Wow. That looks ridiculous. Negative transmission isn't even possible. It looks like someone naively spliced the IR curve onto the visible curve without...
Hi Richard ... As it was probably me that brought you to this idea, I'll explain to you what I actually meant. If one has two close, parallel, plane,...
Hello That thread in August/September was mainly about the out-of- band blocking in the NIR. The result of the discussion on the NBI and ccd-tech list was: -...
Hi Wolfgang, that issue was resolved in post 1594, see: << http://tech.groups.yahoo.com/group/Astroimaging_filters/message/1594 ... Regards, Richard ... might ...
Hello That thread in August/September was mainly about the out-of- band blocking in the NIR. The result of the discussion on the NBI and ccd-tech list was: -...
Hi Wolfgang, I asked Don to return to this message board. He told me that he would not again allow himself to be browbeaten by certain members of this group. I...
Just wanting to know if it can be controlled by Maxim DL. I know the product description says it can, but am looking for confirmation. Thanks, -Phil...
... If you think that anybody will pay a single cent for low- resolution scans of their filters (especially NB ones) you are plain wrong. -- Wolfgang Renz,...
Hi Wolfgang, you sure are feisty today. LOL Work on the Spectronic 1001 Plus is proceeding well. The spectrophotometer is working well and it has an RS232 port...
Good Morning, In searching for threads on the 20DA I read with interest about daytime use. I did not find anything on night time (astrophotography) use with ...
Dear group, I have a new ST2000xm camera that I am using with 4 year old custom scientific filters from a previous camera. Using a double thick t- shirt flat...
Hi Doug, if my memory serves me the 20Da is the Canon "astronomy" camera with sensitivity to H-alpha? I don't think that an UV/IR cut will help with sky...
Hi Andrew, I think you are on the wrong group for your search - there are lots of expert amateur astronomers using their 20Da's. Have a look and join the...
Hi Doug, on reviewing some past work, I discovered that I gave you bad advice on using an Orion Ultrablock filter for imaging with your 20Da. The Ultrablock is...
Hi, I just purchased a Baader component from Alpine Astronomical (US). When checking on the price, the owner of Alpine said that he is currently absorbing the...
Hi Richard, you are certainly right about that. For me it's the other way round. I'll be ordering soon from US. :o)) But I think whatever is on stock should be...
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...
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