My latest M45 shot from Dec 5th in PTC

LT_5

Hi,

When arriving at the carpark at 7pm, felt very strange why no PTC fans there except me alone. Later I known that they were scared by the haze and all had gone up to the midlevel of TMS!

Transparency was real very poor, about 5/10. So, this M45 image was not anything stunning but that has been what I can work the best on it to dig out the nebulosity around the 7 sister cluster. It is so sad that under such so low transparency the gain was no way equal to what to get in 5 min at the Taiwan mountaintop, though the total exposure of this image is 66 min already!

Photographic details:
Telescope: Vixen DED108SS (540mm F5) + LPS + modded 300D @iso400 RAW
Mount: Vixen non-goto Atlux (old version)
Guiding: Vixen AM80SS + QHY5 + PHD
Stacking: 11x360s stack w/4 FF + 4 DF calibrated in DSS
Air temp: ~13 *C

Focus is a bit out and have no idea how to remove the reflection by the LPS filter.

Though quite noisey, wish you would like to take a look.

Clear skies,

LT

carfield

What is PTC?

Wales

西貢北潭涌

CHYeung

I think you you have to clean the LPS filter and take a flat field to eliminate the effect of dust in the optical train.


YCH

LT_5

Hi CH,

That should not be produced by the way as you said, and I think it is caused by the reflection or even multiple reflection between the LPS filter and the rear surface of the last element of the corrector lens assembly built-in the focusser. However, the reflection will be weaker if both surfaces are clean. The "defect" was enhanced  in the processing.

My guess may be wrong. If so, please correct me.

LT

I think you you have to clean the LPS filter and take a flat field to eliminate the effect of dust in the optical train.


YCH
CHYeung 發表於 2009-12-8 21:24