Filters - do I need both 2" and 1.25"

[sacredblack (Steve)]

Hi all,

This maybe a silly question but I don't know the answer.

Ok I know that you mount 1.25" filters on the end of the eyepiece. Check

But I want to get a OIII filter for viewing and to help with taking astropix. I currently use 1.25" eyepieces.

So the question is do I need to buy both a 1.25" and 2" ?

Is there some sort of adaptor that would allow me to just get 2" filters ?

And finally. Where do I actually mount the 2" filter anyway when doing photography word. Since there is no eyepiece to attach it to

Scope is a Meade LXD75 SN 10".

Cheers !

Steve R - missing the bleeding obvious

[astro744]

Some 2"-1.25" adaptors are threaded for 2" filters and this is where you place the 2" filter. However, you must be very careful when using 1.25" eyepieces that have a long barrel since you wil put a nice hole straight through your 2" filter.

If you enjoy low power wide fields with low power wide field 2" eyepieces then get the 2" filter. If you are looking for small planetary nebula then the 1.25" O-III is all you need. Note you can still get a nice wide field with an eyepiece such as a 24mm Panoptic which is 1.25".

You may find you end up with both 1.25" & 2" versions of you favourite filters.

I'm not an imager and cannot comment on the photo useage other than to say the O-III has a very narrow bandpass and exposure times would be quite long.

[sacredblack (Steve)]

Thanks for the help,

I should have added that I'm thinking (very soon) to replace the focuser. So once I get that in place I can see how this is going to work.

But I get your point about needed both sizes of filter.

I think I've found where I would mount the 2" filter for the astropix. The T adaptor that I got from Bintel for my Canon 1000d has a thread on the side that faces the camera. Only concern here is that it's going to protrude into the camera hitting the mirror. I'll have to suck and see I suppose.

Thanks again,

Steve R.