5" refractor for photographing planets

[C.]

Hello
I was wondering if any of your members are taking planetary photos using a 5" refractor. I do not have an astronomy group in my area and will be buying a telescope without having the opportunity to look through one first. I would feel much more at ease about the deal if I could see what is possible with this size telescope first. Sorry if it's not enough info, I am very new at this.

[asimov (John)]

Hi & welcome to IIS.

I have a 6" refractor, & I use it solely for photographing planets. have a look in the solar system part of this forum to see what a 6" can do.

[C.]

Thank you for the welcome and reply Asimov. I've just had a quick look at a Saturn and Jupiter shot of yours and they are terrific. Tomorrow night I will go through the gallery and check out all of your images (my internet is about to cut out).

Do you have any idea how close a 5" would come to that kind of detail? I realise I would have a huge amount to learn about telescopes and prime photography, but I don't want to spend a heap of money if I'm never going to get a decent result.

I'm thinking of a s/hand 5" refracter on a new EQ5 mount using a manual film SLR with MLU.

Any help appreciated.

[asimov (John)]

I would suspect a 5" would come close to what I can get with the 6" but I'm not sure.

I can tell you straight out an achromatic refractor is not an easy thing to get good planet shots with. The main problem being getting natural colours, all to do with the design of the lens system a achromatic refractor has.

In all honesty I suggest getting a reflector or an apochromatic refractor for astrophotography!

I only received a special filter today to combat this colour problem, & I'm testing it right now to see what will happen, so I may alter my opinion on this shortly! (& I may not too!)

[davidpretorius]

got a budget C?

[Robert_T]

Hi C. Asimovs shots are about the best I've seen from an acromatic refractor and unless your investing thousands on an apochromat I'll assume the 5 inch you're considering is an acro like Asi's. The 5 inch will not be able to achieve the same detail due to lesser resolution. Let's hope the filter Asi's trialling will help, but failing that if it's planetary imaging you're after and you're on a budget I'd recommend getting say an 8inch reflector.

cheers,

[janoskiss (Steve H)]

Originally Posted by C.

Do you have any idea how close a 5" would come to that kind of detail?

Angular resolution is proportional to aperture, so a 5" will have 5/6 = 83% the resolution, or capture (5/6)*(5/6) = 69% the detail of a 6".

[C.]

Thank you so much for the advice. As you can see I might have made a regrettable mistake which is what I'm trying to avoid. I shall do a lot more research before I make a decision.

My budget is around $1,000 and from what I've read on the internet I can expect to pay at least half of that on the mount. If it's not stable whatever I put on it I'm going to sorry.

Your help is much appreciated.

[janoskiss (Steve H)]

$1000 will not get you far in astrophotography. For planets you really need more aperture to capture detail. But you can do deep sky with smaller scopes. Browse the Deep Sky forum for shots taken with an ED80 (80mm apo).

[ving (David)]

like steve said, for DSOs you may very well be ok. a faster refractor would go better tho, and there lays more problems

[C.]

Thank you all for the honest advice. Maybe I'll get lucky and find something s/hand. You have a great site here with a terrific gallery and many helpful people. Cheers. Carol.

[janoskiss (Steve H)]

A good second hand all-mechanical film SLR camera with a half decent telephoto lens on a motorised EQ3 mount will get you some stunning deep sky shots if you have the patience and persistence. And it is doable well under $1000. (No good for planetary close-ups though)

[C.]

Yes Janoskiss I have a couple of manual SLR bodies, so I'll keep using those for a bit longer. I will just have to wait for the planets until I can justify the outlay for the right setup. Sigh. Patience isn't my strong point. Nevermind the moon is always a beautiful subject and I can still come here to see what you are all producing.

[janoskiss (Steve H)]

Well, if you are really have your heart set on planets you could always go the Dob and a Toucam. Play around with it for a while and then motorise the Dob with pseudo tracking. This means you track but not EQ aligned, so you get field rotation, which you have to remove in software. If Snake Valley near Ballarat was not too far for you to drive this weekend you could come along to the star camp, starting today Friday. You could see Dave P's 10" Dob-cam setup first hand there (he's bringing it up all the way from Tassie ). He's been getting some stunning images of Jupiter with that scope + toucam.

[C.]

I think I'll hold off until I can get just the right gear. I would like to be able to take pics of the planets with a film SLR and maybe later with a toucam or similar (as yet I don't know enough about them). I'm looking at this as a one-off purchase as I probably wont be in a position to buy something better later on. I also have so much to learn about the different types of telescopes, half of the language means nothing to me.

I hope you all have a terrific time at Ballarat with good skies and look forward to seeing some great shots in the gallery.

[janoskiss (Steve H)]

film (or even digital ??) SLR will not cut it for planets. You need a CCD + computer that can take 100s or even 1000s of short exposure shots/frames in succession which you combine in software to make a single image. This is a must in order to minimise the effects of atmospheric turbulence.

thanks for the good wishes.