Help with solar viewing

[Dazzler]

Hi all

I bought a second hand ETX105 a few weeks ago and it came with what I assume is a glass solar filter.

I decided to give it a go with the first sunshine we've had in weeks here on Sunday. I have never attempted solar viewing or seen it done before.

It sounds silly but I found it very difficult to find the sun looking solely through my eyepiece as I could not use the view finder (for obvious resons).

I had assumed that I would see some glare in the EP when I got close to the sun to guide me in but I got nothing. This assumption is based on what you see with the moon or even a bright planet when you get close.

Am I doing something wrong or are there any tips I should follow.

Thanks.

[Sharnbrook]

One tip that I expect others will offer, is not to assume that you have a solar filter, but to ENSURE that you have a solar filter before you attempt looking at the sun through the scope.

Regards,

Mike

[casstony]

Here's one idea for making a zero power sun finder http://www.eclipse-chasers.com/sunfind.htm

On a safety note, I recommend getting into a routine of checking that the solar filter is in place each time before you put your eye to the eyepiece - just a quick glance on your way to the eyepiece. I was in a hurry and distracted one time and almost looked through the scope without the filter.

[Dennis]

For solar viewing, I verbally (out aloud) go through a mental check list before putting eye to ‘scope;


Full aperture Baader solar film filter fitted to objective end of telescope – check.
Finder scope either:
NOT fitted – check, or
Objective and Eyepiece caps securely fitted -check.
Then I insert my eyepiece into the telescope focuser and run through the checklist once again - check.



Then I place my hand behind the eyepiece before I put eye to ‘scope.
Then the very first look is a very, very swift glance, just in case.
One final check of solar filter and finder scope.

I then begin normal viewing. I usually use a low power eyepiece and point the tube until the shadow of the tube on the ground is minimised. Using this technique, 75% of the time the Sun is in the 1 ½ degree FOV.

On my refractor I have a TeleVue Sol Searcher (http://www.optcorp.com/product.aspx?pid=471-309-3351)fitted and that puts the Sun in the FOV 100% of the time.

Cheers

Dennis

[sheeny]

G'Day Darren,

It sounds like you're on the right track.

Please, make sure it's a solar filter before you use it! It's just not worth "assuming"!

It's also a good idea to inspect it thoroughly. It is is scratched or has pin-holes - don't use it.

Make sure it is securely fastened to the scope so it can't fall off, and do the same with the lens cap on the finder.

Now, onto your question... i.e. how to find the sun... Use the shadow of the scope to point it. When you OTA is perfectly aligned with the sun , it's shadow will be circular (OK probably a perfect ellipse on the ground). I usually watch the shadow of the front cell of the scope on the OTA to do a rough aim. Then when the front cell casts a shadow along the whole length of the OTA I watch the shadow on the ground to fine tune, which can usually be done accurately enough to pick up the sun in a wide EP.

Hope this helps,

Al.

[Dazzler]

all good tips guys. I thought there would be a simple answer.

On the safety tips I am going to heed all of your advice and think I will pass on the current filter as there is nothing on it or the box for me to confirm exactly what it is.

There is also a small scratch on the inside of the glass so I think it is just not worth the risk.

Thanks again!

[casstony]

You could take it to an astro shop or post a photo here to check that its a proper filter. Then, regarding the scratch, if you hold the filter up to the sun and can't see any bright spots or pinholes it's fine to use. If you ultimately decide not to use the fitler, don't throw it away as the cell can be used to mount Baader solar film in after removing the glass.

[csb]

Perhaps it's a moon filter. Is it green.

Also if it screws into the eyepiece then DONOT use it for solar. It can heat up and crack. AND I think this type is illegal here.

Only safe solar filters fit onto front of scope (except herschel wedge but expensive).

[Dazzler]

It is a snug fit over the front of the scope and looks to be an aluminium frame with coated glass infill. I'll take a photo or two of it over the weekend and see what you guys think.

Thanks again.