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Equipment Discussions >> Video and Electronically Assisted Astronomy

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mpgxsvcd
Carpal Tunnel


Reged: 12/21/11

Loc: Raleigh, North Carolina
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
scholastic sledgehammer


Reged: 05/18/05

Loc: Kansas, USA
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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ccs_hello
Postmaster
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Reged: 07/03/04

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
member


Reged: 08/13/12

Loc: Santa Fe, NM, USA
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
Carpal Tunnel
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Reged: 05/03/09

Loc: Silsbee Texas
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
scholastic sledgehammer


Reged: 09/15/08

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
super member
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Reged: 07/15/08

Loc: Richmond, Virginia USA
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
professor emeritus


Reged: 02/15/12

Loc: Romania
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
professor emeritus


Reged: 02/15/12

Loc: Romania
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
scholastic sledgehammer


Reged: 02/03/07

Loc: Toronto, Canada
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
professor emeritus


Reged: 02/15/12

Loc: Romania
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
Thread Killer
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Reged: 02/25/06

Loc: New Brunswick, Canada
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
scholastic sledgehammer


Reged: 02/03/07

Loc: Toronto, Canada
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
professor emeritus


Reged: 02/15/12

Loc: Romania
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
Pooh-Bah
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Reged: 02/25/11

Loc: Springfield, MO
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
scholastic sledgehammer


Reged: 02/03/07

Loc: Toronto, Canada
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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Reged: 02/25/11

Loc: Springfield, MO
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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Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
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
professor emeritus


Reged: 02/15/12

Loc: Romania
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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Reged: 11/26/11

Re: DBK 21AU618.AS vs Mallincam [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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