Attaching Filters

[Oto]

I ordered a set of filters to go with my Celestron 127eq Powerseeker Telescope and noticed that a lens and the barlow that came with my telescope do not have threads that i can attach my filter to:

 

I also noticed that some of these filters have threads on both sides except the moon filter, not sure what thats about but doesnt seem to help the situation:

As far as the Barlow goes, can I just drop the moon filter into it then drop the lens over it like this?

 

[RT65CB-SWL]

Hi Oto and welcome to SGL. 

Filters normally are screwed into the nosepiece of an eyepiece. 

[Ricochet]

If there is enough room in the barlow to drop a filter in with an eyepiece on top I guess you could use it like that. You would have to be careful doing so though. When you buy some decent eyepieces you will find they are threaded to take filters. The filters with two sets of threads are so that you can stack them if required.

I would also suggest buying from a specialist retailer rather than Amazon as they are much more able to provide advice and aftersales support as well as usually not selling the lowest quality equipment that is best avoided.

[Cornelius Varley]

Normally you would screw the filter onto the nosepiece of the eyepiece. The barlow lens doesn't have a filter thread for that reason and the 20mm eyepiece, I believe, is an erect image eyepiece designed primarily for daytime terrestrial viewing so doesn't need a filter thread for astronomical filters.

[Cornelius Varley]

Another option would be to hold the filter above the eyepiece.

[rwilkey]

If Amazon are worth their salt they should take back and refund.  This is a problem with some cheap ep's. 

[S.A.M]

Always go for the best filters you can afford, they should last a life time if looked after properly, ie left in the case when not in use.

Peter

[RT65CB-SWL]

6 hours ago, Cornelius Varley said:

Another option would be to hold the filter above the eyepiece.

In other words... Make sure you place it into the rubber eyeguard, (I am assuming you are using a Plossl e/p), and you don't go for silly angles in altitude/elevation, otherwise it will fall out. 

[LukeSkywatcher]

The reason why some filters have threads on both sides is so you can stack them together and use them in the EP. I cant think of many instances when a person would do this (im sure i'll be enlightened). The only time i have stacked 2 filters is for solar observing in white light. I stack a variable polarizing filter with a solar continuum filter. This presents a problem of its own, so ive now stopped doing that and have them at different positions along the optical train.

[TareqPhoto]

Buy a filter wheel