I took this sunspot 971 just now after it was announced that the Sun became active again.  Didn't want to do work, thus spent the afternoon imaging and processing this set of images for comparison.  

The first image was taken in white light using Baader Herschel Wedge.

The second image was taken in H-alpha, using a single SM40.

The third image was taken in HH-alpha, using a double stacked SM40. 

Notice the difference in contrast due to the double stacked filter.  art of the colour and contrast also resulted from post-processing.  But I'm sure you will be awed by the high activity beneath the surface of the Sun.  Click on the image to view full size.

Enjoy the view!  Comments to improve my post-processing are most welcome! 

[em07]

[此贴子已经被作者于2007-9-29 19:03:33编辑过]

黄兄的太阳照片简直是绝了！

谢谢您的赞美！我还得多多努力呢！[em01]

的确是相当震撼！

It seems the Baader Continuum filter accompanying the Herschel prism was not used.  In my opinion, the continuum filter can provide better contrast to solar granulation.

It seems the built-in Continuum filter accompanying the Baader Herschel
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$ h: m' R, U8 C( h4 Dwww.astroview.com.cnbetter contrast to solar granulation.

QUOTE:

以下是引用amoebahydra在2007-10-3 0:28:13的发言：
It seems the built-in Continuum filter accompanying the Baader Herschel
prism was not used.  In my opinion, the continuum filter can provide
better contrast to solar granulation.

The continuum filter was used.  I could barely see the activity surrounding the sunspot.  However, I think that it could be due to the exposure settings that some of the surface details were not captured. I will need to check my data files again.  Thanks for bringing this point out. 

QUOTE:

以下是引用huangwy在2007-10-3 20:19:42的发言：

The continuum filter was used.  I could barely see the activity surrounding the sunspot.  However, I think that it could be due to the exposure settings that some of the surface details were not captured. I will need to check my data files again.  Thanks for bringing this point out. 

It is strange, are you taking monochrome picture and colorise to orange later on after image processing?  If you are using continuum filter, the image taken should be green as continuum filter has a narrowband pass at the greem spectrum. (white light image with orange color tint is obtained with Thousand Oaks filter)

[此贴子已经被作者于2007-10-4 2:58:44编辑过]

QUOTE:

以下是引用amoebahydra在2007-10-4 2:49:48的发言：

It is strange, are you taking monochrome picture and colorise to orange later on after image processing?  If you are using continuum filter, the image taken should be green as continuum filter has a narrowband pass at the greem spectrum. (white light image with orange color tint is obtained with Thousand Oaks filter)

I was using a monochrome camera. I think i was unable to see the details because the sunspot was quite small.  reviously, when I take images of other larger sunspots, the details could be seen quite clearly.  Note:  the image below was taken with a DSLR using the baader herschel wedge.

QUOTE:

以下是引用huangwy在2007-10-4 5:19:05的发言：

I was using a monochrome camera. I think i was unable to see the details because the sunspot was quite small.  reviously, when I take images of other larger sunspots, the details could be seen quite clearly.  Note:  the image below was taken with a DSLR using the baader herschel wedge.

This gives the explanation!

I am also using Baader Herschel solar wedge prism for white light observation and photography, it gives the best detail image of photosphere.

For hydrogen alpha observation in the chromosphere, I also use Coronado's double stack etalon.   I am using one SolarMax 90 at the front and one etalon at the back of the telescope to obtain <0.5A performance.  Both etalons were matched by Coronado in order to achieve the specification (both etalons offset a little bit for peak center frequency performance).  This configuration has advantage of better weight balance as SM90 is very heavy and will affect balance when both is attached to the front of the telescope.  Besides, this configuration also has better control of internal reflection as the etalon are widely separated.   However, the disadvantage is a specific cocentric optics has to be tailor made by Coronado for the telescope (in my case Takahashi SKY90) such that rays pass through the second etalon perpendicularly. 

I understand you are using BF10 blocking filter.  Have you ask Coronado to modify it for photographic use.  The standard BF10 has the band selection filter installed at the nose piece and the infra-red rejection filter at the eyepiece end of the diagonal.   I am using both BF15 and BF30, the BF15 have a diagonal and consume a lot of back focus which would affect use of DSLR.  Coronado provides a custom solution of installing both band selection and infra-red rejection filters at the nosepiece such that it can mount to a T2 adapter for DSLR.

For the calcium K-line observation at the inner chromospere, I am using Coronado CaK 70 telescope. 

[此贴子已经被作者于2007-10-4 13:14:48编辑过]

Regarding solar observation information, I believe you have ordered the Baader Hershel solar wedge prism from Alpine Astronomical, have you ever spoken to its owner Bob Luffel?    He is a very helpful guy and carries many solar observation equipment.

At one time,  I am considering false color solar photography which obviously using CaK for blue and H-alpha for red.  I am seeking for solar filter for Helium-I line (587.5nm)at the green light spectrum for green.  Bob introduce to me Mark Wagner, who is the owner of Solar Spectrum and produce a lot of high end H-alpha filter with bandpass <0.3A.  After some research at university, Mark returned and stated that a <0.1A filter is required for sufficient surface detail at Helium-I which means unaffordable price for carrying on.  We work through other possibility at Magnesium-I which bandwidth requirement is less but would not expect good result because Magnesium-I is an absorption line which is not good for photography.  Finally, the project was shelved.

You can also contact Bob for his professional expertise at solar observation.  You will learn a lot when speaking to people.

Yes,  I have communicated to Bob before, over the use of Solar Spectrum.  I was at a stage where i decided to get a set, but then realised the importance of having a f-ratio of 30 or more.  My setup does not allow that thus my purchase was aborted. Bob gave me much advice as a friend rather than a seller.  He even advised me to think twice.  And my 80mm scope will be too dark to work with Solar Spectrum.  

My herschel wedge was bought through a local vendor in Singapore.  This is a really good piece of equipment.  APM has come up with one too, but I'm not too sure of its specs.  

Thanks for your advice!

Solar Spectrum Ha filter is a completely different leaque when compare with Coronado.  The Etalon of Solar Spectrum uses fused silica as cavity media while Coronado use air space as cavity media.  Because of this etalon of Solar Spectrum is more sensitive to temperature and needs a oven to control the temperature such that the centre frequency of the filter is maintained at 535.15A.  For observing prominence, it use oven to varies temperature and thence thickness of the cavity media in order to drift centre frequency instead of tilting filter for frequency drift.  Ha filters of Solar Spectrum is excellant but it need power for the oven and time for temperature settlement, therefore it is cumbersome to use in the field.  Because of this, I finally choose Coronado product.

There is an interesting aspect of oven controlled center frequency, it can be use for variable frequency filter for different spectral lines of solar emission.  As you should know, transmission through the etalon are harmonics of the central frequency and blocking filter is use to reject all other harmonics except the centre frequency.  Using oven to vary temperature of the etalon will drift centre frequency between antinodes of harmonics, then using blocking filters at different spectral range can select the required spectral lines of the sun for observation.

Actually, Coronado used to have this type of product but when I enquire they refused to manufacture again.

QUOTE:

以下是引用huangwy在2007-10-5 6:23:49的发言：
Yes,  I have communicated to Bob before, over the use of Solar Spectrum.  I was at a stage where i decided to get a set, but then realised the importance of having a f-ratio of 30 or more.  My setup does not allow that thus my purchase was aborted. Bob gave me much advice as a friend rather than a seller.  He even advised me to think twice.  And my 80mm scope will be too dark to work with Solar Spectrum.  

My herschel wedge was bought through a local vendor in Singapore.  This is a really good piece of equipment.  APM has come up with one too, but I'm not too sure of its specs.  

Thanks for your advice!

I have also considered APM before purchasing Baader's product.  APM does not process rear heat dissipating plate and will burn your cloth or even USB cables if you are not carefull enough.