Help with afocal shot of M42

[prova]

I have a Nikon D50 DSLR and want to take some pics via the afocal method of M42 tonight (weather pending)

Can anyone please recommend the best settings I should use on my camera - eg. iso, shutter speeds, etc etc

I promise to post my results

[iceman (Mike)]

Hi Prova. Will your scope be tracking?

Start with the widest field eyepiece you have - and you need a way to attach the camera to the eyepiece, so that the camera moves WITH the eyepiece/scope.

Try ISO800, 4s exposures to start, and see how much trailing you get - then increase the exposures to 10+ seconds.

[prova]

beautiful conditions last night but i came away extremely disappointed ..

i really don't even know if i have the right adapters to do what i want to do which is to take some shots of M42 (to start with)

i used manual mode on my DSLR and set up all the ISO's etc but I can't see where to set the exposure times and after 25-odd pics with instant exposure i came out with 25 plain black pics ..

really need some help!

[edwardsdj (Doug)]

Hi Prova,

I have yet to attempt anything other than prime focus lunar with my D80 but like iceman says, you will need a way to rigidly attach the camera to the eyepiece/telescope.

It sounds like your not sure you have the correct adapters. I find I need to be familiar with all the equipment I'm using in daylight before attempting to use it in the dark.

I've only done prime focus photography where you don't use an eyepiece and attach the camera body directly to the telescope using the telescope as the camera lens. I would have thought this would be the easiest place to start for deep sky objects.

On my Nikon D80 you set the exposure in manual mode with the "Main command dail" (the one under your thumb when holding the camera normally). This will all be described in the Nikon manual.

Have you attempted to image the Moon yet?

Hope this is of some help.

Good luck,
Doug

[prova]

Hi Doug

Thanks for the reply .. I have no problems firmly attaching the camera to my scope but to do this i need to take the eyepiece off my scope and take the lens off the camera, i believe this is called "the afocal technique?"

The only pic I've taken that has come out is the attached moon pic a few months ago ..

Wanna give M42 another crack tonight but no idea and how I should approach it

[edwardsdj (Doug)]

Nice image of the Moon Prova

My understanding is that the afocal technique is where you just put the camera with lens attached up to the telescope eyepiece.

The technique you describe where there is no camera lens or telescope eyepiece involved is called prime focus.

I'm no expert at this but M42 is comparable in size to the Moon so the image scale you have at prime focus seems good to me.

You will need to play with the manual mode on your D50 until you can work out how to take exposures that are seconds long. On my D80 it is rotating the main command dial that does this.

My limited attempts at prime focus deep space imaging have highlighted the need for careful attention to accurate polar alignment and focus. You do have the EQ5 though so you are in a much better position than me for both of these.

Sorry I've yet to suceed on M42 myself so there's not much more I can say.

Have fun,
Doug

[prova]

cheers, ill give it another crack tonight and post my results