Sony Nex-5N at prime focus -settings?

[silv (Annette)]

Hi there,

I will have to replace the focuser and possibly move the primary mirror of my 8" newt to reach a focal point with my Sony Nex-5N.

I have not yet bought T-mount accessories because I think, the focuser will eventually determine them and I have no money t spare to buy the wrong stuff or redundant stuff.

With the lens off, the camera has no option to be focused.

I take images outside at daylight of some close by object (with differing distance - no change) but only get whitish light in the life view and on the photos.

If you are using your camera lens-less at prime focus: which settings do you use?

I must be missing something obvious - as I didn't find any info regarding this on the web nor in the camera manual.

I'm going nuts here. I really don't like it to find myself in a one-way cul-de-sac - knowing it is only my limited intellect and knowledge causing the obstruction... bugger!

HELP

[dannat (Daniel)]

when you take the lens off you use the focuser off the telescope, you can get a t-ring for your camera from cnc supply in the US (i have just bought off them)

you will the possibly need a 2" - to T thread adapter - though CNC now make an all in one unit called the t-minus adapter for Sone new & u4/3 CNC all in one t-ring/adapter

what newt do you have?

[silv (Annette)]

when you take the lens off you use the focuser off the telescope

m-m-m-m-b-b-b-but my current focuser only slides the barrel up and down, closer or further away from the secondary mirror.
that's all it does.
which means as much as moving my camera closer or further away from an object.

from what I can see in pictures from T-mount accessories, they DON't have any optical mechanics, either - they're just plastic stuff to connect parts with each other.
right?

or is THAT the false assumption that makes my hair grow white?

[silv (Annette)]

what newt do you have?

a blue one.



Says Eden Optic on the side.
The focuser is near the front of the tube... hmm.

[silv (Annette)]

in case someone else has difficulties getting their head around this:
in my other thread I learned that
* indeed you will only see stray light without a lens
* the camera chip needs a bundle of light - just as one is projected by the telescope through the focuser.
*apparently, it is possible to get to the focal point by holding the lens less camera on top of the focuser (with the eyepiece adapter removed) and sliding the focuser barrel upwards
*for some reason or other, this is better tested while aiming for a distant object a few km away
* the T thingies don't have an optical effect (well, none that has to do with the focal point, anyway)

[Shiraz (Ray)]

Originally Posted by silv

*apparently, it is possible to get to the focal point by holding the lens less camera on top of the focuser (with the eyepiece adapter removed) and sliding the focuser barrel upwards
yes, but it will only come to focus if the focal point is within the adjustment range of the focuser
*for some reason or other, this is better tested while aiming for a distant object a few km away
the scope is designed to image objects in space - it needs to be tested on things that are a long way away or you need to calculate compensating focal distances
* the T thingies don't have an optical effect (well, none that has to do with the focal point, anyway)
they do add a bit to the back focus distance though

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