Jump to content


Photo

Vying For The "Most Ridiculous Question Award"

  • Please log in to reply
13 replies to this topic

#1 Chris2882

Chris2882

    Lift Off

  • -----
  • Posts: 8
  • Joined: 03 Jan 2013
  • Loc: McKinney, Texas

Posted 05 February 2013 - 03:49 PM

My apologies, first off, if there is somewhere else that this question is addressed ... I have scoured this (and other forums) and simply have not been able to find an answer. In fact, it's possible the question is so ridiculous, so amateurish, so unbelievably obvious that no one has thought it ever needed to be said. So here it is:

How do you use filters? How do you attach them to the eyepiece and/or diagonal?

Background: I have a recently acquired CPC 1100. Besides a JMI case, power tank and dew shield, that's all I have. I want to purchase a 2" diagonal and some 2" eyepieces but before I do, I am trying to determine how filters are attached.

I'm looking specifically at the Celestron Ultima LX series of eyepieces, starting with the 32mm all the way down to the 8mm (I don't see a need to get the 5mm since with 2800mm of focal length I think this magnification puts me over the useful limit). The catch is, only the 32mm and 22mm eyepieces are true 2" and the rest are 2" / 1.25". I want to get UHC and OIII filters, but it would seem I need to get both the 2" and 1.25" sizes in order to use them on all of the Ultima LXs eyepieces. That is, unless, I can attach the filters directly to the diagonal in which case I would get only the 2" size.

Or, with eyepieces like the Ultima LXs ... do I even need filters to view nebulas and galaxies?

If I end up needing to buy both 2" and 1.25" filters, I wonder if it would be better to get the Celestron 2" Eyepiece Kit where each eyepiece is 2" and I can get away with only buying 2" filters. I know this kit is very basic and introductory, but it may help me understand what focal length combinations get me the most enjoyable views. I could then use that knowledge to later purchase a few high quality eyepieces.

Coming back up out of the rabbit hole I got into, back to my original question! Filters? How do you apply these to your telescope?

#2 Midnight Dan

Midnight Dan

    Voyager 1

  • *****
  • Posts: 11286
  • Joined: 23 Jan 2008
  • Loc: Hilton, NY, Yellow Zone (Bortle 4.5)

Posted 05 February 2013 - 03:57 PM

Not at all ridiculous.

I ended up buying a very short 2" extension tube to put into my 2" diagonal. I then can screw the 2" filters onto the extension tube, swap eyepieces of any size and still be viewing through the filter.

-Dan

#3 Fogboundturtle

Fogboundturtle

    Viking 1

  • -----
  • Posts: 716
  • Joined: 20 May 2009
  • Loc: Burnaby, BC

Posted 05 February 2013 - 03:57 PM

You can screw them at the bottom of the eyepiece.

#4 Peshmerga

Peshmerga

    Lift Off

  • -----
  • Posts: 21
  • Joined: 25 Dec 2012

Posted 05 February 2013 - 03:57 PM

2" filter only here. Screw it onto a 2" to 1.25" adapter for 1.25" eyepieces. Saves me money from buying a 1.25" filter. Plus saves me time and frustration while fiddling/changing with a tiny filter in the dark.

For 2" eyepiece, I just attach the same 2" filter onto it.

#5 csrlice12

csrlice12

    Voyager 1

  • *****
  • Posts: 10806
  • Joined: 22 May 2012
  • Loc: Denver, CO

Posted 05 February 2013 - 04:01 PM

Some diagonals allow you to screw the filter onto the scope end of the diagonal. I also have a 2" to 1.25" adapter that you can screw filters onto. From what I've read, the ES82 30mm spits out filters before you can even get them into the focuser (which might be a good thing, otherwise...)

#6 Jon Isaacs

Jon Isaacs

    ISS

  • *****
  • Posts: 43875
  • Joined: 16 Jun 2004
  • Loc: San Diego and Boulevard, CA

Posted 05 February 2013 - 04:03 PM

Coming back up out of the rabbit hole I got into, back to my original question! Filters? How do you apply these to your telescope?



:goodjob:

Chris:

Far from ridiculous, your question is a very good one and very perceptive. And it's one that has no easy answer. But this is my thinking:

- Filters like the O-III and UHC are useful with long focal length eyepieces, therefore they need to be 2 inch filters. Hopefully your 2 inch to 1.25 inch adapter is threaded for filters so if you are using 1.25 inch eyepieces, you can just thread the filter to the adapter.

- Planetary filters will only be used at relatively high magnifications so the 1.25 inch format should be fine.

Jon

#7 wirenut

wirenut

    Apollo

  • -----
  • Posts: 1084
  • Joined: 21 Sep 2006
  • Loc: m'dale Pa

Posted 05 February 2013 - 04:19 PM

it's a simple question but not ridiculous. filter are made to screw onto Eps. they also have slides or wheels that attach to or a part of focuser. some have a extension tube or barlow without lens to make swapping EPs easier. many 2-1.25 adaptors are threaded for 2" filters so you can use a 2" filter with a 1.25" EP. (just make sure EP wont hit first)
Do you need them to see galaxies and nebulae? no, but they can help make them stand out better or at least with nebulas, nothing really helps galaxies but darker skies. I like my nebula filter but my wife likes seeing the dimmer stars in the view that the filter would block out.

#8 csrlice12

csrlice12

    Voyager 1

  • *****
  • Posts: 10806
  • Joined: 22 May 2012
  • Loc: Denver, CO

Posted 05 February 2013 - 04:20 PM

For planetary, theres also the UO Planetary Orthos. Hard to find now though. On these, the glass is coated to enhance the contrast, much like a filter would do. They're not much use for anything else though, but for planets, WOW.

#9 panhard

panhard

    It's All Good

  • *****
  • Moderators
  • Posts: 13661
  • Joined: 20 Jan 2008
  • Loc: Markham Ontario Canada

Posted 05 February 2013 - 05:08 PM

In fact, it's possible the question is so ridiculous, so amateurish, so unbelievably obvious that no one has thought it ever needed to be said.

We all where new at one time or another. Questions like you asked are not amateurish or ridiculous. You asked because you needed an answer.

#10 Madratter

Madratter

    Fly Me to the Moon

  • *****
  • Posts: 6340
  • Joined: 14 Jan 2013

Posted 05 February 2013 - 05:17 PM

For what it is worth, I have been doing this to some degree since the middle half of the 1960s, and I had to look just the other day at whether a new diagonal I purchased had filter threads or not.

Also, there are occasions I will use a Skyglow Filter without actually threading it into an eyepiece. I just move it in and out of the field of view. It helps spot difficult planetaries.

#11 Gert K A

Gert K A

    Mariner 2

  • -----
  • Posts: 291
  • Joined: 16 Jul 2012
  • Loc: Copenhagen, Denmark

Posted 05 February 2013 - 06:47 PM

I think the question is sound
and I too would like to know if for any filter, that filter would work to full effect anywhere in the optical train?

#12 Lancem

Lancem

    Vostok 1

  • -----
  • Posts: 152
  • Joined: 17 Mar 2011
  • Loc: Ontario, Canada

Posted 05 February 2013 - 09:28 PM

You might want to consider a Denkmeier Power Switch Diagonal. There are many fans of these diagonals on these forums. It is a high quality 2 inch diagonal which has an adapter allowing it to thread onto the back of your CPC. It has a 1.25 inch eyepiece adapter also. But the beauty of it is the power switch which allows a reducer or Barlow lens to be slid into the light path, giving three magnifications for every eyepiece. And it can be fitted with a filter slide which allows you to pre load two 2 inch filters. The convenience is amazing being able to view three different magnifications along with two different filters without your eye ever leaving the eyepiece. It has been my favorite equipment purchase for my scope.

#13 Chris2882

Chris2882

    Lift Off

  • -----
  • Posts: 8
  • Joined: 03 Jan 2013
  • Loc: McKinney, Texas

Posted 07 February 2013 - 02:07 PM

Thanks, guys, for the replies! Now I know!

#14 csrlice12

csrlice12

    Voyager 1

  • *****
  • Posts: 10806
  • Joined: 22 May 2012
  • Loc: Denver, CO

Posted 07 February 2013 - 02:59 PM

"In fact, it's possible the question is so ridiculous, so amateurish, so unbelievably obvious that no one has thought it ever needed to be said."

This sounds like it was taken right out of "The Hitchhiker's Guide to the Galaxy"...... :lol:

Which, oddly enough, was about this same thing.....






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics