Canon Community Canon Community
 


Reply
Occasional Contributor
Posts: 18
Registered: ‎12-25-2014
Accepted Solution

Getting started with my Canon T1i

I just bought me a Canon T1i (body only) for Christmas to use for astrophotography. I'm having some problems getting started and am hoping to get some answers from here. 

 

First off bc I'm using this for astrophotography I didn't buy a lens for the camera as I will be using my telescope as my lens. The problem I am having is once I switch the camera ON, all I see is the AF points in the viewfinder and can't figure out how to get it off. How can I see what I'm shooting through the viewfinder? 

Esteemed Contributor
Posts: 3,854
Registered: ‎06-11-2013

Re: Getting started with my Canon T1i

The points you see are etched on the focusing screen... this is up in the roof of the camera (above the reflex mirror). You will, of course, not see these in your images. You also will not see them when using Live View (which is how you'll use it when astro-imaging.)

For astrophotography, I would suggest either making or buying a "Bahtinov focusing mask". This goes over the end of your telescope (like a scope cap) and has slots cut into it. Point your telescope to a moderately bright star and it will cause the star to throw diffraction spikes in the shape of an X with a vertical line through the middle. If the vertical spike intersects with the middle of the X then your scope is perfectly focused... as you focus in and out the vertical spike will move off center.

You can make your own by using this website to generate a template (you print it, then overlay that on a more durable material ... and cut out the slots): http://astrojargon.net/MaskGen.aspx

You can also buy one pre-made. Lots of telescope vendors sell them. I use the masks produced by Spike-A (they are metal masks... they appeared to be annodized aluminum (or some light metal) about 1/8" thick.) : http://spike-a.com

To focus, point a somewhat bright star, put the Bahtinov mask on the front of the scope, switch on "live view" mode and crank up the ISO and slow down the shutter speed (Canon cameras's "simulate" exposure on the live view screen so you'll get a brighter image by cranking up the exposure). Adjust the focus on the telescope until the diffraction spikes converge (you may need to magnify live-view to 10x to make this easy).

Once focused, remove the focus mask, return the camera back the exposure settings you want to use for your object, point the telescope back on that object (be careful not to touch focus), and begin collecting your images.

Don't worry about the 9 auto-focus points you see when you look through the viewfinder.

If you didn't alreaady purchase one, you may be interested in buying an AC adapter for the camera (it slides in like a battery... but runs off AC power). This is because the somewhat long exposure times of astrophotography combined with the number of lights, darks, flats, etc. that you need to record will kill the batteries rather quickly. I have a 60Da which is designed specifically for astrophotography and Canon includes the AC adapter with the camera.

You will also likely want either a remote wired shutter release (so you can use bulb mode) *or* you may want to use BackYard EOS to control the camera (BackYard EOS only runs on Windows... I use a Mac but I can run it in a virtual machine). Also... if you do happen to be on a Mac, Nebulosity (by Stark Labs) will control the camera for image acquisition.

Lastly... if you are completely removing the IR filter, then you might want to look at the "OWC filter" by Astronomik.com (OWC = Original White Balance). This is a filter which clips into the body and restores the IR filter so that you can use it for regular terrestrial photography. The "catch" is that with the snap-in clip filter you cannot use any Canon EF-S lenses ... only Canon EOS "EF" lenses can be used with the Astronomik clip-in filter. In the US, OPTcorp.com sells them.

Good luck and clear skies!

Tim Campbell
5D III, 5D IV, 60Da
Occasional Contributor
Posts: 18
Registered: ‎12-25-2014

Re: Getting started with my Canon T1i

Thanks for the info. I still haven't figured out how to get the Live View display to work either. All I see is a white screen. I can see this is going to be a little of a learning curve. I had been doing astrophotography the afocal way by just mounting my point  and shoot up to the eyepiece and was getting some great images that way which is what led me to get this dslr. However I don't know if I have the proper kind of mount to do long exposure astrophotography. I just have an eq2 mount with an eq2 motor drive.

Esteemed Contributor
Posts: 3,854
Registered: ‎06-11-2013

Re: Getting started with my Canon T1i

[ Edited ]

Without a lens on the camera you wont get an image... it's just going to be a solid color and usually white.  The telescope will become your lens.  Once you get it mounted on the telescope, you'll be able to get it to come to focus and see something other than just a plain white image.  Right now you just have random photons landing everywhere.

 

How you attach to a scope depends on the scope but you will definitely need a T-Ring (or "T-Adapter") for Canon EOS mount, and the rest depends on the scope.  

 

A "T-Ring" has the bayonet mount type on the camera-facing side... and industry-standard "t-threads" on the scope-facing side.

 

E.g. one of these:  

Here's the Celestron brand T-ring:  http://www.bhphotovideo.com/c/search?N=10261256&InitialSearch=yes&sts=pi

But that's not a very good image of it... so here's an Orion brand (which happens to be more expensive but I'll link it because you can get a closer look):  http://www.optcorp.com/orion-t-ring-canon-eos-5224.html

 

LOTS of companies make these and it doesn't matter which brand you buy or which scope you have... the T-ring concept is universal... it has the camera-specific mount on the camera facing side... and the universal t-threads on the opposite side.

 

Some scopes have t-threads on the end of the focus (where you'd drop in the eyepiece) and if yours does... you may be able to thread the T-ring directly onto the t-thread and attach your camera.  Many scopes wont have t-threads right on the end of the focuser, so you'd get a camera nosepiece... this is a barrel that inserts just like an eyepiece would... except it has t-threads on the end so that you can thread it onto your t-ring.  You then mount the nosepiece & t-ring onto the camera and insert the whole thing into your telescope... in the same way you'd insert an eyepiece onto the telescope.

 

Here's an example:  http://www.celestron.com/browse-shop/astronomy/astroimaging-accessories/t-rings-and-adapters/univers...

 

They do make 2" nosepieces and 1.25" nosepieces (that's the diameter... not the length).  Either will work with a camera that has an APS-C size sensor like your T1i.  The 2" is, of course, intended for scopes that can accept 2" eyepieces.  Cameras with large sensor can get vignetting in the corners but an APS-C size sensor should not get vignetting even with the 1.25" size.

 

Here's a link to a camera nosepiece (note that the nosepiece is "universal" in that it is not camera-brand/model specific.... it has industry-standard "t-threads" on the end.  You then add the "t-adapter" or "t-ring" (they use this name interchangeably) and that's what gives it the camera specific mounting so that it attaches to your camera just like a lens would be attached... and the telescope becomes the lens:   http://www.celestron.com/browse-shop/astronomy/astroimaging-accessories/t-rings-and-adapters/univers...

 

The next question is:  What type of telescope do you have?   

 

You wont have a problem with refractors or compound (catadioptric) telescopes (like a Maksutov Cassegrain or Schmidt Cassegrain type design).  But Newtonian type reflectors can sometimes be a problem.

 

Many Newtonian type scopes have their focus travel designed for visual eyepieces.  The problem with a DSLR camera is that the sensor has to be moved back a bit farther to make room for that reflex mirror to swing clear.  That extra distance means the focus plane is farther back than the scope wants.  As you focus "in" you'll notice th image is just starting to come to focus... but then you run out of focus travel before it is able to focus to a sharp image.  Not all Newtonians have this problem.  ...and some owners will "shim" the primary mirror up a few millimeters to fix the problem.

 

Long exposures need:


(a) an equatorial type mount (you can use an alt/az mount for exposures typically less than 30 seconds before the field rotation blurs the image too much to be useful).

 

(b) it needs to have a pretty decent alignment (imagers will often do a "drift alignement").  A typical alignment which is good enough for visual may result in the object just *slightly* drifting upward or downward in the field of view as the scope tracks the object (this indicates that the scope didn't have a very precise polar alignment.)

 

(c) for long exposures the mount needs to have decent tracking performance.  Worm gears can have "periodic error" where the scope seems to slightly speed up and slow down throughout the rotation of the gear -- and that will blur the object you're trying to image.  I try to insert my camera so that "north is up" relative to my field of view (e.g. which direction would I need to go in the image to find Polaris)... because that way I can tell if my image is bluring on the right ascension axis (which usually means it's a tracking error) or if it's drifting along the declination axis (which usually means it's an alignment error -- alignment errors are easier to fix.)

 

Even with a decent mount ... if the exposure time is long enough you may need to use an auto-guider.  The auto-guider can either be off-axis (through the same telescope as the imaging camera) *or* it can be in a separate telescope (piggy-backed on the first).  The guider takes frequent images (e.g. once every couple of seconds... rather than a single image that takes several minutes to expose).  As it does this, it notes if the selected guide star appears on the same pixel in the image in every frame.  If it notices the star is drifting, it will send a corrective movement command to the mount to keep it on track.   Commonly a mount intended for imaging will have an autoguider port.  The standard is VERY simple... it's a 5-pin port.  One pin is "ground" and the other four pins are "up", "down", "left", and "right"... and that's all it does is send little pulses to the mount.

 

I suspect that your EQ2 mount (I'm thinking you are referring to the Orion EQ2 and motor drive) is not going to provide ideal tracking for long exposures and you may have to shorten your exposures times to avoid blur.  But this also depends on the focal length of your scope.  The higher the focal length, the narrower the field of view and the more noticeable a tracking error will be.  It's easier to work at low power and wider field of view because the error may not be enough to be noticeable.  But do pay careful attention to how you align the camera... so that when you get non-round stars in your image you'll need to know if they are elongated along the declination axis or the RA axis (because it's a different fix depending on which way it's blurring.)

 

I went through two mounts (and much frustration) and ultimately caved and bought a MUCH better mount than the previous two.  I now use a Losmandy G11 mount with the Gemini II system (that's their "go to" computer... but you can use their mounts without the Gemini and they are still motorized and can be auto-guided).  

 

My first mount was a Celestron CG-5 mount (now discontinued and replaced by the Celestron Advanced VX mount (sometimes just abbreviated "AVX") which is a bit better than the CG-5.   I then "upgraded" to a Meade LX-80 mount.  I have to put "upgraded" in quotation marks because I was happier when I had the CG-5 mount (the LX-80 was not suitable for imaging... tracking performance was surprisingly poor.) 

 

Wide field images are less fussy about precise tracking than narrow field images. 

Bright objects take less time to expose than dim objects.

 

That means that narrow-field images of dim objects are VERY fussy about tracking AND require long exposure times -- making this the most difficult.  But wide-field / low-power images of bright objects are not as fussy and don't require long exposures... making this the easiest type of image.   

 

The moon is very easy and the exposure times is very fast.  At f/11 the exposure for the moon is the inverse of the ISO setting... so at ISO 100, the moon is 1/100th sec exposure.  At ISO 200 it's 1/200th, etc.  (But remember that's at f/11... you have to know the focal ratio of your scope.  If your scope is closer to f/8 then double the shutter speed (use 1/200th at ISO 100).  If your scope is closer to f/5.6 then quadruple your shutter speed (1/400th at ISO 100).  

 

Planets are slightly more difficult... but still on the relatively easy side.  But these are so much tinier than the moon that any distortion is more obvious.  To image these, you usually take many exposures (and usually it's a few hundred frames of video... which your T1i can do for you) and then you use "stacking" software.  Registax is popular (and free) for processing planetary images.

 

Deep space "faint fuzzy" objects are hard because they require exposures that are usually many minutes long (4 mins.. 8 mins... 15 mins... etc.).

Tim Campbell
5D III, 5D IV, 60Da
Occasional Contributor
Posts: 18
Registered: ‎12-25-2014

Re: Getting started with my Canon T1i

I already have the T-Ring and T-Adapter, however I haven't been able to achieve focus using both yet. I have a Newtonian telescope which I know is not made for AP. What I was able to do though is unscrew the lens tip from my 3X Barlow and screw it on to my T-Adapter and I was able to get the moon to come into focus. I am still in the process of trying to figure something out to achieve focus with just the camera and the T-Ring. The next thing I will try is attaching my camera with the T-Ring to the focuser and see if I can get focus that way. 

Esteemed Contributor
Posts: 3,854
Registered: ‎06-11-2013

Re: Getting started with my Canon T1i

This is a somewhat classic problem when using Newtonian reflectors.  You should notice that it's only starting to get more focused as you rack the focus travel all the way inward.  

 

A 2x barlow will help (because that pushes the focus distance back... but of course it's changing the effective focal length and focal ratio of your scope and you end up with a much narrower field of view.  

 

I do know of some telescope owners who had to shim up the primary mirror at the bottom of the scope to fix the problem.  You'd do this just *barely* enough to get the camera to achieve focus.  If you go too far then the camera achieves focus but regular eyepieces wont achieve focus.

 

 

Tim Campbell
5D III, 5D IV, 60Da
Occasional Contributor
Posts: 18
Registered: ‎12-25-2014

Re: Getting started with my Canon T1i

I've heard of that method and is one I am considering. Thanks

powered by Lithium

LIKE US on Facebook FOLLOW US on Twitter WATCH US on YouTube CONNECT WITH US on Linkedin WATCH US on Vimeo FOLLOW US on Instagram SHOP CANON at the Canon Online Store
© Canon U.S.A., Inc.   |    Terms of Use   |    Privacy Statement