ollypenrice

The minimum mount is the mount which is a little above the minimum mount you need! But seriously, this really is the truth. If you joined an astrosoc you might find someone who could look over a mount for you. Buying second hand is certainly the biggest way to cut costs. A large majority of the kit I use as an astronomy provider was second hand, including 2xMesu 200 mounts, Takahashi FSQ106, TEC140, Meade LX200 14 inch and DMK planetary camera and Atik 460 CCD. It's all perfectly good kit and no different from new.

The HEQ5 is a good mount with plenty of backup available.

Olly

1 hour ago, RolandKol said:

Why it's so secret?

I am even getting curious

Skipper Billy started it with his submarines!

Olly

Yes, it is worth repeating that mount tops do not need to be level and this can simplify their construction. Polar alignment is not affected though it might need a couple more iterations of drift. Takahshi mounts and tripods have no facility for levelling, just in case you're doubtful about this!

Olly

Well, you have the data! That's beautifully processed as well.

Olly

Firstly I would only add star colour to a NB image which was aiming to approximate natural nebular colour in the first place, probably HOO.

Rather than try to 'fill in' the star colour on the HOO you could use Photoshop like this:

1) Process the RGB, the Ha and the OIII and align them to fit each other. In processing the RGB concentrate on the stars, keeping them small and colourful and don't worry about the nebula which will be coming from the NB layers.

2) Add Ha to red in blend mode lighten, making sure your Ha stars are smaller and fainter than your red stars. (Use multiple iterations of a star reduction routine like Noel's actions or whatever on the NB layers.) save three copies of this. Call this Ha to red.

3) Add OIII to green in blend mode lighten in one of the copies and call it OIII to green.

4) Add OIII to blue in blend mode lighten in another copy and call it OIII to blue.

5) Make a three-layer stack like this:

OIII to blue

OIII to green

Ha to red.

Now you can choose opacities for the top two layers which give you the most natural nebular colour. Your RGB star colour should be unaffected.  As you can see, this method does not work by replacing star colour so it gives a more natural look, yet the NB contribution to the nebulosity is the same.

Olly

54 minutes ago, John said:

I worry a bit when I see scope decisions based on the achivement (or not) of a very specific observational challenge.

Ten members here could say that they can easily see E & F Trapezium with a certain scope, then you get one, and can't make them out. I'm not sure where that has got you ?

 

I'm intrigued by this as well. I have a very dark sky, sometimes reaching SQM22, but the seeing is predictably variable. I have never found E and F 'easy' though this may be me. I'm not a double or multiple specialist. Sometimes I'd call E reasonably easy but never F. Possible but not easy. I've used 10 and 14 inch SCTs, 20 inch Newt, TEC 140 apo, and F has never been 'easy' for me.

Olly

Stunning extensions and a nebula which is both fluffy and sharp. The Holy Grail! When you can get the stars as good as this the case for camera lens imaging becomes very hard to refute...

Olly

Very nice deep luminance. This should bag you some rich brown dust when you add the colour.

Olly

Deep and sharp. Good job.

Olly

On 14/02/2019 at 16:27, Barry-Wilson said:

? - that's correct.

Cropping included? This seems odd to me. Mind you I don't know the routine at all but I'd have thought that stacked image borders had unique artefacts of their own.

Olly

The TEC140/Mesu/Atik 460 has been busy this year.

Bubble in HaOIIILRGB

An insane amount of effort went into catching a hint of the fossil accretion loop around NGC5907. Please tell me you can see it!

A widefield from the Twin Taks in Vulpecula setting M27 in context. (High res M27 data blended in.)

As with the image above, the interesting NGC7129 below was done with guest Paul Kummer:

And finally a comparison of two planetaries, the Owl and the Cat's eye at the same scale:

Happy new imaging year to all.

Olly

It seems to me that the camera manufacturers are imposing on us a kind of mental double negative which isn't very helpful. I have had to look this thread up again since I'm back in the reducer spacing jungle! Groan.

I'm going to follow Don Goldman and add 1mm of metal to the hardware connecting flattener to camera. That is, I'm going to make it an 86mm separation rather than a filterless 85mm.

Olly

I find I can't do darks on the scope at all and that's that. I have to do them with the camera out of the system and the metal screw-on chip cover fitted. And this is on refractors with fully sealed electric filterwheels. How does the light get in? Not a clue - but it does. I compared 30 minute darks done on the scope and off. They were certainly very different from each other.

There do seem to be a lot of threads discussing reflections in CMOS cameras.

Olly

4 hours ago, Rusted said:

More worrying is that the Brewery seems somewhat larger than the observatory.

Do we detect a conflict in priorities? 

No, a rare sign of sanity by SGL standards!

Olly

And does the shed at right angles on the right contain a conveyor belt of instruments ready to feed into the observatory in the event of a target needing a small change in resolution, aperture, field of view, etc??? How splendid!

Or, more seriously, this really does look great. 

Olly

On 17/12/2018 at 23:40, MartinB said:

That's very interesting and helpful, thanks Mark.

Not worth any angst though, Alnitak creates an extreme situation and a quick Photoshop 100% radial blur on Alnitak will have it fixed in a jiffy!

This is the processing solution. I have the process saved as an action - indeed I have three versions of it for different sized stars. Use the magic wand to select the star and then

Start recording.

Select, modify expand (by x.)

Feather (by y)

Filter, blur, radial blur, spin, best quality. (Put this command in twice.)

Deselect

Stop recording.

The values for x and Y you have to find by experiment and the larger the star the larger the value, which is why I have three saved. If you save the action to a function key all you have to do is click on the star with the magic wand and then hit the key to run the action. It is one star at once but not many will be affected so the whole process is quick. You could experiment with the best stage in the stretch to run the action.

Olly

46 minutes ago, Whirlwind said:

I didn't read the article myself but this in itself should not be a surprise.  I'm assuming the resolution of the test between the 14 inch and 6 inch were similar overall?  

The benefit of a larger scope comes from that at the same arcsec/pixel you can get more flux per pixel for the same amount of time.  So if you 0.8" per pixel on the 6" then on a 14" at the same resolution (and assuming same sensitivity) you'll get more flux on each pixel.  As such fainter details should show up earlier for less time observed. Usually though longer focal length instruments have "/pixel that are much smaller and spread the light out further so you don't see this gain in aperture.

I think sometimes this is where getting more resolution issue comes from.  There is likely a limit in any sky as to how well resolved you can make an object (without fancy tech anyway and 8000ft high telescopes). However you should get to the fainter stuff quicker *at the same "/pixel* which might make it seem like you are getting a higher resolution.

The resolutions were 0.66 for the big scope and 0.9 for the small one. Realized detail was honestly about the same.

The test was complicated by the greater sensitivity of the small pixel camera. In fact the smaller telescope with smaller but more sensitive pixels was probably faster but I didn't have the original raw data to explore this side of the comparison.

In priniciple I agree with you, though.

Olly

In my view these conversations spend too much time on the weight issue and not enough on the accuracy which, at these pixel scales, can be the dominant factor.

Olly

Why are you keen to add resolution via focal length and then reduce it via binning? It really doesn't matter whether you fill the frame or not. What matters is how many pixels (single or 4 pixel superpixels) you put under the object's image as projected by the telescope. It is this which determines the object's image's final size at full size (1 camera pixel = 1 screen pixel.) *

Earlier in the year I did a comparison in Astronomy Now between a 14 inch scope (2.4M FL) with large pixels and a 150mm scope (1M FL) with small pixels on galaxies. I found that the level of resolution and the size at which the images could be presented on screen was effectively the same. It seems that the considerably greater optical resolution of the larger scope was not translating into more final details. In both cases the mount was running with an RMS of less than half the image scale.

Personally I'd look for a scope with a FL which will give you about an arcsecond per pixel or a tiny bit less and make it the kind of nice simple design that you know you will find productive. I've struggled with one of those RCs with a guest and got nowhere. The theory is one thing but this example did not behave according to the theory.

Olly

*Not the best sentence I ever wrote! 

7 minutes ago, emadmoussa said:

I'll probably test the scope under the stars first and see if it needs cleaning at all. Standing in front of it, the corrector looks fine, shining light on it, it looks horrifying -ish. 

I'll be bugging you once I've received all the kit and cleaning products. I should be collecting the scope on Friday. 

The 'flashlight test' makes anything look horrible. Ignore it.

Nice one from Dave here!

Olly

32 minutes ago, emadmoussa said:

I've got an LX90/LX200 tripod, but it's missing the tension bolt and, unfortunately, I'm struggling to find a replacement. Otherwise, I'll be forced to find a whole tripod just for the bolt. 

 

 

You'll get one from any country still so primitive and misguided as to be using imperial threads. No further comment, but don't mention Mars landers...

Olly

11 hours ago, Viktiste said:

No I have not done that  - yet. But I will do. Another thing i found is that there are no physical surfaces to place a level on (unless you take the head off the tripod - which I don't want to do every time). And the built in level seems a bit inaccurate... 

To be honest leveling really makes no significant difference. 'About level' E-W will set your reticle 'clock' to an orientation which will be good enough. Leveling N-S is meaningless anyway since you're going to tilt the mount to the angle of your latitude and the angle of your tripod on this axis matters not. (Avalon mounts have a good bubble level but it operates only on an E-W axis. You only need to level mounts N-S as well if they are alt-azimuthal with Go-To and tracking.)

Olly

On 27/11/2018 at 18:43, Viktiste said:

OK, thanks. So the circle in the polar scope is just like a regular 12 hour clock? 

Yes, and the only critical reason for leveling your mount is to set the polarscope 'clock' onto a horizontal surface so you get a true reading.

Have you checked that your polarscope is parallel with the RA axis? To do this you set the mount up so the polarscope's central marker sits on a distant point like the tip of a church. You then rotate the RA axis. When properly aligned the marker will stay on the steeple tip. If it's out it will describe a circle. It can be adjusted with its three radial screws.

Olly

I'll be studying this with interest, Steve, since I have never been able to get any sense out of deconvolution (other than with a small format 8 bit system in an old copy of Astra Image which I once had.)

Thanks for posting.

Olly

Edit Corrected the name of Astra Image.

I'd read this characteristically excellent article by Jerry Lodigruss. Seagulls are in there!

http://www.astropix.com/html/i_astrop/Diagnosing_Trailed_Stars.html

Which looks like a 'best fit' with your problem?

The fact that a scope is new doesn't mean you should expect it to be collimated after delivery. This is unlikely, alas.

Olly