smr Posted February 24, 2021 Share Posted February 24, 2021 (edited) Just trying to verify whether I have got this right if someone can help... I have the 2600MC-Pro which has a 17.5mm back focus from the sensor to the Camera flange. Added to the Camera is the 21mm spacer, then a 16.5mm spacer (55mm) according to the diagram below I need 54.8mm of back focus with this flattener. It's the first Z73 (non adjustable) flattener. Is this right for back focus? If so, is it ok if I am out by 0.2mm? Presumably the required back focus for me is 54.8mm. Edited February 24, 2021 by smr Link to comment Share on other sites More sharing options...
Clarkey Posted February 24, 2021 Share Posted February 24, 2021 Assuming that the additional extension of 15.7mm is part of the flattener then 54.8 looks right. Just looking at your image, have you made any allowance for the tilt adjuster or is that part of the distance to the sensor of 17.5? With regards to the question of whether 55mm will be OK, I would try it and see. You might need to reduce it a fraction if you are very fussy about star shapes, but equally it might be acceptable. 1 Link to comment Share on other sites More sharing options...
smr Posted February 24, 2021 Author Share Posted February 24, 2021 25 minutes ago, Clarkey said: Assuming that the additional extension of 15.7mm is part of the flattener then 54.8 looks right. Just looking at your image, have you made any allowance for the tilt adjuster or is that part of the distance to the sensor of 17.5? With regards to the question of whether 55mm will be OK, I would try it and see. You might need to reduce it a fraction if you are very fussy about star shapes, but equally it might be acceptable. I don't know, I'm confused. That 15.70mm part is a spacing ring, which does come with the flattener, but the glass in the flattener ends here: Link to comment Share on other sites More sharing options...
Budgie1 Posted February 24, 2021 Share Posted February 24, 2021 I cleaned up the WO Back Focus diagram to make it a bit clearer. It looks like you've got it correct, you're just 0.2mm long and the 15.70mm is part of the train. 1 Link to comment Share on other sites More sharing options...
smr Posted February 25, 2021 Author Share Posted February 25, 2021 15 hours ago, Budgie1 said: I cleaned up the WO Back Focus diagram to make it a bit clearer. It looks like you've got it correct, you're just 0.2mm long and the 15.70mm is part of the train. Thank you Martin. Link to comment Share on other sites More sharing options...
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