Baader solar film - eyepiece nerves

[AlanK]

HI

I have just made a cardboard holder to place this film over the 2" offset cutout in the 12" dob tube cover. This will effectively give a 2" aperture at f30 by my reckoning. I'm quite glad that the sun has now set and the forecast for tomorrow is not the best for observing as I find I have now become nervous at the thought of putting my eye to the eyepiece.

Is there any way to test the light (heat I suppose is the problem) coming through the eyepiece before putting my eye up to it, other than the recommended checking the film for obvious holes and scratches? What do others do?

[Andrew*]

Don't worry too much

It's a good idea to point at a blank bit of sky away from the sun as a secondary check. It should appear very dark/black. If you can see any blue, then you can start to be worried!

I'm sure the first light will settle your fears. Solar observing is not dangerous if you stick to the precautions! Check your filters every time, and make sure they couldn't be knocked off accidentally.

Andrew

[spaceboy]

I tape my film to the inside of my dust cover so it is better protected and there is no risk of it blowing off. A quick check up to the sun before each use and common sense is all that's needed. Be aware that you have to check for PIN HOLES through the film. You will see some that look like holes but they are just spots missed on one side of the coatings which should be of no concern as Baader film is coated on both sides. I have also seen it recommended that you spend no longer than 5 minutes at a time viewing the sun as your OTA is in direct sunlight and will get very hot.

[Andrew*]

If there is a solar filter at the front, the telescope will get no warmer than anything else sitting in sunlight. It will not get hot. Most front aperture filters reflect over 99% of sunlight, so barely any heat from the sun enters the telescope. The black tube cap may get a bit warm though.

Your comment applies more to methods of observing that do not use front aperture filters, such as using eyepiece projection or a Herschel wedge.

[spaceboy]

Don't get me wrong I'm not saying damage to you OTA or cracked mirrors hot. Just that if it is in direct sunlight too long it will get hot as anything would. I was looking at the sun the other day and the front dust cover got so hot it was difficult to handle. TBH I should have known better as the mercury was reading 28' C but there was so much solar activity I got carried away with enjoying the views.

[AlanK]

thanks for the reassurances guys. (But will still look through my left eye frst)

[iwatkins]

All the other advice is good. Final test I do is put eye to eyepiece with eye closed. You'll feel any IR energy as heat on your eyelid.

Cheers

Ian

[Peter Drew]

At 2" F30 you're not going to get much heat, or light for that matter. .

[DarkSky71]

I have a AstroZap Baader Solar Filter coming this week from FLO. I too have concerns as i am having eye problems anyways. I am going to view on a netbook using my spc900nc web cam first. Rather melt a web cam than my eyes even if it is brand new camera. The web cam itself came with a IR filter is this for use when observing sun in conjunction with AstroZap Baader Solar Filter or is it for viewing planets/moon ??

Anyone know of any issues with me using my webcam for this type of work other than the fact it will be a small FOV due to high magnification . May need a focal reducer . Have ETX 90

What do you think

[AlanK]

been cloudy all day here today so not had an opportunity to try out the solar filter. I'm certain (well 99.999% certain) there will be no 'danger' in using it otherwise it would not have been on the market for so long. As said above, commonsense precautions should make it safe. Looking forward to a bit of sunshine tomorrow and 'first light'. If the 2" aperture provides inadequate illunimation I can go up to about 4.5" avoiding any obstructions (spiders and secondary mirror holder). Will see how it goes.

[johntrob]

Get a friend to look through it first?

[spaceboy]

no the wife! that way if all goes wrong at least she won't be able to see you buying more astro gear. PST maybe

[AlanK]

Job done.Lovely sunny day today and had a quick peek this morning. The 2" aperture seems to be sufficient and the sunspots were obvious. It was surprisingly difficult to line the scope up on the sun (using the scope's shadow as a guide - the telrad was not much use!)

May use the remaining film to make a mask for the 6" scope which doesn't get much use these days.

[spaceboy]

Glad to hear all went well. The sun's not always the best for viewing in white light as you rely on sun spots being active which is not always the case but £15 for film compared to £450 for a PST you can't go far wrong.