Sunshine

14 minutes ago, vlaiv said:

It does not quite work like that.

What spider supports actually do is alter PSF of a telescope. PSF is short for point spread function and you can deduce how it behaves from its name (with a bit of imagination and help of math ). It describes how light "spreads" from each point.

Stars are single points of light so star image is good representation of PSF itself.

Extended objects behave differently - like they are composed out of vast number of tiny points placed next to each other, and each of those points is affected by same PSF as above star is.

However, this process differs from waves in that it won't be susceptible to interference - but rather it is simple addition. Where spikes from multiple points cross - there won't be cancellation on phase (like you get with interference) - but always overlap / addition.

For several points this is what happens:

In each place spikes overlap - you get just a tad brighter spot.

It took some searching online to find suitable image - but look at this crop:

Now - we need to "extrapolate" the effect on entire planet - where each little bit of planet's image is single "star" and has its own spikes that overlap. That reduces contrast on the features just a tiny bit and leaves one "gigantic" cross that looks like this:

which is really just "tightly" packed pattern like this:

If I find suitable image and adjust exposure - we should be able to see it in the images as well. Let me try.

This is probably the best example that I could find - not sure if this is imaging attempt or phone at the eyepiece - but it shows the effect:

I knew that 😂

55 minutes ago, Craney said:

I might be wrong here ..... often am .....   but I thought that extended object like planets  did not give significant diffraction patterns whereas 'point' objects like stars did produce them.  All to do with image formation and superposition of waves.

That's why I thought you could only use stars for Bahtinov masks as well.

Bright objects like Mars, Jupiter do give diffraction spikes, hefty wide ones but not as bright or dense as stars, my 8” dob produces obvious and wide spikes on Jupiter.

Simply beautiful!

27 minutes ago, vlaiv said:

Most people imaging with newtonians don't in fact have curved spiders.

We see spikes in deep sky images because of vast difference in brightness between stars producing them and objects that we try to image so we stretch our data a lot.

Planets are on the other hand much much brighter and don't have nearly as much dynamic range as DSO images. Spider effect will be there - but won't be visible in images, so you don't have to worry about that.

Thank you! I was wondering about a Jupiter image with four bright spikes, not so pretty.

As some may have heard, I have been mulling over purchasing a larger refractor but as I take into consideration my yearning to continue planetary imaging I have had a change of heart, somewhat. Lately, my curiosity over a Mewlon 180 has me considering one, but a thought hit me like a brick regarding diffraction spikes, these are not present in SCT’s and Mak designs. How would diffraction spikes produced by the Mewlon show in planetary imaging? I certainly would not like planetary images with glaring spikes, I am not sure how and if they would present themselves. Pardon my ignorance but I have no experience imaging planets in Newtonian or the like which have secondary veins, though I am aware that many do planetary imaging with Newtonians and even dobs, yet I haven’t seen images of Jupiter with spikes anywhere so am I missing something? do they show up in planetary cameras? Thanks.

Wow! great images, the sun looks like it has a bad case of acne.

1 minute ago, mikeDnight said:

The Equinox 120ED is a beautiful scope and can hold its own against many other ED's both doublet and triplet. The very first time I looked through one at the Moon and jupiter, I remember exclaiming "that's very Tak"!  By that I meant I thought it was close to my Tak FS128, though the two were never used side by side. The Equinox came on the scene after I suffered a misadventure with a NP101, and it was a real breath of fresh air. However, after buying a FC100DC in 2015, I ran both scopes alongside eachother while observing Jupiter and found the DC gave a more vibrant and better defined view of the intricate belt detail, so I decided to let the Equinox go.The difference was subtle, I just prefered the DC.

That is very interesting, that you say your DC outperformed it despite the equinox having 20mm more clear aperture, a testament to Tak optics.

1 hour ago, mikeDnight said:

A single black and white photo of John Mallas 4" Unitron was so gorgeous that it made me determined have a refractor of my own.

A 1950's advert for Unitron.

 

These are some of the ones I've owned and some I still own. IT'S AN ILLNESS AS YOU'LL SEE! They are all works of art to me, and given the British weather, why not buy a scope that's as beautiful to look at as it is to look through!

My first was a 60mm Astral. I still have a real soft spot for this scope.

Here are some more recent:

   Takahashi FS128

Takahashi FS152

 

Equinox 120

Takahashi FC100DC 

 

Takahashi FC100DZ 

Vintage Genesis SDF

 

6" F10 achromat

And a sweet vintage 60mm Carton .

 

An inspiring collection! Your place must look like a monument to the refractor telescope, I notice you have an Equinox 120, I like the look of that scope with it’s silver accent rings. Having had as many refractors of such high quality as you have, does the Equinox impress and stand among the others with its head high? I have seen them once in a blue moon in the classifieds.

This is just a tripod but I am giddy with its curved legs and gold accents, I pulled this image off google, may be a moonraker creation.

On 29/11/2022 at 17:53, plyscope said:

Some years ago I had two 6 inch refractors. The longer one used a D&G f15 lens. The shorter one used a Jaegers f5 lens. They were complimentary in that the f5 was good from 25x to 59x and the f15 started at 58x and was good up to 200x and more.

Wow, these certainty belong in this thread, they really are unique! 

Beautiful! It reminds me of the Antikythera Mechanism.

This is the fist such map of Mars I have seen on SGL, this is great!

This is a wonderful image, and big!

R.I.P Sir, you will be missed.

6 minutes ago, mikeDnight said:

6 feet high on an Orion field tripod

Whoa! thats one tall monument to amateur astronomy!

My trusty and much loved Vixen GP carries my fav scope so well, still silky smooth considering it’s age. When I’m in the mood for alt-az I have a UA Doublestar tandem mount, the image shows dual saddles but I have removed the unused saddle to save weight.

On 13/03/2022 at 05:12, badhex said:

An ancient Charles Frank GEM in storage and in need of refurbishment 

An (undermounted here) LXD-55 clone also in storage

EQ6-R Pro which sees no use at the moment

AZ-GTi, my most used mount

Skytee-2, current most used manual mount

I've just purchased a Scopetech Mount Zero as well as the Skytee is a bit cumbersome at times, but don't have any great photos yet. Will post up once I do. 

 

Wow! I am surprised to see that 152 on an LXD-55, it carries it without issue? I wouldn't have thought.

On 26/02/2022 at 05:56, johninderby said:

OK I’ll start with my Rowan AZ100 Alt-Az GOTO or manual mount on a Planet tripod..

What a beauty!

2 hours ago, 900SL said:

 

Wow, this looks like something out of a Dr. Who episode (the originals) what is it? it is beautiful.

2 minutes ago, Joef said:

I didn’t even realise we had a duck, must pay more attention. 

Yes, he seems to love the scope!

9 minutes ago, Joef said:

A 200PDS and a HEQ5 PRO, arrived Monday and yesterday, all I need now is some clear weather to try it out. Dave the cat has always been here. 

It seems Dave the cat doesn't care at all about your new scope, dewey the duck like it! CONGRATULATIONS!

This is beautiful, I love wide field DSO images.

That is a beautiful Vixen! I have a soft spot for the creme colour tones of those old Vixen's, it look beautiful on the Vixen mount!. You mentioned you are having the mirror restored? that would be great, I would love to find one just like it but I'm sure they are rare birds. As much as the SXD2 offers modern conveniences, I still prefer how it looks on the original polaris mount, wonderful looking telescope!.

Fantastic!

That depends on who is behind the telescope, with my imaging knowledge if you gave me your C11 and your laptop for a night I would utilize my button mashing skills and end up with an image just like the first one! but I'd still be pumped enough to post it here 🤣