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Unknown - help wanted...

johankj

By johankj
in Imaging - Deep Sky

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johankj

johankj

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So I was actually going for Andromeda, just for a test. It was in a position that was good for my altaz goto. But I got this, so I kept the camera going. Now that I'm looking at them, I'm really not sure what I captured. Sorry, a bit of a DSO noob. To me it looks like M110...

This is a really rough stack in DSS of 10x30sec@1600ISO + darks, since I'm not sure of what I'm doing in DSS just yet...

Canon D1000 in prime focus on my f11.81 mak.

post-16339-133877527411_thumb.jpg

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Jannis

Jannis

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I'd say, acording to the look and size, it looks very much like m110, and nothing like m31 (unless, like mentiond, it's the core only. but then it's got to be a prettu dark pic i must say). m31 would be like, filling up the whole picture at 1500mm on a 1.6 crop camera (i didn't even have space for the whole galaxy in my 1000mm scope with the canon 550d...).

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johankj

johankj

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I'd say, acording to the look and size, it looks very much like m110, and nothing like m31 (unless, like mentiond, it's the core only. but then it's got to be a prettu dark pic i must say). m31 would be like, filling up the whole picture at 1500mm on a 1.6 crop camera (i didn't even have space for the whole galaxy in my 1000mm scope with the canon 550d...).

That's what I was thinking too, according to size and sensor crop, it's the right size for M110.

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johankj

johankj

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You will need longer exposures than 30 seconds to pull out the finer detail. There are very faint suggestions of data further out than the core in your image.

Steve

Yeah, it seems like the norm is 180s. I guess I need timer remote...

And a shorter scope...

Hmmm...

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pete_l

pete_l

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Could be the core too, but I would have expected something different...

Me too. I'd expect a lot more in the image - even though with that scope/camera you probably only have about half a degree FoV.

One mistake I'm well practised in is thinking I have my camera in Bulb mode, when it's really in auto (or with a shutter time set). Have you got any metadata (EXIF, etc) that can say what the exposure time actually was?

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AndyUK

AndyUK

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Hi Johan - As other's have noted, you need a lot more, and longer, images to capture the outer areas of M31. The core of M31 is extremely bright... and with the focal length of the Mak 127 being 1500mm, you're going to be REALLY close in - I've attached a screenshot which shows the image you might expect from a Mak 127 with a 1000D using this tool here.

For my first attempt at M31 I also used ISO1600 and then set the exposure for as long as I could without getting star trails (which was dependent upon my polar alignment that night- The max exposure that I could get away with that night (using a 100mm/f9 refractor) was 60s (If you like I'll pm the result)

To really bring out the whispier outer galaxy areas, you'll really need longer (and more) subs, but be wary that, with an AZ mount, you're also in danger of suffering from object rotation whilst you expose (although I'm not sure of the exposure length where this might creep in).

post-18819-13387752748_thumb.jpg

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johankj

johankj

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Me too. I'd expect a lot more in the image - even though with that scope/camer you probably only have about half a degree FoV.

One mistake I'm well practised in is thinking I have my camera in Bulb mode, when it's really in auto (or with a shutter time set). Have you got any metadata (EXIF, etc) that can say what the exposure time actually was?

Here is a raw (canon) and a jpeg:

Jpeg:

http://dl.dropbox.com/u/9547820/IMG_9465.JPG

Raw:

http://dl.dropbox.com/u/9547820/IMG_9465.CR2

The metadata is as I set to, but maybe there is something else...

I calculated my FOV here: Calculator for DSLR Astrophotography

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johankj

johankj

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you're also in danger of suffering from object rotation whilst you expose (although I'm not sure of the exposure length where this might creep in).

It was in the west, so I could probably have pushed it even further :)

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johankj

johankj

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You need a faster focal ratio! F5 gets four times the DS signal per second as f10.

That's a lot...

Olly

I been looking at an 70mm F6 ED, and it just got a whole more tempting.

I've also tried to figure out if I could attach a focal-reducer to my current mak, but it seems a bit too 'magic', if you know what I mean. Also, I couldn't make heads or tails of which type or what kind of connection.

So, it's probably going to be the refractor :)

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Uranium235

Uranium235

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You need a faster focal ratio! F5 gets four times the DS signal per second as f10.

That's a lot...

Olly

Exactly as the man says... at F11 youre going to be there for the rest of your life. Speed speed speed is the way forward. And with a faster F ratio you will be able to drop your ISO to 800 as 1600 will just introduce excessive noise at longer exposures.

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