Mars - Realistic Expectations?

[Guest]

5 minutes ago, johninderby said:

Hmmmmm.............wondering if this is a bit like lunar observation in that some seem affected by the brightness and for others it's no problem. A question of light sensitivity? 🤔

You maybe right...   I wear sunglasses for much of the year, as I find strong sunlight is blinding and makes my eyes tired.  I get them regularly checked by the optician, but don't have any problems than a slight prescription to wear for reading.  I find that I don't have to use a lunar filter, but perhaps I could try that on Mars, till I can get something more suitable.  I'm going down the route of getting the collimation checked out sooner, rather than later.

[johninderby]

Reminds me of my annual retinopathy test where they put drops in your eyes to fully dilate the pupils. I hope it’s a cloudy day as bright sunlight is physically painfull afterwards. No driving for four hours after the test. . 

Edited August 8, 2020 by johninderby

[John]

Dark adapted eyes are not helpful for picking out subtle planetary detail IMHO. I've had my best views of Jupiter when there has been quite a lot of light still left in the sky. As the sky darkened, the subtle detail becomes harder to pick out.

I believe some experienced planetary observers deliberately stare at a large white card illuminated with a flashlight immediately before observing. 

Must be fun at a star party if your neighbour is trying for faint deep sky stuff

[Guest]

6 minutes ago, John said:

Dark adapted eyes are not helpful for picking out subtle planetary detail IMHO. I've had my best views of Jupiter when there has been quite a lot of light still left in the sky. As the sky darkened, the subtle detail becomes harder to pick out.

I believe some experienced planetary observers deliberately stare at a large white card illuminated with a flashlight immediately before observing. 

Must be fun at a star party if your neighbour is trying for faint deep sky stuff

I can't claim that my eyes were fully dark adapted, as there's quite a bit of light from the neighbour's gardens and I was going in and out a few times...

Edited August 8, 2020 by Guest

[Victor Boesen]

I've found that my small Evostar 72ED DS-Pro actually succeeds my 10" dob on Mars sometimes. The dob is of course far better under good conditions but for regular views of Mars I prefer using my small refractor. Last week I could easily spot surface markings (rough changes in surface color that is) and the polar cap was also visible. I use 90X in my refractor.

Further details can be found here if you're interested: https://myastronomyjourney.wordpress.com/2020/05/29/skywatcher-evostar-72ed-ds-pro-observing-jupiter-saturn-and-mars/

[Guest]

9 hours ago, John said:

Dark adapted eyes are not helpful for picking out subtle planetary detail IMHO. I've had my best views of Jupiter when there has been quite a lot of light still left in the sky. As the sky darkened, the subtle detail becomes harder to pick out.

I believe some experienced planetary observers deliberately stare at a large white card illuminated with a flashlight immediately before observing. 

Must be fun at a star party if your neighbour is trying for faint deep sky stuff

One thing that strikes me as odd, is that I can make out the 2 orange bands on Jupiter and the rings of Saturn at 150x magnification (this evening), when the gas giants are low in the sky - yet I can't see any details on the Martian disk, even though it's a lot nearer (allowing for size and magnitude variation). 

[John]

23 minutes ago, merlin100 said:

One thing that strikes me as odd, is that I can make out the 2 orange bands on Jupiter and the rings of Saturn at 150x magnification (this evening), when the gas giants are low in the sky - yet I can't see any details on the Martian disk, even though it's a lot nearer (allowing for size and magnitude variation). 

The details on Mars are more subtle than Jupiter's two main cloud belts. Saturn's rings are very strong contrast features. Saturn's surface belts are somewhat tougher to make out than Jupiter's. Jupiter's festoons are a bit like Mars darker areas:

[Guest]

2 minutes ago, John said:

The details on Mars are more subtle than Jupiter's two main cloud belts. Saturn's rings are very strong contrast features. Saturn's surface belts are somewhat tougher to make out than Jupiter's. Jupiter's festoons are a bit like Mars darker areas:

I guess it must the the Equatorial Belts on the Jovian disk, that I'm seeing.  Would it be fair to say that if the collimation was out, that I wouldn't see them?

[Ags]

Collimation is rarely perfect and it is possible for collimation to be a bit a little bit off and still see the bands on Jupiter, which are very prominent.

To test collimation, point the telescope at a moderately bright star, use your highest magnification, and place the star at the very center of the field. Is the star symmetrical? If you can see the main diffraction ring, is evenly lit all the way round?

Regarding contrast on Mars - remember the whole planet is layered with uniform fine red dust. The features we can see are consequently quite subtle.

Edited August 8, 2020 by Ags

[John]

8 minutes ago, merlin100 said:

I guess it must the the Equatorial Belts on the Jovian disk, that I'm seeing.  Would it be fair to say that if the collimation was out, that I wouldn't see them?

The two main belts are the first thing you see on Jupiter. I used to see them with my 60mm refractor quite easily.

I would say that even a scope that is out of collimation would still show them. The finer details and lesser belts, maybe not.

Try a star test as @AGS suggests. Polaris is a good one to use because it stays still. Use around 200x and rack through focus a little either side and compare the views. Concentric rings and a central secondary shadow either side of sharp focus are good signs.

If you can split Epsilon Lyrae then things are probably not far off.

 

[Guest]

Just back in from briefly observing Mars. I thought I could make out a darker area in the centre of the Martian disk, running vertically. It was almost in the shape of the African continent. There did appear to be some atmospheric distortion, unfortunately. 

I did the Airy disk test in both directions on the Martian disk and it should the classic in-collimation pattern. I couldn't see any starts due to it being partly cloudy and LP, but in the past I've had classic in-collimation Airy disks.  I'll still be ordering a Cheshire EP and collimation cap, though. 

[John]

The "african continent" shaped darker area may well be the Syrtis Major. It has a rather triangular shape.

The airy disk / star test is done on stars rather than planets.

 

[markse68]

Had a quick look just now as the moon and Mars were pretty clear of clouds and Mars is getting really quite high now! I remembered I’d bought this filter a while back so thought i’d give it a try- well it is called a Mars type B filter so why not! Well it definitely makes for a properly red planet! Even the ice cap... But it did most definitely increase the contrast and make the dark features stand out better. I don’t think it’s available anymore but there maybe something similar? it’s an orange colour to look through with dichroic reflective coatings on each surface. Seeing was terrible tonight though- really shimmering most of the time. I’ll definitely use it again in better seeing. Oddly the moon which was lower suffered less from the poor seeing 🤷‍♂️

Mark

[John]

Good seeing here just now. No filter (Tele Vue discontinued them after a couple of seasons) but the Martian disk looks pretty much like this with the Tak 100mm:

 

[Guest]

5 hours ago, John said:

The "african continent" shaped darker area may well be the Syrtis Major. It has a rather triangular shape.

The airy disk / star test is done on stars rather than planets.

 

It was difficult to tell what I was seeing, I thought I was imagining it like Lowell did.  I realise that stars are preferred to do the Airy disk test on, I've done that in the past and the results were okay.

[Guest]

5 hours ago, markse68 said:

Had a quick look just now as the moon and Mars were pretty clear of clouds and Mars is getting really quite high now! I remembered I’d bought this filter a while back so thought i’d give it a try- well it is called a Mars type B filter so why not! Well it definitely makes for a properly red planet! Even the ice cap... But it did most definitely increase the contrast and make the dark features stand out better. I don’t think it’s available anymore but there maybe something similar? it’s an orange colour to look through with dichroic reflective coatings on each surface. Seeing was terrible tonight though- really shimmering most of the time. I’ll definitely use it again in better seeing. Oddly the moon which was lower suffered less from the poor seeing 🤷‍♂️

Mark

 

I tried my lunar ND filter on Mars, but couldn't really see much difference.  I used it just on the off chance that it would increase the contrast, it certainly works on the moon...

[Guest]

5 hours ago, John said:

Good seeing here just now. No filter (Tele Vue discontinued them after a couple of seasons) but the Martian disk looks pretty much like this with the Tak 100mm:

 

Are refractors better for planetary observing?🤔

[mikeDnight]

Refractors are probably the scopes least affected by seeing conditions, and their relatively small aperture doesn't create an overly bright planetary image, so detail can appear better defined. They are still limited by their aperture in terms of resolution, but their sharp images often present a more pleasing view, often revealing detail lost in the glare of large aperture scopes. And because of their ability to sharply define detail, the observer can often increase the image scale by using high powers to reveal a greater discernible level of detail.

Try enlarging John's image of Mars to find the sweet spot. The same detail is in the image at every stage, but I find enlarging it to between 8 & 10mm gives the best discernible amount of subtle detail. Frac's are good at this as they take magnification well!