Help with dslr and astrophotography

[Benno85 (Ben)]

Hi All,

I have an unmodded 450D, and a 900mm reflector telescope (for those that can make sens of it the model# is 114F900EQ-111A, with the word "Precision" on the tube). As you can tell I am very very new to all of this....

My question is two-fold.....when using just the camera on a tripod with shutter release cable, how can I focus on objects in the sky (eg I look at the moon through a 75-300mm lens on auto focus, and the image is very out of focus).....and secondly,what accessories will I need to use my camera through my scope (with the intention to capture multiple exposures for later processing).

Any and all all advice will be greatly received. If anyone is near Picton NSW and can lend some hands-on practical advice then you'll score even more brownie points!!

Thanks everyone,

Ben.

[dannat (Daniel)]

as far as the focus is concerned you could focus at somehting very far away during the day using the AF, then switch the camera to MF before taking any more hots. the camera focus should remain at infinity (or close to) and take a test shot or two, blow it up on the lcd or download it and tweak the manual focus ring ever so slightly.

in saying that usually most cameras do an ok job of focusing on the moon, did you handhold or have on tripod.

as for the 2nd part most don't use d-slr fr shots thru a reflector - most ota's don't have the right amount of travel focus and quite often you need to move the mirror further up the tube closer to the focuser. hence most use a webcam or ccd for reflectors to take luna/planet shots

[Octane (Humayun)]

Ben,

If the 75-300mm lens is having kittens trying to focus on the Moon, then, I think your only option is going to be: rough focus; take a shot; inspect image; focus; take shot; inspect image; focus; take shot; inspect image, and so on.

A lot of us DSLR astrophotographers use software, such as DSLR Focus (which is pretty much now defunct and has no support for newer cameras) or DSLR Shutter, which allow you to program multiple exposures.

To attach the camera to the telescope, you will need a T-adapter and a T-ring for your EOS camera. You might also need an extension tube to bring the image to focus.

Bintel stock these items.

Examples:

https://www.bintelshop.com.au/Product.aspx?ID=5439
https://www.bintelshop.com.au/Product.aspx?ID=5551
https://www.bintelshop.com.au/Product.aspx?ID=7082

Email don AT bintel DOT com DOT au

He'll guide you in the right direction.

Hope this helps.

Regards,
Humayun

[Kal (Andrew)]

The 450D has liveview on the LCD screen of the camera feature, and pressing the zoom button twice will bring up 10x digital zoom with this to assist with manual focus. It might be easier to use this for focusing rather than looking through the camera eyepiece.

[RobF (Rob)]

Originally Posted by Kal

The 450D has liveview on the LCD screen of the camera feature, and pressing the zoom button twice will bring up 10x digital zoom with this to assist with manual focus. It might be easier to use this for focusing rather than looking through the camera eyepiece.

I'll 2nd Andrew here - I've had pretty good success using Liveview to get the focus set. Generally get my object framed ok, save position on my GOTO scope, move to a bright star, use Liveview to focus until diffraction spikes nicely visible, then slew back to saved position and start taking shots.

I'd suggest putting your DSLR right up to your focuser (screwed all the way in) in the daylight - look through the camera viewfinder to check if you can get enough in travel on the focuser to reach (prime) focus. If you've got enough travel then worry about suitable adaptors, T-rings, etc.

Rob