Mars with Fullerscope

[astroman001]

An excellent image, lots of detail Looking forward to imaging Mars as it gets higher in the sky.

Peter

[CraigT82]

So having spent a few hours studying what seems like a hundred different Mars maps and atlases, I think I've identified the main features in my Mars image.  Some could be not quite correctly placed/identified or just plain wrong!

[CraigT82]

I took some time this morning to reprocess this Mars image, as I wasn't entirely happy with the soft/bright limb of the original (and it was a bit hurried as they always are - just wanted to see it done!)

This time around I:

1. Tested various alignment point numbers and sizes - decided that 8 largeish points spread evenly around the visible disc worked best. This had probably the most effect of improving the limb

2. Further sharpened, using unsharp mask in PS after the wavelets, each stacked tiff before loading into winjupos for measurement. This allowed more confidence and accuracy in placing the alignment frame for each image. Normally I just apply the wavelets then go to winjupos.

3. Was less aggresive with the final sharpening and contrast boosting, aiming for a bit more of a natural feel.

I feel that these differences have yielded an improved image with a better limb and more natural detail, particularly around the S polar cap.

 

 

 

 

[vlaiv]

7 minutes ago, CraigT82 said:

I feel that these differences have yielded an improved image with a better limb and more natural detail, particularly around the S polar cap.

Indeed!

[MarkAR]

Much better definition. Well done.

[Tommohawk]

Great stuff Craig - lots of detail there.

[Pete Presland]

Excellent Mars image, some lovely detail visible there.

[Tommohawk]

You seem to get really good results with your Fullerscope, and I'm just wondering quite what the trick is. I'm sure a lot is down to capturing / processing skills, and wouldn't want to underrate that of course, but for a 222mm mirror the result seems exceptional. I have long held the view that a reduced central obstruction plays a large part in this, and I imagine the secondary on your scope is quite small - have you any idea what the diameter is?

From my own experience I have a 200P (not DS) with the old smaller secondary and this has consistently given images comparable to the OMC200 I owned for a while (which cost about 10x the price!) and also comparable to the C9.25 I used to own. 

Just wondered what you thought on that?

[CraigT82]

My scope has a CO of 20% which is obviously pretty small but I think the quality of the primary is the bigger factor. Its only a B grade mirror and so probably somewhere around 1/6th wave PtV but it's very smooth and visually the stellar images are fabulous. Being f/7.5 its also very easy to collimate and being a newt it's very easy to thermally manage. These two last things probably the 2nd and 3rd most important factors in planetary work (the first being the seeing!). 

I think there is a shift occurring amongst planetary imagers, with some of the best switching away from the big SCTs in favour of smaller but optically better scopes. Damian Peach now uses a mewlon 250 and is producing stunning images, and also a chap named Jean Luc Dauvergne who uses a mewlon 250 as well as a mewlon 300 and is producing some of the best images ive seen from his central paris 10th floor balcony.  You would not believe the detail you van get from a 250mm scope!

Check this out: 

 

Edited August 15, 2020 by CraigT82

[Tommohawk]

Hi Craig - that's very interesting, and as you say fantastic images by Luc Dauvergne.

So... your small CO of 20%  fits the idea that a smaller CO is beneficial. That said the Mewlon doesn't have a particularly small secondary (70mm for the 250mm) so with the Mewlon I guess it must be more about mirror quality.

I guess it must be the case that producing a larger mirror that's optically of the same quality is going to be more challenging/expensive, so maybe a smaller better quality scope fares better. It's probably also true that faster mirrors are generally more aberration prone. 

With a smaller CO in mind I've been playing around with a 250mm F4 Quattro mirror which I've mounted in a longer OTA and fitted a small (42mm dia) camera at prime focus by adapting the secondary spider. Havent really had much of a chance to test it so far, but first impressions are that it works but doenst have quite the resolution that I'd hoped for. Probably this just says that a 250mm Synta mirror isnt as good as a Tak mirror. No surprise there!

But its early days, and I will test it more rigorously with Mars when weather/covid/house move/other domestic stuff allows.

[skyhog]

Nice image craig.

 

Ed

[orion25]

Gorgeous, image, Craig. It's getting closer and brighter

 

Regards,

Reggie