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tenbyfifty

Will a 6" Skywatcher Dob show any detail on Mars?

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debating whether to buy a scope just to have a look at Mars (without spending a small fortune)

and a 6" Dob is all I can stretch to - will it show any detail or just a red disc?

(PS I know you can track it better with an eq mount but I find them a bit of a faff in icy weather.)

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It should show some of the major features but this will depend on getting the magnification up to the 160 to 200 range. Also poor seeing will limit the detail you can see.

John

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Indeed, I've had several attempts and observing Mars with an 8" reflector and a 6" Mak Cass and the best I've had is very faint detail.

Tony..

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You should see some features on Mars but as Tony has pointed out it does depend how clear it is I was looking at it tuesday night with a 6" Celestron next star and could see features including the ice cap

Stephen

Eastbourne AS East Sussex

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If you decide to go ahead with buying your scope TBF, you will increase your chances of success by the use of suitable filters.

I will leave the recommendations as to what filters are best, to a good mars observer.

I would hope Starman might be prepared to offer you some advice, but some avid mars observer will soon come to your aid on this subject. I have said this before, I saw mars at last opposition at Dalby Forest starfest through a 4.5" f6 reflector. The owner of the scope was using filters, and the detail they brought out was just amazing.

Ron. :rolleyes:

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If you decide to go ahead with buying your scope TBF, you will increase your chances of success by the use of suitable filters.

thanks for that - well i found these on on scs astro (not my favourite vendor btw)

Orion Mars Observation Filter Set:

http://www.scsastro.co.uk/it020007.htm

but its another £50 - making £200 inc the scope just to have a look at Mars:

hmmmm..........

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I have seen detail on mars with a 4.5" Newt, but you have to concentrate, as features tend to be a bit evanescent on the planet.

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If you decide to go ahead with buying your scope TBF, you will increase your chances of success by the use of suitable filters.

I will leave the recommendations as to what filters are best, to a good mars observer.

I would hope Starman might be prepared to offer you some advice, but some avid mars observer will soon come to your aid on this subject. I have said this before, I saw mars at last opposition at Dalby Forest starfest through a 4.5" f6 reflector. The owner of the scope was using filters, and the detail they brought out was just amazing.

Ron. :D

I don't live a million miles from Dalby forest - any idea when the next event will be?

Cheers

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hi there

you may be best trying to contact an astronomer locally who may be able to share an evening with you and show you Mars through his/her scope. This will probably be more likely if you offer to ply them with chocolate/alcohol etc. during the evening!

according to Find Astronomy societies, shops and events near Tenby in the astronomy community | Clubbz - The Sports & Hobbies Website. there's a club in Cardiff. Would be cheaper than buying a scope if they are having an event soon.

Sorry if this is teaching grannie to suck eggs.

I have been getting reasonable detail with my celestron 120mm refractor - seen the ice caps and some dark shading easily but I note you are not keen on eq mounts.

hope this helps.

Shane

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I have a modest 5.1" Dob and so far in the last few weeks since it arrived i have not seen ANY detail on Mars. My Dob is showing the same image as my 3.5" refractor. I KNOW the Dob is capable of better because i have observed other objects and compared them to the refractor. With Mars i reckon it is all down to seeing conditions.

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I have a modest 5.1" Dob and so far in the last few weeks since it arrived i have not seen ANY detail on Mars. My Dob is showing the same image as my 3.5" refractor. I KNOW the Dob is capable of better because i have observed other objects and compared them to the refractor. With Mars i reckon it is all down to seeing conditions.

With planetary and lunar observing your 90mm refractor will probably show pretty much as good images / details as your 5.1" dob on most nights. It may well show better views on nights of poor seeing. The central obstruction of the dob plus a few other factors reduce the contrast a bit so equalising the aperture gap.

On the very best nights with the dob in excellent collimation it should show a bit more detail and will always out perform the smaller refractor on deep sky objects.

Edited by John

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I have 150/750 SkyWatcher on EQ3-2 and if the seeing is good I'm able to go to up to 300x (with NLV 5mm and 2x barlow) on Mars and I'm able to see ice cap, and bright/dark Mars terrain (quite sharp and detailed view). But it does require good seeing :)

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Mars is a tough object as it is so small but my standard Skywatcher 8" Dob shows the major features well. A simple light orange #21 will help you to see features easier on a large telescope (6" upwards).

A good 6" F/8 Newtonian, with a small secondary, well cool and collimated would be the minimum for Mars.

A widefield 5mm eyepiece giving x240 would be ideal.

Check out the drawings in the sketching section to see what can be seen.

Edited by dweller25

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Grab a SW 150P (new Black Diamond model) for £145 from FLO.. best cheap scope I ever bought!!.. super on the planets. Pop that on your EQ mount.

I have to disagree on the (large scope for planets opinions). Anything over a 10" is a waste, and will work against you. An 8" is the perfect scope size to pull best details without having to worry about things being to bright and using filters or stopping down the scope to achieve a balanced view. The 150P has provided a super planet view, and not much less to a 8" scope. I've used a 16" meade and felt it did not really offer much more than the 8"!!.

Rob

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I had Mars in the scope a few nighst ago using my baby Mak (4") sky conditions were amazingly stable and using a light blue filter I could just about make out some dark patches on the planet. I was using alternately a 5mm giving x265 and a 13mm Barlowed to give x200.

A red filter allowed the ice caps to very faintly show but you had to stare a long time to see them.

The planet appeared about the size of a frozen pea.

Seeing conditions, thanks to the cold, were extremely stable. Unfortunately after about 2 hours worth it was so cold I wimped out and packed up.

At high mags though its a perisher. I didnt have the Nexstar aligned for tracking and as aresult at high mags Mars just whizzes across the eyepice field of view. I spent more time manually guiding the scope than actually geting a decent look - high mag on planets is very hard work without tracking I find.

Edited by Astro_Baby

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With planetary and lunar observing your 90mm refractor will probably show pretty much as good images / details as your 5.1" dob on most nights. It may well show better views on nights of poor seeing. The central obstruction of the dob plus a few other factors reduce the contrast a bit so equalising the aperture gap.

On the very best nights with the dob in excellent collimation it should show a bit more detail and will always out perform the smaller refractor on deep sky objects.

Really so far with the Dob the only REAL test i have been able to do is observing the moon. With the Dob and a 6mm EP(and/or)+2x barlow i have been able to observe the lunar terminator in detail i have never seen before with the 90EQ. Infact i have never been able to use the 6mm OR barlow with the 90EQ......................so that is a VAST difference.

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You should certainly be able to make out detail with that scope but don't expect to see it straight away. All you will see at first is a tiny peachy disc. Keep looking and looking and looking and looking. After some time you will start to discern some slight variation within the disc, may be a bit of extra brightness at one point around the edge and an occn the suggestion of a smudge. Keep looking, gradually your brain will start to process what you are seeing just like registax, it will filter out the views blurred by the seeing and hang onto just the periods of tightest focus. Keep looking for at least 30minutes and gradually detail will start to emerge. Mars isn't a target that gives an instant wow but enjoys persistent careful viewing

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So far I have only seen Mars as a tiny disc through my 8" Dob and the standard EP's. I wonder if a 6mm 66 Deg widefield EP would help a lot :)

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At 150x you should see small ball with ice cap on one side and some terrain details. At 300x it should be more detailed. But to see this scope ma not shake and the seeing needs to be decent :)

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I can easily see the main features of Mars with my Skywatcher 8" F/6 Dobsonian.

I find the best ocular setup is a x2 Celestron Ultima barlow with a TMB 9mm Planetary eyepiece giving x267. This gives good magnification and a wide field of view. I also use an Orange #21 filter to maximize contrast and reduce glare.

To go back to the OP's question - a 6" scope will show less than an 8" but not much less and is a cracking workhorse without being too expensive or heavy.

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I agree 100% with dweller. Mars is showing some tremendous detail when the seeing is good, even with it's small apparent size. The high altitude really does enable the use of high magnification to increase the disk size and make the features more apparent. As Martin said, prolonged viewing is the key to seeing extra detail. And filters do help.

Like dweller i use an 8" f6 dob which has been very happy using a Tal 3x barlow with a Paradigm 12mm for 300x. My last view was 9 days ago now and on that night the main details just jumped out.

Your 6" f8 shouldn't be too far off the 8" f6. It can certainly handle the same 300x magnification (providing the collimation is good) and although the view will be slightly dimmer, the detail should be almost the same.

Don't be afraid to pump up the mags :)

Russ

Edited by russ

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Hvan't seen Mars for a little while, but got some great views just before Christmas when it was still low in the east with my 4" mak. Lovely definition on the north polar ice cap, even though seeing was a bit off.

Keep at it! I will do.

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In the past I've had some good detail visible on Mars using my 6" f8 Newtonian. On many nights however it just appears as a slightly pink disc. The polar cap is usually easy but the darker patches are often surprisingly difficult to pick out.

I would definitely agree that filters help. In fact, in my opinion they help more with Mars than with any other planet!

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I go along with part timer. I built a 6" F/8 Newtonian and have seen details on Mars with it. You do need good seeing and patience (filters will also help a lot). The advantage of an F/8 is its small central obstruction, especially when compared to Maksutov and SCT designs, but also fast Dobs. This small central obstruction leads to a reduction of both the central disk diameter and the brightness of the first fringe surrounding it in the so-called point-spread function of the optics (i.e. the light distribution of the image of a single point source. The practical upshot of this is better resolution and better contrast. Though my current Celestron C8 gathers a lot more light, I do not think it is much sharper than the old 6" F/8.

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