Live View and Micro Four Thirds

[CowsonConcrete]

Hi,

I have a Skywatcher 130 pds (doesn't everyone) and an Olly Pen E Pl1.

I have done Ep projection shots in the past using a 120mm refractor and got recognisable images. I know what to expect from a light polluted back garden and what is achievable from such a locale.

However, since buying this scope I can't use afocal, I'm unsure whether this is due to the micro four thirds element or the tubes primary mirror distance, no great shakes, o have a Barlow but other than the moon I can find nothing in the live view. I have tried Vega, Deneb, Altair, the Plaides and nothing. I was hoping for some better Saturn or Jupiter shots with my kit but unless I find a way of seeing I'm guessing this is going to be difficult!

Amy ideas? Am I missing something? Is the 130 letting in less light than my old reflector?

Thanks

[ronin]

The amount of light should be very much the same, as I would have expected the refractor to be slower then f/5 I would say the images from the refractor would have been larger and so dimmer. In effect the 130P image would be a bit smaller and brighter, as brighter then being more visible in live view and also fit easier on the sensor. Overall afocal I would have expected to be easier, slightly, with the 130P then the 120 refractor, or no worse.

All I can think of is that the camera is no being held square to the optical axis and so the image is missing the sensor. However that is a guess. The refractor is probably easier to get the camera square whereas the 130P may have the focuser at an angle and so allow the camera to tilt under it's weight.

If the refractor is a 120 f/5 then really they would be so similar that the result would be almost undetectable.

[Avocette]

You say 'other than the moon I can find nothing in live view' - my guess would be that the scope is off the star target by the time you get the camera to the eyepiece and make focusing adjustments. By the way which method are you using - eyepiece projection with the camera sensor exposed directly to the eyepiece or afocal where the camera lens is still in place and itself needs to be focused?

[CowsonConcrete]

I'm using both. For the moon shots I used a 3x barlow directly into the focusser but have tried, and historically always used, an Ep projector. The comment regarding being off target may have some truth but when using only the Barlow I presumed my fov was so large I would capture at least one star in the live view screen.

I will add that the scope is great for viewing and the moon images, whereas not better than the refractors yet have thr potential to be so as no chromatic aberration his present (I'm guessing that's due to less glass in the set up).

[nicks90]

what about ditching the afocal and ep projection business and buying an adaptor and having a go prime focus?

[CowsonConcrete]

Excuse my ignorance but is prime focus when you aim the camera+lens to the eyepiece or affix the camera and exposed CCD directly to the scopes focuser.

Again, sorry if I sound a little naive.

[CowsonConcrete]

Anyways, a quick google of the words prime focus telles me what it is and unfortunately yes, I have tried prime focus.   The focal tube isn't long enough for my micro four thirds camera to find focus (without a barlow that is).

Thanks for your response though.

[CowsonConcrete]

Hi,

I don't know if anyone goes through old topics but I thought I would update this and mention that I discovered an aid last night which people may know but I certainly didn't;

The 2" to 1.25" EP adapter that comes with the Skywatcher 130p DS actually comes in two parts which are tightly screwed together.  Once undone you can screw your t ring directly onto this and, hey presto, an inch has been shaved off the focal plane and the scope can be used for direct afocal photography

As I say, most people probably know this but as the scope came with no instructions I was relieved and happy to discover this.

Thank you