DSLR with SWE 130P - can you check this?

[teh_orph]

Hi there,

I'd like to get into imaging DSOs and am thinking of getting a Canon 1000D (original, I know!) to go with my Skywatcher Explorer 130P. Does anyone else have this set-up?

Some questions if anyone could help me out:

- I've heard that you can have problems getting cameras to focus with Newtonian reflectors. Am I likely to have this problem, and if I do is there anything I can do about it?

- Are all the parts I need to connect the camera are a T-ring adaptor ie one of these,

Adaptors - T Rings

as well as a T-mount camera adaptor, eg

Adaptors - 1.25" T mount camera adapter

- I have a light pollution filter that screws into the thread at the end of my eyepieces - where would I attach this is I wanted to use it with the camera?

Big thanks!

Simon

[brantuk]

All you need to attach the camera is a T-ring - there's a thread on the drawtube to attach it directly when you take the ep out.

[teh_orph]

Ah, I see - so what's the point of the T-mount camera adapter? (just for adding filters?)

And I'm starting to worry about this focus issue - there seems to be conflicting info around the web as to whether this telescope can even take an SLR!

[Uplooker]

Not had this issue myself, but from what i have read, it is not possible to achieve focus because there is not sufficient travel on the telescope focuser. I think this specific to the SW 130P, not relectors in general. One solution is to move the primary mirror up the tube assembly. Never attempted anything like this personally. This problem has been well documented. I will see if I can post links to some threads, otherwise search on here.

[brantuk]

The T-ring threads onto the scope and the camera attaches to the other side of the T-ring. I don't know why you'd use a "T-mount adaptor" - or even if it's a different thing all together, or the same thing.

But you wouldn't want to extend the drawtube any further out because, as I understand it, the problem is not enough "in-focus" rather than "out-focus" - wich is why people move the primary mirror up the tube sometimes.

[teh_orph]

I think this specific to the SW 130P, not relectors in general. One solution is to move the primary mirror up the tube assembly. Never attempted anything like this personally. This problem has been well documented. I will see if I can post links to some threads, otherwise search on here.

I've had a hunt around online about this and there seems to be a lot of conflicting info for this telescope - it doesn't help that there's the non-p model too! It seems that the 900 mm model is a no-no, but there seems more ambiguity over whether the 650 mm model (which is what I've got) can make it work.

Also surely it should depend on the camera in use too since some may have the sensor set further back in than others? I'm pretty wary of modding my telescope

The T-ring threads onto the scope and the camera attaches to the other side of the T-ring. I don't know why you'd use a "T-mount adaptor" - or even if it's a different thing all together, or the same thing.

Maybe these are for adding filters then. If you have just the T-ring, can you still connect filters to the front of it?

[Sparrow]

I don't know about your specific telescope, but yes, achieving focus can be a problem with Newtonians and I did indeed have this problem with my Celestron 8" Newt. As previously mentioned, one solution is to move the primary mirror up the tube. There are also low profile focusers on the market which may solve the problem. In my case I butchered the 2" eyepiece adaptor which came with the telescope and glued it to a T Adaptor to enable mine to achive focus. Not a method I'd recommend but it did work for me.

P.S. Canon 1000D - excellent choice - what I use for imaging.

[rwg]

Hi there,

I had the 650mm FL model and you definitely couldn't reach focus with it with an SLR - there wasn't enough in focus by maybe 10mm or so (can't remember exactly and no longer have the scope, sorry).

Robin

[teh_orph]

Ah nuts, I think I'm gonna have to change my purchase choice! At least I found out first

Looks like I'm gonna have to get a CCD instead I think...

[rwg]

Not sure what mount your 130P is on, but unless it is on a tracking mount of some sort (preferably equatorial), you are not going to be able to do much beyond planetary/lunar imaging. A good intro to this would be the SPC880/900 webcams that are being sold here : Cheap Philips SPC880 webcam - 49269 - discounts & offers (there is a long thread around here somewhere - search for SPC880).

You can even buy a couple and do the long exposure mod on one of them. A nice way to get started and build your skills without spending too much.

Robin

[teh_orph]

I'm currently using a webcam and a motorised mount (in RA only) but I'm disappointed by the huge amount of noise I get when I use exposures longer than one second which I think may rule out nebulas and galaxies and so on. I may try and cool the camera though to see if I can reduce this.

(Maybe I should look into these other webcams to see if they're more suited to this...)

[Nick]

I use an SW 130 explorer with a Nikon D70 and a t-mount. I could not get sufficient backfocus without a minor modification, this is really easy and works well. You need to remove the mirror cell, take out the mirror and replace the collimation bolts with some that are 10 mm longer (they are counter sunk bolts, M5 thread, easily available). This has the effect of moving the primary mirror up the tube by 10 mm. I have not found any problems and I can still get all my eyepieces to work. The diagonal appears to be just big enough to work OK. It may seem a bit scary taking your mirror cell apart but it really is quite simply and completely reversible.

[teh_orph]

I might take my OTA apart at the weekend to see if I can make that work or not...

Btw, do you have to P/650 mm version of the scope?

[Nick]

Yes it is a Skywatcher 130 x 650 mm newtonian, I assume the P suffix refers to the parabolic mirror which would make it an SW130P. One extra bit if info - I used some nyloc nuts on the threads of the adjusting screws half way along to maintain the same compression on the springs. You will see what I mean when you take it apart. Any probs let me know.