Which CCD ?

[gingergeek]

Yes I'm very much looking forward to this new venture but just planning it is exhausting ! I have emailed Steve Richards enquiring about his SX OAG + Atik EFW2 mod so I shall just wait and see since I'm in no rush.

A brand spanking new Atik460ex + SX OAG and Atik EFW2 will set me back some £2761 and that's before any filters !!! What a good job I save up for these things, I could gain some cash back by selling my ST80/QYH5 combo if necessary and I could buy a manual filter wheel (TruTek) as suggested by Sara and Olly but I would need to recalculate any distance differences.

[ollypenrice]

I think you'd find a used 1.25 inch manual wheel for peanuts. I have one but am hanging onto it 'just in case.' Baader do sets of stacking extension rings which allow for chip distance adjustment.

Olly

[johnrt]

I thought it was just me that still used a manual filter wheel and shunned those fancy automated devices! Mine was £100 from Bern at Modern Astronomy, does the job it needs to do!

[RikM]

I thought it was just me that still used a manual filter wheel and shunned those fancy automated devices! Mine was £100 from Bern at Modern Astronomy, does the job it needs to do!

You're not alone. I have one of those as well

[gingergeek]

So here's a stupid question from a CCD wannabe - do you use a light pollution filter in the imaging train with LRGB filters or not ? or do you treat them as narrowband where noise pollution has less effect ?

[johnrt]

So here's a stupid question from a CCD wannabe - do you use a light pollution filter in the imaging train with LRGB filters or not ? or do you treat them as narrowband where noise pollution has less effect ?

RGB filters do have "notches" in their spectrum to cut out sodium emission for example, so a mono camera with rgb filters will do better than a dslr.

However this isn't enough in some cases - especially in the Lum channel which is where most importance lies. I have a flickr contact who successfully images from New York suburbs using an IDAS l/p filter in front of his LRGB - and a very good job he does with it too. I also think Sara has recently done the same and I plan to do something very similar when the finance director authorises the cash outlay!

[gingergeek]

Thankyou, everyone here has been so understanding in answering my newbie questions. Now I just need to sit down with no distractions and make up a shopping list. I think the Atik 460ex and SX OAG are pretty much a given, it's just the rest of the kit I need to settle on (incl LP filter) to get the dreaded spacing correct.

[ollypenrice]

Until now all my non-ODK images are via manual filterwheel. I believe Rob Hodkinson is of similar persuasion. When I get the full frame running it will have an electric wheel, mainly because you can't get 5 filter manuals in 2 inch.

Olly

[swag72]

Manual filter wheel for me - I'm just too much of a ludite to want too much connected to my PC. It already has FAR too much power over the running of things, so I'm going to retain the bits I can for myself!! Shame really, as it's generally me that makes the mistakes and not the computer!

Re the IDAS filter - I have just started using mine as a luminance filter. I did originally have a 2" that I was going to put in the imaging train so that it would be there for RGB as well. But the general concensus of opinion was that for NB it would be preferable to not have the IDAS in place. As I have my filters in the carousel all the time I didn't want to take the imaging train apart just for NB imaging. So I've just got a 1.25" that I have put in the luminance slot. I was quite impressed on my last outing how the 'luminance' frames came out. I'm a happy girl using this setup.

[Gina]

I think I'm getting some LP problems when taking luminence frames as the luminence ones look worse than RGB combined and then converted to greyscale. So in my case too, that would indicate getting a 1.25" LP filter to put in my filter wheel.

[RikM]

I have a 2" LP filter on the front of my Newtonian coma corrector. I leave it in place for all filters LRGB+Ha and it doesn't seem to have much, if any effect on the final image.

[johnrt]

I have a 2" LP filter on the front of my Newtonian coma corrector. I leave it in place for all filters LRGB+Ha and it doesn't seem to have much, if any effect on the final image.

Sorry Rik, do you mean doesn't have any effect as in you don't lose any data or doesn't have any effect as in doesn't aid the image in reduction of light pollution? My brain is being slow!

[RikM]

sorry John, didn't realise it could be read both ways

I mean it doesn't seem to have a big detrimental effect on the final image.

The total integration time might be a bit longer, but reducing the LP is worth the effort for me. The LRG & B all seem to be better with the LP filter in place and I just can't be bothered to remove it just for Ha so I just shoot longer to compensate. I don't shoot long subs in any event, 10 - 15 min for Ha normally. I have done a couple of 30min just to see that I could, but I don't have the clear sky time to get enough of those for it to be worth the risk.

[Gina]

I'm rather surprised you find an improvement with RGB as the band-pass shapes are supposed to stop sodium and mercury emission lines. Yes, I would expect an improvement with the IR blocking L filter as that has a wide pass-band which will pass Na and Hg emissions.

Seems to me that the best option would be to use an IDAS filter as L as it has IR blocking properties. The only slight downside I can see is that it might not be parfocal with Baader RGB filters.

[RikM]

I'm rather surprised you find an improvement with RGB as the band-pass shapes are supposed to stop sodium and mercury emission lines. Yes, I would expect an improvement with the IR blocking L filter as that has a wide pass-band which will pass Na and Hg emissions.

Seems to me that the best option would be to use an IDAS filter as L as it has IR blocking properties. The only slight downside I can see is that it might not be parfocal with Baader RGB filters.

I was quite surprised as well but I tried a with and without comparison and it was clearly better with the filter in place. This is of course specific for my local light pollution, so probably won't be the case for everyone.

[gingergeek]

An IDAS filter for the L slot it is then ! Even though I have the savings there is a strange feeling at blowing that amount of money in one go so I may get the various items in small batches spread over the next couple of months. I was also thinking of a faster scope such as the WO ZS71 2013 which will give me a slightly wider FOV than the ED80.....so many decisions I'm like a kid in toy shop !

[Gina]

Amazing how much these bits of glass with some coatings on seem to cost!!

I would really like the opinion of some experts in mono CCD imaging as to how efficacious an IDAS filter for luminance would be before parting with anothe £148.

[gingergeek]

Yes it is getting expensive but luckily my girlfriend very understanding just the CCD bits is going to set me back £2500-3000 depending on the bits. In fact I just had to order a 80mm extension tube (£21) since I don't have enough backfocus on my ST80 with my new Lodestar which I setup last night purely to get it working since the sky by me was high cloud and lots of moisture in the air. I slowly pulled all the extenders out till they were on the edge of their length and I was just able to get focus but not wanting anything to pop out I decided the 80mm tube was a safer bet. Of course when I get the CCD setup I will go OAG anyway and then I can do a dual scope setup hence the ZS71. I still can't find any reviews on that scope and I think Olly doesn't rate WO too highly either.

[swag72]

I did a comparison between IDAS and Luminance a while back - http://stargazerslounge.com/topic/167792-idas-p2-lps-filter-mono-camera-can-you-tell-a-difference/

It was only with a short number of subs - 5x300s but in the stacked image there was a difference.

[kirkster501]

Hi Ginergeek, can you update us please on how you are getting on with the 460EX and OAG? And your general thoughts and experiences after owning the kit for a few months?

[gingergeek]

Hi Kirkster,

Sorry for the delay I've been away in Switzerland, sounds great but it was not a holiday I only managed to get a quick first light image the night before I was due to fly out.

I do indeed have the new OV OAG which I use with the SX Lodestar. Originally I used a Baader Expanding ring m48/T-2 adapter to correct it to the WO Flattener VI. The first attempt when I had the Atik460 CCD camera in focus I could not get the Lodestar in focus at the same time. After talking with Steppenwolf he correctly pointed out that I should have used the baader low profile adapter from Modern Astronomy [Zero profile M48(male) - T Thread (female adapter)] as described on his OAG review, this brought the OAG 3.5mm closer to the FR and allowed focus but also meant I was nicely under the 55.5mm lens to CCD distance so I could easily add distance with spacers. You need to read and follow his instructions carefully (I obviously didn't) and the important bit is putting the zero profile adapter in the FR first and then connect the OAG.

I still find that on the OAG the stars are slightly out of focus even when the OAG stalk touching the Lodestar sensor. I think the stalk could do with just a few mm being machined off which I'm considering, the stars are in focus enough for PHD to work.

My test image was out of focus (need a mask) but my issue at the moment is as Steppenwolf pointed out I have severe field curvature due to the FR not sitting square in the tube being pushed off centre. This is shown in his CCD analysis of my test image :

The ZS71 has two screws to secure the FR and there is enough space in the tube for it to "move" so it is not secured centre, in fact the FLO webpage now suggests an adapter to go with the WO Flattener VI. It would be interesting to find why FLO have recommended the adapter and out who is using it and if it improves the FR position before I chough up £41.

At the moment this project is still a work in progress but Steppenwolf has helped me to progress greatly . Martin_h has demonstrated that in the right hands excellent images from the ZS71 are possible. If you want I can post images of the assembled kit with measurements but ideally I would love to post an astro image one day but still enjoying myself though.....at the moment.

[sloz1664]

I am seriously considering buying the Williams Optics ZS71 2013 with the associated FR. I am unhappy that something that has been manufactured to a high standard has a design flaw that makes it optically imperfect.

A simple solution is to add a third screw, which will allow the FR to be centred & secured.

If you are unsure of doing this mod yourself a reputable workshop would do this for a lot less than the £41.00 + P&P adaptor.

cheers

Steve

[kirkster501]

I am seriously considering buying the Williams Optics ZS71 2013 with the associated FR. I am unhappy that something that has been manufactured to a high standard has a design flaw that makes it optically imperfect.

A simple solution is to add a third screw, which will allow the FR to be centred & secured.

If you are unsure of doing this mod yourself a reputable workshop would do this for a lot less than the £41.00 + P&P adaptor.

cheers

Steve

+1 Steve

Looks a very useful scope for the wider angle AP shots - maybe better than the ED80 with a Atik 460EX.

Should be a simple matter to drill and tap a 4mm hole for this.

[sloz1664]

+1 Steve

Looks a very useful scope for the wider angle AP shots - maybe better than the ED80 with a Atik 460EX.

Should be a simple matter to drill and tap a 4mm hole for this.

The f4.72 with reducer is the juicy bit, especially with our Nottingham LP skies.

cheers

Steve

[ollypenrice]

Well, WO scopes come in two flavours, those they get right and those they get wrong. If they made fewer scopes and made them more carefully the balance between the two might become more favourable. They are all pretty, though.

Sorry, somebody needs needs to fight back against their immense marketing machine. They are worth a look but always a careful look.

Olly