DSLR's and eyepieces

[WhySoSirius]

So taking in to account the advice received in my other thread about eye piece sets, i was thinking of opting for the hyperion mk3 zoom lense instead of getting a set. before i commit though, i was hoping to get 1 small thing cleared up.

I would eventually like to do some astro photography using a dslr (i dont have one of those yet) and have watched a few tutorial videos online so am aware of t-adapters/mounts. but as of yet i havent managed to get my head around one thing...

Upon removing the detatchable lense from a dslr camera so that you can attach the t-adapter etc., do you lose the ability to zoom in using your camera when mounting it directly to the scope?. what i mean is, on a dslr camera, is the ability to zoom solely reliant on the attachable lense, or is there some zooming ability even without a lense attached? (sorry if this is a dumb question, ive never even held a dslr camera before, and havent got a clue) Because if im right in thinking you lose zooming ability upon removing the camera lense to attach a t adapter, i cant imagine the pictures you can take being very good.

I ask about this because i know that you can get a dslr adapter for the hyperion mk3, thus restoreing the ability to zoom while the camera is mounted to the scope with it. If im right in my assumptions (unlikely) then this would definately make the mk3 worthwile. i also like the idea of not having to actually change the eyepiece to increase magnification.(lazy?!)

i hope someone knows what im talking about, as ive probably not made myself clear, but its late and im very tired.

i would be very greatful if someone could straighten this one out for me.

depending on when you read this, good morning, good afternoon, good evening, or goodnight

cheers

[chemtom24]

yes you lose the 'zoom' function, but you wouldnt have had this if it was a prime lens anyway.

the other method you talk about is called afocal astrophotography. basically you have a normal camera setup, and a normal telescope setup, and literally point your camera lens down the eyepiece of the telescope and take a picture. in this way, the camera+lens is acting the same way as your eye. would be best with an adapter to hold the camera in position to keep it steady n stuff.

[Digz]

In attaching your camera to your scope you are effectively using your scope as one big prime lens.

A certain level of "zoom" can be achieved with a barlow (i.e. this will double your effective focal length depending on the strength of Barlow, in this case a 2x.)

Before you go any further what scope and mount do you have? Astrophotography is achievable on most scope and mount combinations but the level of what you can achieve varies.

HTH

[WhySoSirius]

i have a celestron nexstar 130 slt, so i think photography will be fairly achievable as it has pretty good tracking. dont get me wrong im not expecting to get amazing pictures of dso's, i'll be happy with some good pics of the moon, saturn, jupiter, and maybe some brighter stars/ constellations.

[Digz]

Thats good as this is probably the best kind of targets for an alt az mount. For serious AP an EQ mount is preferential.

[DaBozUK]

Really stupid question, but what stops you just seeing the mirror down the eyepiece hole as your eye sees it, i.e. reflection of the tube walls, secondary mirror, spider vanes etc.?

Surely you need a lens of some sort to focus to beyond the sky?

[ItIsOnlyMe]

Really stupid question, but what stops you just seeing the mirror down the eyepiece hole as your eye sees it, i.e. reflection of the tube walls, secondary mirror, spider vanes etc.?

Surely you need a lens of some sort to focus to beyond the sky?

Not a technical person but I would guess the camera doesn't see the tube walls because it is seeing only the focused light hitting the mirror and reflecting back up the tube via the secondary. When you stick your head down the end you see alL the unfocused light bouncing off these things.

All a lens does is focus the light and your mirror is doing this for you.

I use the method that the OP is suggesting to connect my DSLR via t2-ring to the focuser of the dob, it works great. Also used to connect to Hyperion ep via the adapter ring and this also works just fine. Haven't used the zoom ep but I can see where you are going with that as it is a much more practical idea than removing the EP and adding a barlow, which I would guess would mean refocusing and risk of moving the scope off target.