The light bulb moment

[LewisM]

Been farting around having custom adaptors made with M48 filter threads for my Tak FSQ85 so I can mount UV/IR filters. Then looking at Tak charts today the light bulb flickered above my head, then went on like a light house.

Tak 2.7” CAA’s are front threaded for 67mm filters...the Tak FSQ85 flattener (special product for large sensors) are 58mm filter threaded... into camera bag I go and pull out one of each size. Decided to go with the 58mm in front of the special flattener and voila! Plus Tak says no ghosting at the position or the CAA position.

So, if you want to avoid 2” filters if doing RGB, LP mitigation etc in your Taks, check out the filter threads on the CAA or other extras like reducers, flattener etc . No need to use nosepieces etc - all threaded connections now.

Probably ancient news to some but sharing is caring

[LewisM]

BTW here is the FSQ85 flattener for larger sensors. So uncommon AEC didn’t know it exists. Special order.

[Atmos (Colin)]

Is that for sensors larger than APS-C?

[LewisM]

Da.

[Merlin66 (Ken)]

Not being a Tak guy.....does this mean you are now looking for58mm filters??

[LewisM]

Nope - already had the 58 and 67 filters from my camera lenses (Hoya).

So, it'll stay in there permanently and not have to now worry about any tilt from nosepiece attachments etc.

[LewisM]

Just had a look on Fleabay - $10 (58mm) and $12 (67mm) posted from Hong Kong too - so I bought some spares seeing I took the 58mm off one of my camera lenses . Might not be the prime quality, but you never know til you try.

[Merlin66 (Ken)]

Hmm
I haven’t seen any camera sized UV/IR filters....normally UV cut.
You may need a combo of a UV cut and an IR cut (haven’t seen many of those)

What happens if you want to use a NB type filter? Are these available in 58mm?

Just interested.

[LewisM]

Dunno - I use an OSC (in regards to NB). If I want to apply an H-a filter, I can revert to the nosepiece and M48 filter as I have done previously. Leaving the UV/IR in place shouldn't make any difference.

The Hoyas I have are marked UV-IR cut, and the ones I ordered today from Fleabay are UV/IR cut too.

[Merlin66 (Ken)]

I stand corrrected....
Just checked eBay and it appears there are many UV/IR camera filters now available.

My interest is to consider them as possible ERF lenses in Ha solar telescopes.

[LewisM]

Traded a mate in QLD for one of these: https://www.ebay.com.au/itm/Marumi-U...72.m2749.l2649

SUPERB reviews of them.

[LewisM]

Just an update.

I traded a mate for a 67mm Marumi (Japanese made) UV/IR cut filter. The back of the case is pretty specific about mentioning CCD applications.

I have fitted it to the front of my Tak CAA on my FSQ-85, now awaiting a clear night to try it out. VERY nice quality, good anti-reflection coating too.

[Atmos (Colin)]

I put a reasonable quality UV filter on the front of my Sigma Art 85mm when I first got it and had soft stars are some zonal errors. These went away when I took the UV lens off. So, whatever filter you add to the system has to be at least as optically good as the rest of the system.

It wasn’t a softness that showned up in every day photography though as I’d been using it for about a week and still had very sharp images.

[traveller (Bo)]

Originally Posted by LewisM

BTW here is the FSQ85 flattener for larger sensors. So uncommon AEC didn’t know it exists. Special order.

Sorry to ask a noob question Lewis, but doesn't FSQ already give a flat and corrected view being an astrograph?
What additional advantage does a flattener offer the quaddie set up does not?
Bo

[LewisM]

The FSQ-85 was made to be flat to the edges for sensors SMALLER than APS-C. With my 8300 chip CCD which is smaller than APS-C, I do NOT need the flattener - it is flat RIGHT to the edges. If I want to use the SXVR M26C (eventually, when it's back to spec) which has an APS-C chip, I either use the flattener, or have to crop it.

This is NOT the case with the FSQ-106N or ED, nor the FSQ-130, as all were made for the large chips from the beginning.

[traveller (Bo)]

Got it, thanks Lewis.

[Logieberra (Logan)]

Struth. All that hassle. Having to use a flattener on an FSQ is criminal. Sell it and buy a 106!

[LewisM]

It doesn't take much intellect to figure it out. Heck, even a lawyer could (maybe)

[Logieberra (Logan)]

Originally Posted by LewisM

It doesn't take much intellect to figure it out. Heck, even a lawyer could (maybe)

No what I mean is - using a flattener - on an FSQ - defeats the whole purpose of that telescope design. It’s akin to needing to use an extender on an RC, or a reducer on a Honders...