Question on ND filters and solar imaging

[dpastern]

Hey guys,

I was thinking of attaching my ZWO 1600mm pro directly to a Canon EOS lens, probably the 70-200, for some quick and dirty solar imaging.

Would several stacked ND filters be safe for this procedure, in terms of not damaging anything? I did do some googling, and found this CN thread:

https://www.cloudynights.com/topic/370583-filmfilter-for-dslr-photography/

which suggests not to use photographic ND filters, but wanted to check with others as to what their opinions are.

I did find these:

http://thousandoaksoptical.com/shop/solar-filters/threaded-camera-filters/

any thoughts?

[Merlin66]

IMHO the 110% safe way is to use a Baader Solar film filter over the front of the lens.
You can easily make a suitable and safe filter holder.......

[OICURMT]

Did not know T'Oaks made these... they should be safe as they have a good reputation.

Thanks for the link.
OIC!

[dpastern]

thousand oaks have a very good reputation when it comes to solar filters, certainly not inferior to baader. I'd much prefer a screw on filter than using film and a DiY attachment method!



yw! I didn't know either.

It seems like photographic ND filters are not really recommended, so will pass on that idea and save the pennies for a thousand oaks filter!

Thanks guys.

[OICURMT]

To be clear, absolutely nothing wrong with Baader film. Best in class. I use it visually on my SCT with no issues or problems.


Can understnad the concern re: DiY attachment, but there are a lot of solid plans on the web.

That said, I'm very interested in getting the T'Oaks for my DSLR and TV Pronto.

OIC!

[dpastern]

I wasn't implying there was anything wrong with baader solar film (I know it's very good), I'm just a wee bit wary of DIY attachments - all it takes is for something to go wrong and voila...hence really liking the idea of a proper filter/filter thread.

[OzEclipse]

Some of us have worked out the problems with DIY attachments.

My design was designed to be optimal for solar eclipses where unscrewing a filter in the seconds before totality is not practical. It is designed to be secure and able to be removed quickly. However, it works perfectly well for normal white light solar viewing and if made to the instructions will never come loose.

http://joe-cali.com/eclipses/EQUIPMENT/solarfilters.html

Joe

[dpastern]

excellent instructional webpage Joe, but I'm still not confident enough to risk my eyesight with a DIY method! Sorry! Just not for me!!!

[AstroJunk]

An Orion 4" solar filter secures firmly to my 100-400mm lens.

I do tend to apply a little extra gaffa tape though if I'm using anything that could potentially be knocked off (it wouldn't just fall off - it is quite secure!).

BTW, that's a really big chip to be imaging the sun at 200mm.

[Merlin66]

Dave,
The solar image at 200mm fl will be less than 2mm diameter......

[dpastern]

I'd have to compare the OD on my 2 lenses (70-200 f2.8 and 300mm f4) to see how they compare to the 100-400's OD. I still think I'd prefer a screw on filter - just really eliminates accidents!



I didn't expect it to be that small an image. I have a 300mm f4 IS and 2 TC could always go that way I guess.

Once I've been able to check my EQ6 mount out, I'll be imaging with my Esprit 80 and the ZWO camera!

Much to think about.

Thanks guys!