Nikon D3000 Focussing problems with OTA's

[Catweasle]

Can anyone tell me if it is possible to achieve focus for basic DSO imaging with a Nikon D3000 and a Skywatcher Startravel 102 or 80.None of my scopes can manage this and I don't really want to buy yet another OTA just to find I still can't do it.As I understand it the problem is that the Nikons sensor is further into the body of the camera than on Canons but I wondered if the direct SLR/DSLR connection on the Startravels might make focussing possible with a Nikon

[Psychobilly]

A cheap 50 mm long T extension is all you need between the scope and the t-ring on the camera... you will definitely be able to focus then... keep an eye on astroboot...

http://www.scopesnskies.com/AstroBoot

I wanted to check a few things out... I have just been trying my Nikon D200 on my ST80...

It will come to focus on a pylon about 3 miles away .. the direct connect part of the focuser can be adjusted turn the end piece anti clockwise and it will start to unscrew, the knurled ring is a seperate locking ring so you can gain a few mm of extra length... the focuser is racked out approximately 50mm in this config... personally I would prefer to add 30-40mm of T extension so the focuser isnt racked out so much... a couple 10mm extensions (cheap on Astroboot) would guarantee you getting focus...

Once you have a t ring on the camera they all end up with the same register (distance between front of lens mount and focal plane) of 55mmm so any make camera will come to focus at the same point when the appropriate T ring is used...

This pic might help...

Peter...

[Catweasle]

Many thanks psychobilly.I'm ging to strip down an old barlow to give me some extension to try this out before I go the whole hog as it were.All my tubes at the moment have to be racked right in to achieve focus at about half a mile away and anything any further away can't be focussed on at all.Have also just managed to lash together a way of attaching the camera to my mount ( but it's not particularly secure ) so I can at least play with my cameras 300mm lens for the time being but without autoguiding so will be restricted to fairly short exposures for now ( weather permitting )

[Psychobilly]

No worries... Good luck and clear skies

Peter...

[Catweasle]

Decided to take the plunge & ordered 102 from FLO & extenders from Scopes.Whats the worst that can happen eh