Darks, flats and filter

[Scooot]

If I take the lights with a cls clip filter in place should I also take the darks and flats with it in place?

[Davey-T]

Flats yes, you can leave it in for the darks but doesn't matter.

Dave

[udaiveer]

Wondering how can one take Darks n bias with a filter?!? ;-)

Won't you be covering the lens(filter and all) with a lens cap?

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[udaiveer]

Darks are very temperature (of the sensor/CCD) sensitive ie. Should be the same as your lights

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[Scott]

Wondering how can one take Darks n bias with a filter?!? ;-)

Won't you be covering the lens(filter and all) with a lens cap?

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a clip filter is mounted inside the dslr so capping the lens is no different. of course it makes no difference but I've never bothered removing the clip.

[udaiveer]

;-). Same difference?

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[Scooot]

Thanks everyone. I took 30 bias with the filter and also without,and after stacking the image with the filter had a slight blue hue to the stars which I didn't like so I'll leave it out in future for bias. Wondered about the darks and flats as it's obviously easier to leave it in.

[ollypenrice]

A filter can only affect a bias is if some light is getting through it. This shouldn't be happening. If it is happening then your method  for excluding light while taking bias and darks is not working. This will make both darks and bias totally useless - or far worse than useless.

I have found that the only way to exclude all light from my darks and bias is by taking off the CCD camera and using the supplied screw on metal cap. All digital sensors are very sensitive to the tiniest light leaks. I tried taking darks with Takahashi's tight fitting metal lens cap and a sealed electric filterwheel with no off axis guider in the system. They were not darks. Light was getting in there. I have no idea how but it certainly was.

Olly

[Scooot]

A filter can only affect a bias is if some light is getting through it. This shouldn't be happening. If it is happening then your method  for excluding light while taking bias and darks is not working. This will make both darks and bias totally useless - or far worse than useless.

I have found that the only way to exclude all light from my darks and bias is by taking off the CCD camera and using the supplied screw on metal cap. All digital sensors are very sensitive to the tiniest light leaks. I tried taking darks with Takahashi's tight fitting metal lens cap and a sealed electric filterwheel with no off axis guider in the system. They were not darks. Light was getting in there. I have no idea how but it certainly was.

Olly

Thanks Olly, I'll have a look at a couple of the raw images to see if I can detect any light getting to them, maybe the difference was caused by something else in the stacking or processing.

[Scooot]

They look the same to me, from a light viewpoint anyway, which I'm pleased about now

With both these images I turned the brightness up full, the contrast down full and moved the far right slider of the histogram left without clipping. The first one is with the filter the second one without.

[udaiveer]

I have noticed "Letter boxing" (white bands on top n bottom) in my Darks too, especially on the bottom. Very obvious in darks(exposures) of longer than 3mins.

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