Solar filter for 8" Dob

[Kon]

I have order the Baader AstroSolar Safety Film ND 5.0  solar filter from FLO for my SW 200p Dob for some occasional solar viewing  including the upcoming partial solar eclipse. I have never observed the sun before and I have read various info on the web and the SGL forums about precautions etc. My question is, am I better off using the full aperture of my Dob or shall I make a filter to fit the small removable dust cup at the front. Will I lose much details by doing that?

[Stu]

If you have the full aperture solar filter coming, then use that. Much better to use the full resolution of the scope, which should show you more detail than just the small aperture.

[Nik271]

I think the cap is only 50mm and the scope is 1200mm focal length, right?

Apart from losing resolution from small aperture the cap will make your scope F/24 and the image will be quite dim. Solar filter over all the 8inches is the way to go. The extra aperture is a big plus if you decide to do any kind of imaging as well.

[Kon]

@Stuand @Nik271 thank you. It makes sense to use the full aperture. I had seen mixed messages that you do not need the full aperture for solar viewing.

[Stu]

6 minutes ago, Kon said:

@Stuand @Nik271 thank you. It makes sense to use the full aperture. I had seen mixed messages that you do not need the full aperture for solar viewing.

The only problem you may get is a little more sensitivity to poor seeing conditions but otherwise it’s worth using the full resolution.

[Tiny Clanger]

I wondered the same, altho'  I was cautiously  starting my solar observing with a little 80mm refractor .  The nearly A4 sheet of Baader film turned out to be big enough to make a full  aperture filter for my ST80 and a smaller filter (or two ...) the size of the small cap-within-a-cap aperture. I've only had very brief chances to test both filters when the clouds have cleared, but reckon that the larger aperture gives a better (visual) image .

If you are careful with making your filter there will probably be a corner of Baader film left over which will be big enough for you to make both, I have  sufficient for a full aperture filter for my  127 mak as well , which I  intend to make now I feel confident in the filter : all those years of dire warnings about not looking at the Sun meant it took me a while to trust the stuff !

Heather

[Kon]

@Tiny ClangerThanks Heather. Excellent idea to try make two filters; once it is here i will give it a try. I agree with your worry....I am super worried about looking at the sun but i have seen many excellent ideas/advices of this forum that should put me to ease. I think the two that seem to be very good are look at the sun/bright light holding the filter (not in the telescope) for tiny holes and once in the telescope put your hand at front of the EP (better get a hand burn than your eye). I am sure i will do 1000s of checks before i put my eye at the EP 😎

[Tiny Clanger]

19 minutes ago, Kon said:

@Tiny ClangerThanks Heather. Excellent idea to try make two filters; once it is here i will give it a try. I agree with your worry....I am super worried about looking at the sun but i have seen many excellent ideas/advices of this forum that should put me to ease. I think the two that seem to be very good are look at the sun/bright light holding the filter (not in the telescope) for tiny holes and once in the telescope put your hand at front of the EP (better get a hand burn than your eye). I am sure i will do 1000s of checks before i put my eye at the EP 😎

I don't think it is possible to be too careful with your sight !

Remember to remove , or leave the caps on, any magnifying finder on your telescope too : I bought a simple solar finder for about £15 off amazon, not so much to find the Sun,  more as a physical reminder to put it on the 'scope instead, and not use the usual finder.

Heather

[Louis D]

If you're careful and push the cutout against two sides, that will maximize the leftover filter material in the opposite corner for a finder filter or small refractor filter.

I'd recommend getting a SVBONY IR/UV cut filter to put on your eyepiece.  I'm not convinced the filter material is doing a good job of blocking nonvisible wavelengths.  After some time observing, I get a fatigued feeling in my observing eye as if it is being cooked without the filter.  A variable polarizing filter may also come in handy to knock down the brightness a bit further if you find ND5 too bright.  I know I find it a bit too bright.

[Kon]

40 minutes ago, Louis D said:

If you're careful and push the cutout against two sides, that will maximize the leftover filter material in the opposite corner for a finder filter or small refractor filter.

I'd recommend getting a SVBONY IR/UV cut filter to put on your eyepiece.  I'm not convinced the filter material is doing a good job of blocking nonvisible wavelengths.  After some time observing, I get a fatigued feeling in my observing eye as if it is being cooked without the filter.  A variable polarizing filter may also come in handy to knock down the brightness a bit further if you find ND5 too bright.  I know I find it a bit too bright.

Thanks for the suggestions. I already have a variable polarising filter so worth trying it.