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is 4 inch enough for serious planet observing?

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#101 PKDfan

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Posted 23 November 2020 - 11:56 PM

I found with my superb night of seeing I NEEDED the ~270x power just to dim Mars enough to discern any detail at all it was so bright! I cant imagine anyone using a 10-12" Dob would'nt be blinded without either mag. or a ND filter I certainly was looking at the near pure white pinpointish brilliance of the SPC, it made my eye water copiously. Remember;using a 4" scope here!

CS & GS

#102 Lookitup

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Posted 24 November 2020 - 12:16 AM

Higher mag does make it easier for me to discern planetary details. ED120 pro lets me use x200+ without much flouter interference. With the 4" Tak x170 is max. on planets, sky is the limit on everything else. Dark adaptation is not needed or even desired for planetary IMO. CS 



#103 PKDfan

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Posted 24 November 2020 - 12:33 AM

Hi Lookitup! I'm one of the select few who is'nt bothered(so far!)with floaters so could use .37mm exit pupil. I'm perfectly fine with 4" though a 5";its a significant jump in price and mount. I would'nt want the 120ed pro 'evostar' on my eqm-35 for instance. My setup is at the outer limit for grab n' go and I bought it thinking that I wanted stability for high mag.& honestly its good at 270x (with no wind) Did'nt want alt az mount. Dont think my experience would be as great as that night was with a lesser setup and I can be ready in 10-15minutes top. Also my location is ideal for planet observing, I'd never get dark adapted here!, I have 'several' multilight hwy interchange lighting where I am. Actually only time I appreciated my site was for Mars observing. 🧐

CS & GS
Edit:typo,clarity

Edited by PKDfan, 24 November 2020 - 12:43 AM.

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#104 Ihtegla Sar

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Posted 24 November 2020 - 12:38 AM

I found with my superb night of seeing I NEEDED the ~270x power just to dim Mars enough to discern any detail at all it was so bright! I cant imagine anyone using a 10-12" Dob would'nt be blinded without either mag. or a ND filter I certainly was looking at the near pure white pinpointish brilliance of the SPC, it made my eye water copiously. Remember;using a 4" scope here!

CS & GS


Some people seem more sensitive to brightness than others. I usually view Mars with one of my four inch refractors because my dobs don't cool down very well in the summer but once the weather cools down, my dobs cool down fine and, I spent about an hour viewing Mars a couple weeks ago just after sunset in my 20" unfiltered at 195x. Gave me some of the best views I've had of Mars all season and I didn't feel the need of a filter.
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#105 PKDfan

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Posted 24 November 2020 - 12:58 AM

Hi Ihtegla Sar! Well to be fair I did say magnification though I am still somewhat surprised the brightness was'nt a hindrance. Just enough power to dim and the acoustics of your visual acuity. I have surmised my eyesight brightness acuity may be above the curve. I would have LOVED to have looked at Mars with your 20"(!). I'll never have one of those!

CS & GS
Edit typo

Edited by PKDfan, 24 November 2020 - 02:10 AM.


#106 Jon Isaacs

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Posted 24 November 2020 - 02:05 AM

To a degree, but lets not broad-brush it too much.  A novice looking through a 10 inch scope on a good night for about 30 minutes is going to see more than an experienced observer looking through a 4 inch scope.

 

I have to say..

 

Not really.

 

It might happen if I set the scope up, made sure it had cooled and was properly collimated. But if the novice sets up the scope... 

 

Put your novice up against Thomas Jensen, I'm sure Thomas would come out on top.

 

Jon


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#107 PKDfan

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Posted 24 November 2020 - 02:24 AM

Even with the perfect setup the novice still has to know to wait for those split second moments to see 'ultra' detail. The strength of the observation if you will😗. A long time observer can maximize those split seconds into hundreths of a second maximizing detail seen to the finite response time of the eye to stimuli. IMHO.

Just my .02cents worth.


CS & GS

Edited by PKDfan, 24 November 2020 - 02:28 AM.


#108 CHASLX200

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Posted 24 November 2020 - 06:46 AM

I found with my superb night of seeing I NEEDED the ~270x power just to dim Mars enough to discern any detail at all it was so bright! I cant imagine anyone using a 10-12" Dob would'nt be blinded without either mag. or a ND filter I certainly was looking at the near pure white pinpointish brilliance of the SPC, it made my eye water copiously. Remember;using a 4" scope here!

CS & GS

I have used 350x to 400x on Mars when big and close with many good 4" scopes. Jupiter and Saturn are just too dim at them powers with a 4". My best views of Mars was in the 90's with a 10" F/8.3 Newt.


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#109 tom_fowler

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Posted 30 November 2020 - 02:32 PM

I recently purchased a 115mm APM/LZOS APO.  This gives great views of the planets, good up to about 250x (haven't had a chance yet to go above that), mostly limited by lousy seeing conditions.  With a Baader binoviewer it is even better.  I can get great DSO images with it as well.  Easy to handle--OTA is 13.5 lbs.  Admittedly at $4K this is a premium product, but given its performance and portability, I expect to get a lot of use from it.  Here's a photo of the scope on a GM8-G, and a sample DSO image.  These are drastically reduced for this forum; email me tfowler@gmu.edu for more info or photos.m31 reduced.jpg scope reduced.jpg


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#110 Bomber Bob

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Posted 30 November 2020 - 08:42 PM

Some Oldies but Goodies...

 

1970s Dakin 4" F10:

 

Dakin 4 - Jupiter (Io Transit) 20170609V04AS21.jpg

 

1950s Edmund 4" F15:

 

Edmund 4 - Saturn 20170707V06AS12.jpg

 

My 2 best achromatic refractors.  Need to image with the C-102, but 2020 is not a good gas giant year!


Edited by Bomber Bob, 01 December 2020 - 04:18 PM.

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#111 N-1

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Posted 01 December 2020 - 03:32 PM

Finally got to try out my new 102 f/11 ED, on the Sun using a 1.25" wedge (not much of a dark night happening here ATM). Seeing was just average but the views were great nonetheless, putting plages near the limb, granulation and the penumbral "spokes" of AR2786 in plain view for example. The tube seemed happy enough on the Vixen GP, but that's just a first-light note. Jupiter-Saturn are next. I think observing with this thing is going to be great!  


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