DSLR focusing

[gdheib0430]

So I am going to receive a mount for a dslr camera and mess around on my little 3" reflector before buying any good eyepieces and bigger aperature.

With my dslr sony a300 and everything set to manual, would anyone have the norms for ~10s stills as far as settings go? I am probably just going to take different setting shots to try and narrow it down as I usually am up all night being on night shifts, but my big concern was focusing the camera when I take shots...are there different focus lengths needed for each different eyepiece that is put on the scope or is there a good set focus that I can just set it to and keep it at? Just curious as to if it is going to have to be a trial and error kind of thing everytime I take a picture or if I can fine tune it and keep it as is...

Just to catch all my basis I am thinking on setting the ISO to it's max 3600 to have a bit more exporsure...is it a good thing or is it one of those just experiement and see what works best kind of approaches?

[jgs001]

What are you mounting it all on, that'll have a large bearing on your exposure time. It's better to go for longer exposures, than bump the ISO that high, if possible. I'd suggest having a structured plan ready, so maybe, ISO 3200, 10s, 20s, 30s etc, to determine what you can get away with in exposure time. Once you've determined your max exposure time your kit will allow, then drop back the ISO to something like 800, and capture a sequence of many exposures, and combine them with Deep Sky Stacker.

[gdheib0430]

kk I will look into doing that would be good times figuring it all out. I am going to be using a dlsr mount from orion:

Orion SteadyPix Deluxe Camera Mount | Orion Telescopes

BTW, this sky stacker does it just intelligently line up the exposures onto themselves? I should be able to just get away with doing that in PS correct? Been doing digital design for about 12 years now in PS CS3, 4 and 5.

[jgs001]

You shouldn't need something like that for an SLR... unless there's something peculiar about the scope and fixings. A T-Ring is a much better option, then an ep fitting, you replace the ep with the camera. You should be able to do the registration and stacking in PS, but DSS does the hard work for you, automatically aligns all the images and combines them.

[rocketandroll]

don't bother trying to stack exposures in PS... just download DSS and use that... its simple as anything and does all the hard work for you... oh, and it does more than just align exposures... it actually checks the images pixel by pixel to remove transient errors, hot pixels etc. What DSS does automatically in a fee minutes would take you weeks in Photoshop... no matter how good you are at using it :-)

And as others have said... your better off attaching the camera direct to the scope rather than shooting through an eyepiece.

Ben

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[gdheib0430]

kk will look into that...with the t adapters connecting to a dslr without a lense how does the camera zoom in on an object or can that not happen? I see they connect directly to the focuser so I am guessing you can't zoom in close to get a planetary picture or am I missing something here?

[jgs001]

It's a bit more complicated than that. An slr is not really the best tool for planetary imaging. The subject is too small. A webcam is a better choice. However an slr can get some results and you probably would want to use ep projection rather than a focal. Don't use the camera lens, but use an ep

[gdheib0430]

Yeah I did a bit more reading and this really helps a lot I appreciate all the information and patients on helping me out...have read a bit more through the searches and it looks like I am more inclined to take some wide field or DSO exporsure shots with a dslr...but having a altaz mount can't really go too deep into it yet.

I am guessing with ep projection if you want more deep field view to grab a good barrlow to attack to the scope? Last question I swears lol, but with the camera not having a lense which I kind of understand now, I am assuming you set it to manual focuse and just focuse with the telescope's adjustments? Man I feel really dumb right now I haven't felt like I couldn't understand something by reading a bit for such a long time I have no clue what is going on with this sometimes. I really do appreciate the help.

[jgs001]

I think you'll be surprised what you can achieve with an altaz when you try and push it. You should be able to get 30 - 45 second exposures for wide field, depends on the capacity of the mount really.

You're correct, without a camera lens attached (with or without an ep), your scope becomes a telephoto lens in it's own right, and you focus with the normal focusser.

[gdheib0430]

Sweet I think I am finally getting the grasp of it now...just wasn't aware of all the different attachments needed for a dslr thought it was a tiny bit more straightforward, but pretty cool though I will be getting some images here in a week to see what I can/can't do...thanks for the help and point towards dss that program looks pretty spot on.