DMK vs DBK?

[Matty P]

I want to get into Astrophotography the best way possible. The Imaging Source cameras sit in my price range and I have read some very convincing reviews about these new cameras. So now I have a very tough decision to make, DBK or DMK?

I could go with the DMK and start out with B&W images before advancing to RGB imaging. I know there is extra cost involved to buy the filter wheel and colour filter, but is the extra cost & sensitivity really worth it?

If I do go with DBK, it is a one shot-colour camera and does not need the extra accessories of filter wheel and colour filters. Making it much cheaper compared to the DMK. As a result the images produced won't be as great compared to the DMK but will be much easier to produce.

Which one? :confused:

Regards
Matt

[Radar]

Hi Matt,

Welcome to the MyAstroSpace.com.

I guess both cameras will do the job for you, the only decision is how important is the final result to you? The monochrome camera will yield more resolution, so you will be able to make those images larger than the single shot images. But as you've already mentioned, the monochrome camera requires filters and much more knowledge of image processing. The single shot colour camera may be a smoother ride into astrophotography. You can always upgrade later.

There are others here that will be able to shed more light on this than me.

Where abouts are you based mate?

Ray

[Matty P]

Thanks for that reply Ray,

To be honest, for me I want the best results possible. I’ve seen some images taken with the DBK and compared to the DMK the final image is much noisier. I have to say it is a very tough decision. I am hoping to get the camera before Mars reaches its opposition. :biggrin:

I live in Canberra, it has been very cloudy lately :frown:

[beren]

Gday Matt I recently brought a DBK, I too had difficulty choosing between the monochrome and colour version but it came down to cost :itsme!: My first light with the camera involved some lunar trials, I noted a significant difference between it and the ToUcam I was using in noise levels. Been able to shoot at higher frame rates and in different modes {colour/raw} is great. If your prepared to put in the time and the budget allows it I would go for the DMK. Have you factored in supplementary hardware into the cost ? not sure what scope you have but you'll need at least a 3x barlow for image scale {for mars}, a reasonably fast PC/laptop and a motorized focuser. Having all this gear doesn't guarantee success, collimation needs to be spot on and the seeing/transparency has to be decent to record good data. I have been out nearly every-night since I got the camera and have only had 2 nights where I could say the seeing was semi-good :wink: Good luck with the decision I can recommend Steve Massey from My Astro Shop for advice etc .

[Matty P]

Have you factored in supplementary hardware into the cost ? not sure what scope you have but you'll need at least a 3x barlow for image scale {for mars}, a reasonably fast PC/laptop and a motorized focuser.

I have a Celestron 8" SCT f/10.
A 2x barlow
A laptop

Do I need a motorized focuser?

I'm still weighing the possibilites with each camera. With the DMK comes extra cost but better quality images. (I think the camera is capable of DSOs aswell) The DBK is probably my best option but I'm not sure which one to get.

Any suggestions?

[beren]

Matt what are the specs for your laptop.....Ram/disk drive speed/processor speed/does it have a firewire port ?

I guess if you have patience you could endure not having a motorized focuser but man it makes a big difference for fine tuning, if you go the DMK with filters/filterwheel I reckon its mandatory. With Jupiter and Mars your limited to how long you can shoot due to the planets rotation so you need to operate pretty quickly if your dealing with the DMK. I use a Moonlite motorized focuser, its a great unit but expensive at around 500au.

To add more cost to the DMK package I think you need to seriously consider the quality of filters you would use to, the better type are parfocal {I think astrodon are the best?}. So with the DMK and cables {$500-550} filter wheel {manual filter wheel $150-300} filters {400-500 ?} and add a motorized focuser {400-500} plus a set of bobs knobs {$15} the total cost is getting up beyond $1500. Thats quite a investment to begin with :eek: if you determined to give planetary imagering a serious go then that's the way but if you have some slight doubt for less then say 170 bucks you could pick a phililips cnc900 /adapter/ir filter and trial it and see how you go. The DBK is the middle ground :smile:

[Matty P]

Matt what are the specs for your laptop.....Ram/disk drive speed/processor speed/does it have a firewire port ?

Toshiba Qosmio G25

Intel Pentium M 760 / 2 GHz
2 GB RAM
200GB HDD - 5400 rpm
Firewire port

By the way, I forgot to say that I want to get the USB2.0 version. :eartoear:


To add more cost to the DMK package I think you need to seriously consider the quality of filters you would use to, the better type are parfocal {I think astrodon are the best?}. So with the DMK and cables {$500-550} filter wheel {manual filter wheel $150-300} filters {400-500 ?} and add a motorized focuser {400-500} plus a set of bobs knobs {$15} the total cost is getting up beyond $1500. Thats quite a investment to begin with :eek: if you determined to give planetary imagering a serious go then that's the way but if you have some slight doubt for less then say 170 bucks you could pick a phililips cnc900 /adapter/ir filter and trial it and see how you go. The DBK is the middle ground :smile:

I've done some bugeting and here it is....

DMK USB2.0 with the lot = $430
Baader RGB-Filter Set with IR block = $165
Filter Wheel = $199
Bobs knobs $15

Camera = $430
Acessories = $ 379
Total = $809

If I do go with the DMK, I will buy the acessories later when I get the hang of using it. :wink:

[beren]

Cool Matt sounds like you have it all sussed, go for it and place the order :biggrin: look forward to your first light with it :woot:

[Matty P]

I have a quick question,

When I purchased my telescope I recieved a free EP & filter pack. Searching through them. I found one RED, GREEN, BLUE filter.

RED #25
GREEN #56
BLUE #80A

Are these suitable for RGB imaging with the DMK?

[beren]

Not sure Matt, might work but you might have more focus tweaking issues with cheaper filters. Worth a try but if you're going all out on a good camera it probably deserves the best you can afford {astronomicks/astrodon :smile: }

[Radar]

Canberra? Shouldn't take too long to get delivered then. Yeah it's been cloudy here in Perth to. I was hoping to try my DSI on Mars tonight but again another cloudy night :ahh!:

I'm still learning the planetary side of things, and in the near future will probably purchase one of these Imaging Source cameras. I also will be using an 8inch SCT for planetary so our setups may be similar. Keep us posted with your purcahse and progress.

What telescope did your filters come with?

Ray

[Matty P]

What telescope did your filters come with?

When I purchased my Celestron 8SE, I received a free $499 Celestron EP & filter set. It came with 5 different sized Plossl and 7 coloured filters including a Moon filter.

I have to say so myself, the filters don't look cheap. :wink: They seem like they could do the job but I could be wrong. Astronomicks/Astrodon filters are way to expensive for my budget. :frown: Are there any "good" filters that sit in the middle of the price range?

P.S. Last night started out cloudy so I disregarded it as being a suitable night for stargazing. Then just before I went to sleep. I looked outside and what do you know! Crystal clear skies with Mars staring me in the eye. ARRRGGHH!:ahh!: :I_ANGR~14:

Thanks for your help :bow:

[Matty P]

I forgot to add this.

The total length of time you should capture each avi for varies depending on the object you’re imaging and it’s rotation speed. Jupiter for 2 minutes, Saturn for 5 minutes or more, Mars for 4 minutes and the Moon for several minutes. Also the longer focal length you a working the faster the rotation will be visible.

Quite handy for a beginner :woot:

[Radar]

Then just before I went to sleep. I looked outside and what do you know! Crystal clear skies with Mars staring me in the eye. ARRRGGHH!:ahh!


Exact same thing happened to me last night to. Cloudy until about ten then crystal clear.

With the filters, if you have red, green and blue, then I'd say give them a go first. Celestron make good filters so I can't see why these wouldn't work. It would be a waste to have two sets of filters that do exactly the same thing.

I just did some research. I have found nothing that says you can't use these filters for photography. In saying that, I found nothing that says you can, but if I had to make the call, I'd say these filters would work nicely.

Have you ordered the camera yet?

Ray

[Matty P]

Have you ordered the camera yet?

Not yet :frown: I will very soon, just getting everying sorted before I order it. Can't wait :woot: I can't see why the Celestron filters wont work.

Just setting up the scope for what looks like a great night. Crystal clear skies and Mars coming over the roof.

How's Perth, still cloudy?

[Radar]

How's Perth, still cloudy?

Yeah it's quite windy and we have scattered cloud (about 80% sky coverage). I'm in and out at the moment trying to see some Geminids, but all I'm really seeing a "Cloudemids" :biggrin:.

I have two cameras outside at the moment, a digital and a film camera. I really want a geminid before I pull the pin.

I think you'll be fine with those celestron filters as well. I'm in the same boat as you when it comes to planetary. It'll be interesting to see what our 8 inch scopes can do.

Ray

[Matty P]

I just ordered the camera and it should be here within 5 to 7 days depending on the postage company. I can't wait! :woot: :woot: :woot:

I will definately post my first light with the camera. :wink:

Ray what telescope do you have? I can't wait to see what my 8 inch SCT can do.:smile:

Thanks for your help
Matt

[Radar]

G'day Matt,

My two main imaging scopes are a Meade LX-50 (8 inch SCT). And also a Takahashi Epsilon E160.

The Meade will be what I use for planetary imaging. I'm going to be using my DSI Pro II for it. It's a monochrome camera so I'll be shooting with the filter set. I'm really hoping to get some good shots of Mars whilst it close. The only thing I have to do is get my Meade collimated properly. I usually just collimate my scopes by eye, but I think for planetary I'll need perfect alignment.

I noticed that a great way to collimate the SCT is to use a live view from the CCD camera on the laptop screen. This way you don't have to be a contortionist to turn the knobs and see the star at the same time. Beren and Paul will be getting lots of questions from me soon I imagine :biggrin:

Are you one of these lucky people with an observatory?

Cheers

Ray

[Tenacious Del]

I wouldn't have thought photographing a planet was so hard, but I've looked at a couple of tutorials, got down to about the third paragraph and quickly closed the web page down. Way over my head.:crazy: :crazy:

[Matty P]

Are you one of these lucky people with an observatory?

Unfortunately, I'm not one of those lucky people with an observatory.

Great idea Ray, using a CCD camera to help collimate a SCT.:biggrin: My scope was collimated in the factory, so I'm not so sure how well it held up during postage. I will have to check, seems like a daunting task. :confused:

[beren]

Collimating a SCT isn't daunting :smile: with a little practice it should become second nature. I think you mentioned your getting some Bobs Knobs for your C8, this will make it much easier {when you install them follow the accompanying instructions exactly}. Use the popular chart and instructions found here http://www.starrynights.us/Articles/Collimation.htm

To have your scope operating at its best it needs to be collimated, you really need to master this if you expect results imaging the planets/Moon.

[Matty P]

Thanks for the link Beren. :biggrin:

Now where is the best place to get Bob's Knobs from?

P.S. As soon as I ordered the camera, it started to bucket down with rain. Same thing happened when I got my scope. :hmm:

[Radar]

Unfortunately, I'm not one of those lucky people with an observatory.

I'm converting a cubbyhouse (hopefully next weekend), into a Fold Off Roof Observatory. I can't wait! :woot: :woot: :woot:

I will take tonnes of photo's during the construction. Hopefully I can complete the task in one weekend. It will be such a luxury just having everything setup all the time and ready to roll.



Great idea Ray, using a CCD camera to help collimate a SCT.:biggrin: My scope was collimated in the factory, so I'm not so sure how well it held up during postage. I will have to check, seems like a daunting task. :confused:

I've found that collimation holds well through when telescopes are in transit, but again with planetary photography collimation is everything. I like the idea of using a CCD camera, because the CCD chips are so small and are dead centre. So if you get a star in the centre of the screen, you know you are dead centre on the mirror and also the star is magnified so much on a screen, seeing the slight differences in alignment should be easy. In saying that, collimation is not one of my strong points :frown:


Use the popular chart and instructions found here http://www.starrynights.us/Articles/Collimation.htm


Great tutorial Stu.

Thanks

Ray

[Matty P]

Now where is the best place to get Bob's Knobs from?


anyone??? :biggrin:

[Radar]

Hi Matt, I must have missed that question.:frown:

Try this link -

http://www.bobsknobs.com/MiscInfo/dealerlocator.htm

Ray

[beren]

I think most astro stores should sell them, whether they have any on hand is another matter :itsme!: Bintel was the last store I received some from or you could order them direct from the source ......

http://www.bobsknobs.com/

Be aware for Celestron scopes, as described on the linked site, make a note of the stock collimation screws on your scope before ordering. Newer scopes have black metric screws, older scopes have silver imperial screw. Don't forget to have a gander at the installation instructions too :smile:

[Rumples Riot]

Ok, bobs knobs can be bought from shell lap supplies in Adelaide for a celestron. Bintel for a meade.

Use the astronomiks filters, they are focused matched so that you don't need to focus between avi's. They are expensive but worth the results. The filters that you got are for optical work only, not imaging. There is a difference. Light transmission is very important. Without the correct light transmission your avis will contain fewer frames and te colour will look wrong.

You will need to consider image scale too. With an 8" SCT you will not be able to make the image very large due to lack of light. I suggest a maximum scale of 6000mm. Anything over that and your histogram will not be exposed correctly. When capturing use the histogram view in IC Capture. Click the log function and you can see the histogram live. Ensure that the histogram is at 250 when capturing for all colours. The scale goes from 0-255. If the histogram is at 255 and stays there you are over exposing. You want the histo to hover around 250. If your image scale is too large you will not be able to reach 250. If that is the case reduce the image scale.

Also the rate of frames is dependant upon the amount of light you are getting. At 6000mm I doubt you will be anything above 30 frames per second. An 8" is very small when imaging the planets. Just do some trials and you will see that there is a maximum scale at which you can image and keep the histo looking correct. The larger the scale the less light you will get as it falls onto the chip. Each colour lets through differing amounts of light too, with blue being the worst. If you can get 30fps with red you will only get around 18 for blue. You can adjust the gain between each run by leaving the Properties box open. The most common question I hear is "why can't I get 60fps with my 10" scope and have a large image scale?".

To get really large image scales you need a large aperture, you can get some nice stuff with smaller scopes, but you cannot go large image scale. Just bear this in mind when you are getting frustrated with your image scale. I learnt this the hard way. Large image scale needs a lot more light. Anthony Welsey, Maurice Valimberti and myself are using scopes over 13" in diameter. If you decide you love planetary imaging, buy a big scope next. Nothing under 12" is best. You will be surprised what you can see with a large scope on planets and the moon.

Let me know if there is anything you need help with.

[Matty P]

Hi,

Thanks for the post Rumples, you've cleared up heaps of things concerning the camera. With the filters, I am currently looking around for cheap (cheaper) filters than are around the same quality of the Astronomiks. If not I will have to go with the Astronomiks. Any suggestions?


Also the rate of frames is dependant upon the amount of light you are getting. At 6000mm I doubt you will be anything above 30 frames per second. An 8" is very small when imaging the planets. Just do some trials and you will see that there is a maximum scale at which you can image and keep the histo looking correct. The larger the scale the less light you will get as it falls onto the chip. Each colour lets through differing amounts of light too, with blue being the worst. If you can get 30fps with red you will only get around 18 for blue. You can adjust the gain between each run by leaving the Properties box open. The most common question I hear is "why can't I get 60fps with my 10" scope and have a large image scale?".

As you said, at 6000mm I doubt you will be anything above 30 frames per second.

Why is that? I know an 8 inch scope does not capture as much light as a 10-12" inch scope but saying that is it still possible to shoot a 60fps with the camera at a high image scale?

I'm sure when I receive the camera I will be asking some more questions, so be ready! :biggrin:

Thanks for the help

Also when imaging with the DMK.

Is it better with or without a diagonal? When using the camera without a diagonal, do I need any extra accessories?

[Rumples Riot]

Hmmm, ok

You could go with some baader imaging filters to start with, but you will need to buy the astronomiks in the end. Nearly everyone uses them and when I bought mine I just figured I would go with the best.

In terms of the light, what you need to consider is two fold. To get the image scale you need, you will need a barlow. The more magnification you use the less light that falls on the chip. That is because each time light passes through a piece of glass it will lose a little intensity. To use very high magnification you need a lot of light to start with. So when if you were to use say a 5x powermate on your 8" this would give you around 10,000mm. The light would be insufficient to light the chip. This is because the chip reacts in similar method to film. Photographic principles apply to exposure. (I suggest you read some books on photogrpahic exposure to help you understand here) CCD chips are very sensitive but you still need to think about how they react photographically.

So the general principle is, you need to keep the CCD fully exposed at around 250 on the histogram. The larger the image scale the larger the aperture that is needed to fully expose your image correctly.

So the fact that the camera will take 60fps does not mean it will actually do that with your telescope. I cannot even get 60fps with my C14. The most I have got so far is 32fps on the planets and 53 fps on the moon with just a barlow.

You also need to consider that once you pass light through your filters the light will once again be diminished. So by the time the light his your CCD you will have nearly half the light to deal with from the primary.

Hope that makes sense.