet APO Refractor
Philips SNC900NC Webcam
Faymax FC-1000m Webcam with cooling fan
Orion Star Shoot Deep-Space CCD
POD Observatory
www.whitedwarfobservatory.com
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rumples riot
Carpal Tunnel
Reged: 07/01/04
Posts: 2231
Loc: South Australia
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Hmmm, well I got to say the Skynyx is better. I have owned both and the differences I found remarkable. For a start the noise is so much greater in the DMK just in raw frames. Now this image is done with Mars. I would be interested to see what he gets on Jupiter. With a short time to take the frames I reckon the difference would be more remarkable. You can take frames for over 5 minutes with Mars.
The other difference is that you can use 12 bit on the Skynyx; its not available on the DMK.
I reckon the larger pixel size makes a large difference too. With a larger well depth the larger pixels can take in more information before they discharge than the smaller versions.
The DMK is good, but it is not the same as the Skynyx. More tests of differing planets would be needed to convince me otherwise.
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EARTH AND COSMOS
My Solar System Imaging BLOG
How to peltier cool a C14 SCT
SOUTH CELESTIAL POLE
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iceman
Post Laureate
Reged: 03/07/04
Posts: 4219
Loc: Gosford, Australia
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I don't think the comparison states any conclusions - and I don't think there's anyone in this thread saying the DMK is a better camera.
When you compare price for performance, I believe that's where the DMK comes out tops.
At more than twice the price, you certainly don't get more than twice the performance. For some people, price isn't a consideration and so if spending more money means an extra 5-10% improvement in their images, then it could be worth it.
As Bird points out, the ptgrey cameras are probably a step up again from the Skynyx. But again they are more expensive. For most people, the trade-off between price and performance is a very big factor in their decision. For others, they'll just buy the best even if it delivers only a small % of improvement. There's no right or wrong. It depends on their budget etc.
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Mike
. My Bio | My Jupiter 2007 Gallery | My Image Gallery
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Lunatiki
Pooh-Bah
Reged: 08/07/05
Posts: 1133
Loc: Amarillo, TX
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Well, in the comparison the DMK sure doesn't appear to have more noise in my opinion. They were imaged minutes apart, same set up, same processing.
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Mars Watch
All images taken with:
Celestron NexStar 8i SCT
DBK 21AF04.AS
K3ccd/Registax4/PSP8
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rumples riot
Carpal Tunnel
Reged: 07/01/04
Posts: 2231
Loc: South Australia
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I was not stating that the tests say one way or another Mike. I am telling you my opinion as I have owned both. I know what both are capable of. I guess that counts for nothing though these days. So many people make assessments without actually using the equipment.
Yes the price difference does not yeld a 50% increase in performance, but there is in my mind at least a 20% increase in performance.
Luna, the images while taken minutes apart could have been taken for several minutes. I think the imaging runs where over 30 odd minutes.
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EARTH AND COSMOS
My Solar System Imaging BLOG
How to peltier cool a C14 SCT
SOUTH CELESTIAL POLE
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iceman
Post Laureate
Reged: 03/07/04
Posts: 4219
Loc: Gosford, Australia
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Quote:
Yes the price difference does not yeld a 50% increase in performance, but there is in my mind at least a 20% increase in performance.
You're right - 20% is a big difference if that is your experience. You sold your DMK didn't you? It would've been good to see a side by side comparison test like the one in the link in this thread.
In the comparison test here, there is certainly not a 20% difference. In Sean Walker's review, he stated that the difference was very small (certainly not a 20% difference).
Bird has used both, as well as his ptgrey. I don't think his side by sides yeileded a 20% difference either.
Maybe the seeing was 20% better on the night you used the skynyx for good results 
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Mike
. My Bio | My Jupiter 2007 Gallery | My Image Gallery
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Bird
Carpal Tunnel
Reged: 08/07/03
Posts: 2600
Loc: Canberra, Australia
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I own a DMK21AF04.as, a Dragonfly2 and a Dragonfly Express. Side by side testing shows a clear win for the Dragonfly2/Draonfly Express cameras, both in sensitivity and lower noise and more features (ie format7 support which I use all the time).
But on the other hand they are 2x more expensive than the DMK. Seems pretty clear that if you want to spend around $US350 then get the DMK, but if you have $US750 to spend then get the Dragonfly2.
It's hard to directly compare the Dragonfly2 and Dragonfly Express, they are very different cameras. My personal opinion is that the Dragonfly Express is a perfect lunar camera cause it can do up to 200fps in capturing, and lunar work is probably the only place you'll get enough light to do that.
For other planetary work the Dragonfly2 is practically the same as the dragonfly express and a bit cheaper.
I don't own any of the usb cameras, so I can't compare them to the firewire ones. Also I use these cameras exclusively under Linux, so I can't compare the Windows software for each of them. My linux capture program (Coriander) works with all firewire cameras.
Jon - there's no reason for sensitivity or noise to depend on the data interface (usb or firewire). If anyone told you otherwise then I'd be suspicious.
cheers, Bird
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Deep Sky Optics 13.1" f/5.5 newtonian,
PGR Dragonfly Express, PGR Dragonfly 2
RedHat Linux + Coriander
http://www.acquerra.com.au/astro/
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davidpretorius
professor emeritus
Reged: 09/25/05
Posts: 574
Loc: Tasmania, Australia
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i know I would like to go SKYNYX just so i can not have the gain at 100% in RGB at 30fps
the extra sensitivity would be nice...........
so would birds setup in linux!!!
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Davo
10" peltier cooled Next with dob driver II, Lu075 camera
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Gendo
Post Laureate
Reged: 12/12/05
Posts: 3231
Loc: Rexburg, ID
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I see about a 10% difference in the visibility of fine detail in the comparison images, and that's mainly just in the red channel. SkyNyx displays a little bit better image overall. However, I also see a bit of an onion ring effect in the SkyNyx camera (low right).
It is possible though that seeing slightly fluctuated between the DMK captures and the SkyNyx captures. I see that happen often in the span of 20-30 minutes.
The end all debate test would be 2 identical telescopes imaging the same target at the same time, and then swap cameras on the scopes (since even identical scopes won't have identical optical quality), and repeat. That's pretty much the most objective way to really compare them. Now's a good time with Venus, Saturn, and especially Mars in the predawn sky so as to have a multiple planet comparison.
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Lunatiki
Pooh-Bah
Reged: 08/07/05
Posts: 1133
Loc: Amarillo, TX
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Quote:
i know I would like to go SKYNYX just so i can not have the gain at 100% in RGB at 30fps
Perhaps I'm missing something, but there is no way I could capture at 100% gain with the DBK. The result would be burned out with no details. Lately for Mars, Its been at about 650, or what I would call 60% gain.
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Mars Watch
All images taken with:
Celestron NexStar 8i SCT
DBK 21AF04.AS
K3ccd/Registax4/PSP8
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Gendo
Post Laureate
Reged: 12/12/05
Posts: 3231
Loc: Rexburg, ID
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^^ Yeah, maxing the gain doesn't look good on the DMK either, at pretty much any framerate. Some things work well with 600-700, others I set at 800-900. I've yet to find an acceptable setting with gain at anything past 1,000 (I think it goes to 1,024 or so).
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rumples riot
Carpal Tunnel
Reged: 07/01/04
Posts: 2231
Loc: South Australia
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Luna, all this depends on the image scale you are working with. If you go above 10,000mm with a 9"-11" scope, you will have significantly less light than say at 5000-7000mm. This will result in having the gain at 100% most of the time.
Dave works at 10,000mm and above and this is the reason for the gain being so high. unfortunately you need high focal lengths to get significant detail increases in images. You simply cannot get detail out of images that are too small and don't cover enough pixels.
Justin, yes getting scopes side by side might be instructive, but the fact that I have owned both units; the DMK I was the second to use it here and the first in Australia. I used this for 16 months at a variety of focal lengths and am very confident in my assessment. The skynyx I have owned for 3 months and have used it extensively and have seen immediate results. So in this respect I am well qualified to give my word that the skynyx is better and well worth the extra money. I cannot say it plainer than that. My images have not only improved from larger aperture but also from a better camera.
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EARTH AND COSMOS
My Solar System Imaging BLOG
How to peltier cool a C14 SCT
SOUTH CELESTIAL POLE
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Lunatiki
Pooh-Bah
Reged: 08/07/05
Posts: 1133
Loc: Amarillo, TX
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RR, I will certainly take your word for it because of your experience and of course your images, because they speak for themselves, but can you explain to me how Larry's images came so close to each other in every aspect if there is a big difference between the cameras? Thanks....
Joel
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Mars Watch
All images taken with:
Celestron NexStar 8i SCT
DBK 21AF04.AS
K3ccd/Registax4/PSP8
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gazerjim
Postmaster
Reged: 02/12/04
Posts: 7533
Loc: San Angelo, TX
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My 2 worth: The skynyx shows up slightly better in contrast and tonal range on my screen. Whether the difference is worth the price is a value judgement. Also, one test does not make for a valid comparison between cameras. We would need to see the cameras tested under a variety of conditions with various targets IMHO.
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Jim Fisher
If you're not part of the solution, you're part of the precipitate.
Henry J. Tillman
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rumples riot
Carpal Tunnel
Reged: 07/01/04
Posts: 2231
Loc: South Australia
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One certain factor that I have mentioned and not explained totally is that planets like Jupiter you can only really image for 35-40 seconds per channel (sometimes more like Bird does); rotational issues come into play and so with such a short time you can only really get a limited number of frames in poor to above average seeing. Maybe a 1500 frames if you are imaging at 7000mm and 1000 frames if you have a 14" (at 12000mm +) per channel (this is for a fully exposed histogram). Of which you would use maybe 4-700 frames depending on the seeing conditions. Most commonly around 400 frames. This really is not enough frames to use on the DMK and Jupiter. You really need 550+ frames for a really smooth image to start with. Bird I think uses something like 1200 frames + in really good seeing. (I don't get that sort of seeing consistently)
Now planets like Mars which rotate at a similar rate to earth can be imaged for much longer. You can image for a total of 4-5minutes worth of data. This means that you will easily in average seeing conditions get 7-800 frames per channel to stack out of runs over 2-3000 frames taken per channel.
With this amount of frames you cannot help getting great results from the DMK on Mars. Aside from the fact that we have not considered the guys individual talents in processing.
However, generally the more frames you can get the better the image. And; the more frames that are clean of distortions the larger you can resample from a 12000mm standard fl. A good example is Anthony's images this year in great conditions he can resample a lot to attain the massive image scale. Damian Peach's images this year are larger still and show fantastic detail (he uses a skynyx too)
Now on top of all this is that each image contains more data because of the well depth of the pixels. The deeper the well the better the images. So when you combine this with lower noise, more frames andwell depth you get great images.
Like I said the DMK is good but the Skynyx and the Dragonfly express are better again. The images from Damian, Bird show that is the case. And I really think that Jupiter would be a better test comparison given the short duration of exposure.
Did I explain that well?
Paul
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EARTH AND COSMOS
My Solar System Imaging BLOG
How to peltier cool a C14 SCT
SOUTH CELESTIAL POLE
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Lunatiki
Pooh-Bah
Reged: 08/07/05
Posts: 1133
Loc: Amarillo, TX
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