LX200 14"/F.R./DSLR, imaging

[Lester]

Hi all,

I am trying to hook up to my 14" LX200 the following.

The Meade f6.3 focal reducer/flattener and image with 40D. I have found out that the distance between the last lens of the F.R. should be 105mm from the chip of the camera. What fitting do others use to get the required spacing?

I tried to get my 2" flip-mirror in the train, but the distance with it inbetween the F.R. and camera was 165mm, and couldn't get focus.

The F.R. screws onto the rear of the OTA, but I cannot find what adapters/spacers to use inbetween that and the camera. There doesn't seem to be anything on the major astro shop pages to cover this.

Thanks for your input.:thumbsup:

[higginsdj]

I would imagine that the standard camera adapter fittings will work just fine. On my ST-8 I just mount it directly to the FR (.33 or .63) with appropriate thread converters and don't worry about the distance. I still achieve focus though the actual FR is different (f/4 on the .33 - can't remember what it was with the .63)

Cheers

David

[Lester]

Hi David, thats what I use to do. but after getting huge amounts of vignetting and star distortions, I thought I would try the correct distance to see if I get any better star images.

[[1ponders]]

The way I used to hook them up Lester was Camera>T Ring>Meade extension (I think they call it a T adapter), focal reducer> SC adapter>focuser. I've got a photo of the setup around here somewhere, I'll see if I can find it.

[[1ponders]]

Try this setup
http://www.iceinspace.com.au/forum/attachment_browse.php?a=14242

only use the flip mirror instead of the T adapter.....if the threads fit.

[[1ponders]]

You might need one of these after the flip mirror. An Orion 2" Prime focus adapter. The silver barrel unthreads to an SC thread inside the bronze ring. It depends I guess on what the rear of the flip mirror is, T thread or SC thread.

[Lester]

Thanks Paul for your help, I appreciate it.

[Lester]

I got the fittings and tried them tonight, with the last element of the focal reducer 105mm from the camera chip. I cannot get focus. The focal reducer was screwed directly onto the rear of the OTA and then the spacer to get 105mm and then the 40D camera. I cannot get the camera close enough to the telescope to focus. Almost, like a few centimetres short.

Any further suggestions will be appreciated.

Thanks.

[Kal]

The Meade F6.3 reducer is known to have a manufacturing problem a couple of years ago, with the elements ground wrong and people not being able to come to focus (it was ground to more of an F5 reducer I believe). Meade swapped out the defective units at the time.

Did you buy this reducer a couple of years ago, or second hand recently?

[Lester]

Hi Andrew,

I purchased it new in 2003. Thanks I will contact the astro shop and see what they say.

[Lester]

I recieved an email from the supplier of where I got the focal reducer and my 14" LX200 some years ago.

They informed me that the optimum distance is meant to be 45mm and not 105mm. So I will try that now.

Perhaps there are different configeration f6.3 focal reducer/flatteners for SCT scopes that require different spacings. eg. could Celestron be different to Meade? The Celestron 14 is f11 and the Meade 14 is f10.

[Kal]

I found this page (http://pws.prserv.net/testani/FR_Report.htm) with some tests on both the meade 3.3 and 6.3 reducers over various spacings. They tested the .63 reducer from 38mm spacing (.84 reduction) through to 83mm spacing (.72 reduction). It certainly seems, however, that the 105mm that you were trying before is going to be too long.

[Lester]

Thanks Andrew for that information.

Atleast I now know that with less spacing than 105mm, I will be able to get focus. With the fittings I have on hand the distance I have achieved is 65mm.

[rogerg]

To reduce optical problems like star distortions I had a local engineer make a 2" tube to fit the optics of the F/6.3 reducer inside and then slide that inside the draw tube.

What I had my engineer make is the same as what is sold here:
http://www.ziplink.net/users/lester/FLR.html

My problem was that I was trying to have a NGF-C crayford focuser in the mix:
SCT -> NGFC -> F/6.3 reducer -> meade spacer -> camera

... that didn't work well, there was distortion.

Having the reducer optics inside the focuser made all the difference. It also significantly shortened my imaging train so I can slew more south than I could otherwise.

I work at F/7.5. I can use the 3.3 optics to get f/5.5 ... but prefer 7.5.

Roger.

[Lester]

Hi Roger, thanks for your comments. As you will be aware of the image shift with the LX scopes and from what I have experienced it gets worse with the larger diameters; I want to use my Feather Touch focuser with the focal reducer.

To use the F.R. as designed to screw onto the rear of the OTA and then in my case rely on standard focus, shifting the primary, with image shift is a quick way to get frustrated.

So I have screwed a 2" adapter onto the front of the FR, that will slide inside the Feather Touch focuser. Then I get focus on a bright star with the camera, lock the focuser and remove the camera; slide in a eyepiece and extention tube to find the DSO. The eyepiece is locked into the tube to be parfocal with the camera focus.

If I had GOTO, I most likely would not have to do all that to find the faint objects.

[Kal]

What are you going to have on your Titan Lester? Gemini or DSC? either should assist greatly in finding the fuzzies with your camera equipment attached :)

[Lester]

Hi Andrew, I am sure it comes with Gemini.

That will be a whole new learning curve for me. I am looking forward to getting perfect tracking and being able to take longer exposures.

[higginsdj]

The use of the F/3.3 and f/6.3 FR's were designed for use with small sized CCD chips in mind. No matter what you do, you are going to get severe vignetting using the f/3.3 and a large sized CCD/CMOS chip and moderate vignetting with the f/6.3.

Cheers