[PentaxPoke]

Mr. Tibbs,
Those are starting to look better. The part that you may be missing, is that now you have stacked the images (both dark and light frames) you have increased the signal to noise, so now you can "push" the exposure and change the sliders in postprocessing. I simply use Adobe Photoshop Elements (the cheap consumer one).

[wildlifephotog]

Mr. Tibbs,

What you are seeing is coma. It happens to many short primes wide open. Here is a 5 second shot with a 50/1.7 wide open. You need to stop the lens down at least 2 stops.

[LeoTaylor]

What you are seeing is coma. It happens to many short primes wide open. ... You need to stop the lens down at least 2 stops.

I agree. It may seem like heresy to say this among people who don't do astrophotography but expensive camera lenses often are not as good around the edges as medium priced telescopes. Telescopes lack an iris to adjust aperture. If they don't focus all the way to the edge they get bad reviews. Astroimagers buy all sorts of gadgets to flatten their telescope's field. When imaging a star field you can easily spot blur near the edges that a daytime photo would not reveal.

For many years I've read that camera lenses must be stopped down when used for astronomy. I usually go down 1 or 2 clicks on my manual lenses.

[LeoTaylor]

Another question, why are my brighter stars cone shaped??

Guess 1: The brighter stars reveal more of the focus/coma problems discussed.

Guess 2: Based on the blob shape of your brightest star you seem to be saturated. Exceeding the maximum pixel value causes blooming where the sensor smears the excess into adjacent pixels. Usually this smear is in one direction. Look at this photo where I intentionally let a few bright stars bloom to get a brighter nebula. This is the "big tradeoff" where you want longer exposures for the dim objects but not so long as to make the stars bloom.

Note: this example was not taken with a DSLR.

Attached Images

 

[mr tibbs]

I see, more techniques to try for the next round. I'll get some good photos yet!! Thanks for all the tips everyone!

[nightfly]

It is a result of the software or lens. I suspect it is due to the wide open lens & out-of-focus coma. Try stopping down a bit next time.

Dave

I second that opinion. A wide open lens will not fully illuminate the corners and aberrations that are present in all lenses are reduced by stopping down.

A longer exposure will be required but stopping down the lens will provide a better quality image.

[melander]

Was planing on doing some startrails last night but my camera stopped taking pictures after only 4 shots (grumble gruble)
Here is a 180% crop from one of the trial photos I took before just to check exposure. 10s, iso 100 f2.0 Pentax DA*55 and Pentax K20D

I assume that what Im looking at is the andromeda galaxy. Will do some more photos tonight and try stacking them if the weather allows it.

[michalko99]

here is my shot. I used K20 + kit 18-55mm lens and bulb for 2hours and 17 minutes. Both are same shots, only WB is moved in Photo laboratory. This was first night shot..Michal

[Ash]

Terrific work Michal.
One of the longest I've seen done with a dSLR.
Brilliant effect.

[michalko99]

Thanks a lot. I will also try to experiment, but at this season it is pretty hard to find clear sky for such a shooting. BTW: Yellowish tint of first photo is caused by lights from another city. I have to find another place for such as experiments

[LeoTaylor]

Michal,

I amazed at the long exposure!

Are you in Rabča Slovakia? You must have a dark sky compared to where I live! In 15 minutes our light pollution would saturate the frame.

[LeoTaylor]

...
I assume that what Im looking at is the andromeda galaxy.

It is hard to say what it is but I don't think it is a galaxy. Looks more like a cluster. Were you aimed at Andromeda?

[hinman]

here is my shot. I used K20 + kit 18-55mm lens and bulb for 2hours and 17 minutes. Both are same shots, only WB is moved in Photo laboratory. This was first night shot..Michal

Michael, you have terrific work. I have the naive question on bulb mode. Last when I tried on bulb mode, I need to press either the shutter or the wireless remote button the whole time before I release it. What are your steps to use bulb mode for that long in K20D? It is not obvious to me that I can use bulb mode without holding down the shutter or the button release in the wireless remote.

Thanks for the help,
Hin

[hinman]

Here are some of my failed attempts on Perseid Meteor Night. All light traces are from 30 sec exposures on plane flying through

Meteor Night Attempt with Pentax DA 10-17mm f/3.5-4.5 fisheye

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#3

And I don't have photoshop to stack pictures together to see the star trails as happen in Michael's long blub shot

#4
This comes from the use of paint.net using layering from 30 second consecutive exposures, you see the faint traces of light from three planes that passed over
camera fisheye view at different times but stacked together in the final image

I am still experimenting on stacking 50 to 70 images in about 1 hour interval but so far, I am almost clueless to get some good results.

Hin

[mr tibbs]

Hinman, I would love to fail like that! Even though the shots did not turn out like you wanted I think they look great!!