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18-04-2005, 04:29 PM
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Registered User
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Join Date: Mar 2005
Location: Hunter Valley nsw australia
Posts: 535
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dobsonian tracking
Hi All,
I have another question re Dobs.
How hard is it to keep an object in the eyepiece at high powers?
I can track objects at high power 200x, quite easily,with my Tasco 8v,
But given an 8 inch dob,could go to approx 400x in good conditions,would you be able to track the object ok,at that magnification, or would you have to reduce magnification drastically to keep it in view?
I ask this, as I know Dobs are meant to be nudged into position,rather than controlled by slow motion control.
Thanks for any advice.
Regards,John
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18-04-2005, 04:52 PM
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~Dust bunny breeder~
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Join Date: Nov 2004
Location: The town of campbells
Posts: 12,359
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with dobs you dont really track at all.
put the object at the edge of the FOV and let it drift across till it disapears then place it back over the other side of the FOV again.
so as stated, no tracking.
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18-04-2005, 06:30 PM
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luke
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Join Date: Mar 2005
Location: Mullumbimby{near Byron}
Posts: 126
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Hey Jonno. Ive only had my dob for a month or so ,its not to hard at all feeping things in the fov even at the highest mag. Most times the nudging has me losing my prey, but other times i can keep it within sight for awhile by just applying some pressure.
Im very new at this but i havent found it a prob at all,although any time a friend wants to have a look at high mag they have trouble because they have no experiance,they tend to lose things straight away
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18-04-2005, 06:35 PM
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4000 post club member
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Join Date: Sep 2004
Location: Melbourne
Posts: 4,900
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Practice (and a smoothly moving dob) makes perfect
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19-04-2005, 08:36 AM
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Compulsive Tinkerer
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Join Date: Jan 2005
Location: Blue Mountains, NSW
Posts: 1,766
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Keeping sight of objects is not a problem with practice but it helps if you work at keeping your bearing surfaces really clean.
Cheers
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19-04-2005, 08:42 AM
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Sir Post a Lot!
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Join Date: Sep 2004
Location: Gosford, NSW, Australia
Posts: 36,799
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The others have said it all already.. but I think you'll really be pushing it (pardon the pun) to go 400x with an 8" dob. The conditions would have to be really good to allow that magnification.
Most times you'll be working between 90 and 200x, and tracking/nudging isn't difficult.. it's not like your constantly moving it.. when it gets to the edge you swing the scope to align it back to the other edge.. and once you get a feel for the direction it's travelling it's quite easy to predict where it'll be even when you overshoot it sometimes.
And as the others said, keep the alt/az motion smooth by using milk bottle washers, replacement teflon pads or super sliders, ebony star or other mods that will ensure the movement isn't "sticky".
oh btw johnno, are you coming down to the May 7 star party? Brendan (also from around your area) is coming..
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20-04-2005, 01:37 AM
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Registered User
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Join Date: Mar 2005
Location: Hunter Valley nsw australia
Posts: 535
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Hi All,
Many thanks for your replies,as allways,good info and advice.
I have never used a Dob type mount before,and as I mentioned in an earlier thread I am thinking of buying an 8 inch (when finances permit),and was a little concerned that it would be very hard to keep things in view at the higher powers,once again your help has set my mind at ease.Thank you.
Mike,I doubt I will be able to make it to the Star Party,I have a few medical problems which restricts my mobility most of the time,But thank you anyway.
Regards to all.John
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20-04-2005, 10:09 AM
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~Dust bunny breeder~
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Join Date: Nov 2004
Location: The town of campbells
Posts: 12,359
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400x power isnt that bad in an 8" mike. just depends on what you are trying to do. I split double at the magnification all the time, even with mediocre seeing. getting planetary detail at 400 does require good seeing tho
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