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Equipment Discussions >> Electronically Assisted Astronomy

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Moromete
professor emeritus


Reged: 02/15/12

Loc: Romania
DBK 21AU618.AS vs Mallincam
      #5761832 - 03/28/13 07:23 AM

Considering the big price difference in favor of the Imaging Source camera and maximum useful exposure time of up to 1 minute (to avoid autoguiding), isn't the DBK 21AU618.AS (with Sony ICX618AQA sensor) more appropriate for live video DSO than Mallincam for someone who uses only a PC for live viewing instead of a CRT TV?

Similarities:
- DBK 21AU618.AS and Mallincam have the same Sony ExView HAD CCD sensor
- long integration time of up to 60 minutes for both cameras
- live DSO viewing ability
- up to 36db manual gain increase for DBK 21AU618.AS
- resolution quite similar
- C-mount adaptation
- no IR filter.

Differences:
- much cheaper DBK 21AU618.AS
- Mallincam has double pixel size than DBK 21AU618.AS
- 1/2" sensor (Mallincam) vs 1/4" sensor (DBK21) => bigger FOV for Mallincam
- lack of active cooling for DBK 21AU618.AS in contrast with Mallincam
- DBK 21AU618.AS better for planets due to smaller pixel size
- DBK 21AU618.AS easier to operate from in house PC via USB cable extension.

For exposures of maximum 1 minute I see no important advantage for Mallincam other than double light gathering capability due to double pixel size. Considering the big price difference I can cope with half sensitivity and FOV of DBK 21AU618.AS.



Are my assumptions correct?

Does anyone know how much noise DBK 21AU618.AS has at maximum gain and 1 minute exposure?


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Moromete
professor emeritus


Reged: 02/15/12

Loc: Romania
Re: DBK 21AU618.AS vs Mallincam new [Re: Moromete]
      #5761849 - 03/28/13 07:39 AM

I forgot to mention that maybe due to the smaller sensor (1/4" vs 1/2")you can use stronger focal reduction with the DBK 21AU618.AS than Mallincam.

Imagine using a F/1.5 focal reduction (like mattlastro's reducer from another post) with the DBK 21AU618.AS without vignieting or significant optical aberrations visible!

Maybe with DBK 21AU618.AS an SCT user can use a cheap 1.25" x0.5 reducer after a Meade x0.33 reducer and get down to F/1.7 without vignieting or significant optical aberrations visible due to its diagonal of only 4.5mm!


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GlennLeDrew
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Reged: 06/18/08

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Re: DBK 21AU618.AS vs Mallincam new [Re: Moromete]
      #5762125 - 03/28/13 10:30 AM

The smaller pixels and lack of cooling will play significant roles. Obtaining *actual* focal ratios of less than about f/2.5 using available reducers on telescopes will be difficult (as I pointed out in the thread mentioned.)

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Chris A
Pooh-Bah


Reged: 02/03/07

Loc: Toronto, Canada
Re: DBK 21AU618.AS vs Mallincam new [Re: Moromete]
      #5762178 - 03/28/13 10:58 AM

The reason for the cost difference is because of the important extras you get with a Mallincam which make a huge difference esp. when viewing deepsky objects. Again these extras are.

- Mallincam has double pixel size than DBK 21AU618.AS
- 1/2" sensor (Mallincam) vs 1/4" sensor (DBK21) => bigger FOV for Mallincam
- lack of active cooling for DBK 21AU618.AS in contrast with Mallincam

You do not mention what your main interest are such as planetary or deepsky observing? The DBK 21AU618.AS is more suited for planetary and lunar where as the Mallincam is superior for deepsky.

This topic is flagging a dead horse and it has been discuss over & over. At the current time you just cannot beat a Mallincam for it's value, built quality and sensitivity for deepsky observations.

Chris A
Astrogate


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Chris A
Pooh-Bah


Reged: 02/03/07

Loc: Toronto, Canada
Re: DBK 21AU618.AS vs Mallincam new [Re: Moromete]
      #5762196 - 03/28/13 11:08 AM

I will add to the fantastic points that Glenn has previously mentioned to your post. Yes you can use a focal reducer to kind of makeup for the half size ccd sensor but you must remember that when using a reducer to such extremes, the DSO of interest (galaxies, planetary nebulas etc.) will start to become very small to observe on your screen unless you plan to look at it by putting a magnifying glass up to your screen

Also you have already lost the sensitivity by having much smaller pixels for DSO and now will lose the benefits of resolution when dramatically reducing your focal length.

Chris A
Astrogate


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Moromete
professor emeritus


Reged: 02/15/12

Loc: Romania
Re: DBK 21AU618.AS vs Mallincam new [Re: Chris A]
      #5762362 - 03/28/13 01:02 PM

Chris I have specified in my first post that main interest is live video observation of DSOs.

I have to disagree with you regarding DSO size when using a strong focal reducer. In fact, in my humble experience, a 1/4" sensor will "magnify" the image 2 times more than a 1/2" sensor.

Lastly, maybe for you such topics are like dead horses because you have lots of money to spend on astro gear and already have a Mallincam. Lucky you than!
I'm not interested in Mallincam's value or built quality but just in its price/performance ratio.


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Dwight J
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Reged: 05/14/09

Loc: Lethbridge, Alberta, Canada
Re: DBK 21AU618.AS vs Mallincam new [Re: Moromete]
      #5762444 - 03/28/13 01:51 PM

The DBK camera is less than ideal and an economical alternative is the Samsung line of cameras which are proven performers.

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Moromete
professor emeritus


Reged: 02/15/12

Loc: Romania
Re: DBK 21AU618.AS vs Mallincam new [Re: Dwight J]
      #5762529 - 03/28/13 02:49 PM

I agree with you Dwight but Samsung CCTVs have too short exposures of only 8/10s and you don't reach mount's limits without autoguiding of 30-60s.
Secondly Samsung has AGC which must be kept on Low to avoid washing out the image.
Otherwise a Samsung SCB-2001 seems quite attractive for the money and having a Sony Super HAD II CCD sensor.

Mallincam sensor has a sensitivity of 1400mV.
DBK's sensor has a sensitivity of 1000mV.
SCB-2001 has a sensitivity of 2250mV.
In my understanding 1000mV=6dB.
DBK has manual gain adjustable between 0-36dB.
Considering you have to keep AGC on Low on SCB-2001 than DBK will equal Samsung's sensitivity after a 7dB gain increase and after this it has a gain advantage of roughly ~25dB (or a 4000mV sensitivity gain) without washing out the image and keeping the colors.


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Dwight J
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Reged: 05/14/09

Loc: Lethbridge, Alberta, Canada
Re: DBK 21AU618.AS vs Mallincam new [Re: Moromete]
      #5762643 - 03/28/13 04:09 PM

Not having seen a DBK in action, it is hard to compare cameras. I have seen the Samsung ones on NSN. Screen shots just don't convey what the particular camera can really do. I wouldn't be afraid to try out the DBK to see what it's capabilities are as we are often limited by what equipment we have on hand.

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jonbosley
scholastic sledgehammer


Reged: 10/19/05

Loc: Texas
Re: DBK 21AU618.AS vs Mallincam new [Re: Dwight J]
      #5762690 - 03/28/13 04:40 PM

The DBK21AU618 is an excellent planetary imager. The small sensor and pixel size makes it much more limited for DSO. It has no cooling and has very high noise levels for long exposures. Outside of planetary imaging in no way can it be-compared to a Mallincam.

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Ed Wiley
scholastic sledgehammer


Reged: 05/18/05

Loc: Kansas, USA
Re: DBK 21AU618.AS vs Mallincam new [Re: jonbosley]
      #5762721 - 03/28/13 04:59 PM

I tried a bit of live view with my DMK21AU618. Great for Luna and Jupiter. I haven't tried a Mallincam, but the DMK is not the tool for live viewing of DSOs IMHO. It is great for another imaging task not mentioned, double stars.

Clear skies, Ed


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Moromete
professor emeritus


Reged: 02/15/12

Loc: Romania
Re: DBK 21AU618.AS vs Mallincam new [Re: Ed Wiley]
      #5762737 - 03/28/13 05:13 PM

Ed, can you shares with us why your DMK21AU618 is not good for live viewing of DSOs?
As an owner of such a camera your opinion is valuable. Thx.


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jgraham
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Re: DBK 21AU618.AS vs Mallincam new [Re: Moromete]
      #5762963 - 03/28/13 06:54 PM

Hmmm, I've used my older DBK21 to observe deepsky objects using 15 second exposures and I was impressed. It is no Hubble, but not at all shabby. If you have an Imaging Source camera there is no reason not to give it a try, but I wouldn't buy one with the idea of using it as a deepsky camera.

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Chris A
Pooh-Bah


Reged: 02/03/07

Loc: Toronto, Canada
Re: DBK 21AU618.AS vs Mallincam new [Re: Moromete]
      #5763087 - 03/28/13 08:03 PM

Sorry I did not realize that you mentioned your interest on another post, I really do not read all the posts on the forum. Your title specifies "DBK 21AU618.AS vs Mallincam "
and to me that includes value & built quality.

When I said flagging a dead horse is because it seems to come up often comparing a certain camera to a Mallincam for DSO observations and they all have their pros and cons.

Chris A


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Ed Wiley
scholastic sledgehammer


Reged: 05/18/05

Loc: Kansas, USA
Re: DBK 21AU618.AS vs Mallincam new [Re: Moromete]
      #5766680 - 03/30/13 11:57 AM

I think John said it all -- yes 15 second exposures will show you something and not bad for this kind of camera, but that is not live viewing its AP. On the other hand, I consider my DMK21AU618 and outstanding high-resolution camera and suspect it will beat the socks off the large pixel Mallincam for imaging doubles that at 1" separation or the craterlets in Plato. Different cameras, different functions different strengths.

Ed


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Moromete
professor emeritus


Reged: 02/15/12

Loc: Romania
Re: DBK 21AU618.AS vs Mallincam new [Re: Ed Wiley]
      #5766858 - 03/30/13 01:12 PM

Chris, no problem. But I still think the horse is not dead yet.

Ed, could you post a single exposure of 20s of Running Man nebula with your DMK21AU618 and WO66ED with AGC Max?

This way I'll be able to compare it with mine taken with ST80 and my CCTV at 20s exposure.

PS: I agree 15s is not quite live viewing but Mallincam owners go up to even 2 min or more. Problem is current video technology available to us is has it's shortcomings and needs prolonged exposures. I'm ok up to 30-60s.


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mclewis1
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Re: DBK 21AU618.AS vs Mallincam new [Re: Moromete]
      #5767439 - 03/30/13 07:33 PM

I can't believe we're still having this discussion. The DMK isn't even in the same league as the Mallincam on DSOs.

The Mallincam starts with a sensor that's 60% more sensitive (comparing an EXView HAD in both cameras) ... and the sensitivity comparison only gets worse if you want color images. The larger fov from the larger sensor in the Mallincam also makes for a more enjoyable viewing experience.
The DMK is an 8 bit camera, the Mallincam is a 12 bit. The gain circuitry in the Mallincam is optimized for low light operation. Then there's the built in cooling. All of which means much better sensitivity and signal to noise ratios in those low light conditions. It's also part of the reason why the Mallincam is almost 3 times the price of the DMK.

To answer your question ... the Mallincam would actually be more appropriate for live viewing. The better sensitivity means shorter exposures to achieve the same image density, and the shorter exposures mean more accurate tracking. Yes you have to handle a more complex setup (video through a frame grabber, separate control and power connections) but you're getting substantially better sensitivity as the trade off.

What would be more interesting to me is a comparison between the $500 video cameras with their shorter integration times and the DMK. High quality planetary cameras like the DMK have come a long way (especially when using the great Sony sensors) and are certainly much more versatile than the older webcam derived technologies ... but just because they can perform longer exposures doesn't mean that they're comparable to cameras specifically designed for that type of work.


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jgraham
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Re: DBK 21AU618.AS vs Mallincam new [Re: mclewis1]
      #5767621 - 03/30/13 09:05 PM

"that is not live viewing its AP"

Huh? Where did that come from? Does exposure time determine live viewing vs AP? If it does then most of the cameras that are discussed in this forum aren't live viewing either. Live viewing with an Imaging Source camera is like live viewing with any other camera; spontaneous and in real-time.

Is the DBK21 'better' than some other camera? One would hope that a camera costing many times as much would be 'better', but no one can make that judgement for someone else. This vs that is an invitation to compare and contrast, not to pontificate which is 'better'.

There are any ways to participate in camera-assisted observing. The DBK21 is certainly capable and it would be interesting to give it a thorough testing in this role. It would be neat to be able to offer this as an option for someone on a budget (my hand is up). In contrast, the Mallincam is purpose-built for this activity and by all accounts it does a fine job.

So much to try, so few clear nights...


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Ed Wiley
scholastic sledgehammer


Reged: 05/18/05

Loc: Kansas, USA
Re: DBK 21AU618.AS vs Mallincam new [Re: jgraham]
      #5767666 - 03/30/13 09:32 PM

Hi Moromete: I only do high resolution imaging with my DMK21, sorry, no Running Man. I am running at F22.5 and the little 66mm is in the box right now as I do not guide the DK. I would try the Image Source web site, there are probably DSO images there.

Ed


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Lorence
scholastic sledgehammer


Reged: 09/15/08

Re: DBK 21AU618.AS vs Mallincam new [Re: jgraham]
      #5768989 - 03/31/13 02:57 PM

Quote:

"that is not live viewing its AP"

Huh? Where did that come from? Does exposure time determine live viewing vs AP? If it does then most of the cameras that are discussed in this forum aren't live viewing either. Live viewing with an Imaging Source camera is like live viewing with any other camera; spontaneous and in real-time.




A while ago I would have said the main difference between live viewing and astrophotography was the image processing involved in AP. A live or near live viewer just sees what the camera sees.

A few recent developments have changed that idea somewhat. I use Deep Sky Stacker Live to stack images as they are downloaded from my Universe. The stacking acts like a filter to clean up noise generated by the camera. I watch the stacking process on the screen as it take place. I'm viewing near live but with some image processing taking place between the camera and the screen. Where does that fit into viewing? It's not video but I view it as though it was video. It's not AP because I don't save the images and post them for all to see.

If that wasn't enough to cloud the issue there is software available that processes live video as you are viewing. Similar to the type of processing done by the astrophotographers but the processing is taking place as the image is being viewed. No longer just seeing what the camera sees but using processing to see the video image the way you want to see it.

It's called Video and Electronically Assisted Astronomy. At what point is it no longer video but electronically assisted viewing. Personally I don't care what it's called, I just enjoy it more and more with every new development.


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Moromete
professor emeritus


Reged: 02/15/12

Loc: Romania
Re: DBK 21AU618.AS vs Mallincam new [Re: mclewis1]
      #5770659 - 04/01/13 11:59 AM

Mark, John said his old DBK21 does a good job on DSOs with longer exposures. I think he knows what he is speaking as a DBK21 user.

Yes, the new DBK21 with ExView sensor is 60% less sensitive than Mallincam and is only 8bit vs 12bit. But neither the price is the same. For a 60% difference Mallincam is 3-4 times more expensive which is too much for me. Nobody says Mallincam is not the best for live video astronomy.
So Mark don't be so surprised we are comparing DBK21 to Mallincam under these circumstances. Nobody said DBK21 is better or the same with Mallincam.
But don't forget that price is very important for some of us and the planetary bonus DBK21 has.

The question is how much worse is DBK21 compared to Mallincam considering the big price difference.

I know there is more noise with the new DBK21 than Mallincam due to lack of cooling especially but I wonder how much more noisy is in practice DBK21 after 1min exposures.

I just feel the new DBK21 has DSO potential for the money but I don't know how much. That's all.

Don't forget that due to smaller sensor one can use stronger focal reduction with the DBK21 than Mallincam without vignetting and DBK21 can recuperate its sensitivity handicap this way.

John could you help us with some answers regarding:
- for live viewing on my laptop of DSOs with DBK21 at exposures of say 1 min each, do I have to record movies on my HDD or that's not mandatory?
- could you show us some images or an Youtube movie of Running Man or M51 (or other faint DSOs) taken with 1 min exposure and maximum Gain to see how much noise the camera generates?


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mclewis1
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Reged: 02/25/06

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Re: DBK 21AU618.AS vs Mallincam new [Re: Moromete]
      #5770850 - 04/01/13 01:42 PM

I never suggested that the DBK can't do DSO work or that it isn't a great value as a planetary camera that can do some other work too. I was primarily focused on your comment/question about the DBK being "more appropriate for live video DSO than Mallincam ...".

I think it is very valid to question "how much better" or "how much noise" and to look into actual comparisons.

Your point about the smaller sensor being able to handle more aggressive focal reduction is a very valid point for small objects. This would be very apparent on smaller galaxies for example.

I don't think John said it would do a "good job on DSOs", he did say he was "impressed" and that it's "not at all shabby" ... but he also said he wouldn't suggest buying a DBK specifically for DSO work. But if the DBK capabilities worked out for you I think that would be great because I think we need more DSO cameras in this price range.

I'm totally in line with your desire for a reasonably sensitive, easy to use camera with a 30-60s maximum exposure capability that priced in the $500-700 range. I see this as a really under served "sweet spot" in the market. There are tons of alt az goto or small gem mounted scopes around that were purchased by folks who have very restricted budgets (for example high end Mallincams are out) but would still love to do near live viewing. This would be a very strong market for a good 30 second camera at a reasonable price.

I'm also very curious about the upcoming Starlight Xpress SX Video camera.


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Ed Wiley
scholastic sledgehammer


Reged: 05/18/05

Loc: Kansas, USA
Re: DBK 21AU618.AS vs Mallincam new [Re: Lorence]
      #5771709 - 04/01/13 09:13 PM

I'm not about to get into a debate parsing what is live view and what is AP and what is video observing. Everyone can have it their way so far as I am concerned.

Ed


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akjudge
member


Reged: 02/25/08

Loc: Western NY, USA
Re: DBK 21AU618.AS vs Mallincam new [Re: Ed Wiley]
      #5772405 - 04/02/13 09:18 AM

Interesting thread... I have a DMK that I use mainly for lunar/planetary viewing. Have not tried it on DSO's since I use my Stellacam3 for DSO's.

But getting back to the idea of a cheaper alternative to the Mallicam (great camera), has anyone tried the ASI120MM camera? Specs say it has a resolution of 1280x960 @ 35fps. Exposure range up to 1000s (16 minutes). It is USB and sells for less than $300.

Here is a link to the specs:

http://www.zwoptical.com/eng/Cameras/ASI120/index.asp

More interestingly, here is a link to actual images. While most are lunar/planetary, there are several DSO images that look very impressive (middle of the page):

https://www.google.com/search?q=ASI120MM&hl=en&tbm=isch&tbo=u&...

I am just curious whether anyone has any DSO experience with this camera (which is priced at 1/6 of the Mallicam)?

Jim


Edited by akjudge (04/02/13 09:26 AM)


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jgraham
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Re: DBK 21AU618.AS vs Mallincam new [Re: akjudge]
      #5772937 - 04/02/13 01:17 PM

I was just going to make a comment about the ASI120MM. This looks like a very interesting camera along the same lines as the Imaging Source and Point Grey cameras. I'm waiting to hear whether a bid I placed on a scope was successful or not. If not I may have to drown my sorrows by picking up one of these.

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Moromete
professor emeritus


Reged: 02/15/12

Loc: Romania
Re: DBK 21AU618.AS vs Mallincam new [Re: jgraham]
      #5773092 - 04/02/13 02:51 PM

Oh boy, I think we have here a DBK21AU618 with TEC cooling! http://www.teleskop-express.de/shop/product_info.php/info/p5165_Astrolumina-A...

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mpgxsvcd
Carpal Tunnel


Reged: 12/21/11

Loc: Raleigh, North Carolina
Re: DBK 21AU618.AS vs Mallincam new [Re: Moromete]
      #5773195 - 04/02/13 03:49 PM

It seems like there will never be an end to this whole “My camera is better than yours” argument. Quite frankly no one single person has tested them all under identical conditions so no one really knows what works best in every situation.

Everyone has an idea of what works well for their needs. However, you can’t possibly know what everyone’s needs are.

One person may prefer resolution. One person may prefer shorter exposures. One person may have a tight budget. Another person may prefer less wires. Another person may need better cooling. And yet another person may need all of those things with none of them being of greatest importance.

The bottom line is that you need to gather as much information about what works for other people in similar situations to yours. Then you can make an educated guess as to what options you should try.

We all have solutions that produce excellent results under certain circumstances. However, I guarantee each of us could find faults in the solutions of others if we wanted to. I hope that is not what this forum will always come down to though.


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Moromete
professor emeritus


Reged: 02/15/12

Loc: Romania
Re: DBK 21AU618.AS vs Mallincam new [Re: mpgxsvcd]
      #5773220 - 04/02/13 04:00 PM

I think you got it wrong. Nobody said here “My camera is better than yours”. Secondly, we are trying to gather as much information about what works for other people in similar situations to ours, as you correctly said. It's all about information sharing.

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mpgxsvcd
Carpal Tunnel


Reged: 12/21/11

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Re: DBK 21AU618.AS vs Mallincam new [Re: Moromete]
      #5773256 - 04/02/13 04:18 PM

Quote:

I think you got it wrong. Nobody said here “My camera is better than yours”. Secondly, we are trying to gather as much information about what works for other people in similar situations to ours, as you correctly said. It's all about information sharing.




Chris did.

"At the current time you just cannot beat a Mallincam for it's value, built quality and sensitivity for deepsky observations." This statement is purely speculative since he hasn't tried all of the cameras against each other in the same situations.

This was basically the first response to the thread and it always seems that someone throws out their idea of what works best as fact.


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mpgxsvcd
Carpal Tunnel


Reged: 12/21/11

Loc: Raleigh, North Carolina
Re: DBK 21AU618.AS vs Mallincam new [Re: Moromete]
      #5773265 - 04/02/13 04:23 PM

Quote:

Nobody says Mallincam is not the best for live video astronomy.




Speaking for everyone I see.


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Chris A
Pooh-Bah


Reged: 02/03/07

Loc: Toronto, Canada
Re: DBK 21AU618.AS vs Mallincam new [Re: mpgxsvcd]
      #5773650 - 04/02/13 06:37 PM

Hi Travis

I am not going to get into a big debate over what I said, but I still believe (and have tested several cameras) what I previously said. We have a fantastic tool for 3 years now that anyone can use and it's called Night Skies Network (NSN) open to ALL!

To this day I have not seen hardly any people and I am on NSN a lot showing their results live with their particular camera. I have always believed in actions speak louder than words. Lets start seeing some broadcast of DSO's and that will provide us the best idea of what can be expected under certain conditions.

Chris A
Astrogate


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ccs_hello
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Reged: 07/03/04

Re: DBK 21AU618.AS vs Mallincam new [Re: jgraham]
      #5773912 - 04/02/13 08:13 PM

RE: ASI120MM

It is using a Aptina (Micron) CMOS sensor.
IMO, the current technologies used in its sensor is not so fine-tuned toward low-light, low readout noise implementation called for by DSO imaging/viewing.

The situation may change in the near future since SONY and Aptina exchanged patent cross-licensing few months back for the entire patent portfolio. Basically Aptina will learn a lot from SONY while SONY will be granted with a few fundamental CMOS Image Sensor (CIS) original inventions (Photobit days, etc.)

One major thing that will affect future view of SONY CIS by astro folks due to this cross-licensing is:
SONY probably will produce more CMOS sensors with "contract detection" pixels embedded to perform the CDAF demanded by consumers. This means (1) some regular pixels will be replaced with CDAF pixels, (2) the gaps left by CDAF pixels will be "doctored", and (2) RAW is not true raw any more.

Again, this is mass-production day-light photography/movie vs. a very small group of niche applications. If you know SONY, the answer is obvious.

Clear Skies!

ccs_hello


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mclewis1
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Re: DBK 21AU618.AS vs Mallincam new [Re: Moromete]
      #5774118 - 04/02/13 09:20 PM

Now that's a camera (Astrolumina ALccdIMG0H) I'd like to take a look at. Too bad the sensor is webcam sized (really small).

Software seems a little sparse but functional.

Edited by mclewis1 (04/02/13 09:28 PM)


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ccs_hello
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Re: DBK 21AU618.AS vs Mallincam new [Re: mclewis1]
      #5774392 - 04/02/13 11:07 PM

Mark,

That cam seems to be QHY's IMG0H (using Exview HAD II type-1/4" VGA resolution ICX618 SONY interline progressive CCD). Note: tiny pixel pitch.
See this CN thread.

Clear Skies!

ccs_hello


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Re: DBK 21AU618.AS vs Mallincam new [Re: ccs_hello]
      #5774552 - 04/03/13 12:43 AM

CCS, Yes I recognized it after looking around a bit ... you'd think the "IMG0H" in the product name would have tipped me off ... lol.

What I'm really curious about is the ability to produce the camera at that price point and the potential ability to produce it with something like the 428-AKL 1/2" ExView HAD sensor. I'm not sure how much if anything would need to change in the camera. For example that big pixel sensor wouldn't require too much more storage for the buffer.

The real problem is likely the fact that the planetary imagers don't want that sensor so there wouldn't be that ready made market for it, reducing the potential numbers. I wonder what it would take for the QHY folks (or others) to see the potential for a live view camera based on something like a modified IMG0H?

Edited by mclewis1 (04/03/13 01:09 PM)


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Moromete
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Re: DBK 21AU618.AS vs Mallincam new [Re: mclewis1]
      #5774667 - 04/03/13 03:12 AM

Almost all cameras, including Mallincam Xtreme, have old Sony sensors. Both Sony ICX428AKL and ICX618 are same old technology with low sensivity for today standards.

Now we need newer Sony CCD sensors (which already exist) like this http://www.sony.net/Products/SC-HP/cx_news/vol71/pdf/icx828_829aka_ala.pdf

The Sony ICX828AKA (ExView HAD II) has a sensitivity of 3200mV compared to 1400mV of ICX428AKL. Secondly, the ICX828AKA has big pixels and much higher resolution than ICX428AKL besides beeing 2.5 times more sensitive.

Considering the huge price, Mallincam should have now an ICX828AKA CCD inside now. Just my 2 cents.

Am I wrong?


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Re: DBK 21AU618.AS vs Mallincam new [Re: Moromete]
      #5774795 - 04/03/13 07:43 AM

Moromete,

Great find! SONY Japan actually announced it as early as in Jan 2013.
For years (many years!) I thought SONY will ever upgrade its outdated/neglected ICX 408/409/428/429 to SuperHAD II or ExviewHAD II.
With ICX828 and ICX829 announcement, finally the overdued change took pace. Luckily it is still the same large pixel pitch and using complementary-color CMYG Bayer filter array.

We'll have to wait a bit longer (usually 3-6 month cycle) to see 828/829 based products showing up in the market. Type-1/2" is a bit expensive and I would guess will first be used in Mintron, Samsung, etc. and gradually trickle down to smaller security videocam mfg. Price-wise, gut feeling, probably no more than 5% higher than the current SCB4000 price.

Clear Skies!

ccs_hello


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Re: DBK 21AU618.AS vs Mallincam new [Re: ccs_hello]
      #5774908 - 04/03/13 08:55 AM

I've owned a DMK21, a Flea3 and the ASI120MM. I'd say none are particularly well suited to live viewing faint objects. All have problems with noise at longer exposures and small chips.

However, the ASI is much better than the other two in this regard. I've done a bit of DSO imaging using the camera and seen a good bit of others. My avatar is the Eskimo Nebula recorded with the ASI, using 5s exposures and fairly low gain. It was very pleasing watching the nebula on screen while collecting all the subs.

But, again, I wouldn't advise anyone on buying one of these cameras for the express intent of using them for live viewing of faint objects. If you own one for other purposes (all three are excellent planetary, lunar and solar imagers) and don't have funds for a live viewer. Or you only want to occasionally use live viewing, then they can certainly be ably used in that fashion, assuming you arren't going after 18th magnitude galaxies.

If live viewing is going to be your primary means of observing/imaging, then it would probably be worth the extra money to do it "right". Realizing "right" varies considerably amongst us by time, money and interest.

Also, note that I've never used a Mallincam so I can't make a direct comparison. But, for the original question, long exposures with the DMK/DBK are very, very noisy.


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Re: DBK 21AU618.AS vs Mallincam new [Re: Chris A]
      #5774978 - 04/03/13 09:19 AM

Quote:

Hi Travis

I am not going to get into a big debate over what I said, but I still believe (and have tested several cameras) what I previously said. We have a fantastic tool for 3 years now that anyone can use and it's called Night Skies Network (NSN) open to ALL!

To this day I have not seen hardly any people and I am on NSN a lot showing their results live with their particular camera. I have always believed in actions speak louder than words. Lets start seeing some broadcast of DSO's and that will provide us the best idea of what can be expected under certain conditions.

Chris A
Astrogate




NSN is not the only place to share your experience. NSN requires that you have a computer and an internet connection where you observe. A lot of people don't have that or really just don't want to have that(A computer and cables). Like I said there are many different needs for each person. It is all live viewing though. It doesn't have to be on NSN to be considered as an option.


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Re: DBK 21AU618.AS vs Mallincam new [Re: bunyon]
      #5775068 - 04/03/13 09:46 AM

Thank you Paul for sharing your experience with us. I'm worried about strong image noise too. Have you owned the DMK21 with the Sony ICX618 CCD sensor or with an older sensor?


@ccs_hello or other experts: Please judge my following judgement: In theory a Meade 3.3 reducer takes down a 41mm image circle (its clear aperture in fact) to a 13,53mm image circle. If I put a GSO 0.5x reducer after Meade 3.3 one, than I'll shrink the 13,53mm image circle in half to 6,76mm (which is not good for Mallincam's 12mm diagonal due to strong vignetting but perfect for a 1/3" Sony CCD with 6mm diagonal like SuperHAD II -ICX810 or ExView HAD II - ICX672). This means that a C11 can work at F/1,65 with a CCTV with a current 1/3" Sony CCD sensor of 6mm diagonal without vignetting (like Samsung SCB-2001).
On the other hand, with a CCTV which has a 1/4" Sony CCD sensor of only 4.5mm diagonal we can reduce a C11 to F/1.1 by using a cheap GSO 0.5x reducer after a Meade 3.3 reducer with appropriate spacing (like 2 1.25" extension tubes of ~60mm in total) to take the GSO down to x0.33 and almost without vignetting!
Take a look here at the bottom of the page http://www.teleskop-express.de/shop/product_info.php/info/p676_Focal-reducer-...


1) Am I wrong/crazy or correct?
2) Has anyone of you tried one of these combinations with a CCTV like Samsung SCB-2000/2001 (which has half the sensor size of SCB-4000 or Mallincam) or a DBK21AU618 or a QHY IMG0H?
3) How obvious are SCT's optical abberations with Mallincam and a Meade 3.3 reducer?


PS: I think nobody used such strong focal reduction till now because the sensors used in Mallincam and dedicated astrophotography cameras are not smaller than 12mm but generally are bigger than this.
In conclusion I think for live DSO viewing the best camera must have a new generation Sony CCD sensor of 4.5mm diagonal with high sensitivity in mV and must be used in a very fast SCT near F/1.2 to be able to gather photons faster than before and to achieve a wider FOV equal to today's Mallincam.
Oh, and this way Hyperstar becomes obsolete too for video astronomy.


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Re: DBK 21AU618.AS vs Mallincam new [Re: mpgxsvcd]
      #5775076 - 04/03/13 09:49 AM

While NSN is a great site (I visit it often), it is not necessarily one "that anyone can use". I am not knocking the site. Originally, I posted on NSN with my Stellacam3 and DMK (lunar). However, Adobe Flash updates eventually made it impossible for me to connect to NSN. In spite of the fact that Jim tried hard to help me fix my problem (going back to older versions of Adobe Flash, etc.), we were unable to get me "on-line" anymore. This is not a criticism of NSN, but rather Adobe Flash and potential conflicts with other installed software. Apparently after reading posts on the NSN Yahoo group, I am not the only one unable to get on line. My point is that there probably are a fair number of other types of live-view camera owners that can't broadcast their images on NSN for technical reasons.

Jim


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Moromete
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Re: DBK 21AU618.AS vs Mallincam new [Re: akjudge]
      #5775124 - 04/03/13 10:06 AM

Sorry, 1/2" Sony CCD sensors are 8mm in diagonal and not 12mm like I wrote previously but my judgment remains unchanged regarding focal redutcion factor.

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Re: DBK 21AU618.AS vs Mallincam new [Re: Moromete]
      #5775331 - 04/03/13 11:26 AM

I purchased the DBK 21AU618.AS from OPT when they cam out, over a year ago. It is no doubt a solid camera, with fair to fiddly software.

Back then I had a Meade LX200 Classic 10, f6.3, and the DBK was a good match. I was able to capture planets like Mars, Jupiter, and Saturn, with aplomb, even though I did struggle with the software. The Moon was always a good time too. I did try the camera on brighter DSO's, M42 to be specific.

The results were nothing more than fair, I could capture the central bright area, and even some color. When I extended the time, thats where the camera lost its "shine" to me. It just wasnt sensitive enough to capture anything more than the brightest of bright objects.

I had hoped that this camera might be a real sleeper.....almost a something for nothing proposition. I mean that It was known the camera did well on Luna and Planets, but if I could eek-out DSO's, that would be a plus, and making it a keeper. After some thought, I ended up selling the camera off, I couldnt justify $450.00 for a super-planetary camera....so away it went.

I have had for some time Mallincam Hyper Plus Color, and thoroughly enjoy
it. I would compare the M42 view an the DBK camera to a 2 second integration at AGC 1 or 2 on the Mallincam.

I hope this helps!

Andy

Edited by budman1961 (04/03/13 11:28 AM)


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Re: DBK 21AU618.AS vs Mallincam new [Re: budman1961]
      #5775378 - 04/03/13 11:45 AM

I had a 618 chip, Moromete. The software that came with it was a little clunky - I like FireCapture better. SharpCap is good for single images.

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mpgxsvcd
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Re: DBK 21AU618.AS vs Mallincam new [Re: Chris A]
      #5775520 - 04/03/13 01:01 PM

Quote:

Hi Travis

I am not going to get into a big debate over what I said, but I still believe (and have tested several cameras) what I previously said. We have a fantastic tool for 3 years now that anyone can use and it's called Night Skies Network (NSN) open to ALL!

To this day I have not seen hardly any people and I am on NSN a lot showing their results live with their particular camera. I have always believed in actions speak louder than words. Lets start seeing some broadcast of DSO's and that will provide us the best idea of what can be expected under certain conditions.

Chris A
Astrogate




I just bought a capture device for my computer. I will try NSN out next week from my house. If that works then I can try it with my phone's 4G hotspot where it is darker.


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jimthompson
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Re: DBK 21AU618.AS vs Mallincam new [Re: Moromete]
      #5775529 - 04/03/13 01:11 PM

I just clued into this discussion when chasing down links on the Sony ICX828, so I apologise for hopping in late. Some of the basic assumptions regarding similarities between the DBK21AU618 and Mallincam are incorrect. The ICX618 and ICX428 are not all that similar. An easy mistake to make considering how difficult it is to understand the information on these devices that is available from Sony. I looked at this problem a while back, and wrote a paper on it. You can view the paper from my website:

http://karmalimbo.com/aro/reports/Astrovideo%20Camera%20CCD%20Survey.pdf

The gyst is the following:

1. Sony quoted sensitivity values are 100% misleading. The method used to measure and reduce the data for a sensitivity value is different from one CCD model to another. This information can be found in the Sony spec sheets but it is easy to miss. Sneaky marketing dogs.
2. One shot colour CCD's are very different from monochrome. The colour matrix that is applied to achieve colour images has a profound impact on the resulting sensitivity of the detector. This information is barried in the Sony specs as well, once you figure it out.
3. RGBG colour matrix chips (eg. ICX618) suffer a significantly larger penalty from their colour matrix than CMYG matrix chips. This is a result of the net transmissivity you get from a colour filter that gives Red Green and Blue versus Cyan Magenta and Yellow.
4. When you roll up points #1 to #3 above, the full sensor band sensitivity of the ICX618 is 64% that of the ICX428. If you are using a light pollution filter the ICX618 sensitivity is affectively 52% that of the ICX428.
5. The Dark Current noise of the ICX618 is quoted by Sony to be 4 mV. This is twice that quoted for the ICX428. Even if the DBK21 had cooling equal to the Mallincam, it would still be noisier due to the very nature of the CCD.

It is too bad we are not looking for cameras to do security or general consumer type stuff. If we were we'd be riding the wave of demand that is driving the industry. Unfortunately we are amateur astronomers, and the best we can do is scrounge for scraps from an industry that has no real commercial reason to pay attention to us. There are more sensitive chips being developed, sure, but they are designed to serve the mass market who has different requirements than we do. Camera companies like Flea, Imaging Source, and others are producing some very nice cameras (I own a DBK51 that I love), but they are stuck using what is available for sensors. Good camera developers have actually tested all these different sensors and picked what was the best fit for the particular camera they are making. I know for a fact that the current configuration of the Mallincam came about in this way, after years of trial and error with numerous sensors. All we as users can do is ask questions, test, compare. Don't forget that we are still at the beginning of this field of astronomy, not the middle, the beginning.

Regarding the prospect of reducing a scope down to f/1.5...I am very doubtful this would ever be possible. I have tried many variations of stacked multiple reducers, and have never been able to achieve focus on my refractors below about f/3, and below about f/2.5 on my 8" SCT. To create such a fast scope would require custom designed optics, tube and focuser. Think about it, the focus plane for an f/1.5 8" aperture would be only 12" from the objective/primary! Even just dealing with the field curvature would be a big challenge. In my own testing I have also found that narrow band filters for light pollution or imaging perform poorly below f/2, a result of the difference in the incident light angle from center to edge of the light cone.

Regards,

Jim Thompson
AbbeyRoadObservatory


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mclewis1
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Re: DBK 21AU618.AS vs Mallincam new [Re: jimthompson]
      #5775555 - 04/03/13 01:21 PM

Jim,

Nice to see you posting ... instead of "just" lurking for all these years



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jimthompson
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Re: DBK 21AU618.AS vs Mallincam new [Re: mclewis1]
      #5775599 - 04/03/13 01:38 PM

Heh heh, to be honest Mark I just don't have the time for all these different forum discussions. I think I need to retire or something.

Cheers,

Jim T.


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GlennLeDrew
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Re: DBK 21AU618.AS vs Mallincam new [Re: jimthompson]
      #5775656 - 04/03/13 01:56 PM

Moromete,
Jim has stolen some of my thunder. The Meade f/3.3 reducer *just* comfortably covers a Mallincam's 1/2" format (8mm) diagonal. I once tried it on a mono CCD of 15mm diagonal and only the central circle was good; the outer field was horrible!

As Jim imtimated, obtaining something approaching f/1.5 performance from a focal reducer will almost certainly require a specialized design using several elements.

One saving grace of the video chip's small size; it enables to employ a reducer whose clear aperture is not larger than a 2" filter, allowing a narrow-band filter to be placed ahead of the reducer, where the light cone is not too steeply converging.


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Chris A
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Re: DBK 21AU618.AS vs Mallincam new [Re: Moromete]
      #5775812 - 04/03/13 03:27 PM

I hate to brake the news to you Luc (think this is your name from glancing at your NSN broadcast), but these CCD sensors as of March 8th 2013 are still not available to the consumer yet. Trust me, when available Rock Mallin will be looking into these sensors as he always keeps up with the times.

Chris A
Astrogate


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Chris A
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Re: DBK 21AU618.AS vs Mallincam new [Re: mpgxsvcd]
      #5775816 - 04/03/13 03:30 PM

Hey great Travis and I am looking forward to your 1st light broadcast. If there is any help you need getting going/connected just let me know.

Clear skies,

Chris A
Astrogate


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Chris A
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Re: DBK 21AU618.AS vs Mallincam new [Re: mpgxsvcd]
      #5775824 - 04/03/13 03:34 PM

You have a good point Travis, but I cannot think of a better way to show your views to a huge audience for instant feedback from them regarding the views.

Chris A


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Chris A
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Re: DBK 21AU618.AS vs Mallincam new [Re: akjudge]
      #5775853 - 04/03/13 03:46 PM

Hi Jim

You have a point and sorry to hear that you have issues with Flash Player and I do wished that there was a better way to show the live feed. Many (including myself) have used Manycam or WebcamMax to display their video feed from the desktop directly into NSN.

My only issue is finding a better true way to show ones image/show then NSN. Yes one can post images here but it is way too easy to apply post processing to them prior to posting them here. At least you can just use say the Mallincam and only it's camera control software software (MC Control) and just use the video sliders to tweak live. Yes you can apply live stacking using DSSLive & VirtualDub filters to further enhance the object being viewed but the audience can easily pick up on that. However keep in mind that these programs DSSLive & VirtualDub are applied to the video stream on the fly and not post processed using PS or any other program and a later time when not connected to NSN - This is a big difference.

Chris A
Astrogate


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Chris A
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Re: DBK 21AU618.AS vs Mallincam new [Re: jimthompson]
      #5775869 - 04/03/13 03:56 PM

Hey Jim are you now getting caught in the CN Spiders web LOL?

On the serious side I am glad to see you here and what great valuble information you have just provided.

Clear skies,

Chris A
Astrogate


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Chris A
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Re: DBK 21AU618.AS vs Mallincam new [Re: GlennLeDrew]
      #5775874 - 04/03/13 03:58 PM

Glenn wait until you have to deal with the big CCD sensor in the MC Universe like I am dealing with now LOL!

Chris A
Astrogate


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GlennLeDrew
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Re: DBK 21AU618.AS vs Mallincam new [Re: Chris A]
      #5776140 - 04/03/13 06:27 PM

Chris,
In a fashion I'm already dealing with the Universe, as I'm helping a friend get up and running with his. Started in the late summer/fall, and about to get back at it after the winter shut-down.


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Re: DBK 21AU618.AS vs Mallincam new [Re: jimthompson]
      #5776206 - 04/03/13 07:02 PM

Hah, kind of funny seeing newbie under that name. I've been to your site and read your work - loved the survey.

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Ed Wiley
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Re: DBK 21AU618.AS vs Mallincam new [Re: Lorence]
      #5778123 - 04/04/13 04:49 PM

I kind of jumped in because of the questions about the DMK21 and did not want to get into a discussion of AP versus "live viewing" since I don't do "live viewing" in the sense in which the original question was posed. I have visited folks on the field who do "live view" and peeked at their screens and I do visit NSN web site to see what the Mallincam folks are broadcasting (impressive). I have done some "live viewing" on Luna and Jupiter with the DMK21 to show neighbors who drop by my backyard observatory from time to time and the DMK21 is great for that, you can show 5-6 people a nice live image on the computer screen. But it is not, IMHO, a tool for DSO "live viewing."

It was my impression, perhaps incorrect, that those who do "live viewing" are substituting the video camera for an eyepiece. This gives the experience of "at the eyepiece" but the ability to go deeper and even see some colors in some DSOs that cannot be captured with oculars for that particular aperture. In other words, its a visual not photographic experience.

Naturally one can capture frames and its AP. Of course, I could be completely off-base and uninformed.

Ed


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mpgxsvcd
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Re: DBK 21AU618.AS vs Mallincam new [Re: Ed Wiley]
      #5779436 - 04/05/13 11:31 AM

To this day the only true live view(1/30th of a second or less duration) electronic image I have seen of a deep space object was with an image intensifier.

Near real-time live view just depends on your definition of near-real time.

For me 1 minute or less is near real time.

Also I don't believe "video camera" is a relevant term with anything but the image intensifier because that is the only camera that is truly capturing a real time 30 FPS or faster image.

All of the others are just cameras that output their signal to a display device. They either output 1 image only or a sequence of the same image over and over.

The LCD screen on a camera is technically the exact same thing as a monitor or TV. It is attached to the camera via a cable and it outputs a real time NTSC or PAL signal. However, the content that you are capturing is only a true real-time or "video" capture in the case of the image intensifier.

Edited by mpgxsvcd (04/05/13 11:32 AM)


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Lorence
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Re: DBK 21AU618.AS vs Mallincam new [Re: Ed Wiley]
      #5779944 - 04/05/13 03:41 PM

Quote:

It was my impression, perhaps incorrect, that those who do "live viewing" are substituting the video camera for an eyepiece. This gives the experience of "at the eyepiece" but the ability to go deeper and even see some colors in some DSOs that cannot be captured with oculars for that particular aperture. In other words, its a visual not photographic experience.

Ed




Rather than thinking that a video camera replaces an eyepiece, think of it as a better eyepiece.

I use video cameras and a CCD camera. Sometimes I look at live images sometimes they are delayed images. The delay can be a few seconds or a few minutes but essentially the image is viewed as it is as made by the camera.

Astronomy is not an action sport. When an object is in the eyepiece it is usually there for quite some time. Hopefully it will remain still and allow the viewer to see as much detail as possible. The simple reality is that even in an eyepiece the image is just a picture.

The "Improved Electronic Eyepiece" takes the picture from the little round hole in the old eyepiece and displays it on a screen. There are pros and cons to either kind of viewing but as the saying goes "Beauty is in the eye of the beholder"

The magic word is "Eye". All that is important is what goes into that eye. Who cares how it gets in there.

PS. (Sort of) I did run into a few rather narrow minded individuals over in the Deep Sky Observing Forum recently. According to them you can only see an object buy viewing the actual photons that it emits. That struck me as being rather odd until I realized they do see things differently than I do. They are so narrow minded they can see through an eyepiece with both eyes at the same time.


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mpgxsvcd
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Re: DBK 21AU618.AS vs Mallincam new [Re: Lorence]
      #5780099 - 04/05/13 04:30 PM

Quote:

They are so narrow minded they can see through an eyepiece with both eyes at the same time.




That is just awesome.


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Ed Wiley
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Re: DBK 21AU618.AS vs Mallincam new [Re: Lorence]
      #5780357 - 04/05/13 07:07 PM

I can buy the "better eyepiece" reasoning Lorence. Your comment about seeing the photons is a good one, we would need a philosopher to parse out whether seeing photons emitted by an object is actually seeing the object. I sure with can find one who says "yes" and another who says "no." The outcome of the debate is not likely to enhance the viewing experience regardless of your choice of sampling photons.

Ed


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Re: DBK 21AU618.AS vs Mallincam new [Re: Ed Wiley]
      #5780381 - 04/05/13 07:27 PM

This eye (visual viewing directly) vs. electronic assist debate is similar with Digital TV Broadcast vs. the Analog TV Broadcast.

Human mind (or Human Visual System), not just eye, is a very strange mechanism.

DTV has a well-known "cliff fell-off" effect. If you live far away and gradually move away from a broadcast tower, within a certain radius in any distance from the transmitter tower, you always see a nice clear and crisp picture/TV program. When you move away from that zone, very quickly, you can't receive anything at all! This is similar to visual observing experience.

In the analog TV broadcast system, the further away from the broadcast tower, the more snow you'll see. You mentally train yourself, "at least I can watch my favorite program". (Until you fell so uncomfortable and declare it is a loss... ; then your sister walks in and says this program looks good. "Don't switch the channel!" )


I hope you get my point.

Clear Skies!

ccs_hello


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TonyBegg
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Re: DBK 21AU618.AS vs Mallincam new [Re: ccs_hello]
      #5782635 - 04/06/13 09:13 PM

I am looking forward to the day when live viewing projects (and somehow registers) in a heads up display with an eyepiece view. Then you mix the direct photons with the imaged photons, the faint fuzzies become full of color and detail and you still have the visceral feeling of seeing stars.

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Stew57
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Re: DBK 21AU618.AS vs Mallincam new [Re: Lorence]
      #5782780 - 04/06/13 10:19 PM

[quote
Rather than thinking that a video camera replaces an eyepiece, think of it as a better eyepiece.


The magic word is "Eye". All that is important is what goes into that eye. Who cares how it gets in there.






If it wasn't for the discovery of the mallincam my "viewing" would have ended. My eyes are not what they once were. The skies from my backyard aren't either and are getting worse by the day. The mallincam has made seeing DSOs possible again. It has also allowed me to share those views with others that may not know about averted vision nor have the time to truly dark adapt (though with my skies there is no such thing anymore). Besides I am lazy and not interested learning the new skill of spending hours processing. It is all I can do to get a few precious hours in to view as it is.

There are a few other options and some look promising and I am sure that as this market grows others will compete with Rock, but for now I am well pleased with both my mallincams.


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Lorence
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Re: DBK 21AU618.AS vs Mallincam new [Re: Stew57]
      #5784515 - 04/07/13 06:45 PM

Quote:

There are a few other options and some look promising and I am sure that as this market grows others will compete with Rock, but for now I am well pleased with both my mallincams.




The Mallincam group is raising the bar again. They are applying Astro Photography techniques to live video. Quite impressive so far. Could lead to a substantial growth in the market. If you haven't already seen what they are up to, check it out.

http://tech.groups.yahoo.com/group/mallincam/


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Jay B
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Re: DBK 21AU618.AS vs Mallincam new [Re: Moromete]
      #5791503 - 04/10/13 10:45 PM

I am a late to this thread. I have used the dbkAu618 for some live viewing. I posted a few pictures of some quick attempts a month or so ago. This included 42, hubbles variable nebula( a somewhat tougher object) and a galaxy (m82 from what I remember). Do a search under my name and dbk and you will see my attempts and comments. The software works great. However the chip is small and the camera is somewhat noisy at longer exposures 20 second or so. The small chip means you need to have a scope which finds stuff accurately. My opinion is if you already have one give it a try -- you will see way more than visually. I used a .5 focal reducer. Is this the best camera for the job?
I don't think so. However, I suspect that a larger chip CCD camera with the right software (fast imaging) with less noise would work great. For example look at some of the pictures taken by the gentleman from the UK (nytecam) who uses the lodestar on this forum.

Edited by Jay B (04/10/13 10:54 PM)


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Moromete
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Re: DBK 21AU618.AS vs Mallincam new [Re: Jay B]
      #5792230 - 04/11/13 12:08 PM

Thx Jay. I don't have a DBK. I have a CCTV with similar sensor but a bit larger (1/3") and limited maximum exposure of 20s. I was just wondering how good/bad is for "live" DSO viewing. I see noise is a problem with DBK. I have noise too after 20s with my cctv but I don't find it deal breaking.

I saw you have used DBK21 with a C9.25 with x0.5 focal reducer. You need much more focal reduction and at a least x0.33 focal reducer.

With a sensor of 1/4" like DBK21 has you need to work with C9.25 at F/2 or less because the 1/4" sensor magnifies the image 2 times more than a Mallincam which has 1/2" sensor and 9 times more than a APS-C DSLR. With DBK21 you need a focal length of 300-400mm for a wider FOV.

The 1/4" sensor has the advantage that beeing smal you can concentrate more light on its pixels and make the telescope much faster than with bigger sensors and this way you shorten the integration times drastically.

From my point of view for video astronomy a 1/4" sensor with 9um pixel size is ideal in a scope working at F/2 or less.


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Moromete
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Re: DBK 21AU618.AS vs Mallincam new [Re: Moromete]
      #5792236 - 04/11/13 12:13 PM

Regarding the Lodestar-C I don't know if it provides a live feed on screen like DBK21/Mallincam or acts like a DSLR at long exposures when the screen goes black during the exposure. Maybe Nytecam can clarify this.

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Chris A
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Re: DBK 21AU618.AS vs Mallincam new [Re: Moromete]
      #5792316 - 04/11/13 12:53 PM

"The 1/4" sensor has the advantage that beeing smal you can concentrate more light on its pixels and make the telescope much faster than with bigger sensors and this way you shorten the integration times drastically". Remember it is not the size of the CCD/CMOS sensor that determines the light gathering capabilities but the size of the pixels of course determining the focal ratio is equal.

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Moromete
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Re: DBK 21AU618.AS vs Mallincam new [Re: Chris A]
      #5792430 - 04/11/13 01:56 PM

Please read more carefully my previous 2 posts.

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mclewis1
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Re: DBK 21AU618.AS vs Mallincam new [Re: Moromete]
      #5792452 - 04/11/13 02:07 PM

Quote:

Regarding the Lodestar-C I don't know if it provides a live feed on screen like DBK21/Mallincam or acts like a DSLR at long exposures when the screen goes black during the exposure. Maybe Nytecam can clarify this.



Sort of ... It's not the camera, it's the camera control/capture software that is the key here. The Starlight Xpress software for the LodeStar allows you to keep displaying the previous image as well as providing various image processing filters and such. The camera on it's own just downloads single images.

Nytecam can better explain all the details about how this all occurs.

Video cameras continuously download an image in a NTSC or PAL video format and you can use a whole variety of software to display that video image on a PC.


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Chris A
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Re: DBK 21AU618.AS vs Mallincam new [Re: Moromete]
      #5792867 - 04/11/13 05:02 PM

Sorry, I am not gunning for you and it maybe a language communication issue. I re-read your previous 2 posts and still did not find any backup supporting what you said.

What I am saying is for e.g. if you have an APC DSLR size sensor with 9um microns pixels and your 1/4" CCD sensor with 9um micron pixels there will be no boost in sensitivity when dealing with the same focal ratio. Now I am talking about a mono camera and colour filters over the pixels can affect sensitivity whereby CMYG allows light to enter faster than RGB. Yes I agree the magnification will be stronger in the 1/4" CCD sensor


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Moromete
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Re: DBK 21AU618.AS vs Mallincam new [Re: Chris A]
      #5798839 - 04/14/13 04:49 PM

How about combining a DBK 21AU618.AS with a Samyang/Rokinon 85mm F/1.4 lens? (=510mm focal length because DBK21 "magnifies" 6 times more than an APS-C sensor)

This will give an image scale identical to a Canon 550D attached to a ED80 F/6 but with an important difference: what you image in 300s with ED80+Canon 550D, you'll image in 23s with DBK21+Samyang 85mm!

In this combo you don't even need to go higher than 30s exposure and maybe we can get away even without TEC cooling on DBK21 and have acceptable noise. Or maybe instead of a DBK21 we can use QHY IMG0H with TEC cooling.

What do you think?


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budman1961
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Re: DBK 21AU618.AS vs Mallincam new [Re: Moromete]
      #5799042 - 04/14/13 06:24 PM

Just a thought, since I used to own the camera in question. I dont think it matters what lens/focal reducer combo you can screw into a DBK21AU618.AS, or what final focal ratio you end up with, it will not be as sensitive as a Mallincam.

Wishful thinking is fine, but that cam, and its software cant hold a candle to my Mallincam. The ONLY exception might be on planetary/lunar/solar views.....DSO's like M64,65....etc...no way.

Andy


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Chris A
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Re: DBK 21AU618.AS vs Mallincam new [Re: Moromete]
      #5799094 - 04/14/13 06:51 PM

Yes of course now you are talking about focal ratios like I have explained "What I am saying is for e.g. if you have an APC DSLR size sensor with 9um microns pixels and your 1/4" CCD sensor with 9um micron pixels there will be no boost in sensitivity when dealing with the same focal ratio." The lens is at F1.4 and the refractor at F6.

I think what Andy just posted to you is very valid and you should think about what he said. I am not too sure if you are the one on NSN under the name Luc, but if so then maybe go on NSN and show us the results please.

Chris


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budman1961
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Re: DBK 21AU618.AS vs Mallincam new [Re: Chris A]
      #5799429 - 04/14/13 09:02 PM

Thanks Chris!

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GlennLeDrew
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Re: DBK 21AU618.AS vs Mallincam new [Re: budman1961]
      #5799702 - 04/15/13 12:11 AM

Certainly, an f/1.4 lens will provide a quite bright image. With most scopes it's not at all hard to achieve f/4; compared to this, f/1.4 is 8X (3 stops) brighter. The question is, will this make up for the lower sensitivity?

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Moromete
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Re: DBK 21AU618.AS vs Mallincam new [Re: Chris A]
      #5799901 - 04/15/13 05:35 AM

Quote:

"What I am saying is for e.g. if you have an APC DSLR size sensor with 9um microns pixels and your 1/4" CCD sensor with 9um micron pixels there will be no boost in sensitivity when dealing with the same focal ratio." The lens is at F1.4 and the refractor at F6.

I think what Andy just posted to you is very valid and you should think about what he said. I am not too sure if you are the one on NSN under the name Luc, but if so then maybe go on NSN and show us the results please.

Chris




I agree with you that equal pixel size means quite similar sensitivity BUT with one amendment: after playing with a Canon 550D and a CCTV with 1/3" Sony SuperHAD II sensor I concluded that if I keep the cctv with AGC on Low and SenseUp x1024 than image brightness/light sources and detail is quite similar to the one obtained with Canon 550D at ISO1600 after 20s exposure. If raise the AGC on High the Canon remains behind. So a Mallincam/DBK/any Sony sensor cctv beats a Canon 550D especially due to increased Gain. Maybe I'm wrong but that's what I observed.

I'm considering the DBK21 because I don't have the money for a Mallincam (not because DBK21 is more sensitive/better than Mallincam because it isn't) and I don't even want to pay for Mallincam especially due to the old sensor and because it has Amp Glow. But I like the images obtained with Mallincam in spite the fact I don't want to expose for longer than 60s.

So you can think about using a Samyang 85mm F/1.4 lens with Mallincam too but it will give a smaller image scale. This way you don't have to go longer than 30s because the Samyang is a super fast lens which beats even a Hyperstar system regarding photon acquisition speed.
My only concern is image scale with a Samyang and a 1/3" or 1/4" Sony sensor which will be almost equal to the one obtained with a Canon 550D + ED80.

What makes me super happy is that with a Samyang 85mm + CCTV/DBK21/Mallincam/QHY IMG0H you can see in only [b]15s[/b] what you see with a Canon 550D + ED80 after a single [b]300s[/b] exposure! At such high photographic speed even a CCTV with SenseUp x1024 will be enough to view DSOs with low brightness. Look here too http://scantips.com/lights/fstop.html

Here is my question: how many DSOs (especially galaxies) can you discern/see some pleasing detail or structure in pictures made with Canon 550D + ED80 WITHOUT image cropping? (because the same image scale will be a 1/3" or 1/4" Sony sensor + Samyang 85mm F/1.4)


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jujumaster
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Re: DBK 21AU618.AS vs Mallincam new [Re: Lorence]
      #5853191 - 05/11/13 02:37 AM

That was funny Lawrence.... Thanks. I know I'm late to the party but your earlier reference to narrow minded viewing habits struck a cord with me.

Edited by jujumaster (05/11/13 02:49 AM)


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