Jump to content

sgl_imaging_challenge_2021_annual.thumb.jpg.3fc34f695a81b16210333189a3162ac7.jpg

Lodestar x2 and MFR focal reducer


ohills
 Share

Recommended Posts

I would like to be able to align and focus my 8se with an eyepiece and then switch it out with the lodestar x2 attached to the MFR2 focal reducer .  With this camera combo, about what size eyepiece would this be equivalent to?

Link to comment
Share on other sites

I would like to be able to align and focus my 8se with an eyepiece and then switch it out with the lodestar x2 attached to the MFR2 focal reducer .  With this camera combo, about what size eyepiece would this be equivalent to?

It's the MFR 5 reducer.  Sorry!

Link to comment
Share on other sites

Hi,

I'll try to answer this the best I can. The native C8 has a field of view of 10.9' wide with the LS. That's pretty narrow. Somewhat equivalent to a 6mm Televue Radian. The MFR 5 has a variable focal reduction. At .5 it will give you a FOV of 21.9' wide. That's somewhat equivalent to a 12mm Radian. If you can go to .33 with the MFR 5 the FOV would be 33.2'. That's somewhat equivalent to an 18mm Radian. Really 19mm, but I don't think they make one.

The FOV of the LS is rectangular. The FOV of an eyepiece is circular.

Hope this helps.

Don

  • Like 1
Link to comment
Share on other sites

Hi,

I'll try to answer this the best I can. The native C8 has a field of view of 10.9' wide with the LS. That's pretty narrow. Somewhat equivalent to a 6mm Televue Radian. The MFR 5 has a variable focal reduction. At .5 it will give you a FOV of 21.9' wide. That's somewhat equivalent to a 12mm Radian. If you can go to .33 with the MFR 5 the FOV would be 33.2'. That's somewhat equivalent to an 18mm Radian. Really 19mm, but I don't think they make one.

The FOV of the LS is rectangular. The FOV of an eyepiece is circular.

Hope this helps.

Don[/quot

Thanks for the reply Don. Maybe i,m not asking the question right. I really don,t need the FOV calculation. I just want to align the scope then focus with an eyepiece then switch to the X2. . I just wanted to know what eyepiece in mm would be the equivalent to the X2 with the MFR 5 attached to the scope. Does that make sense. With the full MFR 5 would it be a 18 mm eyepiece.

Thanks

Link to comment
Share on other sites

Sorry about that. I see what you mean now. I'm not sure that there's any eyepiece that will do that. It's a matter of position. You may be able to test the position of the camera and eyepiece to give the same focus. I suspect that you would have to have the eyepiece further out of the holder and then use a par focal ring to set the position. Otherwise, the focus with the camera will be quite different than any eyepiece. Maybe someone has done this and can comment on the specifics.

Don

Link to comment
Share on other sites

Hi Chills

You could consider using a flip mirror.

If you put the MFR on the nosepiece of the Lodestar then you will need to move the eyepiece further away form the mirror.

Here's a photo of my 102MAK with flip mirror and SDC435 with an AE x0.6 reducer which is similar to the MFR 5 in that it fits onto the nose piece.

Flip Mirror with SDC 435

Note the T2 extension tube needed to make the eyepiece parafocal with the camera - you will have to focus the camera first then focus the eyepiece.

HTH

Paul

Link to comment
Share on other sites

I find it advantageous to use an eyepiece that has longer focal length than the equivalent of the camera+foal reducer combo. That way the viaw in the ep has a wider field, which helps in positioning the target on the small sensor.

I have a simplified way to get ballpark estimates or comparisons of fields of view of cameras and eyepieces. This is not scientifically accurate but easy to do in the dark without calculators or software. In this approach a Lodestar is comparable to an 8mm Plossl eyepiece. A Lodestar with an x0.5 reducer is then equivalent to a 16mm ep. Based on this, my preferred choice for a finder/positioning eyepiece to be used with this Lodestar+0.5xFR combination would be a 32mm Plossl. This is the widest field ep available with the 1.25" barrel and would give a field about twice as wide as the camea+FR combo. A cross-hair ep is great, when it comes to centering objects in the field. The widest field 1.25" crosshair ep that I know is the 25mm sold by Stellavue.

--Dom

Link to comment
Share on other sites

ohills: I see you are from Oceanside, CA. You have some good people right down the road from you - OPT - Oceanside Photographic and Telescope. One of the best shops in the USA for astronomy related gear of all descriptions. I'm jealous! They know their stuff very well indeed. I'd suggest paying them a visit. I'm sure they'd be happy to lend you assistance and show you - face-to-face - how this stuff works.

Say 'Hi' For Me,

Dave

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.