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[astrokat]

not sure where to post this though i know you all being imagers will give me the best anwser so for christmas i asked for money and santa come though very good indeed lol so i want to get some filters as the meade one are sh t ive been looking at just a rbg set though i like the narrowband though there are a fue more options with picking nb and not sure what ones i would need to get to start me off if anyone could help that would be most helpfull

hope all had a good xmas and wishing all a good new year

thanks toby

[moocher]

Depending on funds i`d say the Baader filters offer very good value!!!!

Alan:)

[astrokat]

thats what i was looking at bud though there is diffrent types of ha eg 35 and 7mm any idea what the diffrence is

[moocher]

Ok the higher the number the higher the "bandpass" ie there not as narrow. I`ve got the 7nm Ha filter and you can image in full moon conditions. I think you`d struggle with the 35nm. On the downside you`ll need longer exposures with the 7 but you`ll get better contrast. They ARE parfocal too!!! HTH

Alan:)

[astrokat]

ahhh that helps thanks what expo times we looking at for half decent images

thanks toby

[astrokat]

so i will need ha 0III and sII though whats h beta sorry about this thanks for your help

[moocher]

10 mins. TBH the longer the better with NB filters...

Alan:)

[moocher]

O3 Ha and S2 are used in HST images (hubble palette) H beta is only used when doing a narrow band RGB image.

Alan:)

[ollypenrice]

H beta is in the blue part of the spectrum and is, obviously, emitted by Hydrogen. I like it and got an interesting result on the Bubble nebula using HaO111Hb.

But you can do three colour narrowband with only 2 filters, Ha and O111. There are various ways.

1) Just put Ha in the red and O111 in green and O111 again in blue.

2)Red and green as above, and in the blue channel a 50-50 blend of Ha and O111. This is STUNNING on the Helix nebula. Also good on the Crescent.

3)Buy Noel's Actions for Ps and use his synthetic third channel.

The Hubble is not always the most appealing narrowband combination. Sometimes it can be seriously yucky...

I like the Baader 7Nm Ha. It is a bit slow but rarely produces haloes. It's what I would recommend., personally. I have a replacement Astronomik 13nm coming but the original was one of a bad batch. Their O111 also throws up haloes in my case.

Exposure times. 10 mins minimum, 15mins is usually better if guiding allows.

Another NB plus is that you don't need a premium telescope. My 20 year old Genesis is hard to tell from an FSQ106 when shooting narrowband. I wish I could say that for RGB!

Olly