Southern Pinwheel Galaxy?

[shaneaust]

Hi all:

I got this (cropped) shot of the skies the other night with my Canon EOS 300D.

I **think** what I have noted is the Southern Pinwheel Galaxy - can anyone verify this? Or is it simply noise from my camera?

It's a reddish-colored dot, and given that the galaxy is pretty distant, I'm assuming it would show up as only that. I did not use my scope for this shot, only the camera, with about a 2 minute exposure.

TIA

[erick]

Several similar in the image? Hot pixels? Would a Canon EOS 300D have that many? Do you have any dark frames?

disclaimer - speaking with little knowledge of the matter :sadeyes:

[ballaratdragons]

I have zoomed waaaayyyy in using ZoomFox and unfortunately I have to inform you that it is a Hot Pixel.

Don't you hate it when it isn't what you think it might be :sadeyes:

[shaneaust]

Yeah, guys, after having a look at other pix taken ~ the same time, it looks to me, too, like a hottie....blast! humbug! :mad2: :mad2: :mad2:

I used Paint Shop Pro to lighten it, but whenever I cross a certain brightness "boundary", the pixels show up....it can be very tricky getting to that magic sweet spot, where the trade-offs are minimal as far as lightness/darkness adjustments are concerned....

But thanks for your efforts!

Cheers!

[iceman]

It looks like your focus is off too. Take a series of shorter test exposures at high ISO until you have tight, pinpoint stars when you zoom in on the LCD preview.

[shaneaust]

Thanks, Mike, but this camera doesnt have a preview feature - it's pretty much suck it & see, and you can't see results till after the photo has been taken.

But I will sure try what you recommend as far as short-exp/high ISO shots go - hadn't thought of that.

[montewilson]

I guess what seals it is the fact that the "object" has not moved even though the stars have. That means the source of the signal is fixed with the camera.

Don't give up - you'll get your galaxy soon!

[Dr Nick]

You will notice that the stars have wobbled slightly during the exposure making them not a perfect dot, you notice however that what you have labelled to be the souther Pinwheel is not this shape.Thats how I check what objects are in my images. ;)

[shaneaust]

Thanks for your comments, Nick - those are some awesome DSO photos you have on your site, too, by the way!

I am having no luck whatsoever in using my Canon EOS 300D in conjunction with my 10" reflector/dob. I just cannot get any kind of image whatsoever using the 2 together....so I'm just using the camera at this stage, on its own, to get a feel for using a cam with unlimited exposure.

[montewilson]

To get an idea of focusing etc with a dob and camera, try taking some daytime shots. Try birds on the telegraph wire and distant buildings. Then when you are happy with that, do the moon. This will help you learn to focus. It will also give you an appreciation of how sensitive your scope is to vibrations and wind. This can be fun especially when you consider you scope is (@f6) a 1524mm telephoto lens!

This will give you some helpful practice.

IMO you are trying something very difficult at the start and I wouldn't want to see you fall into the trap that so many people fall into. That is you try something really hard then get frustrated and soon give up.

Try to do some 50mm or similar shots with a tripod and stack them. You should get some Milky Way and deep sky objects and this will give you the experience and enthusiasm to continue.

I have been doing AP for 15 years and I'm still in no hurry to do prime focus on a large reflector. I am kept quite busy by a 530mm Refractor.

Is your mount driven in any way? If not you are probably never going to get sharp stars even on exposures as short as a few seconds at prime focus.

Please consider my hints at the top. Astrophotography is probably the hardest form of imaging and you will need to take some time to get where you want to be. Good luck. PS post any terrestrial shots you take with the dob too so we can see how they look.

[iceman]

You won't get your DSLR to focus in the dob without moving the mirror up the tube, or making a very low profile focuser. You just can't get enough in-focus. It's been discussed a few times in the past, so do a search.

You're best off just using the camera and lens on a tripod to start with, or simply take some afocal shots of the moon and planets. I honestly wouldn't try and do any DSO photography with your dob, especially without tracking. It's a path that leads straight to frustration and disappointment.

[shaneaust]

Yeah, Mike and Monte, I gave up on that idea awhile back. I've been able to get some fairly good afocal shots of the moon using my webcam (see my signature) and stacking, but no luck, as mentioned, using my Canon with the scope.

I mount the camera on a tripod, to which is attached a home-made barn-door mount, with a hand-operated tracker, which I turn 90° each 15 seconds. I've found that the camera has to be in really good focus in order to use the tracker successfully; thus far I've only exposed my shots for a maximum of 2 minutes. Some have turned out okay/good but many have not!

But I am outside every clear night with that camera and have learned a few tricks, but have a long way to go...especially using the DIY mount and tracker that I made.

As I mentioned earlier, the one big drawback to this camera (Canon 300D EOS) is that it has no preview mode and that makes focusing when doing AP very hard sometimes.

Cheers!

Mick

[montewilson]

Have you tried photographing a street light some kilometres away. This is a good "star" for the purposesof finding focus. Are you sure you can reach focus with this scope/cam pairing? You may need to get a longer doo-hickey or shorter widget to make it all happen.

A bright light at infinity should be a good focus traing target.

That is all I can say about the Dob/Canon matter as for the wide field try once again doing some time exposures of the local horizon to help you learn where focus is. For most uses the infinity as stated by Canon should work fine. Try stopping down one or two stops too.

The other option is to get some paper stickers and place them on the two moving parts of the camera lens. Take a shot at infinity then mark a line between across the two pieces of paper then move it a bit take another and mark again. We are probably only talking about a mm or less of travel but it could help you define where the best focus was achieved by looking at the photo series afterwards. I hope this makes sense, I don't have time to write it all down in detail now.