The achromat is good for exactly that and casual deep sky viewing. I don't use an achomat myself. I can see the CA in a 120mm f/8 or 102mm f/15 achromat quite...
As you might guess, give an ATD some spare time, and inevitably, some strange questions can occur. I started with the idea that a Barlow lens can increase...
It occurs to me that the indictment of achromats for imagining is perhaps unjustified. If you are doing narrow band imagining and refocusing it would seem that...
You are not missing anything. For narrowband, an achromat works just fine. However, there's more to the sky than just narrowband stuff. For springtime and fall...
FPL53 is never "readily" available. It depends how many pieces you need. If you need one or two, you may be able to purchase 5kg strip from stock, which will...
... I tried again: The oiled objective uses the same glass types, but has changed a bit. The amount of figuring on the last surface is roughly the same. The...
Admittedly, I have an older version of ZEMAX that is no longer in maintenance. However, I have tried the "Angular Radius" version of default merit function...
Is it harder to keep an ED doublet in collimation VS a triplet, especially oiled triplet? The Meade ED doublets were notorious for collimation problems after...
Oiled triplets don't lose collimation. Any airspaced lens is subject to miscollimation if the lens elements are not somehow nailed down inside the lens cell....
I have finally found the will to re-check an old Tetra-Schiefspiegel design. In the original design, I forced the mirror layout into a convex shell. I...
I am rather new to ATMOS and cannot see a way to optimize the shape of Schmidt type aspheric surfaces. Is the only way to arrive at a Schmidt surface cut and...
... In Chapter 14.F of "Lens Design Fundamentals", Kingslake indicates a method of determining the form of the corrector by comparing the optical path length...
... Delete that one; I had some residual convexity goals in it. When I got rid of those extraneous goals, the system properly knotted up. It still has low...
Richard -- Yes, only for SA. As Kingslake says this is most certainly the way to do it. But how do you do this within the ATMOS optimization routine? Every...
The Author of ATMOS is working on this in the next release of the program. I don't know when this will become available. I will contact him. Rolando ... From:...
ATMOS Version 8.7 will do what you ask. It not only optimizes high order co-efficients, it can also vary the glass types for best design. Rolando ... From: Jan...
... I also found design CookeT01-30y. I tried to shift the stop near the first surface so that the first and third lenses would also have the same diameter,...
... Or, if you accept a bit more compromise, perhaps especially in glass selection, the geometry could be even more simple: Title: CookeT01-32y 100 mm f/12.4...
Hello all. I joined this group hoping people on here can answer some "simple" questions like this one. I'm getting on fairly well with oslo edu but 2 things...
I spent a bit looking at a problem given on one of the lists. Normally, "field correctors" for reflectors have a note that specifies that the focal ratio is...
