Can I fool a 350D?

[Faz]

Hello, quick intro first as I'm new to the forum. I currently live in Norfolk, working for the RAF as an Avionics Technician. Among other things I enjoy parakarting and photography. I've been into photography for a number of years now having started with a Pentax P50. I upgraded a few years ago to an EOS55 which is almost in retirement with the arrival of my 350D. I'm never far from a camera, even if it's just the little Casio QV-R40.

I've just recently become interested in Astrophotography. A method for capturing images - prime focus - requires the removal of the lens from the camera, attaching the camera directly to the telescope. This brings me to my problem. Focussing, it's flippin' difficult!

If it were possible to fool the camera a lens was attached and in MF mode, it would enable the camera to tell me when focus is achieved by way of the flashing red points and a beep. Given there is all maner of shiney contacts on the front of the camera, does anyone know if this would be possible? Does anyone have access to some form of schematic identifying the contacts?

Any help/advice would be greatly appreciated.

Cheers,

Faz

[ChrisKolb]

...If it were possible to fool the camera a lens was attached and in MF mode, it would enable the camera to tell me when focus is achieved by way of the flashing red points and a beep.

I can't help you with fooling the camera into thinking a lens is attached and in MF mode, and I don't have my camera beside me so I can't verify what I'm about to say... but I'm pretty sure that even when a lens is attached in MF mode the camera does nothing to verify focus... No beep, no flashing of the focus points, just takes the shot when you press the shutter release.

That said, good luck and I hope that there is a way to achieve the focus verification that you want!

Chris

[malum]

You could take a cheap lens and remove all the elements, then find a way of attaching the telescope to the front of that?

[the7ferret]

i know if you focus with a reg lens and you hit the focus spot it will beep on my 300d. 350d im not sure but it should. However with a telescope thier might not be enough light comming in for the focus group to detect correct focus and tell you its done so.

[Faz]

Thanks for the replies guys. I can confirm that the camera will return a beep if focus is achieved under a focusing point when in MF mode - but alas only when attached to a lens :(

Malum, I think you're on to something there - however it would extend the body of the camera too far from the focal point of the 'scope. That said, finding a lens for scrap and removing all the parts down to the mount with AF/MF switch may provide a solution... if the electronics are all contained that far down.

I feel a headache coming on!!!

Thanks again for the inspiration tho,

Faz.

[Jonny]

Thanks for the replies guys. I can confirm that the camera will return a beep if focus is achieved under a focusing point when in MF mode.



Hey, i didn't know that.

So are you saying that with a 300D when you put a lens in MF and turn the focusing ring it will beep when you have correctly focused?
is this correct?

Does this apply to the 20D too?

[Titus213]

I found a web site devoted to EOS astrophotography. I haven't read it all but I see they are using a 10D and they do talk of direct connect to the telescope.....

http://web.canon.jp/Imaging/astro/index-e.html

or

http://www.covingtoninnovations.com/dslr/EOS300Dastro.html

[CyberDyneSystems]

Thanks for the replies guys. I can confirm that the camera will return a beep if focus is achieved under a focusing point when in MF mode - but alas only when attached to a lens :(


Right, it still needs to be a fully "EF" (or EF-S) compatible lens for the focus indicators (light and beep) to function.

I can not imagine a simple way to make a Camera belive that it is attached to an EF lens when it is not,. and even if one could,.. if the method used was just a "hack" I do not know that it would be flashing the red light at the point of correct focus.

[Faz]

Cyber, I envisiged the solution to my problem being a hardware 'hack' as opposed to firmware. I had hoped it would be a simple matter of shortlinking a couple of contacts. Having poked around on the lens contacts with a Fluke it appears to not be the case :(

Thanks for the tip-off Titus, I'll go have a look-see.

Thanks again peeps,

Faz

[WaveRider57]

Hey, i didn't know that.
So are you saying that with a 300D when you put a lens in MF and turn the focusing ring it will beep when you have correctly focused?
is this correct?

Does this apply to the 20D too?

it sure DOES! I was thrilled to read about it in my 20D manual!! :D

[Jonny]

it sure DOES! I was thrilled to read about it in my 20D manual!! :D

My god, u learn something new everyday. I really must RTFM sometime!

[PacAce]

My god, u learn something new everyday. I really must RTFM sometime!
LOL So, I guess you missed the coupon in the manual where you can upgrade your 20D to a 1DmkII for an additional $10.00? But the coupon's was only good until yesterday! :shock:

:lol: :mrgreen: JK! ;)

[Jonny]

LOL So, I guess you missed the coupon in the manual where you can upgrade your 20D to a 1DmkII for an additional $10.00? But the coupon's was only good until yesterday! :shock:

:lol: :mrgreen: JK! ;)

With my luck that would be true!

[Chazs]

Try a Hartmann mask, either on the scope, or on a regular lens. I've had marginal success with this method.

http://www.astropix.com/HTML/I_ASTROP/I08/I0817/I0817.HTM

[Cadwell]

I can not imagine a simple way to make a Camera belive that it is attached to an EF lens when it is not,. .

Sigma, Tokina, Tamron and others seem to have worked out how... some with more success than others ;)

[Faz]

Thanks for that one Chazs. Do you know whether the holes cut into the mask have to be a certain size/ratio or position or is it a case of as long as they're the same?