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Hello Just a quick question. I`m using a 150 PDS (FL 750 mm). According to my calculations using this corrector should come out at 675 mm. I took an image and it plate solved at 698 mm. Does this mean the spacing is too close or too far away from the sensor? Any help appreciated. CS Alan |
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Alan Hancox: Hi Alan, it probably still means you're suffering a hang over from your previous issues/queries around the spacing. The backspace is fixed at 55mm + filters, there's no getting away from that and I don't think anything should correctly be pushing the plate solve it to 698mm except the aforementioned "issue" which caused you to run out of in focus. My 0.9x + 150PDS plate solves to 678 or 679. Apologies, I don't have a reason for this except I'm fairly certain it's related to your first issue from last week. |
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| It could be either way or none at all. The focal length reduction factor isn't necessarily a constant across the board of focal ratios. Neither is a constant across different specimens, so in your case is 0.93x against the advertised 0.9x. Assuming that the original focal length was 750mm, which isn't a given. Have you measured it (the original focal length)? |
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| Actually no i haven`t. I think i need to check that out..... |
