Orpington Astronomical Society

Astronomy => Astrophotography => Topic started by: Kenny on Mar 07, 2015, 11:25:46

Title: DSLR Solar Filter experiment
Post by: Kenny on Mar 07, 2015, 11:25:46
It works!!

Single exposure photograph of the Sun with my new filter. It's not very clear at this resolution but there is sunspot group AR2297 approaching us from the left side of the Sun at the 8 - 9 o'clock position. Photo taken through the 200mm lens of my DSLR with Baader astrosolar filter. Adjusted histogram and curve, and cropped in Adobe Photoshop CS2.

White Light version - as it is displayed by the filter.
(https://farm8.staticflickr.com/7293/16121228313_e0d39ed8a6_c.jpg) (https://flic.kr/p/qyzvwi)

RGB Coloured version - adjusted RGB balance of highlights / midtones / shadows in Photoshop

(https://farm8.staticflickr.com/7289/16118876994_f826b59263_c.jpg) (https://flic.kr/p/qynsyj)
Title: Re: DSLR Solar Filter experiment
Post by: Kenny on Mar 07, 2015, 16:55:59
It definitely works. :)

Experiment / practise for the solar eclipse on 20th March. 26 of 30 timelapse exposures (4 minute interval) of the Sun with solar filter, blended with 1 exposure without the filter. Canon EOS 450D DSLR with Sigma DC 18-200mm lens at 33mm, f/16, 1/250th second, ISO-100. Photos (with filter) stacked in Startrails. Daylight photo (without filter) blended in with Photoshop CS2 with Histogram and Curve edits.

Solar Filter photos stacked.
(https://farm8.staticflickr.com/7615/16123679083_b02932cd14_c.jpg) (https://flic.kr/p/qyN53X)

Daylight photo (before moving the camera) blended in.
(https://farm8.staticflickr.com/7617/16122138894_1b64cf153f_c.jpg) (https://flic.kr/p/qyEbcY)

Title: Re: DSLR Solar Filter experiment
Post by: JohnP on Mar 07, 2015, 17:42:18
Really like the composition of the last photo.. nice work, John.
Title: Re: DSLR Solar Filter experiment
Post by: Fay on Mar 07, 2015, 18:19:25
Is it a piece of film stuck to front of camera, or special fitting?

Title: Re: DSLR Solar Filter experiment
Post by: Rick on Mar 07, 2015, 18:23:38
Quote from: Fay on Mar 07, 2015, 18:19:25
Is it a piece of film stuck to front of camera, or special fitting?

See here: http://forum.orpington-astronomy.org.uk/index.php?topic=10221.0

It seems to work pretty well. Now all we need is nice weather on the day...
Title: Re: DSLR Solar Filter experiment
Post by: RobertM on Mar 07, 2015, 20:08:58
Nice work
Title: Re: DSLR Solar Filter experiment
Post by: The Thing on Mar 07, 2015, 22:13:44
Good job Kenny. I'd forgotten there is an eclipse coming up. I think your going to nab it.
Title: Re: DSLR Solar Filter experiment
Post by: MarkS on Mar 08, 2015, 07:49:26
Excellent Kenny, it's all working and you look really prepared now.

The only comment I would make on the 200mm shots is that they look underexposed to me.
Title: Re: DSLR Solar Filter experiment
Post by: Kenny on Mar 08, 2015, 13:35:39
Yes you could be right. I thought maybe it was my processing as I did play around with the levels to try and pick out the sunspot group on the edge but I've just checked the original and it's fairly comparable. I have a lot of leeway to play with. I was being very cautious not to over-expose. When I initially put the filter on the camera the Sun was far to bright. I dropped the ISO down, eventually ending up on ISO-100 and then played around with the exposure time and aperture. I ended up with 1/500th sec and f/16.
Title: Re: DSLR Solar Filter experiment
Post by: Fay on Mar 10, 2015, 17:00:50
I was practising finding the sun today. do you think I could find it!!!!!!!

I had Canon on back of ed80, but never realised that the Sun is not on the GOTO!  i could not see the shadow as it was amongst the garden twigs, so hard to see. any tips?

as is obvious, I dont often look at the sun!!!!!
Title: Re: DSLR Solar Filter experiment
Post by: Mac on Mar 10, 2015, 20:30:53
QuoteI was practising finding the sun today. do you think I could find it!!!!!!!

It will be easier on the eclipse, just follow the moon  :cheesy:

The sun should be nearby  ;)

Mac.
Title: Re: DSLR Solar Filter experiment
Post by: Fay on Mar 10, 2015, 20:35:24
yes but i want a practice now, i would not have thought of that though Mac!! :oops:
Title: Re: DSLR Solar Filter experiment
Post by: Carole on Mar 10, 2015, 20:46:31
I could not seem to find the Sun using the shadow method, so I bought one of these:

http://www.dynapod.com/dyna-hp1.html

Got it from the USA, so not enough time to order one but you're welcome to borrow mine Fay as I shall be away for the event.

Tomorrow is your last chance to collect it though if you want to borrow it.

Carole
Title: Re: DSLR Solar Filter experiment
Post by: The Thing on Mar 10, 2015, 21:02:24
I have a Colemans English Mustard powder tin with a hole punched in the base. the yellow lid makes a great screen and even has a centre mark for me to line up the sun pinhole image on. Velcro attaches it to the top of my scope. Works a treat and cost zilch.