Best Imageing Refractor?

[Photon]

I am just starting out and looking for my first telescope that will allow me to do imageing of planets and deeper space objects such as galaxies. I have been advised that an 80mm apo refractor will do the job with the correct mount. I am thinking that a 100mm apo scope may be better to to see clearer images but has a f/7. The 80mm has a f/6. I realise the imaging time maybe longer for the 100mm but I am thinking the images will be clearer and worth the extra imageing time. Has anyone had experience of both size refractors to comment on their imageing experience and whether the 80mm or 100mm was better?

[gnomus]

Imaging planets and deep sky objects are somewhat different disciplines.  Planets tend to be imaged using a long focal length scope and a video camera.  Deep sky objects are photographed with long exposure cameras.  Again what scope you need will depend upon what type of DSO you wish to photograph.  Some galaxies are very large in the scope (because they are nearer to us) and some are extremely small.  If DSO is your thing then you are probably better off starting trying larger objects with a small focal length scope - because this is easier than long focal lengths.  (I say easier, but it is still very demanding.). Many people start off with an inexepensive 80mm scope such as an ED80.

BUT....

Before you spend any money, get hold of a book written by a chap who shows up regularly on here called Steve Richards (user name steppenwolf).  The book is called 'Making Every Photon Count'.  The few quid invested in this will repay itself several fold.  

Good luck.

[pipnina]

For planetary imaging, aperture is king. For deep sky, you'll want a fast focal ratio (low f/number) to get the most light onto your sensor.

As gnomus has said above, you will want different sorts of cameras for both types, too. 

[Uranium235]

For DSO, its not just speed, its also colour correction. Not so important for narrowband, but it is for LRGB (colour) imaging.

The aforementioned 80ED at F6 would be a good start, but as soon as you look at F5 and below you will notice a sharp increase in the price and complexity - with a couple of exceptions, ie: TEC, which are slow(ish) but the quality is second to none.

Living in the UK you want to be getting those photons onto your chip as quick as possible, so go for the F6. Its probably best to have two telescopes for both jobs (as there is no such thing as an all-rounder), so the planetary would be and SCT, Mak or barlowed 8" newt).

[ollypenrice]

I've imaged extensively with high quality apochromatic refractors of 85, 106 and 140 mm aperture. Which is best? Meaningless question. They are all best at what they do best. You have a complex trade-off between F ratio, focal length, colour correction, field of view, flatness of field, spot sizes... Many beginners feel, intuitively, that a bigger scope must be a better scope. No, a bigger scope is a different scope.

85mm;

14Omm;

Better, worse, different? For me, different. Nobody would ask a professional photographer whether a 50mm lens were better than a 200mm lens without knowing what the target was.

Olly

 

[Photon]

Many thanks for all the comments, I will get hold of the book you recommend before buying. I was hoping there would be a good all round scope but seems I might need to buy two scopes eventually. Really appreciate the advice.

[Davey-T]

7 minutes ago, Photon said:

Many thanks for all the comments, I will get hold of the book you recommend before buying. I was hoping there would be a good all round scope but seems I might need to buy two scopes eventually. Really appreciate the advice.

Only two ? 

Dave