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Scope Recommendations


Gina

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1 hour ago, pete_l said:

Check it out for yourself Meade 12 inch ACF Optical Tube Net Weight 56 lb (25.4kg)

Interesting, This is the F8 and I can only for what ever reason believe this must weight more because an F10 for sure does not, I actually looked long and hard to find the weight of the F10 as I was going to de-fork mine to try it on my AZ EQ 6. If this is the same weight and I am stronger than I thought then there isn't much chance of using it on the mount. I am fairly sure I read the 10 inch Meade F10 is 13KG and the Celestron 14 inch is 20kg, I would find it hard to believe the 12 inch is 25kg, if you see my point. Guess the acid test is to stop typing and go outside and take it of the fork and weigh it. Thanks for the link though.

Alan

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Out of curiosity, why did no one mention good old slow newtonian as very good planetary imaging scope?

I'm sure one can be purchased well under the price of C9.25 and C11 while providing equal or better resolving power?

For example Orion UK VX10L

It's a 10" scope, so it will out resolve C9.25, it costs a bit less than £700, it has 25% CO so again advantage over SCT type, and most scopes will need barlow anyway for planetary imaging so no much difference there.

VX12L will out resolve C11, but it's a bit over grand (again, less than C11).

Only problem with it is bulk for mounting, but EQ8 will handle them for planetary imaging with ease.

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Getting a bit big for my observatory so would need to check.  I did think of a Newt but only looked on FLO for examples and FLO don't sell Orion.  A 10" should certainly be better than the 7" I have now (MN190).

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On ‎25‎/‎05‎/‎2019 at 11:26, vlaiv said:

Out of curiosity, why did no one mention good old slow newtonian as very good planetary imaging scope?

I'm sure one can be purchased well under the price of C9.25 and C11 while providing equal or better resolving power?

The problem with a Newtonian is getting it to focus. With an unmodified Newtonian I'm told it can be a problem to get the camera to focus.  if one adds useful accessories like a flip mirror, ADC  etc the problem will become acute.  With a SCT the focal range is such that there is no problem. 

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1 hour ago, Cosmic Geoff said:

The problem with a Newtonian is getting it to focus. With an unmodified Newtonian I'm told it can be a problem to get the camera to focus.  if one adds useful accessories like a flip mirror, ADC  etc the problem will become acute.  With a SCT the focal range is such that there is no problem. 

Maybe there is such problem with imaging newtonians that have larger secondary and focal plane closer to it to maximize illuminated field. I don't think there will be problem for regular slow / visual newtonian with smaller secondary.

I've used two such scopes for planetary imaging - one F/6.9 and other F/6 and both had plenty of focus. Barlow lens usually moves focus further away from the tube so that is also beneficial. I'm sure ADC can be fitted, not sure for flip mirror, but then again, I never used one, even with FLs of 3 meters or more. Properly aligned finder is about all that is needed.

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They are popular with planetary imaging but larger SCTs are expensive. As a silly example for the cost of an Edge HD 14" OTA you could get an EQ8 or CEM60-EC; a SW Explorer 300P-DS; plus a Televue 2.5x Powermate, some eyepieces, an ED80 too, and have plenty of cash left over for building a pier and dome/RORO shed., and on old banger to bring the supplies back from the DIY store...

To be honest the best views of the planets I've had have been through longer F/L reflectors or dobs. When imaging, software and camera have a large influence on the final image.

To get the best out of a C11 or C14 on things other than the moon or planets (e.g supernova hunting) you need a strong mount, an EQ6 isn't going to cut it in the long run. 

You can pick up a used C8 for a reasonable price second hand though. As a previous poster suggested there maybe some good deals with the planets in less than optimal altitudes for the next few years.

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I’ve been successfully using a C11 plus spectroscope, four cameras, electronic finder etc mounted on a NEQ6 for the past ten years.

No problem guiding on a 20 micron slit gap indefinitely.

Works for me.

 

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3 minutes ago, Merlin66 said:

I’ve been successfully using a C11 plus spectroscope, four cameras, electronic finder etc mounted on a NEQ6 for the past ten years.

No problem guiding on a 20 micron slit gap indefinitely.

Works for me.

 

Although original topic is related to planetary imaging where there is absolutely no need for guiding, I'll just point out - keeping star on a 20um slit with C11 is really not a great feat of guiding, and I would be surprised if you could not manage to do it with EQ6 class mount.

At 2800mm FL, 20um equates to 1.47", and keeping star in this range is no problem at all, given that most of the time, star FWHM is going to be about as large as the slit or larger, and that EQ6 can easily do below 0.75" RMS in one axis (and usually at least about that total RMS) - and I guess that you align your slit with one axis - probably RA so that any RA motion is up/down the slit and DEC actually moves star off slit.

 

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The slit is arranged along the Dec axis.

There is no or minimal movement in either axis during the guiding.

As you say you can achieve say 0.75 arcsec which is half the average FWHM with good seeing of 1.5 arcsec.

I was answering the post on the use of the C11 on a NEQ6.

 

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11 minutes ago, Merlin66 said:

The slit is arranged along the Dec axis.

There is no or minimal movement in either axis during the guiding.

As you say you can achieve say 0.75 arcsec which is half the average FWHM with good seeing of 1.5 arcsec.

I was answering the post on the use of the C11 on a NEQ6.

 

Ah, yes, I missed that, you were addressing this part then

Quote

To get the best out of a C11 or C14 on things other than the moon or planets (e.g supernova hunting) you need a strong mount, an EQ6 isn't going to cut it in the long run.

Good point - EQ6 and C11 are capable of very serious work

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