Filters ?

[MarsG76]

Two filters is all you need... one is the Baader Neodymium filter for planets and the Lumicon or Astronomik UHC for nebulae..... The neodymium really helps on planetary detail where the UHC will show you an amazing amount of detail within nebulae.

 

Baader Solar film is safe when it fully and firmly covers the telescope objective.

 

[bomberbaz]

On 01/11/2018 at 21:02, MarsG76 said:

Two filters is all you need... one is the Baader Neodymium filter for planets and the Lumicon or Astronomik UHC for nebulae..... The neodymium really helps on planetary detail where the UHC will show you an amazing amount of detail within nebulae.

 

Baader Solar film is safe when it fully and firmly covers the telescope objective.

 

I wouldn't disagree that for the majority of viewing that the two you give above cover the majority of targets. 

However there are a few DSO's where a narrower banded filter will help teasing out more detail. Examples being Horsehead nebula using a HB filter and my best ever view of the crescent was through a O-III filter. 

For the OP, there is also eye pupil size. Due to there being less light getting through the filters, the differing filters perform better at a different pupil size. The link below is a great help and guide towards all filter usage and pupil size.  It also has information about using coloured filters. 

http://www.scopecity.com/how-to/select-telescope-filters.cfm?pn=How+to+select+telescope+filters

Regards colour filters, I have used on planets and the moon and found there really do help in teasing out more detail although I appreciate they are not for everyone.

[Stu]

I do find the neodymium helpful on Jupiter and Mars, less so on Saturn. It is handy on the moon too, and as a general LP filter to reduce the sky background brightness. I often leave mine on for most observing at home.

I think that both a UHC and OIII are useful, they can bring out different features in nebulae; the UHC is better for the fainter more extended parts, whilst the OIII helps boost contrast in the brighter central areas. The OIII is also fab on the Veil and NAN as mentioned previously. I've said elsewhere that I disagree with advice that they are only useable on scopes of 8" and above. With good dark adaptation and darker skies, they can be very useful in small scopes, even 70 or 80mm, but even more so on 100mm. A widefield 100mm scope with fit the whole of the Veil into the fov which is amazing to see.

[bomberbaz]

1 hour ago, Stu said:

I do find the neodymium helpful on Jupiter and Mars, less so on Saturn. It is handy on the moon too, and as a general LP filter to reduce the sky background brightness. I often leave mine on for most observing at home.

I think that both a UHC and OIII are useful, they can bring out different features in nebulae; the UHC is better for the fainter more extended parts, whilst the OIII helps boost contrast in the brighter central areas. The OIII is also fab on the Veil and NAN as mentioned previously. I've said elsewhere that I disagree with advice that they are only useable on scopes of 8" and above. With good dark adaptation and darker skies, they can be very useful in small scopes, even 70 or 80mm, but even more so on 100mm. A widefield 100mm scope with fit the whole of the Veil into the fov which is amazing to see.

I did point out they are generally more effective on scopes of 6", as I am a mak and dob owner I do still think thats a fair statement due to the amount of aperture loss from econdary mirrors etc.   If you are using a refractor however, I would guess you can go much lower in diameter.

EDIT: Just read on another forum of someone using a O3 on a 60mm frac to geat success on the veil but he did stress under dark skies wow ?

[Stu]

Just now, bomberbaz said:

I did point out they are generally more effective on scopes of 6", as I am a mak and dob owner I do still think thats a fair statement. If you are using a refractor however, I would guess you can go much lower in diameter.

EDIT: Just read on another forum of someone using a O3 on a 60mm frac to geat success on the veil but he did stress under dark skies wow ?

Yep, I've used in a 60mm with success, but as you say, dark skies are important plus good dark adaptation. It is also important to keep the exit pupil large in order to keep the brightness level up.

Maks tend to give a smaller exit pupil because of the long focal ratio, so a 4" mak will give a darker, less useable image than a 4" frac. It is the exit pupil difference rather than the secondary obstruction. That, and the fact that it is easier to use 2" eyepieces in fracs so easier to get wider fields along with the brighter image.

For instance, a 100mm f7 frac with a 24mm eyepiece gives a 3.4mm exit pupil, whereas a 102mm f12.7 mak gives 1.9mm, an appreciable difference particularly when using narrowband filters. Mak users often use longer focal length 1.25" Plossls in these cases, not for a wider field of view (they don't give this!) but for the larger exit pupil. A 40mm Plossl would give you 3.1mm in the Mak which is better, but the frac would give 5.7mm so will always give a better result with narrowband filters than the Mak.

[MarsG76]

6 hours ago, bomberbaz said:

I wouldn't disagree that for the majority of viewing that the two you give above cover the majority of targets. 

However there are a few DSO's where a narrower banded filter will help teasing out more detail. Examples being Horsehead nebula using a HB filter and my best ever view of the crescent was through a O-III filter. 

For the OP, there is also eye pupil size. Due to there being less light getting through the filters, the differing filters perform better at a different pupil size. The link below is a great help and guide towards all filter usage and pupil size.  It also has information about using coloured filters. 

http://www.scopecity.com/how-to/select-telescope-filters.cfm?pn=How+to+select+telescope+filters

Regards colour filters, I have used on planets and the moon and found there really do help in teasing out more detail although I appreciate they are not for everyone.

I agree, I was talking about two filters as a starting point to the collection which will be useful and used frequently.

Filters like the H-beta is only really useful on a handful of objects so wouldn't be used as often as a UHC filter... and is not cheap... The OIII would be the next most used filter after UHC so could be added to the arsenal....

As far as the Neodymium filter is concerned, I think it'll be used every time there is a planet in the sky.

 

[fozzybear]

A question for Stu with an OIII filter I see that there are various models avail a bit of a dumb question but what is the difference between say a 25nm and a 12nm and not all manufactures state theirs  is it that one is for imaging and the other for AP with a lower number for light transmissiom? just that the price can start at say 55-00 euros for a TS one and costing say 150 for another brand. your help greatly appreciated

regards

Andy

[fozzybear]

Stu care to comment or anyone else on Oiii filters?

[Stu]

2 hours ago, fozzybear said:

Stu care to comment or anyone else on Oiii filters?

Sorry fozzy, didn't see this post.

I don't actually know what the spec of the Lumicon OIII is, but the waveforms are shown on this site which you may have seen before.

http://www.astrosurf.com/buil/filters/curves.htm#Protocol

As you can see, some filters described as OIII also include the Ha and SII lines which I assume lowers a contrast a little. The Lumicon has a tight bandpass around the two OIII lines for OIII and including the Hb for the UHC, the cutoff is almost vertical and the transmission percentage for the wanted frequencies is near 100%. 

I do enjoy the Lumicon, and definitely feel it offers better contrast and visibility than the Skywatcher and the ES ones I've also tried, most likely as a result of the properties above. I'm sure you could work out the bandwidth from the graphs,  but I'm not sure how to accurately.

[westmarch]

On 01/11/2018 at 06:49, Stu said:

How about a pirate patch? Aarrrggggghhh, me hearties!

 

That’s a serious suggestion!  I have a moulded eyepatch that fits my specs. I keep the viewing eye occluded, taking my specs off under a viewing hood (towel), since I don’t need them for the eyepiece. 

I replace the specs and use the  unoccluded eye for star maps, sketching, etc. 

Here’s an example:

https://www.amazon.co.uk/gp/aw/d/B00ZO9LHWW/ref=sspa_mw_detail_0?ie=UTF8&psc=1

John

 

 

 

 

 

[Stu]

23 minutes ago, westmarch said:

That’s a serious suggestion!  I have a moulded eyepatch that fits my specs. I keep the viewing eye occluded, taking my specs off under a viewing hood (towel), since I don’t need them for the eyepiece. 

I replace the specs and use the  unoccluded eye for star maps, sketching, etc. 

Here’s an example:

https://www.amazon.co.uk/gp/aw/d/B00ZO9LHWW/ref=sspa_mw_detail_0?ie=UTF8&psc=1

John

 

 

 

 

 

It was indeed! I do have a patch, but more often just pull a hat over my observing eye.

[fozzybear]

21 hours ago, Stu said:

Sorry fozzy, didn't see this post.

I don't actually know what the spec of the Lumicon OIII is, but the waveforms are shown on this site which you may have seen before.

http://www.astrosurf.com/buil/filters/curves.htm#Protocol

As you can see, some filters described as OIII also include the Ha and SII lines which I assume lowers a contrast a little. The Lumicon has a tight bandpass around the two OIII lines for OIII and including the Hb for the UHC, the cutoff is almost vertical and the transmission percentage for the wanted frequencies is near 100%. 

I do enjoy the Lumicon, and definitely feel it offers better contrast and visibility than the Skywatcher and the ES ones I've also tried, most likely as a result of the properties above. I'm sure you could work out the bandwidth from the graphs,  but I'm not sure how to accurately.

Stu, Thanks for the info so maybe you get what you pay for the reason for my question I see a few various brands offered for sale small price going skywards....