Return to the Cloudy Nights Telescope Reviews home pageAstronomics discounts for Cloudy Nights members
· Get a Cloudy Nights T-Shirt · Submit a Review / Article

Click here if you are having trouble logging into the forums

Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User

Equipment Discussions >> Video and Electronically Assisted Astronomy

Pages: 1 | 2 | 3 | 4 | (show all)
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?


Post Extras: Print Post   Remind Me!   Notify Moderator  
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!


Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
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.)

Post Extras: Print Post   Remind Me!   Notify Moderator  
Chris A
scholastic sledgehammer


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


Post Extras: Print Post   Remind Me!   Notify Moderator  
Chris A
scholastic sledgehammer


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


Post Extras: Print Post   Remind Me!   Notify Moderator  
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.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Dwight J
scholastic sledgehammer
*****

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.

Post Extras: Print Post   Remind Me!   Notify Moderator  
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.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Dwight J
scholastic sledgehammer
*****

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.

Post Extras: Print Post   Remind Me!   Notify Moderator  
jonbosley
professor emeritus


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.

Post Extras: Print Post   Remind Me!   Notify Moderator  
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


Post Extras: Print Post   Remind Me!   Notify Moderator  
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.


Post Extras: Print Post   Remind Me!   Notify Moderator  
jgraham
Postmaster
*****

Reged: 12/02/04

Loc: Miami Valley Astronomical Soci...
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.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Chris A
scholastic sledgehammer


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


Post Extras: Print Post   Remind Me!   Notify Moderator  
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


Post Extras: Print Post   Remind Me!   Notify Moderator  
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.


Post Extras: Print Post   Remind Me!   Notify Moderator  
mclewis1
Thread Killer
*****

Reged: 02/25/06

Loc: New Brunswick, Canada
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.


Post Extras: Print Post   Remind Me!   Notify Moderator  
jgraham
Postmaster
*****

Reged: 12/02/04

Loc: Miami Valley Astronomical Soci...
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...


Post Extras: Print Post   Remind Me!   Notify Moderator  
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


Post Extras: Print Post   Remind Me!   Notify Moderator  
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.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | 3 | 4 | (show all)


Extra information
2 registered and 12 anonymous users are browsing this forum.

Moderator:  csa/montana, JayinUT 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 4428

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics