Piggybacking a Canon DSLR

[uncmath25]

Hey guys,

I'm brand, brand new to astrophotography, and really to astronomy itself.

I've been enjoying the sights with my Celestron C150-HD on an equatorial mount, and wanted to try some basic astrophotography.

I am interested in hooking up a webcam at some point soon, but in the meantime I have my dad's Canon EOS-7D camera on loan for the next few months.

I don't know anything about photography, but it seems like a decent camera.  There's a screw on point on top of my telescope to piggyback this camera.

I've been playing around with the manual exposure mode of the canon during the day.  It seems easy to adjust the aperture and exposure times.

The aperture ranges from 2-22 (I assume these measurements are in millimeters) and the exposure times range from 0.3-30 seconds.

What are some recommendations on configuring the manual exposure mode?

I assumed that I want the largest aperture possible; is this true?

Also will I add longer exposure times for deep space objects?

[Leveye]

Whatever lens you use I'd shoot wide open. If you stop down you will get a sharper image but diffraction/aperture blade spikes around the stars. Some like that some don't. Experiment

[JamesF]

I believe that it is sometimes recommended to stop the lens down a little on the lower-end lenses because wide open they can be prone to distortion.  It is quite possible to use a ring in front of the lens to reduce the aperture to prevent the diffraction spikes caused by the vanes in the lens though.  My standard 18-55mm Canon lens for instance causes horrible distortion near the edges of the frame when wide open.

As regards exposure times, some experimentation will probably be required.  It's quite possible to get exposures of many minutes on a well-aligned equatorial mount (you may need a laptop and USB lead for the camera to do that), but I'd start at, say, 15 seconds and see how it goes.

Somewhere in the imaging section you should be able to find a sticky post describing how to take wide field images using a DSLR camera on a tripod.  That might be a good place to start.

James

[esxste]

Hi, I've also been playing around with piggybacking my camera to the mount. I found a few you tube videos on how to use the Camera to get good results.

I have a canon 700d, with the 18-55mm is STM lens.

General advice seems to be to stop the aperture down to its lowest setting, raise the ISO to at least 6400, probably higher, and then extend your exposure time depending on results - I'd suggest starting with with 4 seconds.

If your mount is capable of trackin or if your looking for star trails, you can push the exposure length longer. You may find you need to lower the ISO the longer your exposure time becomes.

Certainly, I think those settings might be a good place for you to start, and then experiment with the settings one at a time and see how they affect your images.

[lensman57]

Have read of this, it will tell u what needs to be done just forget the part about Modded cameras, I don't your dad will appreciate it.

http://bf-astro.com/widedslr.pdf

A.G

[uncmath25]

Wow, thanks guys so much for the quick and informative responses.  I'll try them out in about an hour

[JRWASTRO]

Greetings There,

How do you propose to mount your 7D camera on top of the scope?

Mounting the camera "piggy back" will cause a serious weight imbalance that will have to be addressed by adding extra weights to the weights bar if the telecsope/ mount combination was not designed to carry the extra weight.

May I suggest that you look into getting a bracket that may be attached to the weights bar on which to mount the camera. This will make no difference to the the imaging just because it is on the other side of the telescope!

Jeremy

[Astrosurf]

I just used a dovetail bar and ball head joint, like a Manfrotto, to attach the camera to the mount. It worked a treat. I'm not familiar with your mount or camera so can't advise there. Does your mount track?

In general, DSLRs are used for deep sky objects and webcams for the Moon and planets. Although many use a DSLR on video mode to image the Moon and planets.

Alexxx