Hi Richard, Can you clarify a bit further - I notice that the Edmund filters you refer to, are only 25 mm diameter at $125. I would imagine that, if Edmund...
Hi Joe, check the prices of 4nm 1-1/4" (~27mm clear aperture) astronomical filters, they cost hundreds of dollars more. Regards, Richard ... filters you refer ...
Let's see: the Edmund filters you link to are specified for 35% transmission. They have 80-50 surface quality (which corresponds in a complicated way to an...
While we are on the subject, well, sort of, where would a guy find a 1-1/4 holder that will hold a 25mm piece of glass? I looked at the Edmund Optic page and...
Hi Ed, I suspect that the filters are made out of BK7 (optical glass), the Edmund Optics catalog has a precision laser line filters of ~<2nm. IMO if the...
Hi Michael, a very common size for optical components is 1". I have used 1" wedge prisms to make GRISMs with transmission gratings that are already in 1-1/4"...
Hi Ed, how about 1-1/4" ~10nm narrowband astronomy filters for $80? See: http://www.optometrics.com/products_filters_astronomy.html Before you blow them off as...
Have you ever considered the possibility that placing an additional filter ahead of the transmission grating will influence the focal point and the optical...
Did everyone notice that when you buy all four of their narrowband filters as a set ($235) that the price per filter is $58.75? Yet Optometrics still makes a...
Hi, with cloudy skies, there are a few interesting things I can do with my Star Analyser. I have characterized the spectral transmission of my narrowband...
Correction: "The scope used was an f3.0 C9.25 with SA GRISM (Star Analyzer grating + 6 degree wedge prism) ahead of the f3.3 focal reducer, but behind the...
Hi Richard - picky point here. Does anyone make a 1" to 1.25" adapter ring to convert these inexpensive filters for our equipment? If not, how much would one...
Hi Joe, look at the link closer, they supply the filter in full sized 1-1/4" filter cell with maximum aperture. Only the Edmund laser line filters need the...
Richard, Thanks for your reply. I should also say thanks for your support here too. I for one like the way you think on some of these things such as saving...
Hi Richard ... ? If you use a grism and especially a pure prism, the "blurring" due to the dispersion is not just depending on the lp/mm spec and the width of...
The Optometrics .pdf catalog of filters is now working. See: http://www.optometrics.com/design/Optometrics/pdfs/FiltersCatalog.pdf (watch wordwrap) When I...
Hi all I am a very very amateur astrophotographer I have a Celestron 5SE ( soon to upgrade to Meade LXD75 10") I have a Nikon D40 Dslr camera and all the...
Hi Steve, the first thing you can do is use a focal reducer. That will ~double the tracking time while shortening exposure time. The second thing you can do is...
Hi, I just realized that the Optometrics filters are probably 30mm, a standard size for optical filters. The placement in a 1-1/4" filter cell is just...
Hi Richard, Would there be an advantage of letting the filter rattle in a cell? Perhaps as temperature changes, and the glass expands or shrinks, there is less...
Hi Joe, I agree with you, the rattle probably doesn't matter as long as it's not so excessive to cause filter tilt. Cranking down tight with a retaining ring...
only if you want flawed flats how do you ensure that the flats work correctly when the filter is moving around? the dust doughnuts will move for example....
Hi, I did spectrophotometer transmission testing of Optometric filters. An Excel spreadsheet, Optometric filter tests. xls, has been uploaded to the files...
do you have a way to do interferometric testing of the substrates? I bought an optical flat for such work but haven't yet deployed it. substrate flatness,...
Hi Richard, transmission optics are a bit more forgiving than reflection optics. Mirrors need to be twice as good as transmission (lens) optics. You actually...
i'd prefer to see interferometric testing such as I posted in the CCD-tech group that were sent to me by Baader. that's the only way to really get the answers...
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