CCD viable under UK skies?

[jnc71106]

I work that way with my MN190: I focus on green and then can't find any better focus position for red and blue filters. However it seems not to be so with the same (parfocal) filters on my refractor and on a SCT ....... which I suppose are just not perfectly apochromatic: I can always improve focus a little between filters. The MN190 is very good in this respect.

Adrian

yep thats how i do it now after going home so many times with just L subs and then having to wait weeks before another chance to get out i found this to be the best solution under UK skies

[Gina]

+1 for Artemis Capture So easy and a real joy to use. There's good software for DSLRs but the cameras themselves are so complicated compared with mono CCDs that they're bound to be more complicated. That's what I've found anyway. More complicated but less controllable, in fact.

I'm sorry if I seem to be letting DSLR oficionados down but I tell it as I find it and speak from experience.

[RikM]

I do it in stages because I have a manual filter wheel. 90 min L and 1/2 hour per colour, then repeat if still clear. I try and do as Olly says and shoot R&G low down and L&B high up

No matter what set I'm starting with, I focus for Luminance. I used to refocus each colour but I had a few issues of inconsistent FWHM for each colour, so found that if I focus for L and then rely on the Baaders being parfocal enough at f/5 to get good enough colour for an LRGB rather than RGB, then I get better stars.

I shoot Ha as a separate set and refocus just for that.

[ollypenrice]

Rik's right to refocus for Lum. A bit of softness on the colour layer won't hurt but L needs to be bang on.

Olly

[opticalpath]

I've found my Astronomik LRGB filters to be genuinely parfocal, including the L filter. I used to think they were not, at the time I was using them on a SCT and had to refocus between filters. On the MN190 however they really are parfocal, at least within the limits that I can judge (and measure) focus in my LP sky! I normally refocus for L just in case, but so far it has not improved on green-focus position. Since that's the case, I should probably just focus on L as suggested!

Adrian

[Komet]

I've found my Astronomik LRGB filters to be genuinely parfocal, including the L filter. I used to think they were not, at the time I was using them on a SCT and had to refocus between filters. On the MN190 however they really are parfocal, at least within the limits that I can judge (and measure) focus in my LP sky!

I agree with this .... once again in my case using Astronomik RGB with the MN190. There is a tiny, tiny variance but it does not appear big enough to warrant refocusing. NB is fine. I haven't actually tried rotating an RGB sequence using my ZS66SD yet, That will be interesting.

[Sp@ce_d]

I agree with this .... once again in my case using Astronomik RGB with the MN190. There is a tiny, tiny variance but it does not appear big enough to warrant refocusing. NB is fine. I haven't actually tried rotating an RGB sequence using my ZS66SD yet, That will be interesting.

My Baaders now seem parafocal on my ZS66 since I found a WO reducer/Ftattener II for it. Before that they were all parafocal apart from OIII & G. Which were both parafocal to each other. (if that makes sense)

[Fogboundturtle]

My Baaders now seem parafocal on my ZS66 since I found a WO reducer/Ftattener II for it. Before that they were all parafocal apart from OIII & G. Which were both parafocal to each other. (if that makes sense)

I would think this this would be cause by your telescope not the filter itself.

[jazzysam]

Hi,

I've used the Baader filters for a while, and my experience is that they all appear to be parfocal.

i used to use a QHY one shot colour, and gave up in frustration at not getting decent subs. Moved to a Starlight Xpress mono and haven't looked back since.

clear skies...

[opticalpath]

I agree with this .... once again in my case using Astronomik RGB with the MN190. There is a tiny, tiny variance but it does not appear big enough to warrant refocusing. NB is fine. I haven't actually tried rotating an RGB sequence using my ZS66SD yet, That will be interesting.

I found that there was a small focus shift required between filters on my Pentax refractor. I'd be interested to hear how it goes with your ZS66SD if you try it.

Adrian

[ollypenrice]

This has been an interesting thread because I think that a few years ago fewer people would have advocated CCD. Now more people are finding that it is easier, faster and gives better results, though it isn't cheaper. That's certain! I used to be more wary about recommending CCD from day one (though I believed it was best) but now I do it all the time provided the budget goes beyond the very tiny chips. I'd find those frustrating.

Olly

[opticalpath]

This has been an interesting thread because I think that a few years ago fewer people would have advocated CCD. Now more people are finding that it is easier, faster and gives better results, though it isn't cheaper. That's certain! I used to be more wary about recommending CCD from day one (though I believed it was best) but now I do it all the time provided the budget goes beyond the very tiny chips. I'd find those frustrating.

Olly

Absolutely agree. At one time I thought I would collect colour data with my modified DSLR and combine this with luminance/ NB captured with my mono CCD camera. It didn't work out that way for me; it was just too much work: focus and capture was trickier and various kinds of noise in the DSLR images was a pain to deal with. Now the DSLR lies unused - life's too short.

There's no doubt that DSLRs offer a big FOV at a modest entry price. While it's possible to produce excellent images with them, it's not at all easy imo, and therefore not an ideal starter camera. And it's only a cheaper option if you don't subsequently become dissatisfied with it and buy the CCD camera anyway!

Adrian

[Gina]

Absolutely agree. At one time I thought I would collect colour data with my modified DSLR and combine this with luminance/ NB captured with my mono CCD camera. It didn't work out that way for me; it was just too much work: focus and capture was trickier and various kinds of noise in the DSLR images was a pain to deal with. Now the DSLR lies unused - life's too short.

There's no doubt that DSLRs offer a big FOV at a modest entry price. While it's possible to produce excellent images with them, it's not at all easy imo, and therefore not an ideal starter camera. And it's only a cheaper option if you don't subsequently become dissatisfied with it and buy the CCD camera anyway!

Adrian

That's exactly what I've found.

[Naemeth]

At least with the DSLR, when you're upgrading to a CCD, there is always room to sell on to the next person not wanting to shell out for a CCD.

[perfrej]

A note on parfocality...

I thought my filters were parfocal. They were advertised as such an I found them to be so. Then I started using FocusMax... That piece of software is very clever. It moves well out of focus for the focusing, thus minimizing the effect of the seeing. With steady temperature, FocusMax finds quite a difference between the filters, something I didn't manage with a Bahtinov mask.

CCD is the way to go, by the way, and preferably mono.

/p

[Gonzo]

The only issue I see at the present time is that I will not be able to fork out hundreds of £ on a CCD

I've love to have a mono CCD

[perfrej]

It is an expensive hobby, that's for sure

/per

[Astroblagger]

I was in a similar position myself afew months ago, i felt i had taken imaging with my modded 450D as far as i could, i was getting ok images but not brillant ones, and was concerned about the LRGB exposure side of things, but i took the plunge and got an Atik 314L+ and must say im very impressed with it, sensitvity wise the difference i notice is large compared to my 450D, i did a bit of reading up on LRGB imaging and after actually doing it, felt it sounds more compicated than it actually is. i got a fairly decent result first night out with it, (Much better than my previous attempts with the 450D) although still have a lot to learn, No regrets going cooled CCD so far anyway.

[jazzysam]

A quick question on your parfocality comment.

could you elaborate on which brand filters you were using, and by how much did FocusMax change focus point between filters.

i have to confess I don't refocus between filter changes. I generally use FocusMax at the start of the run, and then refocus thru the night to adjust for temperature differentials.

cheers.

Sam

[perfrej]

I think that you should always refocus between filters. I have two different sets of Baader filers, 2" mounted and 36mm unmounted. I have never bothered to find out what one step of the focuser corresponds to in microns moved, but the difference with the Takahashi is in the neighborhood of ten to thirty steps. I have yet to get a clear night for my new QSI that has Astrodon filters - I've had it for a month

/per

[ollypenrice]

It is an expensive hobby, that's for sure

/per

Hobby? It's a religion!!!

Olly

[Gina]

Sure is!!

[todd8137]

Yes they are,but for some one jumping in feet first they can be a pain in the rear and unlike a simple modded dslr they are like chalk and cheese

[Gonzo]

Has anyone compared the price between a fully modded DSLR (with cooling, etc...) and a mid range mono CCD?

[ollypenrice]

Yes they are,but for some one jumping in feet first they can be a pain in the rear and unlike a simple modded dslr they are like chalk and cheese

I simply don't find this. I find trying to get a good result from a DSLR far more complicated than using a CCD. Maybe it's just me.

Has anyone compared the price between a fully modded DSLR (with cooling, etc...) and a mid range mono CCD?

They are about the same. You'll expect to get a bigger chip, though, with a DSLR.

Olly