lodestar x2c and focal reduction

[ohills]

I'm trying to get as much information before I jump into the world of video astronomy.  I was all set to pick up the new mallincam xterminator, until I came upon this forum and all the info on the new x2c.  This looks very possible for my setup.  I have a nexstar 8se and would need a focal reducer.  I can't seem to find a f3.3 but can pick up the mallincam mfr5.  Would this be a good setup with the sct 8" and the loadstar x2c.  I would like to run everything from inside of the house.  With the mallincam 50' cables are commonplace but what about the usb cable.  I would need 50' from scope to pc.  Are there any diagrams showing how to connect this to scope and pc.  Sorry for all of the questions,  but it seems you guys are on the cutting edge of this exciting new gear.  Thanks

Roy 

[HiloDon]

Hi Roy,

I think you would enjoy using a Lodestar X2C for near real time viewing. The Lodestar Live s/w is very easy to use and Paul is always working on improvements. Your 8" SCT is ideal, but you're correct that you will need focal reduction. I have no experience with the mfr5, but I have the Meade 3.3. It works well, but I was getting some vignetting at 3.3 with my Meade 8" SCT. I decided to purchase the Optec NexGen 3.3 and have been very happy with it. It is the same price as the mfr5, but is a 2" design that gives a clear field diameter of 9 mm. The LS and MC sensors are the same at 8mm. The Optec requires an adapter, so I purchased one with a SCT thread connection. I then attach a 1.25" visual back adapter where I can position the LS camera in or out to achieve any FR between .33 and .6. After that I switch over to my Antares 6.3 to get .63 to .8. If you go this way, let me know and I can give you the program link to get all the dimensions.

On the USB cables, I think there was a thread here that addressed that. I use a 15 foot extender that works well and the manufacturer claimed you could put three of them together. I'm sure there are ways to do it and someone else more knowledgeable will surely respond here.

If you have any other questions, just post them here and I'm sure someone will respond, and I certainly will if I know the answer.

Don

[ohills]

Hi Roy,

I think you would enjoy using a Lodestar X2C for near real time viewing. The Lodestar Live s/w is very easy to use and Paul is always working on improvements. Your 8" SCT is ideal, but you're correct that you will need focal reduction. I have no experience with the mfr5, but I have the Meade 3.3. It works well, but I was getting some vignetting at 3.3 with my Meade 8" SCT. I decided to purchase the Optec NexGen 3.3 and have been very happy with it. It is the same price as the mfr5, but is a 2" design that gives a clear field diameter of 9 mm. The LS and MC sensors are the same at 8mm. The Optec requires an adapter, so I purchased one with a SCT thread connection. I then attach a 1.25" visual back adapter where I can position the LS camera in or out to achieve any FR between .33 and .6. After that I switch over to my Antares 6.3 to get .63 to .8. If you go this way, let me know and I can give you the program link to get all the dimensions.

On the USB cables, I think there was a thread here that addressed that. I use a 15 foot extender that works well and the manufacturer claimed you could put three of them together. I'm sure there are ways to do it and someone else more knowledgeable will surely respond here.

If you have any other questions, just post them here and I'm sure someone will respond, and I certainly will if I know the answer.

Don

Don..... this reducer looks good.  Could you give me the info in order to connect this reducer to the 8" sct.  

Roy

[HiloDon]

Sure, Roy. The Optec comes with a 2" nosepiece on the front end. The rear can accept a number of different adapters to fit various cameras and provide the proper spacing to get .33 FR. I chose the adapter for an Apogee KX1 because it has sufficient length and an SCT male thread at the end. The part number is OP-17396-170. OPT had them on clearance sale. I then attach a 1.25" visual back that came with my Meade 8". You probably have one for your C8. I then slide the LS into the 1.25" sleeve and adjust the length to give me the FR I want. The assembly is attached to the scope by using a 2" visual back attached to the scopes SCT thread. I use a ScoppStuff 2" adapter. It comes in handy for a lot of things. Here are some pictures of the setup. The washer you see is one I made to take up the clearance when attaching the 1.25" VB to the Optec adapter. Some SCT thread components don't have sufficient length to seat on the VB adapter. ScopeStuff sells these washers as well, because it's a common problem with SCT connections. Let me know if you need any more info.

Don

[HiloDon]

Roy, here's some additional info. The proper reducer to sensor distance for the Optec is 2.16" or 55mm to get 3.3. Here is a handy calculator to determine other reductions. Back calculating for the 3.3 reduction gives a focal length of the reducer of 82mm. Using this FL, you can then calculate what spacing you need to get other reductions. I think you can get more reduction than 3.3. 3.0 should be achievable, but I think 2.5 would be pressing it, but I haven't tried that yet. If anyone has, please let me know how it worked. One thing I know is that your collimation needs to be very precise or you will start seeing coma.

http://www.wilmslowastro.com/software/formulae.htm#FR

Don

[Dom543]

Roy,

I assume that you will use the Nexstar 8SE with the altaz mount that is part of the package. In that case you will absolutely have to use a diagonal. The Nexstar SE mount doesn't have enough clearance between the back threads of the OTA and the mount itself a accommodate a camera in the straight position. This applies to any cameras, video, Lodestar, you name it.

The optical length of a diagonal is more than the max allowable spacing between a x0.33 focal reducer and the camera sensor. This means that you cannot use a 0.33 reducer if you need a diagonal.

You could use the following arrangement.

1. Screw a Celestron 6.3 reducer/corrector on the back threads of your OTA.

2. Screw a 1.25" visual back on the reducer and attach a 1.25" diagonal to the visual back. If you can find a 1.25" diagonal that can be directly screwed on the 2" SCT threads of the reducer, that is even better. I believe that prism diagonals have shorter optical path then mirror diagonals. If this is true, then a prism diagonal would be preferable.

3.a. You can put your Lodestar directly into the ep holder part of the diagonal for an approximately f/6.3 focal ratio. This is good for smaller and brighter objects, like planetary nebulae e.g M57. 

3.b. For a stonger focal reduction you can screw a 1.25" C-mount nosepiece and a second, 1.25" focal reducer directly on your camera. Such small 1.25" focal reducers are cheap and are sold by AgenaAstro, ScopeStuff or almost any other outfit. I use the reducer from Scopestuff because it also has filter threads on its telescope side surface. I can attach 1.25 filters to it. When I looked a couple of years ago, the 1.25" reducer sold by AgenaAstro didn't have filter threads.

With this two stage reducer you can get down to around f/3. That is good for larger objects with low surface brightness, like M101.

If you plan to do electronically assisted observing on an altaz mount, then Lodestar offers you a special advantage. You can use LodestarLive and stack longer integrations together by sum-stacking several shorter exposures. Paul's LodestarLive software has a phenomenal aligned stacking routine that rotates, shifts and transforms consecutive subs in such a way that their stars accurately overlap. This is particularly important for users of altaz mounts, which don't track as well as equatorial mounts. Filed rotation limits maximum exposure time for subs to about 30 sec on altaz mounts. But the stacking feature of the LL software overcomes this limitation. 

The sophistication and accuracy of Paul's aligned stacking in LL is unparalleled. No other software used in near-live observing comes even close. No program offered for use with video cameras can compensate for field rotation and none uses comparably sophisticated transformations. LL is only available for the Lodestar.

Clear Skies!

--Dom

[HiloDon]

Dom,

Can you use my .33 setup after a 2" diagonal? In other words, replace the visual back with an SCT 2" diagonal. Will it come to focus? Are there other problems? Never tried it because I have a GEM. I could test it though if you think it might work. The diagonal won't affect the FR to sensor spacing.

Don

[Dom543]

Don,

I have not tried it.

A 2" diagonal uses about 120mm backfocus. I don't know how much additional backfocus is needed for the 3.3 FR. If the sum of the two is within the capability of the OTA, then it probably works. One can probably find an adapter that allows to screw the reducer directly on the body of the 2" diagonal, where the ep holder is usually screwed in. That would keep things nice and compact. If there is interest, I can try it out, when I go home to Seattle for Thanksgiving.

I was suggesting to try to keep the distance between the first stage of the FR and the second stage as short as possible (1.25" diagonal, prism instead of mirror, screw-on attachment). That way one has more elbow room for the second stage of the reducer. One can use a stronger reducer of more spacing between the second reducer and the sensor. Bot would result in stronger final reduction factor.

In my flip mirror assembly the distance between the two reducers can vary between 70-100 mm. That allows to use a variety of  second stage reducer configurations: MFR-3, ScopeStuff 0.5x reducer on short nosepiece, Scopestuff 0.5x on longer nosepiece etc. The shortest configuration with the MFR-3 also works on my natively f/6.3 Meade 10" OTA. That is the ultimate near-live EAA platform!

Clear Skies!

--Dom

[ohills]

Roy,

I assume that you will use the Nexstar 8SE with the altaz mount that is part of the package. In that case you will absolutely have to use a diagonal. The Nexstar SE mount doesn't have enough clearance between the back threads of the OTA and the mount itself a accommodate a camera in the straight position. This applies to any cameras, video, Lodestar, you name it.

The optical length of a diagonal is more than the max allowable spacing between a x0.33 focal reducer and the camera sensor. This means that you cannot use a 0.33 reducer if you need a diagonal.

You could use the following arrangement.

1. Screw a Celestron 6.3 reducer/corrector on the back threads of your OTA.

2. Screw a 1.25" visual back on the reducer and attach a 1.25" diagonal to the visual back. If you can find a 1.25" diagonal that can be directly screwed on the 2" SCT threads of the reducer, that is even better. I believe that prism diagonals have shorter optical path then mirror diagonals. If this is true, then a prism diagonal would be preferable.

3.a. You can put your Lodestar directly into the ep holder part of the diagonal for an approximately f/6.3 focal ratio. This is good for smaller and brighter objects, like planetary nebulae e.g M57. 

3.b. For a stonger focal reduction you can screw a 1.25" C-mount nosepiece and a second, 1.25" focal reducer directly on your camera. Such small 1.25" focal reducers are cheap and are sold by AgenaAstro, ScopeStuff or almost any other outfit. I use the reducer from Scopestuff because it also has filter threads on its telescope side surface. I can attach 1.25 filters to it. When I looked a couple of years ago, the 1.25" reducer sold by AgenaAstro didn't have filter threads.

With this two stage reducer you can get down to around f/3. That is good for larger objects with low surface brightness, like M101.

If you plan to do electronically assisted observing on an altaz mount, then Lodestar offers you a special advantage. You can use LodestarLive and stack longer integrations together by sum-stacking several shorter exposures. Paul's LodestarLive software has a phenomenal aligned stacking routine that rotates, shifts and transforms consecutive subs in such a way that their stars accurately overlap. This is particularly important for users of altaz mounts, which don't track as well as equatorial mounts. Filed rotation limits maximum exposure time for subs to about 30 sec on altaz mounts. But the stacking feature of the LL software overcomes this limitation. 

The sophistication and accuracy of Paul's aligned stacking in LL is unparalleled. No other software used in near-live observing comes even close. No program offered for use with video cameras can compensate for field rotation and none uses comparably sophisticated transformations. LL is only available for the Lodestar.

Clear Skies!

--Dom

Dom..... Could I just use a MFR5 attached to the x2 into the diagonal.

Roy

[HiloDon]

Thanks, Dom. I'll do some testing and post the results. Do whatever you can, too. I think it will help those with fork mount set ups.

Don

[Dave In Vermont]

This may set a record! I've posted this earlier today on another thread asking about focal-reduction. Anywho - you will likely find this document quite useful. Regardless of what the intended purpose for using such:

http://www.mallincam.net/uploads/2/6/9/1/26913006/focal_reduction_for_dummies.pdf

The MallinCam site has quite a few useful documents available. Worth a look:

http://www.mallincam.net/

Their MFR-5 and MFR-3 are very nice. I don't have the MFR-6, but it's likely very good as well.

Clear & Dark Skies,

Dave

[arkosg]

Hello all,

I routinely use a 0.33x reducer AFTER the diagonal on a Celestron alt/az setup. Other than some minor coma at the corners at times, which may be a collimation issue, it seems to work just fine.

Cheers,

Greg A

[HiloDon]

Very good, Dave. I had seen this before, but forgot about it. It answers the question of putting the 3.3 FR after the diagonal for using with fork mounted set ups. The one additional thing I can point out is that they do make a diagonal with an SCT coupling instead of the 2" barrel. It's shorter and would provide more clearance for the mount.

Don

[HiloDon]

And, confirmed by Greg!

Don

[Dom543]

Roy,

I have not tried the MFR-5. It's too expensive for my budget. But if you decide to buy it, also buy at least two additional spacers for it. They give you more flexibility.

Based on Greg's input, the 3.3 reducer after the diagonal seems to be the most straightforward solution.

Clear Skies!

--Dom

[Martin Meredith]

The sophistication and accuracy of Paul's aligned stacking in LL is unparalleled. No other software used in near-live observing comes even close. No program offered for use with video cameras can compensate for field rotation and none uses comparably sophisticated transformations. LL is only available for the Lodestar.

I know its a bit off-topic, but I was thinking the very same. I don't recall every having a single problem with live stacking in LL. At times it refuses to stack my awful subs -- which is the correct thing to do -- but if it chooses to stack then it does it extremely robustly. The fact that it can achieve this without the user having to identify the same stars in each frame (as in Nebulosity) or without tons of options (as in DSS) is a real achievement. It adds immensely to the live feel to see objects appear in greater detail as time progresses during the observing session. And since starting to go deeper/fainter/more compact I've really started to appreciate the live stacking option in aiding basic detection of objects.

Martin

[arkosg]

Hi all,

Here's the setup I use, 0.33 FR after the diagonal.  I have a Baader clicklock in place of a 

visual back, then a Baader click lock diagonal into which goes Starizona's filter slider (the

wider diameter, flat piece - looks like a hockey puck ;-)  via a 2" nosepiece, then the FR

and then spacers to get the right distance (the Lodestar, not shown, threads onto the C

mount adapter at the very end).

Perhaps there is a better way to do this (anyone?) but this seems to work, and I can tweak 

it pretty easily for FR with other spacing needs, or swap over to an eyepiece for visual work.

I also like that the fittings seem quite secure - the click locks are great, and the rest is all 

threaded, so there isn't really much slop anywhere in the imaging train, even with it's weight.

Cheers,

- Greg A

[arkosg]

I know its a bit off-topic, but I was thinking the very same. I don't recall every having a single problem with live stacking in LL. At times it refuses to stack my awful subs -- which is the correct thing to do -- but if it chooses to stack then it does it extremely robustly. The fact that it can achieve this without the user having to identify the same stars in each frame (as in Nebulosity) or without tons of options (as in DSS) is a real achievement. It adds immensely to the live feel to see objects appear in greater detail as time progresses during the observing session. And since starting to go deeper/fainter/more compact I've really started to appreciate the live stacking option in aiding basic detection of objects.

Martin

Dom, Martin,

I wholeheartedly agree with all you have said about this.  LL does such a good job, and really does preserve the live feel while allowing even alt-az users to go deeper than they could otherwise.  I've been very, very pleased with the results I've been able to get with my setup, even as a newbie to the whole video astronomy (and Lodestar) thing.  If Paul can get the simplifications for colour correction rolled out, and add an option to output a full-screen view independently to a second screen, I'd be in heaven (pun intended!), and I think the Lodestar would become an incredible outreach tool.

Cheers,

- Greg A

[Paul81]

Thank you for the kind words!

I haven't had anytime to work on LL recently, been on family holiday and work is continuing to be very busy so making it difficult to get some time to sit down and finalise V0.11.

I am aiming to get the new image processing and colour controls finished and then realise V0.11, and then do a subsequent update with some other requested features such as the independent full-screen and auto-white balance.

Paul

[HiloDon]

Thank you for the kind words!

I haven't had anytime to work on LL recently, been on family holiday and work is continuing to be very busy so making it difficult to get some time to sit down and finalise V0.11.

I am aiming to get the new image processing and colour controls finished and then realise V0.11, and then do a subsequent update with some other requested features such as the independent full-screen and auto-white balance.

Paul

Hi Paul,

Just want to agree with the others on LL's exceptional performance and ease of use. And thank you for your continued efforts to improve it.

You may have seen my post in the other thread that I have been playing with Nebulosity 3. I mentioned that the auto color balance works well. When I download a saved LL file and click on auto balance, it corrects the color perfectly, at least to my eyes. You mentioned that you were going to work on an auto balance for LL, so I thought that perhaps knowing about Neb3 might help you. I just have the demo now, but I think I will probably buy it and could generate some examples if you think it will help. Just let me know.

Don

[ohills]

Roy,

I assume that you will use the Nexstar 8SE with the altaz mount that is part of the package. In that case you will absolutely have to use a diagonal. The Nexstar SE mount doesn't have enough clearance between the back threads of the OTA and the mount itself a accommodate a camera in the straight position. This applies to any cameras, video, Lodestar, you name it.

The optical length of a diagonal is more than the max allowable spacing between a x0.33 focal reducer and the camera sensor. This means that you cannot use a 0.33 reducer if you need a diagonal.

You could use the following arrangement.

1. Screw a Celestron 6.3 reducer/corrector on the back threads of your OTA.

2. Screw a 1.25" visual back on the reducer and attach a 1.25" diagonal to the visual back. If you can find a 1.25" diagonal that can be directly screwed on the 2" SCT threads of the reducer, that is even better. I believe that prism diagonals have shorter optical path then mirror diagonals. If this is true, then a prism diagonal would be preferable.

3.a. You can put your Lodestar directly into the ep holder part of the diagonal for an approximately f/6.3 focal ratio. This is good for smaller and brighter objects, like planetary nebulae e.g M57. 

3.b. For a stonger focal reduction you can screw a 1.25" C-mount nosepiece and a second, 1.25" focal reducer directly on your camera. Such small 1.25" focal reducers are cheap and are sold by AgenaAstro, ScopeStuff or almost any other outfit. I use the reducer from Scopestuff because it also has filter threads on its telescope side surface. I can attach 1.25 filters to it. When I looked a couple of years ago, the 1.25" reducer sold by AgenaAstro didn't have filter threads.

With this two stage reducer you can get down to around f/3. That is good for larger objects with low surface brightness, like M101.

If you plan to do electronically assisted observing on an altaz mount, then Lodestar offers you a special advantage. You can use LodestarLive and stack longer integrations together by sum-stacking several shorter exposures. Paul's LodestarLive software has a phenomenal aligned stacking routine that rotates, shifts and transforms consecutive subs in such a way that their stars accurately overlap. This is particularly important for users of altaz mounts, which don't track as well as equatorial mounts. Filed rotation limits maximum exposure time for subs to about 30 sec on altaz mounts. But the stacking feature of the LL software overcomes this limitation. 

The sophistication and accuracy of Paul's aligned stacking in LL is unparalleled. No other software used in near-live observing comes even close. No program offered for use with video cameras can compensate for field rotation and none uses comparably sophisticated transformations. LL is only available for the Lodestar.

Clear Skies!

--Dom

Dom......  I picked up an antares .5 reducer and I'm trying to connect it to the x2c.  It won't connect directly to the camera.  As per 3b. in the quote I need a 1.25" c-mount nose piece that will attach to the reducer.  Can you tell me which one I could get for this.  I'm a little confused  with the different thread possibilities.

Thanks

Roy

[HiloDon]

Hi Roy,

I'm sure Dom will respond, but here's what I use. The Scope Stuff c to 1.25" is a smooth barrel. This will allow the Lodestar to be inserted into a holder beyond the connection. Some nosepieces sold have a flange at the connection which will stop the LS at the connection. Scope Stuff also has 1.25" extension rings which can be added to obtain more focal reduction. They also have 1.25" par focal rings that can be used to set the position of the Lodestar if you need it.

http://www.scopestuff.com/ss_c2b1.htm

Hope this helps.

Don

[ohills]

Hi Roy,

I'm sure Dom will respond, but here's what I use. The Scope Stuff c to 1.25" is a smooth barrel. This will allow the Lodestar to be inserted into a holder beyond the connection. Some nosepieces sold have a flange at the connection which will stop the LS at the connection. Scope Stuff also has 1.25" extension rings which can be added to obtain more focal reduction. They also have 1.25" par focal rings that can be used to set the position of the Lodestar if you need it.

http://www.scopestuff.com/ss_c2b1.htm

Hope this helps.

Don

Don...  yes it does.   This would then increase the length to the sensor.  Would I just have to refocus.  Sorry to ask these basic questions as I have very little experience.  Also would any new combinations of focal reducers and spacers just require new focus?

Roy

[HiloDon]

Yes, the addition of focal reduction will require refocusing which should be no problem with your SCT. The spacing between the Lodestar sensor and the FR will determine which reduction you have. The Antares .5 FR has a focal length of 95mm. The spacing needed to get a reduction of .5 is 47.5 mm. The Lodestar sensor is 12.5mm from the front mount. The ScopeStuff adapter is one inch or 25.4 mm. Therefore you still need one 10mm extension to get the .5 reduction. An additional 10mm extension will give a reduction of about .39 which will be nice for many DSO's with your 8" SCT. More reduction, however, can lead to aberrations. Testing with your setup is the only way to check this. Precise collimation will help a lot. Getting the nosepiece adapter and two .475 inch extensions might be a good way to start. Also, here's a good link explaining the Antares FR and the spacing.

http://agenaastro.com/antares-1-25-0-5x-focal-reducer.html

Let me know if you have any questions.

Don

[HiloDon]

Just another thought, Roy. If you use just the nosepiece adapter with the Antares, the focal reduction will be about .6, which will work nicely for smaller DSO's with your 8" SCT.

Don