8" of travel granted to me by my NiteCrawler focuser rotator, I just need for the focal point to be within the travel of the focuser. So, to get the spacing correct, you can't just move the focuser back and forth as that does NOT change the critical spacing. If I understand Rod's comment, the issue is that the focuser is in front of the flattener. I have no way to adjust 10 microns of backfocus. Second,despite what George said (and he should know) putting in the step size at 1.1microns (which is correct from the OPTEC website) the variations in back focus WERE shown in microns. The instructions say to look in the "Focus Tab". First of all I had one run fail for no discernible reason. I don't have room for a tilt adjuster as I use an OAG which eats up about 13mm of the 58mm back focus that's used in these subs. I think that there is tilt more than anything else but where's it's coming from is a mystery. Here's a link to them if anyone in interested in looking. There's not enough back focus for my OAG as well as a tilt adjuster.Įventually I just more or less gave up and took a couple of hours of subs on M31 to see what it would look like. Eccentricity and tilt varied between exposures whether the system was moved or not.I pulled everything off 4 times and used different spacer combinations to see if I could figure out where the tilt was coming from, but I never actually was able to. No two HF runs produced the same numbers. Perhaps I have a fundamental misunderstanding of the OP's problem or, much worse, i have a serious misunderstanding of back focus and the system I soon (hopefully) will be setting up for myself. With a CFZ of somewhere between 20 microns and 50 microns (classic CFZ or Gold CFZ), I should have plenty of room to find focus and to account for filter offsets. I will, therefore, "zero" focus at approximately 260 microns behind the focal plane. Therefore, instead of an even 6,350 microns of focus travel in front of and behind the sensor, I will have only 6,090 microns of focus travel behind the sensor and 6,610 microns in front of the sensor. My imaging train places my sensor about 0.26mm (260 microns) too long, i.e., my sensor will set up about 260 microns behind the focal plane. In my case, my total available focus travel is about 1/2" or 12,700 microns. I thought that if I know that, then I just need to know that I have enough focus travel on either side of the sensor location so that I can be assured of my ability to achieve focus. Why does one need to have their sensor exactly at the focal plane? I have been working with the presumption that I just need to know where my sensor is relative to the focal plane. So please forgive my apparent ignorance of what issue the OP is attempting to resolve. Therefore, I am in an extreme learning mode, sans a telescope or a focuser, etc. yet and, as I await all of my imaging train components, I have been "gaming" my adoption of N.I.N.A.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |