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Focal reducers and a LX200 12"GPS

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#51 Jack Huerkamp

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Posted 30 June 2008 - 07:19 AM

Gavin and Chris,

This is a work in progress. I was planning on bringing my C-8 with me next weekend on a camping trip but the weather reports are not looking promising. I will let the group know what happens when I do get the chance to test what I took pictures of.

Jack

#52 greg

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Posted 30 June 2008 - 11:50 AM

Hey Matt,
I look forward to your tests.

The Meade 3.3 reducer will react like the MFR-3 in that you can change the spacing between the chip and the reducer to get different reduction, in fact My Meade 3.3 came with the ability to use three different spacers to achieve F/3, F/3.3, and F/5.... The more spacers the more reduction, but also the more reduction the more back focus you need. The whole setup was designed to run straight thru, with no diagonal.

So if I keep the spacing the same as the Meade spacers for F/3 (which is Very close to the space that My Micro focuser gives) and long as I can still achieve focus with a diagonal then I should be around F/3, Also, just like the MFR-3, Vignetting may cause a problem.

It seems to come down to achieving focus, and then Vignetting...

Bare in mind that everything I say could in fact be total wrong because I have very little experience with SCT and focal reducers... :idea:

The images of the moon in this thread are my first and only time using focal redusers with my new to me SCT ...

Greg

#53 greg

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Posted 01 July 2008 - 04:30 PM

Well, there is still too much smoke where I live in Ca. to do any night time testing ... but I was able to do some more day time tests. Still the star tests will need to be done to check out the quality of the image, but I have some good new about focus with a diagonal....

Using Jacks advise I tried a thread on 2" diagonal, then the Meade 3.3 with a 2" barrel, then a Celestron 1.25" visual back, and Bingo ... plenty of focus in both directions...

Then I put on a 1.25 barrel extension and was able to increase the spacing between the MaillinCam and the Meade 3.3 while at the same time refocusing... I was able to watch the focal reduction as it was happening.

By measuring the spacing as close as I could I'm sure I was at or very near the spacing that came with the 3.3 reducer which means by sliding the camera in and out I was watching the reduction change between F/5 and F/ 3... May be a little more.

Then I tried using the MFR-3 and the Meade 3.3 at the same time and I was able to reach focus with this combo also.

I can't wait to try it all under the stars. Then I'll know if all this focal reduction is usable or not...

Here's some pictures of the setup I used.

Greg

Attached Thumbnails

  • 2493895-IMG_0338.jpg


#54 greg

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Posted 01 July 2008 - 04:33 PM

another

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  • 2493897-IMG_0333.jpg


#55 Jack Huerkamp

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Posted 01 July 2008 - 08:55 PM

Greg,

Now if it only works on the stars!

I don't know why I didn;t think of trying this sooner.

Jack :foreheadslap:

#56 greg

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Posted 10 July 2008 - 06:49 PM

Well, I was able to do some testing on M16.... I found that when stacking the Meade 3.3 and the MFR3 the stars fell apart and the images where not worth saving.

I did however save images of M16 using the MallinCam color hyper camera, with no reduction, with the MFR3, MFR3 plus 10mm and then 20mm of spacers, and the most reduction came with the Meade 3.3 which if my measurement are correct puts my Meade 12" F/10 at F/3.

No processing and all images are at 56 Seconds. The first image at F/10 the pillars are barely visible, I could have adjusted camera settings and brightness/contrast but I wanted to show only the changes that focal reduction would make... Sorry about the focus and there was a little wind, I had limited time and had to move fast to change reducers and get these images captured...

Sorry I don't know how to put all the images on one page... Maybe Jack can help us out again and make it easier to compair...

Greg

M16 No Reducer

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  • 2511496-M16 No Reducer.jpg


#57 greg

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Posted 10 July 2008 - 06:51 PM

MFR3

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  • 2511504-M16 With MFR3.jpg


#58 greg

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Posted 10 July 2008 - 06:54 PM

MFR3 & 10mm

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  • 2511510-M16 MFR3 10mm.jpg


#59 greg

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Posted 10 July 2008 - 06:55 PM

MFR3 & 20mm

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  • 2511519-M16 MFR3 20mm.jpg


#60 greg

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Posted 10 July 2008 - 06:57 PM

Meade 3.3

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  • 2511521-M16 Meade 3.3.jpg


#61 Jack Huerkamp

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Posted 10 July 2008 - 09:20 PM

Greg,

Thanks for your images. :bow:

I have compiled them all onto one sheet and then calculated the focal reduction provided. Assuming that your scope starts off at F/10, then your images revealed the following:

MFR-3 only with no extension rings yields an f/7.6 system speed. (I had previoulsy calculate f/8, so the results are close.)

MFR-3 with 10mm ER yields an f/6.6 system speed. (I had previously calculated f/6.4 so the results are very close.)

MRR-3 with 20mm ER yields an f/5.5 system speed.

The Meade f/3.3 focal reducer image calculated out to be f/3.4 - again very close comparison.

The spacing numbers shown on the images are relative lengths only.

Posted Image

Jack

#62 greg

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Posted 10 July 2008 - 10:59 PM

VERY COOL Jack,

Thanks for taking the time to work with the images and figuring out the F/ratio.

I had time to grab two other images, The first is M101 with the Meade 3.3 at 56 seconds and the second is M101 and the Meade 3.3 with the camera slid out away from the reducer by about 10mm.

Same basic setting for deep sky off the cheat sheet that I used for the M16 images. I could have done a lot better if I had played with the settings, but I just wanted to test focal reduction....

Greg

Meade 3.3 @ 56 Sec

Attached Thumbnails

  • 2511946-M101 Meade 3.3 10mm.jpg


#63 greg

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Posted 10 July 2008 - 11:00 PM

Meade 3.3 with extra 10mm of space.... Didn't seem to make much difference....

Attached Thumbnails

  • 2511947-M101 Meade 3.3.jpg


#64 Gavin Bray

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Posted 11 July 2008 - 02:17 AM

Excellent work, Greg and Jack. It's good to see the Meade F/3.3 FR works and achieves close to the expected reduction.

I'm waiting for Matt's Optec 0.33 FR to arrive and if it works then I'll get one too otherwise I'll give the Meade FR a go.

I can't wait to finally be able to get down to F3.3.

Gavin

#65 Gavin Bray

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Posted 11 July 2008 - 02:21 AM

Greg

Are you happy with the image quality using the Meade FR?

Any vignetting or other issues?

Gavin

#66 Chris Schroeder

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Posted 11 July 2008 - 09:37 AM

Well done Greg and Jack, and thank you for the time and effort. This should help us all with similar systems and setups.

#67 greg

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Posted 11 July 2008 - 11:18 AM

Greg

Are you happy with the image quality using the Meade FR?

Any vignetting or other issues?

Gavin


Hey Gavin,

I'm very happy with all the focal reduction. I didn't see any vignetting or other issues, Only poor focus on my part....

F/10 is way to slow for DSO's but I'll try it on Jupiter as soon as the smoke clears...

Depending on the object I'll use both the MRF3 with and without spacers and the Meade 3.3 for large low surface brightness objects.

Also next I'll try more space between the Meade 3.3 and the CCD chip to see how much reduction I can get before vignetting sets in...

Greg

#68 Gavin Bray

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Posted 11 July 2008 - 07:25 PM

Thanks Greg.

It'll be interesting to hear how much reduction you can get before it starts vignetting.

Gavin

#69 leonc

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Posted 12 July 2008 - 01:06 PM

Hello Greg, I have an LX200GPS-12" and Mallincam with three different Focal Reducers. I use a Celestron 0.6FR and a Mallincam 0.6FR for most deep sky objects. I also have a Mogg 0.3FR. Here are a few pictures of M51 for reference.
1st pict is M51 with both the Celestron .6FR and the Mallincam .6FR. 2nd pict is using the Celestron .6FR and Mogg .3FR Regards, Leon Corcoran

Attached Files



#70 greg

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Posted 12 July 2008 - 02:22 PM

Hey Leon,

I would really like to see your images but I can't seem to open them.

Greg

#71 leonc

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Posted 12 July 2008 - 10:29 PM

Hi Greg, I seemed to have difficulty attaching pictures to this site.. Can you give me your e-mail address and I will send them with more detail.. Regards, Leon

#72 greg

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Posted 12 July 2008 - 11:02 PM

Leon,

P.M. sent.

Thanks
Greg

#73 nytecam

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Posted 21 July 2008 - 02:28 PM

Your right they don't make the hyperstar for the 12" Meade. I got a really good deal on this scope so I just need to get the maximum usable focal reduction to see if I will be happy with it. I'm not thinking I'll be able to get down to F/1.8 but F/3 would be nice... Too much light pollution at my house for F/1.8 anyway

Greg - you seem to have solved it - I run my 12" LX200 f/10 at f/2.9 and faster with the Meade f/3.3 FR with extension tubes on my SX Lodestar CCD eg 6.4mm x 4.75mm x 0.08 micron pixels. ;) What's are the comparable dims of the Mallincam :question:

#74 Jack Huerkamp

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Posted 22 July 2008 - 05:14 AM

For the MallinCam Color HYPER PLUS, the chip is 7.40mm X 5.95mm and the pixels are rectangular - 8.4H X 9.8V

Jack

#75 Gavin Bray

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Posted 22 July 2008 - 08:48 PM

Unless it's the PAL (not NTSC) MallinCam Color HYPER PLUS in which case the chip is still 7.40mm X 5.95mm but the pixels are rectangular - 8.6H X 8.3V.

Not sure if that makes much difference though. Just a few more slightly squarer pixels I guess.

Gavin


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