WO Flattener help

[A40farinagolf]

Hi,

Can someone explain please how the flattener below is designed to be used. (hopefully not too daft a question)

https://www.firstlightoptics.com/william-optics-brand/william-optics-afr-iv-08x-reducer-flattener-iv.html

I know that my Canon DSLR connects directly onto one end via a T2 ring and that the other 2" end goes straight into the telescope.

I know that the internal lenses move towards and away from the sensor as the barrel is rotated.

What does 66 to 88mm mean?

What should I set it to or my Canon 600D?

What should I set it to for a ZWO ASI 174 camera? 

 

 

[david_taurus83]

The 66-88mm adjustment means you can use it on a variety of WO scopes. Each scope has an optimum distance the flattener works at from the lens elements to the camera sensor. Its discontinued anyway unless you already have one.

https://williamoptics.com/hot-tech-adjustable-reducer-flattener

[steppenwolf]

I have one of these reducers and it is really excellent giving a VERY flat field on my William Optics FLT 98 refractor and 18mm x 13.5mm sensor. The camera you use is not relevant here, it is the refractor itself that is important and as @david_taurus83 says above, the adjustments allow for reaching the optimum spacing. If your refractor is not on the WO website list then it will be a trial and error adjustment but well worth the work.

[david_taurus83]

31 minutes ago, steppenwolf said:

I have one of these reducers and it is really excellent giving a VERY flat field on my William Optics FLT 98 refractor and 18mm x 13.5mm sensor. The camera you use is not relevant here, it is the refractor itself that is important and as @david_taurus83 says above, the adjustments allow for reaching the optimum spacing. If your refractor is not on the WO website list then it will be a trial and error adjustment but well worth the work.

Does the body rotate as the internal elements are adjusted? If not, then it's a pity all adjustable flatteners dont work this way!

[A40farinagolf]

On 09/11/2019 at 09:38, david_taurus83 said:

The 66-88mm adjustment means you can use it on a variety of WO scopes. Each scope has an optimum distance the flattener works at from the lens elements to the camera sensor. Its discontinued anyway unless you already have one.

https://williamoptics.com/hot-tech-adjustable-reducer-flattener

Many thanks and I already have one that came with a WO110 mm triplet.

So for each camera do I have to use trial and error to find the best setting for the flattest FOV?

Does it adjust the focus in any way? 

[steppenwolf]

On 09/11/2019 at 10:23, david_taurus83 said:

Does the body rotate as the internal elements are adjusted? If not, then it's a pity all adjustable flatteners dont work this way!

I don't think the body does revolve, I am sure that it is only the internals that move but I am loathe to undo mine to confirm as I have perfect spacing at the moment and have had since I first set it over 3 years ago! If you do manage to find one on the second hand market, I have some tips for you (just shout!) on how to ensure that you minimise tilt.

2 hours ago, A40farinagolf said:

So for each camera do I have to use trial and error to find the best setting for the flattest FOV?

Yes you do if your particular refractor is not on the list.

2 hours ago, A40farinagolf said:

Does it adjust the focus in any way? 

Good question and unfortunately, I have never noticed so can't confirm 🙁

[geordie85]

2 hours ago, steppenwolf said:

I don't think the body does revolve, I am sure that it is only the internals that move but I am loathe to undo mine to confirm as I have perfect spacing at the moment and have had since I first set it over 3 years ago! If you do manage to find one on the second hand market, I have some tips for you (just shout!) on how to ensure that you minimise tilt.

Yes you do if your particular refractor is not on the list.

Good question and unfortunately, I have never noticed so can't confirm 🙁

There's a second hand one on ABS at the moment for £280 (which is too expensive if you ask me). 

I have one of these that I bought 2nd hand off here and my star field is pretty flat after alot of fettling. 

Do you have the list at hand? And what's the best way of reducing tilt as I still have slight tilt in one of my corners. 

Thanks

[A40farinagolf]

33 minutes ago, geordie85 said:

There's a second hand one on ABS at the moment for £280 (which is too expensive if you ask me). 

I have one of these that I bought 2nd hand off here and my star field is pretty flat after alot of fettling. 

Do you have the list at hand? And what's the best way of reducing tilt as I still have slight tilt in one of my corners. 

Thanks

Is this the list that you're looking for?

[geordie85]

2 hours ago, A40farinagolf said:

Is this the list that you're looking for?

I guess so. Thanks

[steppenwolf]

2 hours ago, geordie85 said:

Do you have the list at hand? And what's the best way of reducing tilt as I still have slight tilt in one of my corners. 

@A40farinagolf has posted the list as I know it.

Tilt can be introduced in two areas with this flattener - at the camera end jut tighten the locking screw very securely and at the nosepiece end. The 2" nosepiece fits into a standard 2" eyepiece holder and good ones (like William Optics own) have two retaining thumb screws and one grub screw (hidden under a silicone 'plug' 120 degrees from the two screws) - expose the 'hidden' grub screw, slacken off all three screws and insert the flattener with the camera attached. Rock it slightly until you can feel that the two mating faces are touching one another completely flatly then tighten up the two thumb screws very firmly. While still supporting the camera and flattener, tighten up the grub screw. This results in a really good mating of the two surfaces and mitigates any tilt at this point.

If your eyepiece holder doesn't have a third thumb screw or hidden grub screw, drill and tap a suitable hole at 120 degrees from the other two screws and insert a third bolt. If your eyepiece holder only has one thumb screw then drill and tap holes for two more - you need three to make this 'pushfit' connection fit for purpose.

[geordie85]

4 hours ago, steppenwolf said:

@A40farinagolf has posted the list as I know it.

Tilt can be introduced in two areas with this flattener - at the camera end jut tighten the locking screw very securely and at the nosepiece end. The 2" nosepiece fits into a standard 2" eyepiece holder and good ones (like William Optics own) have two retaining thumb screws and one grub screw (hidden under a silicone 'plug' 120 degrees from the two screws) - expose the 'hidden' grub screw, slacken off all three screws and insert the flattener with the camera attached. Rock it slightly until you can feel that the two mating faces are touching one another completely flatly then tighten up the two thumb screws very firmly. While still supporting the camera and flattener, tighten up the grub screw. This results in a really good mating of the two surfaces and mitigates any tilt at this point.

If your eyepiece holder doesn't have a third thumb screw or hidden grub screw, drill and tap a suitable hole at 120 degrees from the other two screws and insert a third bolt. If your eyepiece holder only has one thumb screw then drill and tap holes for two more - you need three to make this 'pushfit' connection fit for purpose.

Thanks for the advice. I'll give it a go and do a star test once the stars are out and I'm not at work. 

My flt98 has a moonlite focuser so it already has 3 screws so no DIY for me which is a good thing as I'd more than likely break something. 

Does it make a difference which 2 thumbscrews I tighten first?  Also won't that make the sensor slightly off center? 

Edited November 12, 2019 by geordie85

[symmetal]

The 66 to 88 mm adjustment distance is only correct if the sensor is mounted 55mm from the flattener rear, the standard distance for mounting a DSLR and its T2 adapter. So your ASI camera sensor should also be mounted 55mm from the flattener.

If you don't have the correct spacers to fit your ASI at 55mm you can use the FF adjustment to correct this. If the camera is say 52mm from the FF you can increase the FF adjustment by 3mm to make up the difference.

The body doesn't revolve as the FF is adjusted. The FF lenses just move along runners in the FF.

The focus is affected if you adjust the FF so you'll have to refocus each time it's moved.

As others have said the actual FF adjustment distance is only dependant on the scope used so if you don't have a WO scope listed you'll have to use trial and error to find the optimal distance for your scope. This is fairly quick to do, just make say 1mm adjustments, refocus and take a test image. No messing about with variable spacers. 

Alan

[steppenwolf]

8 hours ago, geordie85 said:

Does it make a difference which 2 thumbscrews I tighten first?  Also won't that make the sensor slightly off center? 

There is always that risk with any push fit system but the fit on mine is close to interference anyway so I don't think this is an issue. However, I always tighten the screw closest to the top first as this takes the load off my restraining hand a little while I tighten the others!

[carastro]

I have a WO x0.8 reducer and did what Steve suggested above, added a 3rd screw to the draw tube to eliminate tilt. it does seem to have made a significant improvement so long as I do up the screws evenly.

Carole