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are dobsonian mounts frustrating for viewing planets?


tenbyfifty

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just wondered if people who buy dobsonian mounted scopes wish they had something that tracks when they view planets ; are they a bit unwieldy when u go to higher mags?

another way of looking at it : is a 4 inch tracking scope more useful than a 6" dob for planets?

cheers all.

maybe i should have said 5 inch tracking scope as not much more expensive than 6" dob

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I had a 6" F/12 on an alt-az fork mount similar to a dob, and only had narrow FOV EPs (this was 1978). I found planetary viewing fine, and my mount was a bit wobbly. A well made, well balanced, and smoothly moving dob should be better. I now have an SCT on an EQ mount with RA motor, and that is more comfortable.

I would say a 6" scope would provide so much better views of planets than a 4" that I would forgo tracking. You can always put the dob tube on an EQ mount with RA motor later.

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A "standard" dobsonian will always have the "problem" that it does not track, equally an 80ED on a Vixen Porta mount is much the same as is a newtonian on an undriven equitorial.

The dobsonian was produced to provide an inexpensive mount.

Basic idea being keep it simple with regards a mount. You could easily make one at home, and if you had £500 then you are splitting the budget towards an inexpensive moiunt and more glass. The alternative being more on the mount and less on the optics.

It is not just planets as the stars and DSO's all wander out of view at much the same rate.

If you want to spend the time looking and also enable someone else to look then a tracking mount is very useful.

Swings and roundabouts.

I would prefer the tracking option, my reason being that the smaller scope would still show the main objects, M31, M42, M45 etc, a bigger scope would allow the smaller fainter DSO's but they would still be faint and small.

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I use both an 8 inch reflector on a motorised mount and a manual dob. The motorised scope is more convenient but the dob is a pleasure to use also. I did ask myself the same question before buying the dob but have found a little nudge now and then is no bother at all.

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Yes, I didn't like trying to track planets at high magnification on a dob. I'd spend so much time nudging it to keep it in view, then waiting for it to settle, then losing it, I gave up and got an eq6. But the path to the dark side that was!

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I don't think having the nudge the dob is too much of a pain if you have suitable eyepieces, and even then it's perhaps down to how you feel about things. I find with my shorter focal length BGOs that I'm constantly "chasing the target" and I find it frustrating. With a Nagler however, things are more relaxed for me. I believe Shane is quite happy to use BGOs for planetary viewing in a manual dob however.

James

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My only problem is/was remembering not to nudge the wrong way, since the image is reversed I was always pushing when I should have been pulling. I solved that by buying an EQ platform, for visual use it's brilliant.

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Just about anything is frustrating at the moment, due to the short breaks in the cloud cover.

I opted for the EQ mount from the start but haven't had a long enough session yet to align it properly.

A Dob would be up & running quicker in this situation.

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Certainly the ultra wide angle EPs make it less frustrating. I personally prefer the planets tracked, though. At what point to put the budget into the optics or the mount is always going to be personal, I think.

Olly

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I bought a Dob 12 months ago as my first proper scope.

I did find the nudging annoying and looked a lot at how I could turn it into auto tracking.

It all looked pretty expensive, so I put it off.

Since then I have bought a 7mm 82deg (celestron luminos) eyepiece and although the problem hasn't gone away, I don't worry about it as much.

The eyepiece is a lot cheaper than any mount and a worthwhile investment even if you decide to buy a proper mount later.

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for a single person use manual dob is perfectly fine as soon as the base is properly set up and any movement is free and does not result in jerky movements of the scope.i only upgraded to go-to because i have another 3 of my family members taking part in my observations and thats where manual mount becomes a pain in the back as by time we change places,the object is gone out of FOV if normal (up to 60deg) EP are used or is on the edge of FOV if 82 or UWA EP is used.This problem becomes obsolete if tracking is used and all of us can enjoy the views. of course you can still use manual dob even if you have 5 observers on the same scope if each of them adjusts the scope after he has finished viewing,but you need to have sort of experienced people and i cant ask that from my 7 years or 9 years old kids or wifey who understand very little from this.

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Nudging the Dob is surprisingly simple. You don't *need* goto at all. What makes goto *nice* IMO is when you are at high magnification and move away from the scope for a bit and the object has drifted away. You have to find it again. But once found it is much easier to find again.

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Personal choice for me is tracking as a bare mnimum on an EQ. Plantes whizz around pretty fast and I prefer to be able to spend time looking rather than keep worrying that the target is about to exit the EP, nudge the scope, wait for it to settle, oh blast its gone again, nudge the scope, wait for it to settle, twist the focus a but, wait for it to settle, oh dear the target has gone out the field again. It all gets to be a bit of a wind up for me.

Turn the tracking on, bliss, objects stay where they are and a can spend time looking at them........:)

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Yes, I don't mind nudging. Mind you, I don't spend ages on one object anyway. The most I would spend is 10 mins maybe. Slightly more if a GRS or moon transit was happening. And even then i'd probably keep coming back to it. Anyway, you know what I mean.....

Ps nudging no problem!

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If a session is specifically focused on planetary observation over a prolong period then personally I would prefer some form of tracking system, however as mentioned wide angled and low to medium EP's will help. With a dob perhaps an EQ tracking platform might be required.

I quite enjoy nudging though and if (as most dob sessions do) the session includes a diversity of targets, in which planetary observation is one aspect, then nudging is the way to go.

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I don't have any problems tracking objects at high power with my dobsonian. It happens to have very smooth motions which helps and I do have ultra wide eyepieces but I also use orthoscopics at high power too. I've used up to 400x with my dob and kept the object in the field of view with just a little concentration. I use the nudge-and-let-it-drift method :smiley:

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Yes, I don't mind nudging. Mind you, I don't spend ages on one object anyway. The most I would spend is 10 mins maybe......

Exactly like me. I look at dozens of objects a night. I am all over the place an follow no order whatsoever. I always make sure I look at M81/M82. 100% certain.

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I have a 16" Dob and it has given some great views of the planets. I have never used a scope that can track so I'm well use to manually moving the scope and don't find it too much bother. If I had to choose between tracking and aperture, aperture would always win for me.

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it's not that hard to track planets at reasonably high powers even with plossls as long as your mount is well adjusted and smooth.

e.g. in my 6" dob, a 11mm plossl gives 145x (1600 / 11). the true field is 50 degrees/145x = 0.34 degrees. it takes an hour for 15 degrees to pass at sidereal rate so four minutes per degree so at 145x with a plossl you get 4x0.34 = 1.36 minutes with the object in view if you put the object to the extreme side of field and let it drift across. in practice this is perhaps just over a minute.

with my 6" dob though it's a very long tube which takes a few seconds to settle so I do use an equatorial platform which tracks. with more standard dobs they settle very quickly or instantly so it's not an issue.

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