Help with DSLR settings - it's all gone green grommit !

[dishmop]

Soooo... I have been doing some test shots with all the bits I've recently acquired:

- HEQ5 pro

- SW200p (old blue tube)

- Canon 1000D unmodded

I had a look at M42 last night and tried using APT on the laptop to take a couple of 2 minute exposures unguided to see if it's all going to work.

Encountered the expected problem with not enough inward focus available on the old blue tube with the high profile focuser (you can't directly attach the DSLR to the focuser with just the T-ring, and a 2" adapter for the T-ring doesn't give enough inward focus) to used a Celestron Omni 2x Barlow in the optical train to get the outward focus required. So far so good.

I'm not using any filters, either on the barlow or the DSLR like an astronomic clip or anything.

I've tried some of the suggested settings for the 1000d for astrophotography as follows:

- sRGB

- JPEG / quality 10

- ISO 1600

- Bulb (120 second exposure for testing)

- Red-eye off

- Manual Focus

- Long exposure noise reduction auto

- High ISO speed noise reduction on

- AEB / Flash exposure compensation set to 0.

- Sharpness +3

- Contrast +3

- Saturation 0

- Colour tone 0

For some reason, the shots are coming out green ! Any idea what might be wrong? This is my first DSLR camera so I'm fairly sure I'm missing something obvious.

Can any one of you clever chaps can spot what the problem is?

[malc-c]

I was going to say it's quite common when using a LP clip filter but you have stated that no filters are being used. Other than that I'm guessing that the white balance is off.

Playing about with the colour balance in PS it's almost impossible to bring in any red, and everything is biased towards green, so maybe there is something more drastic than white balancing??

Also it's better to work with RAW files rather than JPEGs

[RikM]

Switch to RAW and set the camera white balance to daylight or tungsten if you have some light pollution.

Nothing to do with colour, but you will get better results turning off the long exposure noise reduction and taking a set of darks.

[dishmop]

OK thanks chaps. I will try using RAW and changing my white balance to one of the preset ones like daylight as suggested and see what happens.

[jgs001]

If you're shooting raw the white balance setting doesn't make a lot of difference. In fact deep sky stacker will construct a custom white balance for you which nicely removes any colour cast a filter might cause.

[lukebl]

Ditto all the above. Shoot in RAW mode, Long-exposure noise reduction OFF, and take darks (and flats). Also engage mirror lock-up to avoid vibration. Lots of tutorials here and elsewhere.

I still have my old blue SW200P, and I replaced the focuser with a low-profile one for the focussing reasons you mentioned. Using a barlow is OK to get started, but you are effectively working at a long focal length of 2000mm which leads you to all sorts of problems with guiding accuracy and vibration, as well as a dimmer subject (i.e. operating at f/10, rather than f/5) .

[dishmop]

Just to follow-up and close the thread, the problem seemed to be with not using RAW format. I took a few short (30 sec) exposures with raw, and processed with DSS, happily everything looks less green now!

Been away ok business last week, so next chance I get I'll try Orion again with slightly less idiotic settings.

[Cath]

dishmop: Have got one of the raw files available to download at all?

lukebl: Where did you get your low-profile focuser from I wonder?

[lukebl]

lukebl: Where did you get your low-profile focuser from I wonder?

One of these:

[dishmop]

dishmop: Have got one of the raw files available to download at all?

lukebl: Where did you get your low-profile focuser from I wonder?

Weeelll, the test shots I took after reading the helpful advice were done when it was cloudy and my polar alignment was off so there's horrible drift. I was purely interested to know if in RAW mode the post-processing steps would stop the photos coming out green, and they do. The cloud drifting in front of Orion did introduce a wonderful sodium orange though

As I learned via the explanations above, the white balance is not added/processed by the camera when shooting in RAW mode. This also has the added bonus that there is a LOT less time between exposures where the camera isn't processing the image.

Finally I did have a chat to FLO about the DSLR->SW200p, they also suggested a low profile focuser which I could obtain... or save another 150 for a newer 200PDS. Tricky !

[lukebl]

... or save another 150 for a newer 200PDS. Tricky !

I have to say, I'm none too impressed with the PDS focuser, so beware. Mine is the 250PDS, but it has the same focuser. See my thread here: http://stargazerslounge.com/imaging-image-processing-help-techniques/159919-avoiding-focuser-sag-tips.html

[mallorcasaint]

That's why I love BYEOS as it just about sets everything on the camera for you.

[dishmop]

I still have my old blue SW200P, and I replaced the focuser with a low-profile one for the focussing reasons you mentioned. Using a barlow is OK to get started, but you are effectively working at a long focal length of 2000mm which leads you to all sorts of problems with guiding accuracy and vibration, as well as a dimmer subject (i.e. operating at f/10, rather than f/5) .

Right, I rustled up a few quid. The focuser you refer to here: First Light Optics - Skywatcher Dual-Speed Low Profile 1.25/2 inch Crayford Focuser for your blue tube - I have two questions:

1) Did you have to drill new holes for it?

2) What's the arrangement for the DSLR fitting into it?

Many thanks,

[lukebl]

....

1) Did you have to drill new holes for it?

2) What's the arrangement for the DSLR fitting into it?..

1. Yes. Not very pretty, to be honest, but it still works fine. (If they're made by the same company, and intended for these OTAs anyway, why on earth can't they make them fit the same!)

2. I have a Coma Corrector which provides the 2" nosepiece to fit into the focuser:

And here it is how it fits onto the focuser:

Although it's a low-profile focuser, you need to make sure that all the extra fittings are low-profile themselves. The Coma Corrector slides directly into the 2" focuser, and doesn't add much extra distance. However, if tried to you used a 1.25" fitting, plus an adapter to make it fit the 2" focusser, I suspect you would add distance and still have focus problems. More cost (coma corrector), I'm afraid, but you really need a coma corrector anyway if imaging with an f/5 Newt.

[dishmop]

Sooo... got the new focuser. The scope is third hand and the 1st owner had already drilled holes for a moonlite, so the new focuser fitted perfectly. Went out with the DSLR and a 2" low profile T-fitting and it's all working! I took some 15-25 second exposures at 800 iso for test purposes, the result is below.

The dual speed focuser is awesome. Now the fundamental problems are resolved, I can work my way onto the slightly more complex ones.

Thanks for the help thus far!

[Russe]

Switch to RAW and set the camera white balance to daylight or tungsten if you have some light pollution.

Nothing to do with colour, but you will get better results turning off the long exposure noise reduction and taking a set of darks.

Thanks for the hint! *turning off noise reduction

[Russe]

dishmop: Have got one of the raw files available to download at all?

lukebl: Where did you get your low-profile focuser from I wonder?

Bit delayed answer. Low profile focusers will set you back quite a bit! I'd suggest moving the primary mirror. It's cheaper and easy peasy!!

[lensman57]

Soooo... I have been doing some test shots with all the bits I've recently acquired:

- HEQ5 pro

- SW200p (old blue tube)

- Canon 1000D unmodded

I had a look at M42 last night and tried using APT on the laptop to take a couple of 2 minute exposures unguided to see if it's all going to work.

Encountered the expected problem with not enough inward focus available on the old blue tube with the high profile focuser (you can't directly attach the DSLR to the focuser with just the T-ring, and a 2" adapter for the T-ring doesn't give enough inward focus) to used a Celestron Omni 2x Barlow in the optical train to get the outward focus required. So far so good.

I'm not using any filters, either on the barlow or the DSLR like an astronomic clip or anything.

I've tried some of the suggested settings for the 1000d for astrophotography as follows:

- sRGB

- JPEG / quality 10

- ISO 1600

- Bulb (120 second exposure for testing)

- Red-eye off

- Manual Focus

- Long exposure noise reduction auto

- High ISO speed noise reduction on

- AEB / Flash exposure compensation set to 0.

- Sharpness +3

- Contrast +3

- Saturation 0

- Colour tone 0

For some reason, the shots are coming out green ! Any idea what might be wrong? This is my first DSLR camera so I'm fairly sure I'm missing something obvious.

Can any one of you clever chaps can spot what the problem is?

Hi,

Please do no use Jpeg for capture, take raw images. You loose a lot of data in jpeg conversion. Most astrophotography processing software do not process jpeg files .

A.G