Can't see planetary detail!

[Darth Wader (Wade)]

I've read on this forum and many other places of people viewing moon transits on Jupiter and Saturn, Jupiter's great red spot as well as seeing the polar ice cap and dark features on Mars. I have a collapsible 8" dob and even under optimum conditions I have not managed to see any of these things. The planets are bright, maybe a little too much, but no detail is visible (save for the two cloud bands on Jupiter). Mars has been especially disappointing as all I can see is an orange disc at times of (what I thought was) good seeing. I have read of people with the same aperture scopes seeing them - what am I doing wrong? Could it be because I don't have a light shroud? Do I need filters/higher mag/proper dark skies? Am I better off with more aperture (I can be easily persuaded to upgrade to a 12" dob - in fact, I'm looking for an excuse)?

Thanks in advance

Cheers
Wade

[mswhin63 (Malcolm)]

For the most part there are planetary eyepieces which have significant magnifacation to view planets and there detail, standard eyepieces IMO don't really cut it.

With a DOB it is also a matter of how steady you can hold it.

Finally filters, they hold a big key to detail, I know even with my 12" there is not a significant amount of detail but I know that when filters are used these can also enhance detail.

Most of the time for planets especially the image is way to bright, filters also work well to bring down the brightness of the planet to provide more comfortable viewing.

In some cases I close of the main apeture with the 50mm hole in the standard cover which I find excellent for the moon viewing and imaging.

[el_draco (Rom)]

Hi Wade,
You are experiencing what a lot of people discover when they start out. Big beautiful glossy photos are not what is visible through most amateur scopes. The moon is a exception in that you can see a world of detail without trying hard.

As for the other planets, you have to learn to pick out subtle details and adjust your equpment where possible.

1/ Seeing conditions stuff up a lot of planetary detail because it gets lost in the "boiling"
2/ Filters help by enhancing detail in things like cloud belts, polar caps and the like.
3/ A very accurately aligned optics are important to eliminate optical errors.
4/ Increased magniication or the use of a barlow sometimes helps but both often magnify all the errors listed above and generally wash out the image.

5/ Some targets are just damn hard. Mars is a good example. Its small to start with and only relatively close to us for short periods, now being one of them. Its a challenge in most scopes, very hard in anything short of a large scope.

Jupiter and Saturn are the most rewarding though Saturns rings are just past edge on to us at the moment and not "spectacular". That will change over the next few years.
With your scope, you should be able to pick out more on Jupiter including several cloud belts, the red spot and the four main moons, easily. The shadows from transits are more challeging, but do-able. Both planets will still look relatively smal in your scope.

My first large scope was a 12 inch F4. Newtonian and that gave really good views of these two plaets. If you can afford it, I'd sure as hell up grade but do some research first.

A 12 inch scope will collect 4 times as much light as your 8 inch, reveals much, much more detail, but is also heavier and only marginally transportable unless you get a collapsable scope.

If you want an excuse, to go for a 12, I am happy to provide it:
- I am sure you would not be disappointed with the performance.
- There are 12 inch scope regularly offered on the forums for what I would consider a song!!
- Cheaper than drugs, fast cars, and women of all types...
- Allows you to gain perspective of you place in the universe

Rom

[Screwdriverone (Chris)]

Hi Wade,

Not a light shroud problem, most planets are so bright the light getting into the tube has little effect. The problem is possibly aperture or magnification.

Aperture: more aperture will give more resolution which in turn means you will see more details. My 12" collapsible shows dark areas on Mars as well as the ice caps. However, this is generally at HIGH magnification

Magnification: The more the better on planets, The theoretical limit for magnification is 2 x the aperture of the scope in mm, therefore, yours would be 400x which, if your Focal Length is 1200mm (from the website) means you will need a 3mm eyepiece to get that level of magnification. Now this is generally uncomfortable to view with a 3mm, so you could use a 6mm with a 2x barlow to get the same magnification or any other combination (10mm with 3 x barlow) etc.

You can see similar views that I have achieved in my webcam pics with a 5 inch scope here which was starting to push the limit of the details available from that scope's resolution capability.

Try a 10mm with a 2 or 3 x barlow and see what you can get, best thing is to borrow one from a friend or colleague at a viewing night to see if your scope has enough resolution to make out more than you have been able to see up until now.

Cheers

Chris

[goober (Doug)]

Originally Posted by Darth Wader

I've read on this forum and many other places of people viewing moon transits on Jupiter and Saturn, Jupiter's great red spot as well as seeing the polar ice cap and dark features on Mars. I have a collapsible 8" dob and even under optimum conditions I have not managed to see any of these things. The planets are bright, maybe a little too much, but no detail is visible (save for the two cloud bands on Jupiter). Mars has been especially disappointing as all I can see is an orange disc at times of (what I thought was) good seeing. I have read of people with the same aperture scopes seeing them - what am I doing wrong? Could it be because I don't have a light shroud? Do I need filters/higher mag/proper dark skies? Am I better off with more aperture (I can be easily persuaded to upgrade to a 12" dob - in fact, I'm looking for an excuse)?

Thanks in advance

Cheers
Wade

Wade, if the conditions are optimal, as you say, then check your scope's collimation. I took a peek with my 4" at Mars a few nights ago and saw lovely detail.

[Dennis79 (Keith)]

Mate I have recently learnt the value of collimation, get someone to check that for you, it can significantly improve the viewing quality.

I have seen the dark patches and polar caps on mars with a 6 inch dob at 120X, you should have no trouble spotting those things. Are you sure you are in good seeing conditions? Are you out in the sticks with no moon? That can have a big effect on the view as well.

[Coen]

I have seen the shadow transits of Jupiter's moon regularly with my 70mm & 120mm refractors although Io is a challenge. The red-spot is very hard to impossible due to its incredibly low contrast, however the indentation within the cloud band where the red-spot is is visible. The ice cap on Mars is clearly visible in the 120mm.

I have found a light-blue filter works well, say an 80A and also have success with a light yellow one. Neutral density can also work on something bright like Jupiter.

For Jupiter, grab the programme Jupiter 2: http://www.astrosurf.com/rondi/jupiter/ to give predictions of what the moons and red-spot are up to.

[rmcpb (Rob)]

Its all in the collimation of your scope, your tracking ability (my equatorial platform makes a HUGE difference here), the quality of your eyepieces and your experience (you learn to see subtle things over time).

I was out the other night looking at Mars and initially it was an orange blob but after a while it had an icecap and some dark markings on it.

[Screwdriverone (Chris)]

Originally Posted by rmcpb

Its all in the collimation of your scope, your tracking ability (my equatorial platform makes a HUGE difference here), the quality of your eyepieces and your experience (you learn to see subtle things over time).

I was out the other night looking at Mars and initially it was an orange blob but after a while it had an icecap and some dark markings on it.

Oh yes, I agree with Rob here. The other night I was admiring the surface detail on Mars and the ice caps and my 13 yr old son came out and asked me what I was looking at. He had a squiz at 575x mag and said all he could see was an orange disc.

I spent 5 minutes jogging Mars back for him and exclaiming how blind he must be to not be able to see what I could see quite easily and clearly. His vision wasnt very dark adapted and is normally quite good, but he just couldnt make anything out. It was VERY strange for me as I couldnt understand why he possibly didnt see any details. After 5 mins he gave up in disgust and went back inside (probably because I was stressing him out as well).

This may have something to do with it, patience and knowing what you are looking for.....oh, yeah...collimation, I should have mentioned that before. Bad collimation is a detail killer.

Cheers

Chris

[astro744]

An 8" Aperture is more than enough to provide plenty of detail on planets provided it is not grossly out of collimation. However being Dob mounted makes it more difficult to concentrate on the detail since you are constantly nudging the 'scope.

You could invest in a couple of ultra wide field eyepieces to keep the planet in the field longer but for the cost of these you could also get an EQ mount. Whatever eyepiece you use must be of reasonable quality and most these days are quite satisfactory on axis but better can of course be bought usually to provide wider and sharper off axis views

Jupiter is getting too low now for serious observation as there is too much of the Earth's atmosphere between your telescope and Jupiter making the seeing very poor.

Saturn has close to edge on rings at the moment and some subtle surface banding but not to the extent of Jupiter's festoons, countless bands and other intricate features.

Mars is quite small this opposition and you will have to wait until 2018 for it to be almost twice its current size. However even now the polar cap and dark band surrounding it is clearly visivble in a 4" refractor and 6" reflector and should be quite evident in an 8" reflector. Syrtis Major too is quite obvious when facing our direction.

A 12" telescope will show you more detail when seeing permits but as is often the case a smaller aperture sees less of the air and therefore less of the turbulence and can give you a better image more often but with less resolution than a larger instrument. (Depends on the size of the steady air pockets).

A lot of perseverance and a bit of patience will soon have you seeing lots of detail.

Best magnification is 120x to 240x and more if seeing permits. Jupiter is quite large enough to see detail at 120-150x but Mars will need 160-240x.

[Esseth (Alan)]

I am able to make out the polar caps on Mars with the following setup.

8" Dob, 10mm default eyepiece and a 2x Barlow. i still have to look carefully but i can make it out and it is really sureal.

Not to mention i live pretty much in the middle of Brisbane.

[Darth Wader (Wade)]

Ah, collimation... that old chestnut. I think the collimation is pretty good but I can never get it 100%. The primary mirror has an annulus to aid collimation but I can't ever line it up exactly. It's pretty close, but I'm guessing that's not good enough?

Magnifaction - well, I've never tried anything above 200x. That's mainly because I read that 150x was the maximum clear magnification I could ever expect to use (except in excellent conditions) for my size scope. Might have to try and push the mag up a bit on the weekend.

Thanks for the input all, much appreciated.

[Paul Haese]

I have not read all the thread but a couple of things come to mind.

First, in great seeing detail is always visible in the eyepiece. You might think you have great seeing on one night but when the planet does not move at all at very high magnification of 480-600x and you can see actual barges on Jupiters belts, or polar storms or clouds over Tharis then you will know what great seeing really is like.

Second, collimation must be as near to perfect as you can obtain for planetary viewing.

Third, ensure you mirror is at ambient and that means it must be outside for a minimum of three hours for an eight inch scope. Without doing this you will have no chance.

You can and do see detail such as in the images present on this site and on my site (check out the Earth and Cosmos link in my signature) The best view of Jupiter I have seen was as good as many of my images, it was just smaller in size.

[pgc hunter]

Your collimation must be spot on, you should use a fan on the primary mirror as it will help it acclimate to the outside air much faster - and help it track the falling night time temperature, and seeing needs to be very good.....which on Syrtis Major shouldn't be a problem considering the atmosphere there is a hell of alot thinner than on Earth

[Rigel003 (Graeme)]

There's a lot of good info in these responses. I would list the priority areas as
1) collimation - there is a big difference in image quality between "in the ball park" and "spot on". It's definitely worth the effort of getting it right and knowing how to tweak it quickly and effectively. Buy a sight tube and cheshire eyepiece or laser collimator before you consider upgrading your scope.
2) cooling - your scope will take an hour or more to reach ambient temperature and the images will improve considerably by the end
3) seeing conditions - you have no control over this but you need to accept that the nights of really good seeing will be few and far between. There are some nights when the best scopes show nothing but a blurry blob for Jupiter or Mars.
4) magnification - you'll rarely be able to use over 300x effectively because of the seeing limitations but this power will be achievable on your scope.

[hulloleeds]

My two cents:

I was in the same situation as you. Had an 8, was disappointed with lack of detail.

Bought a 12.

Sitting out here now, on the wireless, looking at Mars. I see nothing but an orange blob. Occasionally, I spy perhaps polar cap, but could just be my imagination. There is a lot of glare at the moment from mars.

I use the plastic cap over the scope. I see a less bright, uniform blob.

Regarding some of the suggestions here.

Scope has been out for around 1hr 30. No fan running. Collimation I judge to be slightly off centre.

From an 8 to a 12, there isn't that much more focal length so it isn't that much bigger and with a bright planet, light gathering isn't exactly the most important thing either.

So I guess I'm saying.. maybe think twice about going up. Try to polish what you've got because I did what you want to do and it didn't help

(It did help dark sky observing).

I should also point out that I am using cheap EP's. EP's that i find difficult to focus, really, always a bit of a bright ghost image overlapping. Hard to get a crisp image. I can see detail but really, that my biggest problem, the coma/ghosting.

[areyouabus (Pauly)]

Could being colour blind have any effect on the detail you can perceive on planets? (i hope not as i am colour blind)
Screwdriverone - has your son been tested?

[Liz]

Finally able to check out Mars last night .... yes, was pretty bright, but THINK I saw ice cap, might try again tonight with some filters.

[Satchmo]

Your collimation needs to be bang on . Any mis -collimation and any faint details will be smeared out by coma, assuming your mirror is not the problem.

[PCH (Paul)]

I ventured out last night with my LB12" to check out Mars. I got the bright orange blob too I'm afraid. It was a good size, but I'd have liked to have been able to see more (some!) detail. M42 was good though - as always.