Probably the dumbest filter question ever!

[swag72]

I have looked at the filters sticky to learn what the different filters do. WHat is not clear though is where do the filters go? Between the eye piece and scope or over the front of the scope itself?

I ask as if I wanted to get filters for astrophotography, where would they go?

Sorry for the totally dumb and stupid question. I keep seeing that the filters are 1.25 or 2 inch, which tells me that they go at the eye piece end

[Demonperformer]

Most filters screw into the eyepiece (the end furthest from the eye)

[RyanParle]

Apart from solar filters which must go at the front of the scope, all other filters go at the eyepiece end of the telescope, they are usually available in 1.25", 2", T2, SCT, and there are also some filters that will clip in to a DSLR.

[Moonshane]

hi there. if you don't know you don't know - doesn't make you dumb!

Ignoring solar work, you have a number of choices where to put filters (you obviously need to match the size of the filter with where it's being screwed into):

1. In the threads in the far end of the eyepiece
   
2. In the end of the star diagonal (if you use one) that goes into the scope
   
3. In the 2" - 1.25" adapter.
   
4. In a drawtube extension piece.
   
5. In a specially made filter wheel.
   

The last option is used I believe by many photographers as is allows you to swap filters without having to take everything apart.

I am visual only and use 1., 3. and 4. depending on whether or not I am likely to be changing eyepieces for use with the same filter.

Hope this helps.

Cheers

Shane

[swag72]

Brilliant - Makes perfect sense. As a photographer I am used to the filter going onto the end of the lens, so just assumed this was the same for a telescope. I hope a photographer will come along soone and give me some pointers as to how best to use filters with a DSLR connected to the back of the scope.

[RyanParle]

With a DSLR most of the time the only filter you will be needing is a light pollution filter. It can be mounted at any point in the imaging train, if you have a canon camera 20d or newer then you can use the Astronomik EOS clip filter, which clips in to the front of the camera, you can also image through a canon fit lens although it must be an EF fit lens, EF-S lenses will not fit when you have the clip filter in place, EF-S lenses have an extra bit of plastic that sits in to the space where the clip filter goes.

In addition to a light pollution filter you may also want to use narrow band filters, I am told this will work with DSLR cameras, but you will need very long exposures to get decent data. Personally I don't see the point in narrow band imaging with a DSLR, considering the bayer matrix will cause a huge loss of data compared with a monochrome sensor. To make use of narrow band filters you will also need to have the hot-filter removed or replaced with one that allows Hydrogen Alpha to pass.

[swag72]

Thanks for that - I don't have any EF-S lens's, so that's no worry. I keep reading mixed comments on LP filters, with some saying yes and others no. May look into that then. I'm just finding all this really exciting at the moment!! I may get a filter for use with the EP, as I understand that the right one will make the viewing a little more like you see with camera imaging.

I do have an IR modded 10D, that has had a 720nm IR filter put in front of the sensor. Gives some really fantastic images. May try this out with the scope at some time, although no one has so far been able to tell me what I can expect with it.

[Psychobilly]

Moon would be ok with IR pass... cant think of that much else to be honest...

Probably the most useful wavelength to image is Ha which is below your filters cut-off...

You could go for filter rmeoval and clear glass if you wanted to maintain AF or look at having the shimmng of the Sensor assembly adjusted...

I have a full Spectrum 350D which I use for all sorts of things including IR pass using R72 front element filters...

I have a filter replaced 1000D and as yet "vanilla" 500D which may or may not go under the knife over the next few weeks... I am not impressed with it as a daytime camera with the lenses that I have available ...

I use Nikon's for everything else...

Billy...