dust on ccd

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PTS
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文章 PTS » 週五 09 12月, 2011 14:26

Wah!! 寫:
PTS 寫:No, I am not tilting the window, nor the filter. All have to be square on.
This is unlike the Coronado or Lunt filters which can make use of the tilt angle for slight adjustment of wavelength. My filter use temperature control for wavelength shifting.
Of course I know you won't tilt it deliberately, but it WILL tilt. Even if the angle is VERY small, it will create a good pattern for you :lol:
I suppose i have to try it out to assess this effect. I suppose I saw some fringes already with the present setup.

observer
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文章 observer » 週五 09 12月, 2011 14:55

Wah!! 寫:
PTS 寫:
Wah!! 寫:Maybe (just maybe) adding a fixed barlow/reducer is better than adding an optical window.
This is not an option.
My telescope is f/9. When I capture full disc, I am using the prime focus, and thus need to stop it down to 50 mm to get to the f/27.9 for the minimum proper working f-ratio of the Solar Spectrum filter.

When I capture close-ups, I use the full aperture of my telescope and thus have to add a 4X telecentric lens. I simply cannot capture full-disc images with this setup and thus cannot keep this permanent.


pts
You won't change the focal length a lot if the barlow/reducer is close enough to the sensor.

If this is not an option, then I just can wish you good luck.
說得正對!

observer
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文章 observer » 週五 09 12月, 2011 14:57

PTS 寫:
Wah!! 寫:
PTS 寫:No, I am not tilting the window, nor the filter. All have to be square on.
This is unlike the Coronado or Lunt filters which can make use of the tilt angle for slight adjustment of wavelength. My filter use temperature control for wavelength shifting.
Of course I know you won't tilt it deliberately, but it WILL tilt. Even if the angle is VERY small, it will create a good pattern for you :lol:
I suppose i have to try it out to assess this effect. I suppose I saw some fringes already with the present setup.
這證明並不如你想像般可以完全 square on,連塵也不夠耐心掃走,不要說其它部份可以做到高精度。

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simonii
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文章 simonii » 週五 09 12月, 2011 16:13

http://www.astronomik.com/en/photograph ... ilter.html

This is probably the thing you want.

If you are really serious in taking IR or UV, go for the following one

http://www.astronomik.com/en/photograph ... rglas.html

PTS
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文章 PTS » 週五 09 12月, 2011 16:19

simonii 寫:http://www.astronomik.com/en/photograph ... ilter.html

This is probably the thing you want.

If you are really serious in taking IR or UV, go for the following one

http://www.astronomik.com/en/photograph ... rglas.html
Thank you for your suggestion. My camera has a Nikon mount. It may be easier to machine a mount for the window than for this filter. Moreover, I don't want any UV or IR cut, and these filters may not be optically as good as the optical window (1/10 wave, 5 arcsec parallelism)

pts

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simonii
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文章 simonii » 週五 09 12月, 2011 22:47

PTS 寫:
simonii 寫:http://www.astronomik.com/en/photograph ... ilter.html

This is probably the thing you want.

If you are really serious in taking IR or UV, go for the following one

http://www.astronomik.com/en/photograph ... rglas.html
Thank you for your suggestion. My camera has a Nikon mount. It may be easier to machine a mount for the window than for this filter. Moreover, I don't want any UV or IR cut, and these filters may not be optically as good as the optical window (1/10 wave, 5 arcsec parallelism)

pts
You are really welcomed.

I don't think this would affect the quality of the image very much if you take it behind all filters. As you can see from the datasheet of the filter (which can be download from the same website but another page), it has very high transmission rate at hydrogen alpha. As I remember, they also provide tailor made filter size. You may send them an email and ask for a quote.

Simon

PTS
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文章: 7456
註冊時間: 週日 28 10月, 2007 08:50
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文章 PTS » 週六 10 12月, 2011 08:30

simonii 寫:
PTS 寫:
simonii 寫:http://www.astronomik.com/en/photograph ... ilter.html

This is probably the thing you want.

If you are really serious in taking IR or UV, go for the following one

http://www.astronomik.com/en/photograph ... rglas.html
Thank you for your suggestion. My camera has a Nikon mount. It may be easier to machine a mount for the window than for this filter. Moreover, I don't want any UV or IR cut, and these filters may not be optically as good as the optical window (1/10 wave, 5 arcsec parallelism)

pts
You are really welcomed.

I don't think this would affect the quality of the image very much if you take it behind all filters. As you can see from the datasheet of the filter (which can be download from the same website but another page), it has very high transmission rate at hydrogen alpha. As I remember, they also provide tailor made filter size. You may send them an email and ask for a quote.

Simon
I'll check and get more information before I decide on this.
Before this can be done, I have to clean the ccd more while taking images.
And it seems there is a good chance today. I'll go back to school and do more solar observations.


pts

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Wah!!
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文章 Wah!! » 週六 10 12月, 2011 09:00

Wah!! 寫:I think the interferenece pattern is related to the particular optical window and the angle installed, any pre-tests are meaningless.
Well, my this statement is not very correct.
Pre-test is very meaningful for trying how the annoying interference pattern affect the images. :D :D

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