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Can I take photos through my 8" Newtonian?

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#1 maxwolfie

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Posted 04 January 2013 - 04:13 AM

Hi all,

I bought a GSO 8" Dobsonian a few months ago and I'm wondering if I will ever be able to hook up my DSLR with my T-ring and achieve focus with it.

I can't focus at the moment but I am wondering if it is feasible to buy an extension tube to allow focus on planets such as Jupiter and Saturn?

#2 Raginar

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Posted 04 January 2013 - 08:49 AM

Is the problem you can't the focuser out far enough or is it that you can't go in far enough?

All you need is a t-ring and a nose piece :).

#3 csrlice12

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Posted 04 January 2013 - 09:03 AM

You might get some moon pics, but that's about the limit for pics with a dob. Dobs are just not made for AP. If you want AP, you'll need either a refractor, or a newt, or a Mak/SCT, (depends on what you want to photograph, as well as your budget) on at least an Alt/Az mount and preferably an EQ mount. Large newts, while capable of fantastic photography, are also large wind socks...a butterfly beats it's wings in China, and it's going to blow that newt around in southern Texas....Large newts for AP really begs for an observatory on a permanent mount. There is not such animal as a "portable" Newt for AP.....now a nice small ED refractor.....

#4 Gene7

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Posted 04 January 2013 - 10:51 AM

I have quite different experience. My best shots are A-Focal with a Lumix FH-1 mounted on the top threads of a Hyperion 17mm eyepiece. Wish I had not moved my mirror forward to reach prime focus SLR, the focal plain shutter jars the scope and gives me mush.

Can give you details for easy camera mounting if you ask. Gene

#5 Mirzam

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Posted 04 January 2013 - 04:06 PM

Gene makes a very good point. Afocal photography uses the camera lens to take a picture of the image formed by an eyepiece. You can, for example, use a cell phone camera held up to an eyepiece to take some very good photos. No mirror repositioning required.

JimC

#6 azure1961p

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Posted 04 January 2013 - 07:02 PM

Ok Jupiter and Saturn...

1. Yes 8" is enough aperture to get fine pics.
2. The bad news is a dslr is the wrong tool. A beautiful camera design but awful on the planets on an undrivrn dob to say nothing of vibration issues.

Ill bet you this. I'm tempted to gamble but well call it gentleman s bet. You go use an iPhone or android ok. Buy Orion's smartphone mount by Orion, pricey but it works($70). Then run video. Don't snap pix with your phone of the planets, rather run the cam on video as it transits the field.

Stop the cam then repeat several times.

Next download REGISTAX (free). Load your footage and pic the frames you want stacked before thf planet runs out of the field.

Here's the magic...

Registax will stack all those individual movie stills and assemble them as one strong image - as if it never came from a video recorder.
Adjust wavelets (sharpening) and other stuff and ill bet you it blows your dslr Saturn out of the water.

Don't do this: don't shoot stills or snap single exposure pix with the phone instead it'll look like *BLEEP*.

Now if your dob followed the stars the tracking would yield a sharper image ultimately but even using the drift method it'll outdo your dslr - so long as you stack and refine.

I used to thinks video was a horrendous way to image the moon and planets. Any given frame is awful by dslr standards but the magic is in the stacking. REGISTAX is an amazing tool. The post stack processing that's easy is dramatic and empowering. It's a modern day imaging phenomenon and the other half of every vid image. Now they have other programs like firecapture and such but I love REGISTAX and its soooo easy because its intuitively layed out. The beauty of it is its a very depthful program too and it'll go as far as you can push.

Good luck.

Pete

#7 maxwolfie

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Posted 04 January 2013 - 07:15 PM

Thanks all, I was actually planning to video Jupiter with my DSLR and process the file in Registax!

No deep space or photos!

#8 Jason D

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Posted 04 January 2013 - 07:24 PM

You can use a smart phone camera. Below is a photo of Saturn with my iphone -- a single frame without stakcing or editing.

Attached Files



#9 Pinbout

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Posted 04 January 2013 - 08:47 PM

I was holding the vid camera up to several eyepieces to do this moon thing.

vid of moon

the lunar x is around 1:38 on timeline

#10 azure1961p

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Posted 05 January 2013 - 12:06 AM

You'll like the results. Keeping the cam on axis, that iOS centered on the eyepiece is tricky . If you see color fringing u r off axis. Also I had a Sony cybershot that shot nice vids actually but the way it processed its own video had artifacts rear their head when wavelet controls were applied. Never mattered much unless I really pushed the mix.

Post your results!!!

Pete

#11 Gilbert D

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Posted 05 January 2013 - 01:07 AM

With DSLR, you need "in focus" to achieve focus. I remember reading somewhere says that adding a barlow can extend the focus plan out far enough thus achieving focus on DSLR. I have not tried it myself yet.

#12 Mirzam

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Posted 05 January 2013 - 05:24 AM

Gilbert if you leave the camera lens on the DSLR and use an eyepiece in the focuser you won't need more in-focus. The camera lens focuses at infinity because the light rays from the exit pupil of the eyepiece are parallel (roughly).

JimC

#13 Gilbert D

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Posted 05 January 2013 - 11:48 PM

Hi, Mirzam,
Thanks for the information. I was thinking about without camera lens and eyepiece.






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