Flt110

[soundworthy (Michael)]

Hi all, I'm just looking to chat about a few WO FLT110 issues.
Before I go into it, is anyone here an owner of the WO FLT110?

[Astronut07 (Ben)]

Hi Michael

I just sold a WO110 only a few weeks ago
In the time I owned scope it performed exceptionally
What are your concerns?

[soundworthy (Michael)]

Thanks, yes love the FLT110 for viewing.
For imaging I’m using the flat 68 and have been getting massive reflections & refractions in some of the images, usually when a bright star is nearby but not in fov. Wondering what FF you have been using?
WO have no idea what the problem is and aren’t really interested anyway.
Recently I changed to the moonlite focuser and still the Same issue, but much nicer focus. It’s Never a problem with the scope by itself.
I was hoping to loan a FF to see if it’s the scope or the FF. Wo recon it might still be the scope reacting with the FF, so it just needs to be tried out with I different FF.

[gregbradley]

Reflections from reducers or flatteners sounds like a lack of good antireflection coatings on the lenses.

Also bright stars outside the view is caused by a lack of good baffling.

You may be able to sort out the later with a round baffle to reduce the diameter of the flattener. The reflections also may be from filters if you are using a mono camera and filterwheel. You may need to get better filters that have the latest antireflection coatings.

Greg.

[soundworthy (Michael)]

Originally Posted by gregbradley

Reflections from reducers or flatteners sounds like a lack of good antireflection coatings on the lenses.

Also bright stars outside the view is caused by a lack of good baffling.

You may be able to sort out the later with a round baffle to reduce the diameter of the flattener. The reflections also may be from filters if you are using a mono camera and filterwheel. You may need to get better filters that have the latest antireflection coatings.

Greg.

Thanks Greg, do you have an FLT110 & the FF68? Re- above details.
William Optics has no idea why this is happening, as does anyone else.
attached are some stretched images to accentuate the extremes of whats happening.
Regardless of the type if imager, (not using any filters) this still occurs. currently using DSLR's

[gregbradley]

No I don't have that scope or FF. I did have a TEC110 F5.6 fluorite triplet with a TEC field flattener that had no issues. But I have seen bright out of view flares from bright stars and reflections from flatteners.

I have even had a reflection issue on an AP quad TCC flattener/reducer which was very expensive. In that case it was my adapter which had a step down inside it and that step caused a reflection artifact. Nothing as bad as your example but it looked like a spiral galaxy in the view which of course wasn't real.

Anodised aluminium does reflect in IR.

Flatteners with poor antireflection coatings will bounce light back and forth from the sensor or filters off the rear flattener element.

This is why Tak and AP and other high end flatteners and reducers cost so much. They need the good glass and the high end coatings to get a good result.

Roland Christen has posted in the past just how much coatings have advanced in the last several years.

Alnitak (from the Horsehead region) is the ultimate torture test for reflections so the fact its horrendous here is the worst it will get.

Try cutting a donut shaped disk out of some black non reflective thin cardboard and stop down your flattener a bit. Put it at the back or the front of the flattener wherever you can mount it and see what happens.

Probably the scope side of the flattener may be the best spot.

Greg.

[soundworthy (Michael)]

Great thanks!
I shall do just that,
I’ll let you know how it went after the next clear night.