Solar filter paper question

[Andrew INT]

Just a quick question for anyone with a full aperture diy filter.

I currently have an 8" newtonion which I fit a small filter over the moon cap which has a diameter of about 2-3".

My question is this: If I purchase a new sheet of A4 and make a filter to cover the full aperture, will the contrast/view be greatly improved or will it be very subtle?

With christamas just around the corner (and the eclipse in March), I want to know if I should start dropping my wife some subtle hints!

Many thanks,

Andrew

[Moonshane]

In my experience each increase in aperture for solar (to a point) does improve the quality of the view. Personally though, I would not put a full aperture filter on an 8" scope unless it was a pre-bought cast ali holder. if you are going to do that though, I would say for not much more cost, you could buy a Lunt wedge for your 102mm f5 which would provide really excellent images and in my experience much better than a full aperture filter on a newtonian. I previously had a full aperture filter which I used on my 6" f11 dob and yes the views were very good but not as stable as those with a Lunt wedge a smaller frac. I currently use the wedge on a 120mm f5 SW achro and the views are the best I have had in white light. Your 102mm won't be far behind.

Whilst film filters are safe if used properly, made properly and if they stay on (i.e. they can fall or be knocked off reasonably easily), a Lunt wedge even if it falls out will not cause any eye damage as the light will just shine on your belly or leg.

[Starlight 1]

I do not think I put that over a 8" newtonion ,it flap about in the wind.

[Steve Ward]

You'll not see much benefit going full aperture unless you're blessed with exceptional seeing for much of the time , 4" is more than enough aperture to get great views.

There's a pretty big jump in price from a sheet of Baader film at £18.00 to a Wedge at £139.00 ... !

It's not difficult to make holder that stays put , I've never had an issue with a filter coming remotely close to coming dislodged , even when the scope is atop a 14' pier in a fierce wind.

[Davey-T]

I just made this for 10" SCT, took a couple of rainy days, mainly waiting for adhesive to dry, made from plastic cloaking profile used by double glazing people, just bits I had lying around.

Don't think cardboard would be up to it., big sheet of Baader film cost over  £50.00 but got lots left over for other filters, may make some bino' ones next time it rains.

Not as easy as making small ones though

Dave.

The cardboard box is to keep it in

 

[Andrew INT]

Thanks folks.

With respect to wind (snigger), I have the filters on my telescope, binoculars and finder all stuck down with a couple of sticky male/female velcro pads. Works very well and I feel comfortable that Im not going to set alight my face.

Hmm, I guess another option is to cut the sheet in half and make a 4" filter each for newt and the 102mm.

im sure if I made an 8" or 7" filter for the newt it could be made to stand up to the wind.

I like the idea of the wedge, but I think I would rather put the money towards a solar filter eyepiece (sorry, cant remember the exact name/brand, but it was in s@n mag review a month or two back)

[Peter Drew]

Quark. 

[Davey-T]

Quark. 

Granted 

Dave

[Andrew INT]

Quark. 

yep, thats the chap. I just asked my wife if I could have that instead of the solar filter paper.

I wont tell you what she said, and to be honest I'm not even too sure what it meant, or how to spell it. I did however get the general idea. So, solar paper it is then!

[LukeSkywatcher]

I have totally given up ever trying to make a home made filter ever again. Ive bought 3 sheets in the past and messed up 3 times. Next time i attempt it, i will just cut out a small square (it means me buying a whole sheet AGAIN) and i will glue/stick it to the inside of the small central hole on my 70mm refractor.

Even i cant get that wrong.

Or can i......................

[Owmuchonomy]

Just a quick question for anyone with a full aperture diy filter.

I currently have an 8" newtonion which I fit a small filter over the moon cap which has a diameter of about 2-3".

My question is this: If I purchase a new sheet of A4 and make a filter to cover the full aperture, will the contrast/view be greatly improved or will it be very subtle?

With christamas just around the corner (and the eclipse in March), I want to know if I should start dropping my wife some subtle hints!

Many thanks,

Andrew

Before you go ahead, remember your focal length will be nearly back to full extent if you go for full aperture so unless you get great seeing you might not be so satisfied in the outcome.

[Moonshane]

now you have softened her up with the quark price, strike now and get the Lunt wedge - you'll never learn

[Andrew INT]

Hi Chris,

Sorry if this sounds a bit dim and Ive missed something. Surely the focal length will remain the same regardless of the area covered by the filter? Also, since I can use full aperture on, say, the moon, why would a filter at the objective end change the focus?

Ive never actually checked but if I focus on the moon and then fit the dust cap with the lunar reduced to bring the aperture down from 8" to 2" or so, wouldnt it still remain in focus?

[bomberbaz]

focal length is determined by the length of the tube and the diameter of the aperture, so if you make the aperture smaller it increases yor scope focal length.

[Steve Ward]

Focal length will not be changed , just the focal ratio ... 

[bomberbaz]

Focal length will not be changed , just the focal ratio ... 

sorry yes thats what i meant duh!