Sun 5-9-11

[Carole]

Made myself a solar filter with Baader film.
Still not having any success using the webcam, so reverted to the DSLR.

Modified Canon DSLR 450D and ED80
Single sub 100 ISO Shutter speed 1/400
Couldn't stack as it crashed Registax (accidentally left the settings as RAW) and DSS needs stars so would only stack 1 sub.  Tried manual stacking in PS but it's a bit of a chore, so might have a go at that later. 

My new home made solar filter
ED80 telescope

[MarkS]

Carole,

That looks very promising.

By the way, did you buy the Baader film for visual use or the film for photographic use?

Mark

[Fay]

Quite a good Sun Carole

Fay

[Carole]

Thanks Fay and Mark. 

By the way, did you buy the Baader film for visual use or the film for photographic use?

It says on the label "Ideally suited for production of objective solar filters, for binoculars, telescopes, photo and video cameras". 

I didn't know there were different types, so I hope I got the right one. 
Got it from Bern.

Carole

[mickw]

Oh that's a shame, you came so close to getting the right stuff 


Or to put it another way, I have no idea what you are talking about 

Nice spotty sun by the way 

[MarkS]

It'll be the visual one then.

I think the only difference is that the photographic one is a less dense filter i.e. it lets through more light.

Mark

[PhilB]

That's a very nice result, especially if it's a single frame, Carole.

By the way, did you buy the Baader film for visual use or the film for photographic use?

It says on the label "Ideally suited for production of objective solar filters, for binoculars, telescopes, photo and video cameras". 
I didn't know there were different types, so I hope I got the right one. 

This film is available in two densities, which Baader refer to as ND 5.0 for visual use and ND 3.8 for photographic use. The ND 3.8 version carries a warning that further filtering is required for safe visual use and also comes with warning labels that should be applied to the filter holder.

The images that I have posted recently have been produced using the ND 5.0 product. The reason for this two fold. Firstly, ND 5.0 allows the use of reasonable exposure times which the camera can handle easily. Secondly, as far as I can establish the ND 3.8 version is available only as a 1000mm X 500mm sheet. This is considerably more that I have use for and, given the cost of an A4 sheet of ND 5.0, is probably also prohibitably expensive.

[Carole]

Yes I have re-looked on Modern Astronomy site and there are two types - I had just thought it was the size that was different.  Yes I got the A4 size ND5. 

ND 5.0 allows the use of reasonable exposure times which the camera can handle easily.

I'll try different exposure next time then.

Carole

[Carole]

I had another "go" at stacking in Registax.  This time I converted the RAWs to TIFFs and managed stack them this time.

This is 8 subs.  I think there is slightly better definition on the sun spots, I did about 40 subs in all but not sure whether this will make much difference it's not like I'm trying to suppress noise - what does every-one think?  

[mickw]

Spots seem a bit better defined, but not sure if that's due to the stacking or the colour processing - second image is a tad more orange.

[Carole]

Mick it's not due to colour processing, I could see the sunspots were better defined when I had finished stacking in Registax. 

The colour varies as I just fiddle around with the various photoshop controls until I get something that looks about right.  Remember I am using a modified DSLR so the Sun is a pinky/red colour before processing.

Carole

[PhilB]

It's not just the spots, the faculae are also better defined. I'd say the reprocess was worthwhile, Carole.

...I have re-looked on Modern Astronomy site and there are two types...

I hadn't realised that Bern was supplying 250mm squares of ND 3.8 - may give some a go

[Carole]

I hadn't realised that Bern was supplying 250mm squares of ND 3.8 - may give some a go

Yes it's only £6 more, I had just assumed that the different codes just applied to the different sizes and thought I didn't need the larger size.

Will be intersting to see how it compares.

Just wondering now whether it's likely to improve any further by stacking the whole 40 subs, though I'll do them a few at a time and then stack the stacks.

Carole

[A.S.I.G.N_Baz]

Great start mate! When I get the observatory finished I would love to give this a go. Hopefully by then you will be an expert and can tell me how to do it!

Baz.

[PhilB]

Yes it's only £6 more, I had just assumed that the different codes just applied to the different sizes and thought I didn't need the larger size.
Will be intersting to see how it compares.
Just wondering now whether it's likely to improve any further by stacking the whole 40 subs, though I'll do them a few at a time and then stack the stacks.

Just got off the phone to Bern. He tells me that he cuts these squares from a roll of film. Very fiddly and time consuming. I've decided to give some 3.8 a go. I suspect that when Baader say "eyepiece projection" they mean afocal imaging so it should be possible to get some nice close ups of sunspot groups. Watch this space!

Stacking 8 frames should give you a signal to noise improvement factor of almost 3. If all 40 frames are good enough to be stacked then, using the same rule of thumb, the signal to noise improvement is somewhat over 6. I'm of the opinion that this is worthwhile.

Baz, you offering to put us up while we should you how?