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Old 28-04-2009, 05:54 PM
sjen2004 (Simon)
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Dfk41af02.as

Hi guys. I've finally got up the courage to post. I have been quoted $870 for the DFK41AF02.AS. Is this a good price? Is there any benefit of firewire over USB. Is this the best value for the price?
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Old 28-04-2009, 06:56 PM
Dennis
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Hi Simon

What type of astro photography are you planning to do with the new camera? Some examples might be:

Planetary, Lunar & Solar.
Double stars.
Deep Sky (e.g. galaxies, nebulae, clusters, etc).

Also, what telescope and mount would you be using a new camera with?

Cheers

Dennis
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Old 28-04-2009, 09:36 PM
sjen2004 (Simon)
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Hi Dennis,
I have a 12" GSO DOB and will be receiving a SW809 refractor on a tracking mount. I want to learn what is possible. Currently I'm using the neximage CCD for planets but I wanted a CCD for Deep Sky images.
Regards Simon
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Old 29-04-2009, 05:46 AM
Dennis
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Hi Simon

Thanks for the details.

In my opinion, the DMK/DBK and DFK series of cameras are more suited to high resolution Lunar, Solar & Planetary imaging where you use short exposures (1/5 to 1/30 sec) and stack 100’s to 1000’s of frames to obtain the final image.

For deep sky images, where typically you might be exposing for say 30 seconds to 300 seconds, these cameras are less suited. They tend to produce a noisy image when exposed for longer than a few seconds.

I think that the DFK also has a built in IR/UV filter which I suspect is not optimised for astro photography, so it may cut out or clip parts of the spectrum unnecessarily, making your exposure times longer.

When I have used my DBK21AF04.AS for exposures of between 5 secs and 10 secs the images were quite noisy and took a lot of work to clean up. Also, these cameras are not as sensitive as dedicated deep sky cameras, so you might struggle when trying to record faint details in galaxies and nebulae.

I do enjoy using my DKB21 on colourful double stars, but my SBIG ST7 is heaps more sensitive, but also a lot more expensive! If you have a DSLR, that might be a good way to experiment before lashing out on a DFK41 and risk being disappointed?

Cheers

Dennis
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Old 29-04-2009, 08:24 AM
sjen2004 (Simon)
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Thanks Dennis,
I'm just starting out and wanted to keep my budget under $1000. SBig's seem a few years away.
Regards Simon
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Old 29-04-2009, 08:28 AM
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iceman (Mike)
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Hi Simon

I agree with Dennis - if you're looking to do deep space photography, the DFK41* is probably not the right camera for you.

Do you own a DSLR?

You can get Canon 300D/350D/400D all for under $1000 and will be perfectly suited to deep space astrophotography with you up and coming refractor (it won't work on your 12" dob without modification).
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Old 29-04-2009, 08:50 AM
Dennis
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Originally Posted by sjen2004 View Post
Thanks Dennis,
I'm just starting out and wanted to keep my budget under $1000. SBig's seem a few years away.
Regards Simon
Yeah – it’s certainly an expensive hobby!

Although some ccd’s can perform like a “Jack of all Trades”, my experience has been that that ccd cameras designed and optimized for specific types of astro photography, such as Lunar/Planetary/Solar versus Deep Sky, tend to produce the best results when used as the designer intended for those targets.

You might find that the DFK41 isn’t the best for Lunar/Planetary/Solar nor is it the best for Deep Sky, so you could end up disappointed on both fronts?

The smaller DMK21 seems to be the (relatively) low cost entry for Lunar/Planetary/Solar, so I would browse the Forum to see what users here have produced with that camera, and maybe leave deep sky stuff for later on?

Also, have a look at Mike’s review of the DMK21 vs. DMK41 in the reviews section.

Cheers

Dennis
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Old 29-04-2009, 10:09 AM
sjen2004 (Simon)
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I've been trying to take images of Saturn with the neximage on the dob but all I get is a bright fuzzy blob. I don't want to spend more money until I can use this CCD better.

Regards Simon
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Old 29-04-2009, 10:20 AM
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iceman (Mike)
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The Neximage will be fine to start out with. Taking photos of planets using your dob can be hard.

Try photographing the moon first, it might be a bit easier.

Have a read of this for some info too:
Astrophotography with a dob
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Old 29-04-2009, 10:31 AM
Dennis
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I've been trying to take images of Saturn with the neximage on the dob but all I get is a bright fuzzy blob. I don't want to spend more money until I can use this CCD better.

Regards Simon
If you’re getting a bright blob with the NexImage, then I suspect you’ll also produce a bright fuzzy blob with any of the D*K series of cameras!

I started off with a Philips ToUcam 840K which I think has a similar CCD chip to the NexImage, and when I first started taking images of Saturn, Mars & Jupiter I also suffered the bright fuzzy blob syndrome. Generally, I’ve found the following factors contribute to the bright fuzzy blob result:
  • Poor focus.
  • Poor seeing combined with low altitude.
  • Poor collimation.
  • Incorrect exposure, Gain, Gamma or all 3!
Let me say from the start that you’re doing it tough with a non-driven dobsonian, as you have to focus and nudge the ‘scope at the same time, which requires considerable skills.

As Mike has wisely suggested, start on the Moon and become familiar with getting good focus and dialing in the camera settings to obtain the correct exposure. You’ll then find that the skills you’ve gained can be put to good use on the smaller and more difficult planets. Good luck!

Cheers

Dennis
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Old 29-04-2009, 11:09 AM
sjen2004 (Simon)
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Thanks for the help Dennis. I can focus well on the moon and when I manually track using the 10mm pssl with the 2xBarlow I get quite a sharp image of Saturn. I usually use a filter because the image is too bright and I can't see detail without it.

I get the general shape of Saturn with the neximage but its so bright. The GSO is quite a good setup to move and I can keep Saturn in view for a couple of minutes with minor nudges.
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Old 29-04-2009, 12:39 PM
Dennis
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Hi Simon

It looks like you’ve got dob imaging under control – well done.

Saturn has very low contrast features on the disc, unlike Jupiter which has distinct bands and other features that are “easier” to record. Just check the various settings in your camera control software – I am not familiar with the NexImage SW.

From experience with my old Philips ToUcam 840K, I had the Gamma set to minimum and the colour saturation set to maximum and I was able to record subtle details on each frame. When these frames are then stacked, the subtle detail reinforces and can be teased out more.

I will agree however, that the 1st few attempts can look quite disappointing when compared to the results as the more experienced planetary imagers here on Ice In Space.

Maybe you could post a few pics here, when you’ve got some good data?

Cheers

Dennis
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Old 29-04-2009, 04:50 PM
sjen2004 (Simon)
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The reason I've posted no pics is that they are all this bright fuzzy ball with a bright fuzzy line going through it. Can't bring myself to post that when so many great pics get posted.
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