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Advice needed pixels used in narrow band dslr ?


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Hi all,ok I've been reading up on taking narrow band with dslr if I'm right in reading it correct it seems that I'm only using 1 of 4 pixels when using narrow band clip filters ha = 1 in 4 sII 1 in 4 oIII 2 in 4.my first thoughts is would monochrome setting or b/w be any better for clipfilters as it seems like they use 2 in 4 pixels I think. has any one tried it or dose this simply dosent work.any advice would be good I'm thinking of selling my 450d and the 3 filters and making the move to a ccd cam my bugget would be approx 1600 quid if I made the move over to ccd cam.so what's a good cam for that amount of cash.i can't get rid of noise once it starts to be stretched out a single tiff file is ok looks good a small amount of stretching is ok but it's still to dark once object becomes inveiw it becomes very noisy sII seems to be the worse oIII is the better of them as it seems it let's the blue in with it so 2 in 4 pixels I suppose is the reason any advice would be great I don't want to go over to ccd just it's another outlay witch I would like to spend out on a better scope.im using dss to stack and ps to do the rest.nothing is ever easy this seems to be a very frustrating hobby !

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Blimey - Capital letters and some paragraphs would be great!! :Envy::grin:

My thoughts are to go for a CCD - Compared to a DSLR they are like night and day. The DSLR had it's place, but the cooled CCD's with their low noise, cooling and diversity win it hands down for me. Depending on your scope a nice Atik 314L+ mono and a set of filters will come in on budget.

Someone asked a couple of days ago about turning on mono on the DSLR for imaging with filters and I knew that it didn't work, but didn't know why. I still can't tell you the answer, but it's a no goer. Ha with the DSLR is doable and I quite enjoyed it at the time, but is is noisy and lacking in detail as only 1 in 4 pixels picks up any data.

CCD is an outlay, but in my opinion, one that is well worth it.

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swag72 has it right.

It's likely that only the red pixels are getting any light.

So first off split your Ha, SII, OIII images into R, G and B in your photo package and look to see what info you are getting.

Then recombine with the best Ha, SII, OIII components.

Mono mode doesn't improve because the green and blue components have little or no signal to add to the mono sum.

A mono chip will have all its pixels illuminated so will be a) more sensitve and B) higher resolution.

Cheers

Michael

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I'm looking at the atik 383L bundle.filter wheel and Lrgb filters ? The reveiw rates this as a good cam.if anyone using this cam please let me know how they find the performance of it

Edited by Hungovergraham
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I'm looking at the atik 383L bundle.filter wheel and Lrgb filters ? The reveiw rates this as a good cam.if anyone using this cam please let me know how they find the performance of it

I use an Atik 314L+, but there are plenty of people who use the 383L that really rate it. It is a noiser chip than the 314L+ and everyone says that, but easily sorted with darks. No reason at all not to get this camera. It's a good solid performer.

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314L is good but it's abit old now there's new Modles out now that will out perform the 314 at the same cost.spoken to Bernard at modern astronomy I'm now looking at Qhy 9 or sxv-h9 starlight exspress I think the sxv will be the one il go for been told it a very good cam quite a good wide veiw low noise Cooling is good as well

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I have had the H9 in the past, with SX filter wheel - great performer! Search through the DSO section, plenty of people use one. The latest model also has set point cooling. The H9 works very well with 1.25" filters as well.

I now have the 383 still with SX filter wheel. Much bigger chip of course, and a great FoV but you will need bigger filters to avoid vignetting. I switched to 36mm unmounted ones and they are perfect.

What scope are you using / planning on ?

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I used to use a Canon 1000D and now have an older SXV-H9 with Baader filters in a Brightstar wheel. The CCD blows the DSLR out of the water in terms of sensitivity, colour depth and low noise.

I thought the H9 used the same chip as the 314L+ though?

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  • 4 weeks later...

I'm currently using a DSLR (1100D) modded and cooled and Ha and OIII filters work quite well. I think the pixel size is about 5 microns square. This compares with 6.45 on the Atik 314L Plus. BUT... for NB use with the DSLR, only one of four pixels is used for Ha and 2 of 4 for OIII, resulting in 1/4 sensitivity in Ha (though filter mod helps) and 1/2 in OIII (filter mod makes no difference). So the mono Atik is going to be 4 times as sensitive in Ha and 2x in OIII, plus a bit extra due to the larger pixels. The resolution of a colour sensor is really only a quarter of a mono sensor in terms of area. So a DSLR sensor of 4000x3000 pixels (approx) will only be effectively 1000x750 for NB. That is one reason Ha images seem lower res than colour. The other is that the eyes are poorer in red than green or blue.

So while a DSLR provides a lovely big sensor and with cooling and filter mod, a nice colour imager, it's somewhat lacking for NB.

I think I'm convincing myself that when I can build up sufficient funds, a grand or so may be better spent on a 314L+ rather than a 190MN Astrograph.

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