How do you use filters in a practical way during observation?

[Linda]

With my scope, there followed a moon filter. I am also considering buying a UHC filter for observing nebulas. But I am very much in doubt how much I am going to use it in practice. With the moon filter, I noticed that it should be screwed into the back of an eyepiece. And when switching the eyepiece, you need to put the filter in the new eyepiece.

So how do you, more experienced filter users do this? Do you first check what your favorite eyepiece is for the evening and then put the filter in that, so that you use that eyepiece when you see a nebula? And do you then only observe nebula's?

Or do you use a filter wheel so that it is easy to switch from with/without filter with any eyepiece?

I usually tend to observe several different objects during an observing session.

[Stu]

If you use a diagonal in either a frac or a mak, you can put the filter in the front barrel of the diagonal so you don't have to keep changing things around. In a newt, it's not so straightforward but if you use an extension tube of any sort then you can put it in that and achieve the same result.

A filter switch is a nice option, provided you have enough inwards focus available to put it in the light path.

[Moonshane]

I use 2" filters and more often than not 1.25" eyepieces. I adopt this method mainly.

I do tend to try and observe fainter stuff first and move to brighter stuff at the end of the session but in truth I do what my mood dictates. At the minutes it's mainly Jupiter and Moon. Soon will be Mars and Saturn.

 

 

[LukeSkywatcher]

As Stu said.....if your scope uses a star diagonal you can attach the filter to this and then just change the eyepiece as and when you want without moving the filter.

[Linda]

17 minutes ago, Stu said:

If you use a diagonal in either a frac or a mak, you can put the filter in the front barrel of the diagonal so you don't have to keep changing things around. In a newt, it's not so straightforward but if you use and extension tube of any sort then you can put it in that and achieve the same result.

A filter switch is a nice option, provided you have enough inwards focus available to put it in the light path.

Yes, I use a diagonal. Good idea to put the filter in that.

I don't know whether the C8 has enough inwards focus for a filter switch.

[LukeSkywatcher]

The C8 and 8SE are almost the same beast and i have no trouble with focus when using a filter in the diagonal.

[Mak the Night]

I find that an exit pupil of at least 3mm is preferable using the more aggressive filters, particularly ultra high contrast types. And I think a minimum of 2mm even for some Wratten filters, especially something like a No. 25 Red which only transmits 14% of the available light. Most ND filters only transmit 13%, although they vary. The exception would be a Baader Neodymium which I've used at high magnifications. I tend to place the filter into the diagonal, but due to different OEM thread sizes sometimes I place the filter between the eyepiece and the diagonal threaded into a Celestron T-Adaptor which seems to accept all threads.

[todd8137]

Hi ,I use my filters all the time  I do not mind taking it of one ep on to another but i have a reflector you could plan you night around your filters and remember some filters will kill the views in little scopes but shine in big ones keep that in mind 

pat

[LukeSkywatcher]

I should have mentioned that i use a 8-24mm zoom EP,so swapping out filters is a thing of the past for me. Swapping over EP's is also now a thing of the past......2 birds......1 stone kind of situation.

[Stu]

13 minutes ago, Linda said:

Yes, I use a diagonal. Good idea to put the filter in that.

I don't know whether the C8 has enough inwards focus for a filter switch.

SCTs are generally fine and have plenty of focus range because the focus by moving the primary mirror. Refractors are a different story and can be more challenging.

[Linda]

I will test it with my moon filter in the diagonal first and see if it works. Otherwise I will add a filter switch to my long astro wishlist.

Buy the way, I use only 1,25 inch eyepieces.

[g30rg313]

Wow .... put the filter in the diagonal..... I never even thought of that! Good to know Stu. .....that will save me some fiddling around in the dark

[laudropb]

I just change them over from ep to ep. I don't find this much of a bother and it is certainly worth it for the improved chances of detecting nebula.

[Dave In Vermont]

If I am intending on observing the Moon, I will be using my 2-piece polarizing-filter. These work by turning one part of the filter around while the second half remains still. This varies the dimming (polarizing) from 3% to 40% on this set. If you do a lot of Moon-watching, one half of the polarizing-filter can be screwed into the nose of the diagonal, and the other half into your eyepiece. To adjust the dimming, you simply turn the eyepiece around in the focuser.

Have fun up there,

Dave

[rockystar]

1 hour ago, Dave In Vermont said:

If I am intending on observing the Moon, I will be using my 2-piece polarizing-filter. These work by turning one part of the filter around while the second half remains still. This varies the dimming (polarizing) from 3% to 40% on this set. If you do a lot of Moon-watching, one half of the polarizing-filter can be screwed into the nose of the diagonal, and the other half into your eyepiece. To adjust the dimming, you simply turn the eyepiece around in the focuser.

Have fun up there,

Dave

I had a feeling you could do something like this, rather than just screwing the two pieces together. However, I have a 2" focuser and use a 2" extension tube (which is threaded), but then use 1.25" eyepieces in an adaptor (or straight in the extension as I have eyepieces that have a 2" housing); so can I still do this, or would I also need a 2" variable filter, and put one half of the 2" in the extension and the other half of the 1.25" in the eyepiece?

Or do I just need to wait until I have fully committed to the purchase of a refractor

[LukeSkywatcher]

1 hour ago, Dave In Vermont said:

If I am intending on observing the Moon, I will be using my 2-piece polarizing-filter. These work by turning one part of the filter around while the second half remains still. This varies the dimming (polarizing) from 3% to 40% on this set. If you do a lot of Moon-watching, one half of the polarizing-filter can be screwed into the nose of the diagonal, and the other half into your eyepiece. To adjust the dimming, you simply turn the eyepiece around in the focuser.

Have fun up there,

Dave

Thanks Dave. You have just sparked my memory as to how i originally used my variable polarising filter when observing the Sun. Last week during the transit i had both parts together as one unit and the whole thing vanished into the EP tube so i basically could not turn it. Now i remember how i used it last time i did.

One part down the end of tube along with SC filter etc and the other part attached to EP.........this allowed me to turn the EP and dim/brighten the view.

I knew i was doing something wrong last week. I just couldnt figure it out.

[Piero]

I generally attach the filter on the eyepiece barrel but this because I don't change magnification. If I want to, then I attach it to the diagonal instead.

Personally, I would go for a very good OIII filter first, and (maybe) an UHC later. To me, the former works better with most of planetary nebulae. As far as extended nebulae concerns, these filters are both equally useable, although to me an OIII maximises image contrast and sharpness a bit better, while an UHC shows more extension. They both complement each other I would say, but if I had to buy only one of them, I would go for a Lumicon or Astronomik OIII. A 2" is expensive, but it's also a keeper.

p.s. I come from the route: UHC first, OIII second. 

[LukeSkywatcher]

5 minutes ago, Piero said:

I generally attach the filter on the eyepiece barrel but this because I don't change magnification. If I want to, then I attach it to the diagonal instead.

Personally, I would go for a very good OIII filter first, and (maybe) an UHC later. To me, the former works better with most of planetary nebulae. As far as extended nebulae concerns, these filters are both equally useable, although to me an OIII maximises image contrast and sharpness a bit better, while an UHC shows more extension. They both complement each other I would say, but if I had to buy only one of them, I would go for a Lumicon or Astronomik OIII. A 2" is expensive, but it's also a keeper.

p.s. I come from the route: UHC first, OIII second. 

Most people would say buy a UHC filter first and then an OIII. The reason simply being there are more targets to be enhanced with a UHC then there are targets to be seen with an OIII. I couldnt decide and i wanted to see as much as possible being a nebulae kind of guy,so i bought one of each at the same time. Mine are the Skywatcher 1.25" filters and they work great for me. Pretty cheap too at about 30-40 quid each.

[Linda]

3 hours ago, LukeSkywatcher said:

Most people would say buy a UHC filter first and then an OIII. The reason simply being there are more targets to be enhanced with a UHC then there are targets to be seen with an OIII.

This is what I had intended, for the same reason. I'm thinking about the Lumicon, as I appreciate buying quality.

[Piero]

4 hours ago, LukeSkywatcher said:

Most people would say buy a UHC filter first and then an OIII. The reason simply being there are more targets to be enhanced with a UHC then there are targets to be seen with an OIII. I couldnt decide and i wanted to see as much as possible being a nebulae kind of guy,so i bought one of each at the same time. Mine are the Skywatcher 1.25" filters and they work great for me. Pretty cheap too at about 30-40 quid each.

Hi Paul, 

Sure, my comment was just my opinion while other people might feel a UHC delivers a better view.   Linda is of course free to get them in the order she prefers. I agree that a UHC can be somehow more versatile (it filters less!), but in practical terms, apart from M27 maybe, I struggle to think of a planetary nebula which jumps up more with a UHC than an OIII filter, and I am limited here with a 60mm. I would reckon that a larger aperture can show more intricate details for these targets when an OIII filter is used rather than a UHC. There are also planetary nebulae which are (almost) invisible with a UHC, while they become visible with an OIII filter. The other way never happens as far as I know at least. Regarding extended nebulae, it is really a matter of what a user prefers to me. UHC filters can show more extension because they filter less, OIII can increase contrast because they filter more. I do prefer the view of M42 with a UHC and I haven't ever changed my mind on this, although this doesn't mean that M42 viewed with an OIII filter does not look pretty!  With an exit pupil of about 4mm, the North America, the Rosette and the Veil can show up very nicely with an OIII filter, to me a bit better than a UHC.

Said this, floating through Cygnus down to Sagittarius with a UHC under dark sky can be an exquisite experience!  

 .. not sure this comment helped the OP.. sorry Linda!    

[John]

For quite a few years a 2" Astronomik O-III filter served as my only deep sky filter and worked really well in my scopes from 4" to 12" in aperture.

It's band pass width is a little more generous than most O-III filters which I guess is why it worked well even with smaller apertures and it seemed pretty effective with a reasonably wide range of target objects.

Now I'm using a Lumicon 2" O-III and an Omega DGM NBP (UHC type) filter. Both seem very effective but complement each other, rather than compete. I do find that objects such as the Veil and the Owl nebulae are quite noticably more enhanced by O-III filtration than by UHC but both produce very noticable improvements over the unfiltered views.

[LukeSkywatcher]

1 hour ago, Piero said:

Hi Paul, 

Sure, my comment was just my opinion while other people might feel a UHC delivers a better view.   Linda is of course free to get them in the order she prefers. I agree that a UHC can be somehow more versatile (it filters less!), but in practical terms, apart from M27 maybe, I struggle to think of a planetary nebula which jumps up more with a UHC than an OIII filter, and I am limited here with a 60mm. I would reckon that a larger aperture can show more intricate details for these targets when an OIII filter is used rather than a UHC. There are also planetary nebulae which are (almost) invisible with a UHC, while they become visible with an OIII filter. The other way never happens as far as I know at least. Regarding extended nebulae, it is really a matter of what a user prefers to me. UHC filters can show more extension because they filter less, OIII can increase contrast because they filter more. I do prefer the view of M42 with a UHC and I haven't ever changed my mind on this, although this doesn't mean that M42 viewed with an OIII filter does not look pretty!  With an exit pupil of about 4mm, the North America, the Rosette and the Veil can show up very nicely with an OIII filter, to me a bit better than a UHC.

Said this, floating through Cygnus down to Sagittarius with a UHC under dark sky can be an exquisite experience!  

 .. not sure this comment helped the OP.. sorry Linda!    

Both a UHC and an OIII do very different jobs on different nebs. I am NOT disputing that. 

"I struggle to think of a planetary nebula which jumps up more with a UHC than an OIII"

One filter shows up one type of nebula (planetary) and the other filter shows up the other (emission).

Planetary nebs show up with OIII.........Emission nebs show up/enhanced with UHC (hope i have that right).

Ive only seen the Rosette,Veil etc with my OIII.....

[Linda]

There is a website by an American local astronomy club that has tested the 3 filters, UHC, OIII en LP. They measured how many first an second places they all got on many DSOs. UHC scored slightly higher on the number of first and second places on nebula. The OIII was a clear second and scored better on a number of objects. The LP filter was not quite so usefull as the other two. Therefore I choose the UHC as a first filter. My scopes are now 5" and 8" and I am still curious how the C8 will perform, even without filter. It won't be dark until the end of August here in the north though...

The filter might be a nice Christmas present,

[Mak the Night]

You may find this PDF useful.

Lumicon Filters1.pdf

[John]

4 hours ago, Linda said:

There is a website by an American local astronomy club that has tested the 3 filters, UHC, OIII en LP. They measured how many first an second places they all got on many DSOs. UHC scored slightly higher on the number of first and second places on nebula. The OIII was a clear second and scored better on a number of objects. The LP filter was not quite so usefull as the other two....

I think you might be referring to this report ?:

http://www.prairieastronomyclub.org/resources/by-dave-knisely/filter-performance-comparisons-for-some-common-nebulae/