advise on filters

[bytor666]

Originally Posted by jeelan

thanks for all the info on this gents,

I've just ordered the 2" NPB and OIII filters from Dan Mcshane at DGM

cheers
Jeelan

One word of caution: The DGM O-III isn`t as good as the DGM NPB. The DGM O-III is supposed to be rated at around 12 nanometers or so like other good O-III filters, but it falls short in performance, don`t know why, but it does. I think the bandpass is wider than a good O-III IIRC.

I compared two different DGM O-III filters to two diff Orion Ultrablock filters and the performance was the same on many targets that are supposed to have O-III and UHC-type filters used for optimal performance. The DGM O-III wasn't horrible, but it wasn't the greatest for an O-III either. The DGM NPB is excellent.

[inertia8 (Australia)]

I've received my 2 ngp filters from DGM. Now to wait for a clear night!

[jeelan (Jeelan)]

Originally Posted by bytor666

One word of caution: The DGM O-III isn`t as good as the DGM NPB. The DGM O-III is supposed to be rated at around 12 nanometers or so like other good O-III filters, but it falls short in performance, don`t know why, but it does. I think the bandpass is wider than a good O-III IIRC.

I compared two different DGM O-III filters to two diff Orion Ultrablock filters and the performance was the same on many targets that are supposed to have O-III and UHC-type filters used for optimal performance. The DGM O-III wasn't horrible, but it wasn't the greatest for an O-III either. The DGM NPB is excellent.

Thanks for that feedback. Unfortunately, the filters have already been mailed so i'm committed to both.

At this stage, I have no idea personally how filters are MEANT to look (never having looked through one before) so my decision has been based soley on feedback from forums like this one.

cheers
Jeelan

[bytor666]

Originally Posted by jeelan

Thanks for that feedback. Unfortunately, the filters have already been mailed so i'm committed to both.

At this stage, I have no idea personally how filters are MEANT to look (never having looked through one before) so my decision has been based soley on feedback from forums like this one.

cheers
Jeelan

I understand mate.

Cheers to you and hope for clear skies for your initial observing with your new filters!

[gaa_ian (Ian)]

Interesting to follow this thread & just to let you know there is another option with the Kson UHC and OIII filters which I import and distribute. Bandpass graphs are on the page. These have been popular with many fellow IIS members as they are effective and I believe well priced :-)

[jeelan (Jeelan)]

hey all,

I got my filters yesterday from DGM.

Now waiting for a clear night to use them.

ON the same note, what's the best way to look after these and clean them if i get finger marks, dust etc?

anyone got a preferred "solution" they use to clean/wipe astronomy filters?

cheers
Jeelan

[ausastronomer (John Bambury)]

Originally Posted by jeelan

hey all,

I got my filters yesterday from DGM.

Now waiting for a clear night to use them.

ON the same note, what's the best way to look after these and clean them if i get finger marks, dust etc?

anyone got a preferred "solution" they use to clean/wipe astronomy filters?

cheers
Jeelan

Hi Jeelan,

The DGM Filters are made by Omega Optical in the USA. They are Surface Coated filters and whilst the coatings are pretty durable you do need to exercise some care in handling them.

Omega Optical have an information page on their website which explains about their filters and how to clean them. They recommend their own cleaning kit and isopropyl alcohol. I don't know that you need their cleaning kit if you have an air blower bulb and some soft lint free cloth. I clean all my optics from rifle scopes to binoculars to camera lenses and eyepieces with an air blower bulb, soft lint free cloth and isopropyl alcohol. Basically blow all the loose dust away, wipe gently with an alcohol soaked patch and then wipe again with a dry patch in a sweeping lifting motion and the optic will dry streak free.

If you go to the wrong place isopropyl alcohol isn't cheap. If you go to the right place it's cheap as chips. I paid about $18 plus $10 shipping for a 5 litre container of it from Sydney Solvents about 2 years ago.
I had previously sourced a 5 litre container of it gratus 20 years ago from a friend who owned a chemical distribution company but he retired. I did get about 18 years out of 5 litres of it.

Cheers,
John B

[jeelan (Jeelan)]

Thanks for that John, appreciate it.

cheers
jeelan