Focal reducers and a LX200 12"GPS
Posted 21 June 2008 - 04:04 PM
Posted 21 June 2008 - 06:23 PM
Posted 21 June 2008 - 11:46 PM
Much easier to compair them.
The 3.3 and MFR-3 combo yielded a very low power wide FOV.... Any Idea what F/ratio it was????
The front lens of the MFR-3 was spaced about 1.25" (just a guess here) from the Meade 3.3.
I will try this combo on larger objects like M16 and M31 from the Golden State Star Party next new moon. Objects that have a lot of stars in the field to see if such a fast combo will be usable.
Posted 22 June 2008 - 03:45 AM
1:Did you noticed any vignetting when using the MFR-3 and the 3.3?
2:Was the 3.3 used the one Meade still puts out now?
3:I take it using the 3.3 and the MFR-3 you would not be able to get focus if you tried to use a diagonal?
4: Can you get focus using just the Meade 3.3 reducer by itself and a diagonal and/or the Microfocuser as I would be happy to get that reduction using just the 3.3 and was wondering if the diagonal can still be used ?
Posted 22 June 2008 - 03:49 AM
Posted 22 June 2008 - 12:53 PM
The moon is 1/2 degree and assuming that, the FOV with the F/3.3 and MFR-3 is about 0.7 degrees high by about 1 degree wide. The keep on DSOs will be vignetting in the corners that may become noticeable on longer exposures.
Posted 22 June 2008 - 04:29 PM
I need to check out the 3.3 & MFR-3 combo on something other than the Moon, with longer exposures and stars across the FOV to check out how much vignetting there is.
Not sure if the 3.3 is the one still sold ... it's the series 4000 #07567.
I was not able to come to focus with the 3.3, micro focuser,a 1.25 diagonal, then MFR-3.... But may be if I remove the Micro focuser and use a zero clearance 1.25 adapter and a 1.25 diagonal????? I couldn't try this combo because I do not have a 1.25 visual back...
I believe we will be able to focus using only the 3.3 and a diagonal, and if we use a 1.25 diagonal with a zero clearance 2' to 1.25 adapter, we may still be able to use our Micro focusers.
The instructions that came with the Meade 3.3 claims F/3 using their spacer and camera.... I'm not sure what F/# I was running at going straight through but adding a diagonal is the same as adding spacers and should increase focal reduction...
If I can I'll try M51 tonight before the moon comes up... I'll try the 3.3 with the Micro focuser, zero clearance 1.25" adapter and a 1.25 diagonal ... also I'll try going from the micro focuser into my 2" diagonal using the zero clearance 1.25" adapter...
I think I will be satisfied with the 3.3 FOV. If I can get an image of M51 you'll see why... M51 was way to small for my liking... M101 or M33 may be nice with the 3.3. I can't wait to check out M16 with it...
Posted 23 June 2008 - 02:43 AM
I was curious as to why you seemed to get a greater reduction using the Meade F3.3 FR rather than the MFR-3 + 25mm ERs but then read that you had the micro-focuser between the FR and Mallincam. You may be getting more reduction than F3.3 with this setup. It will be interesting to see what a star field looks like.
Also, you're using an LX200 rather than an LX200R or ACF?
Posted 26 June 2008 - 08:37 PM
I'm not familiar with the Malincam, but I was able to use my LX200/12 at f/2.2 by rebuilding the f/3.3 reducer optics into a 2" tube, removing the visual back and inserting the reducer into the baffle tube. This eliminated the swing through problem (which is probably why you want to use a diagonal.
I selected the reduction by adjusting the separation of reducer and camera. IIRC, the usable field diameter was around 12 mm, although coma was bad at the edges. Operating at f/2.5 produced significantly better results. Be aware that focus is extremely critical.
If it helps, I later discovered that there's a commercial solution... http://www.ziplink.n...lester/FLR.html
Posted 27 June 2008 - 04:17 AM
Posted 27 June 2008 - 11:43 PM
A very interesting approach ... Thanks for the link.
I am dealing with so much smoke from the fires here in Cal. that I can't do any testing ...
last night I went outside to check conditions and the only stars I could see were VEGA, Arcturus, and the three stars that make up the handle of the Big Dipper...
I did some day time tests on a pine tree about 1/2 mile away... I used the Meade 3.3 treaded on to the scope, I tried a Celestron 1.25 SCT adapter and a 1.25 diagonal... It wouldn't focus... I tried a SCT 2" diagonal with a zero clearance 1.25" adapter and it still wouldn't focus.... With the bits and pieces I have the Meade 3.3 will only focus straight through.... and it will do that with or without the Meade Micro Focuser.
It will also focus straight through using the Meade 3.3 and the MFR-3 for a reduction probably in the F/1.5 to F/2 range, but I need a brake in the smoke before I can see how good or bad the image will be stacking all that glass to run so fast....
Like I said before... At this point it doesn't cost any more to give it a try... :O)
Posted 28 June 2008 - 12:08 AM
It will be nice if you can figure out a way to use a diagonal with a 3.3 reducer... I'm looking forward to your results, hope you can post some images for us.
Here's a link comparing the older Maxfield 3.3 and the Meade 3.3... http://www.isomedia....al_reducers.htm
Looks like they both required about the same amount of back focus, and they both have pros and cons.
The new Maxfield 3.3 looks like a complete rework of the old design, much better, and even a lot better price too...
Please be sure to let us know how it works for you... And show us... ( Images Please )... :O)
Posted 28 June 2008 - 01:07 AM
I will get the Optec 3.3 reducer in the next 2 weeks and have ordered the "C" mount Mallincam adapter from Optec as well. It is a totally re-designed foul reducer and I will let you know when I have got it and done some tests. I will post some images when I get the reducer.
Posted 28 June 2008 - 04:28 PM
I'm still waiting for the smoke to clear.... It doesn't look good for this New Moon..
Posted 28 June 2008 - 04:32 PM
Posted 29 June 2008 - 04:28 PM
By having the F/3.3 focal reducer between the diagonal and the camera, it may be possible to achieve focus. Only testing will tell. Regarding the machined adapters shown in the photos, I had them made several years ago by a machinist. However, they can now be purchased from ScopeStuff.
Posted 30 June 2008 - 01:37 AM
I've read that the distance between the FR and CCD is critical. Does the 1.25" visual back provide the required separation to achieve a 0.33 focal reduction?
Posted 30 June 2008 - 02:51 AM
I really think you are on to something here. It makes sense to place the focal reducer on that side of the diagonal..... I was separating the camera to far from the reducer by putting the diagonal between them.
I have about the same setup ready to test this weekend only instead of the 1.25" visual back I will place my Meade Micro focuser between the 2" diagonal and the MallinCam.
I know that the Micro focuser can add or reduce the space between the MallinCams Chip and the focal reducer and that will change how much focal reduction I end up with, But I'm not sure if my 12" SCT will have enough focuser travel to get the focal plane to the reducer.
A SCT 2" Diagonal may shorten the light path a little, and it would be nice to be able to remove the 2" barrel and thread the reducer right into the diagonal to shorten the path further.
Posted 30 June 2008 - 05:55 AM
The only thing that concerns me is the "R" optics are already corrected for coma at the edge of view and the optec reducer corrects for coma in the older LX200 scopes. I have seen a couple of images taken through the LX200R scope and the Meade .33 reducer and the optec one and it does slightly appear to introduce a little negative coma but that could be because of any number of things could have have been happening with focus etc and the images still look great to me and these were all done using a DSI camera and I am mainly into visual using the Mallincam video so am not too worried if I get a slight bit of coma as I am chasing faster optics.
The older optec 3.3 was designed for chips upto 9mm and now the new Max field goes to a 11mm chip and the Mallincam I think has a 8mm chip so the Mallincam chip will fit onto this extra field with room to spare so I hope this experiment works for my needs.
I will let you know once I get it and try out.
Posted 30 June 2008 - 07:13 AM