best filter for nebula in the city

[skydivephil]

I have a Celestron 8 inch next star evolution. I live in a big city, I can photo some nebula like orion and the dumbbell, but would like to push things further. Any recommendations for a filter . Im told OIII is the best but hear that it depends on the telescope and am looking for guidance. 

 

[pipnina]

Is this for observing or photographing?

If you are observing:

An OIII filter can improve views on many targets, but in a city with a lot of light pollution I don't think it will have as big an impact as you hope. If the light where you are is very orange, then perhaps. If it's the white LEDs or orange-ish, forget it unless you intend to go somewhere dark to use it. Filters are a useful tool, but they aren't magical unfortunately

I don't know much about the same filters for imaging, but the imaging filters tend to have narrower band passes and are better at isolating the colour you're after. The "good" ones are not cheap, however. 

 

Clear skies

    ~pip

[Knighty2112]

Apparently these filters also get quoted a lot as been very good for both visual & camera astronomy. Don't have one myself, but check them out a little. 

http://www.rothervalleyoptics.co.uk/baader-neodymium-ir-cut-filters.html

[skydivephil]

2 hours ago, pipnina said:

Is this for observing or photographing?

If you are observing:

An OIII filter can improve views on many targets, but in a city with a lot of light pollution I don't think it will have as big an impact as you hope. If the light where you are is very orange, then perhaps. If it's the white LEDs or orange-ish, forget it unless you intend to go somewhere dark to use it. Filters are a useful tool, but they aren't magical unfortunately

I don't know much about the same filters for imaging, but the imaging filters tend to have narrower band passes and are better at isolating the colour you're after. The "good" ones are not cheap, however. 

 

Clear skies

    ~pip

 

This is definitely for imaging purposes, thanks 

 

[skydivephil]

1 hour ago, Knighty2112 said:

Apparently these filters also get quoted a lot as been very good for both visual & camera astronomy. Don't have one myself, but check them out a little. 

http://www.rothervalleyoptics.co.uk/baader-neodymium-ir-cut-filters.html

I think those are more for reducing light pollution rather than speficially for nebula imaging. but thanks for the reply 

[pipnina]

 

12 hours ago, skydivephil said:

 

This is definitely for imaging purposes, thanks 

 

What camera are you using? Narrow-band filters for imaging almost require you to have either a de-bayered DSLR body or a monochrome CCD. Using narrow-band filters for colour cameras just wastes light.

If you have a monochrome camera, be it through de-bayering or purpose-buying, you will end up finding imaging filters with their band width noted. Something like "OIII, 7nm". The smaller the number, the less light the filter lets in from either side of the colour. For light polluted skies, narrower passes are probably preferred although they are also more expensive. IMO, if you get a filter for astro imaging, get a hydrogen alpha. Almost every patch of sky has something Ha in it, even if it's extremely dim.

There are better people to talk about this than me, but that should be a fair piece of advice I think.

Hope this helps

    ~pip

[russellhq]

For "big city" skies, you'll get best mileage from narrowband filters. The most commonly used are: HA, OIII, SII from which you can create a false colour image. A popular brand at reasonable cost seems to be Baader. The more expensive, and generally considered best are Astrodon but these come at a cost: the 50mm 3nm Ha filter is just shy of £1000, whereas the Baader 7nm 2" filter is a "more reasonable" £200.

[Adam J]

I am going to assume that you have a DSLR. Also that you are a relative beginner.

I am in the suburbs and use a Astronomic CLS filter, its very good, however, light pollution is still an issue for me in a yellow zone when doing longer exposures. If I was in the city proper (as you imply) I would go for a 2" inch Baader UHC  as a first choice and a Astronomic UHC-S clip filter as a second choice, for nebula.

I really really dont recommend narrow band if you are starting out. Too hard to focus and requires long guided exposures.

I have just started to play with it, but its clearly nothing like worthless for a standard DSLR at all, infact I am finding the complete opposite is true. It will cut through light pollution just the same with your DSLR as it will with a Mono CCD. Although I would always modify a DSLR as a priority prior to getting into narrow band and guiding is essential.

Problem is that a Nextstar Evolution is not a great choice for imaging nebula with the possible exception of planetary nebula. Really you need a much shorted focal lenght to frame them properly.

 

[skydivephil]

On 7 September 2016 at 21:10, Adam J said:

I am going to assume that you have a DSLR. Also that you are a relative beginner.

I am in the suburbs and use a Astronomic CLS filter, its very good, however, light pollution is still an issue for me in a yellow zone when doing longer exposures. If I was in the city proper (as you imply) I would go for a 2" inch Baader UHC  as a first choice and a Astronomic UHC-S clip filter as a second choice, for nebula.

I really really dont recommend narrow band if you are starting out. Too hard to focus and requires long guided exposures.

I have just started to play with it, but its clearly nothing like worthless for a standard DSLR at all, infact I am finding the complete opposite is true. It will cut through light pollution just the same with your DSLR as it will with a Mono CCD. Although I would always modify a DSLR as a priority prior to getting into narrow band and guiding is essential.

Problem is that a Nextstar Evolution is not a great choice for imaging nebula with the possible exception of planetary nebula. Really you need a much shorted focal lenght to frame them properly.

 

Thanks for all your help and advice, to answer questions, the cameras I have is th Sony a7s which is sort of a DSLR ( actually its mirrorless) but has an impressive feature which is the pixels are huge ( 8 microns , I thinks thats twice the size of the canon 5d mark III) I also have a ZWO AS!120 but I want use that for planetary imaging  or guiding. I have tried the CLS filter, its pretty impressive . I also have got a focal reducer to take the f stop down to f6. 

[Adam J]

34 minutes ago, skydivephil said:

Thanks for all your help and advice, to answer questions, the cameras I have is th Sony a7s which is sort of a DSLR ( actually its mirrorless) but has an impressive feature which is the pixels are huge ( 8 microns , I thinks thats twice the size of the canon 5d mark III) I also have a ZWO AS!120 but I want use that for planetary imaging  or guiding. I have tried the CLS filter, its pretty impressive . I also have got a focal reducer to take the f stop down to f6. 

The a7s is a different kettle of fish to be honest. Its got very high low noise gain and so you will not have issues with focusing narrow band filters with it. If you want a one shot color image I would still go with the UHC as a single filter solution to nebula in heavy light pollution, though. Only thing to remember is that while the CLS lets you image galaxies too the UHC wont, it really is just for nebula. 

[skydivephil]

33 minutes ago, Adam J said:

The a7s is a different kettle of fish to be honest. Its got very high low noise gain and so you will not have issues with focusing narrow band filters with it. If you want a one shot color image I would still go with the UHC as a single filter solution to nebula in heavy light pollution, though. Only thing to remember is that while the CLS lets you image galaxies too the UHC wont, it really is just for nebula. 

So if I switched from CLS to UHC Ill lose galaxies but do I get better nebula or is not much better for nebula than the CLS?

[Adam J]

7 minutes ago, skydivephil said:

So if I switched from CLS to UHC Ill lose galaxies but do I get better nebula or is not much better for nebula than the CLS?

UHC normally covers the H-beta, both OIII, H-alpha and SII. Its much narrower than a CLS filter so you will get better contrast with it for nebula. However the same thing that gives you good contrast with a nebula is bad for a broadband source like a galaxy. Astronomic make a UHC with a IR/UV cut thats suitable for use in a modified DSLR. However, you can use the visual one if you have another UV/IR cut still in the camera.

 

[skydivephil]

1 hour ago, Adam J said:

UHC normally covers the H-beta, both OIII, H-alpha and SII. Its much narrower than a CLS filter so you will get better contrast with it for nebula. However the same thing that gives you good contrast with a nebula is bad for a broadband source like a galaxy. Astronomic make a UHC with a IR/UV cut thats suitable for use in a modified DSLR. However, you can use the visual one if you have another UV/IR cut still in the camera.

 

Thanks