Problem using filters / possible solution ??

[mikeyjames]

Hi all,
I have just realised that I cannot reach focus with my normal adapters in place and therefore can't use my 1.25" filters. I know I could use a Barlow to help but for bigger objects like some nebulas this won't work.

Anyway, with the following I can't reach focus

1) 1.25" holder with t-adapter (image 1)

2) 2'' holder (image 2)


The only way I can reach focus
attaching t-ring directly to the adapter where the 1.25" barrel would be attached. The inside thread takes the 1.25" barrel and the outside thread thankfully takes the t-adapter (image 3)

My Possible Solution

Is it possible for me to screw the 1.25" barrel into the holder backwards, then use the bottom (silver bit) of the t-adapter inside it with the filter attached?? I would obviously need to find some much shorter screws to hold the bottom of the adapter/filter in place.

I hope that all made sense

Any advice much appreciated.


Cheers
Mick

[cometcatcher]

There's probably a way to do it, but the trouble you have encountered is why I use 2" filters screwed directly into the T adapter or coma corrector.

[mikeyjames]

Hi Kevin,
My problem is that I have no coma corrector yet and the t-ring attaches directly to the pictured part which has no thread inside for 2" filters.

I wonder if I could find a similar part that has the thread inside?

Thanks
Mick

[silv]

I didn't quite understand what it is you really need to find focus and have a 1.25 filter thread.
Do you need a shorter optical path or a longer one?

does this meet your requirement?
http://www.baader-planetarium.com/en/accessories/adapters-imaging-accessories/astro-t2-system/baader-double-t-filterholder-1%C2%BC%22.html

Baader's T2 adapter range here: http://www.baader-planetarium.com/en/accessories/adapters-imaging-accessories/astro-t2-system.html

They're probably all available directly in Aus, too.

[raymo]

I suggest that you bite the bullet and get the Skywatcher f/5 coma
corrector, which you will need anyway for photography, unless you are prepared to put up with your scope's coma. Get the SW one because it is made specifically for the SW f/5 Newts, so there is no messing around with spacers. It is about $150.
raymo

[mikeyjames]

Thanks, the 'Baader 2" / T-2 Nose Piece and Camera adapter' would be exactly what I need to use 2" filters.

Cheers
Mick

[mikeyjames]

I knew I was going to need one eventually, so I suppose it's a sensible option to overcome the issue.

Thanks
Mick

[mikeyjames]

Hi all,
After searching around I have noticed my problem is quite common. Two of the common answers people asking how to use their 1.25" filters at prime focus are basically what I've been told here: A coma corrector or a nosepiece with a 2" filter thread.

Another possible solution to keep my 1.25" filter is a low profile 2" to 1.25" adapter, which may allow me to focus.

Finally, I have seen a few people who have come up with what I thought of - essentially screwing the 1.25" eyepiece holder in backwards - and stating that it works.

I'll give it a go as soon there's a day with no clouds and report back here about how it went.

Cheers
Mick

[raymo]

I don't know how that method works, because when the T-ring is screwed
directly onto the male thread on the adaptor you can only rack
the focuser out about 12mm if using a Canon DSLR. {not physically, but to get focus}.

raymo

[mikeyjames]

Hi all,
luckily I had some sun to look at for about 60 minutes today, and overall pretty happy. Yesterday I cobbled together something to help me get the mount pointed in the right direction (in my images) as my southerly view is blocked to about 50 degrees and today, for the first time, when I asked Synscan to point at the sun it worked and tracked it for an hour with only minimal corrections needed to keep it centred.:D

Maybe I wasn't explaining things well as I'm still new to all of the terminology. I have added some more pictures and hope it's clearer. Basically, I screwed in the 1.25" eyepiece holder backwards into the 2" to 1.25" nosepiece. I then screwed my filter into a an eyepiece barrel and inserted it.

It worked quite well as per my first ever pics of the sun. one without filter and one with solar continuum filter. I has a very short window to set up and test due to the clouds and I understand the pics aren't the best quality as far as focus and exposure settings (I'm actually quite happy anyway as they are my first ever pics with the scope :D )

From what I can see/understand - and I am happy to be corrected - doing it this way wouldn't limit my field of view any more than using a 1.25" t-adapter I had envisaged using in the first place.

Cheers
Mick

[silv]

uhm, I don't see a primary solar filter on your scope. ?
I realize it was cloudy during the shots you posted. But... you are aware of the need for a primary solar filter on top of your scope or you'll damage eyes or your equipment?

[silv]

so the backwards screw-in solution works?
that's cool! without any more equipment than is already at hand you'll get to keep using your 1.25" filter.
nice one.

[mikeyjames]

Hi Annette,
It's there but hard to see. It's a pre-made one with Baader ND 5.0 that clips in very firmly. At this early stage I didn't trust using one that I had made on the main scope.

I've had a practice run making a small one for my camera lens using some Baader Photo Film ND 3.8 that works but won't win any beauty prizes. I plan on making the ND 3.8 for my main scope soon. I fully understand that I can only use this one for photography using live view and can't use it for visual, which includes not looking through the camera viewfinder.

As for the backwards filter solution, I had jumped the gun buying a few filters, assuming they would work with photography, before getting the scope, so I'm very happy that it works. I suppose there is a lesson in there somewhere.

Cheers
Mick

[silv]

lesson in there somewhere :rofl:
I'd say the lesson is: don't believe all the mantras on how and what everybody else is doing :p

Cool that the solar filter is there.
I admit I was looking for a bulky self-made one like mine :D

[mikeyjames]

This one should make most people feel better about their own efforts.

I made this yesterday. It's Baader Astrosolar Photo Film ND 3.8. Just to be clear I am well aware that I am not to look at the sun with this, including viewfinder on my camera. The reason for the eyepiece in the picture is that I simply threw this on top of my store made proper ND 5.0 one for the picture.

Cheers
Mick

[silv]

I'm very relieved, now. It looks like one of mine. Thank you for posting that photo. :)