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Cassiopeia wide field

JamesF

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JamesF

JamesF

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Last night was my first proper attempt at wide field imaging with the nifty fifty. Focusing turns out to be a bit on the tricky side. I'd stopped it down a little to mitigate some of the distortion at the edges of the field, but I think as a result it's very hard to pick up anything useful to focus on and as a result it's perhaps a little soft. More experimentation is probably required. It's also quite tricky to pick up the fainter objects without blowing out the major stars. I'm quite pleased with the framing though, with the main constellation plus the double cluster, heart and soul and a whole fistful of other clusters showing up. There's something down in the bottom left corner that I've not identified yet, too.

20 subs of 120 seconds @ ISO800 f/3.5 with the 450D and 50mm f/1.8, plus darks, stacked in DSS and tweaked with Photoshop.

cassiopeia-1-small.png

James

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JamesF

JamesF

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Great shot James . . . :laugh:

Bottom left you've caught NGC 7822 and Cederblad 214 I do believe . .

Now I've got my local copy of astrometry to work I can confirm that this is certainly the case.

James

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drummermandan02

drummermandan02

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Great image!

I'm new to astro photography, I had my first try last night, and got some ok-ish images, but nothing as awesome as this!

As I'm new to this and not yet up to speed with terminolgy when you say 20 snubs of 120 secs, I take it that means the image consits of 20 images each of a 120 sec exposure time? If so, did you use the bulb feature to capture those images? And did you stand there for 120 secs for each of the 20 images pressing the shutter (or remote shutter release) button after every shot?

To reduce any vibration did you lock the lens?

Finally, how do you manage to focus on the objects? I tried last night to focus on the brightest star using the view finder, but this is tricky. Didn't know if you had a better way of doing this?

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JamesF

JamesF

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The image is the combination of 20 exposures each of 120 seconds, combined (with darks) using Deep Sky Stacker. In a manner of speaking I used the bulb feature, but actually I connected my 450D up to the laptop using the USB cable, set it to "manual" and then used a piece of software called AstroPhotography Tool (APT) to take the exposures for me. It has a feature that allows an "exposure plan" to be set up and run automatically, so I configured it to take 20 frames of 120 seconds with a short delay between each, hit the "start" button and let it get on with things for the better part of an hour. It is possible to get programmable remotes that can do this sort of thing for you rather than use a computer, but APT has a number of other advantages.

I didn't do anything with the lens. In fact I didn't really worry about vibration at all.

Focusing is tough to do using the camera itself. APT can show the live view image, so I used that in combination with exposures of about fifteen seconds to get the focus set, though I've since discovered that APT can actually control the lens and do the focusing for you as well. Clear nights have been a bit thin on the ground since then though, so I've not managed to test it further.

James

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Black Knight

Black Knight

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Subs are subframes, that is individual exposures that are stacked together to produce an image with better signal. Depending on the features available on the camera will depend on how you take the subs. A remote cable, a self timer, or via software running on a laptop for DSLRs. Focusing is tricky, bu easier if the camera has a zoomable live view screen, or if the live view can be fed to a computer.

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JamesF

JamesF

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Great image James, so many stars it makes it difficult to pick the 'W' out straight away....

I quite often find that with images of that area of the sky. The constellation looks so obvious in the night sky, but once you bring out all the detail of the Milky Way in an image it gets far more difficult :)

James

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JamesF

JamesF

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Great advice :)

I will look into the software and techniques you have mentioned and go from there. Cheers!!

There's a tutorial on basic wide field imaging somewhere. I'll see if I can find it.

James

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Shibby

Shibby

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Very nice image James! Is the camera modded?

I quite often find that with images of that area of the sky. The constellation looks so obvious in the night sky, but once you bring out all the detail of the Milky Way in an image it gets far more difficult :)

I find the same effect apparent from a very dark sky site; difficult to pick out any constellations!

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