How to adjust the Starfield 0.8x Reducer/flattener

[CraigT82]

I've just taken delivery of this and it's supposed to have 13mm adjustment travel for the backspacing but it didn't come with any instructions, does anyone know how to adjust it? There is a larger silver thumbscrew and a small philips head screw but not sure what each does.

 

https://www.firstlightoptics.com/starfield-telescopes/starfield-08x-adjustable-reducer-flattener-for-90102mm-refractors.html

[CraigT82]

I *think* you unscrew the rearmost threaded ring to the point you need, then tighten down the three grub screws circled in blue to set it - can anyone confirm?

 

[Ratlet]

Was having a bit of deja vu.  Think this covers it:

https://stargazerslounge.com/topic/424633-starfield-flattener-issue/#comment-4504985

[CraigT82]

14 minutes ago, Ratlet said:

Was having a bit of deja vu.  Think this covers it:

https://stargazerslounge.com/topic/424633-starfield-flattener-issue/#comment-4504985

Thanks but that's not it, that person was having trouble attaching the flattener to the drawtube, not actually adjusting the backfocus adjuster on the flattener itself.

I've got it screwed to the drawtube ok, just cant figure out how to make the extension adjustments to the flattener

[PhilB61]

If it's anything like my Stella Mira adjustable flattener? then to adjust back focus slacken of the large thumbscrew and rotate the central knurled section, the flattener will telescope in/out and then relock with the thumbscrew at desired position. The allen screws are related to attachment to your focus tube according to the FLO website.

[CraigT82]

44 minutes ago, PhilB61 said:

If it's anything like my Stella Mira adjustable flattener? then to adjust back focus slacken of the large thumbscrew and rotate the central knurled section, the flattener will telescope in/out and then relock with the thumbscrew at desired position. The allen screws are related to attachment to your focus tube according to the FLO website.

Thanks, this is what I expected to do when I first got it in my hands but I can’t get it to budge and don’t want to force it, do you know if it turns clockwise or anti clockwise from the point of view of the camera? 

[PhilB61]

I can't recall offhand and currently can't check as I've just started an imagining session. I will check in the morning and let you know. It might also be worth phoning or emailing FLO I have found them very helpful and responsive in the past.

[WolfieGlos]

Don’t worry about the grub screws.

Loosen the “large” screw (circled red) and I think the grip is the inner patterned part (circled blue), turned clockwise if I recall. The end part should then start to move outwards, increasing your spacing.
It is quite stiff but it does move fairly easily. Tighten the screw back up to ensure the backfocus doesn’t slip.

 

Edited September 17 by WolfieGlos

[CraigT82]

Right managed it, yes it is the central knurled portion that turns once the silver thumbscrew is loosened. It turns clockwise to extend (from the PoV of the camera). Was very tight though had to really grip and turn to get it loose but now turns fine.