Minimum Aperture for Planetary Viewing?

I'm curious. What is the minimum aperture apochromat or achromat you'd consider for your serious planetary viewing?

Thanks!

Clear skies, Alan

When I lived in a NYC apartment, I exclusively used a 105mm f/5.8 APO (AP Traveler) for observing from the rooftop. I had many an enjoyable night with that scope and a few evenings of great seeing that stand out in memory - one in particular during a late 90's Mars apparition was amazing.

Would I want to be limited to 4" for planets for ever? No. But one can spend countless hours on the planets with no more than 4" and mostly be limited by the atmosphere and ones own observational skills.

Philip

For serious, I would set the minimum right at 6".
5" is a good compromise if weight/cost/size/portability/price are a major consideration, 5" is just barely large enough to wet your appetite, but if you switch to a 6" you will quickly realize what you are missing.
And the most popular 4"? too small for serious planetary detail.

Vahe

A bit of clarification regarding my take on the planetary potential of a 6" apo;

The comet crash on Jupiter was one of the most memorable views, I followed that event for weeks until the black scars finally disappeared, for that application my 155 was just barely adequate and it happened to be my only scope at the time.

Last year I struggled to view the Jupiter's GRS and the Junior passing each other with the same apo, many times under decent seeing using binoviewr, 240x, no luck. The same feature was clear as a daylight in my 10"MCT.

Every time that I view Mars with my 155, during oppositions of course, my first reaction; how small the planet is and how inadequate the 6" aperture is in dealing with that particular planet, this year it will dance for us again with a size three times smaller than Jupiter's disc.

And then we have Uranus and Neptune, try that 60mm on those!!!!!

Questions like this clearly demonstrates that there can be agreement as to what "serious" means, so far we have votes for 50-60mm scopes at the low end and mid size Dob at the upper end, is there a correct answer?

Vahe

I have been having a lot of serious fun watching Jupiter for one week with my 80mm apo at 12N. I can see up to ten belts (polar regions included) and a lot of details, including 'spots' in EB and the chain of vortices following GRS in SEB. I have never been able to see such level of detail in my 8" at home.

Dmitri

For me, the planets start to get interesting at 5", but are much better at 6".

I've moved from a TV85 to a TV102 and now to a TEC140. The TEC frequently gives 250X+ , which is the magnification that starts to makes planet detail interesting. I am not an experienced observer but the 160 - 190X that the TV scopes maxed out at in my skies just was not enough power - in my opinion. My neighbour is using an AP 6" f/9. We have done side by side comparison's and I could not justify the significant extra cost (tube and mount), and bulk versus the small increase in resolution over my TEC.