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Equipment Discussions >> Mounts

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Elliottastronomy
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Reged: 09/20/12

Re: Tracking... new [Re: gdd]
      #6058914 - 09/02/13 09:45 AM

If that's the case then ill try the 100mm lens I have a zoom lens that I can try and ill sell the ha and Sii because I would need to have massive exposures just to see something. I could double up and do 2 minute exposures and stack them it could work I have time when I'm out there...but if what is said above that it would take 20 minutes just to get ha with the filter lol sell the filter and get something else to help this mount

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orlyandico
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Reged: 08/10/09

Loc: Singapore
Re: Tracking... new [Re: Elliottastronomy]
      #6059208 - 09/02/13 12:50 PM

I don't think 20 minutes are a necessity. But in my experience at f7, 10 minutes is barely adequate and 20 minutes is desirable.

Obviously if your lens is at f4 you'd only need (7/4)^2 = 3 = one third of the time (e.g. 3.33 minutes).

And at f2 (the widest a 100mm f/2 lens will go) you'd only need (7/2)^2 = 12X less time, thus 2 minutes would work.

So if you can get your hands on a 100mm f/2 lens it might still be worth your while to check if the filters work.


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Elliottastronomy
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Reged: 09/20/12

Re: Tracking... new [Re: orlyandico]
      #6059265 - 09/02/13 01:19 PM

But inserting the h alpha into the DSLR into the telescope is a no go then right just doing wide angle shot with the lens for the camera? Because I have a canon zoom lens 55-300 f/4 and I can put the h alpha 1.25" filter in the camera right before the lens and it fits perfectly in there...

Edited by Elliottastronomy (09/02/13 01:21 PM)


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Elliottastronomy
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Reged: 09/20/12

Re: Tracking... new [Re: Elliottastronomy]
      #6063081 - 09/04/13 05:29 PM

ok so my next big question is...if i sell the mount and the two filters what would be a good mount to buy and what would it cost me.....i want to do the 200-300 second exposures so what mount would do that for me?

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jrcrillyAdministrator
Refractor wienie no more
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Reged: 04/30/03

Loc: NE Ohio
Re: Tracking... new [Re: Elliottastronomy]
      #6063243 - 09/04/13 07:07 PM

Quote:

i want to do the 200-300 second exposures so what mount would do that for me?




Guided or unguided? What focal length? How much payload?


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gramaglia
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Reged: 04/02/12

Re: Tracking... [Re: jrcrilly]
      #6063400 - 09/04/13 09:10 PM

Thanks for selling me the filters Elliot. The OTA if I understand is the 150mm F5 reflector from celestron which weighs 12lbs and has a 750mm FL. The cheapest mount that you can use for that OTA I think is the CG5, you can find great deals on them as it's been replaced by the improved VX. The next step up would be the afore mentioned VX or the ZEQ25 from Ioptron but those will cost you about twice as much. You will be much better off buying a CG5 and getting a cheap autoguide package like the orion mini guide scope and old meade dsi with it than an unguided ZEQ25 or celestron VX. The next items I would consider on the shopping list to image in a light polluted area ( I assume you are in one since you had bought the narrowband filters) would be a CLS clip filter and a coma corrector. Fast Newtonian exhibit a lot of coma off axis and a DSLR as a large sensor.

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