Torn between two APO's

[Prador]

I have only been here for a few days and I would like to thank everybody here who recommended "Making Every Photon Count" as essential reading.

It is a very well written and informative read

Once again I am in need of advice.

I am going for a Skywatcher APO as they are incredibly well priced at FLO but I am torn between two models primarily for DSO imaging

Its either the Skywatcher Evostar 100ED DS-Pro Outfit

or

Skywatcher Equinox 80 APO PRO OTA

The price will be the same once bits and bobs for the Equinox are factored in. It just seems quite compelling to obtain 100mm of ED glass for less than £600.

Any thoughts or actual user experience will be very gratefully received

Dave

[Ags]

The 100 is F9, far too slow for imaging in my inexpert opinion. More knowledgeable people can confirm hopefully.

[riklaunim]

The brighter 80 mm Equinox (+flattener) or something different in that range (not dark, maybe a triplet, with available flattener).

[swag72]

What sort of camera are you looking at using?

[ronin]

The 100 has the longer focal length so any tracking errors will be "amplified" by this aspect.

The 100 however will be better if you decide to switch to doing any visual work at occasions.

[Prador]

As CCD's are waaaay out of my price range I will be imaging with a Canon 1100d

[Hawklord]

If your thinking of using your rig for mobile (rather than permannet observatory) imaging then go for the smaller, faster, and lighter 80mm.

[swag72]

Have you looked at a fov calculator such as http://www.12dstring.me.uk/fov.htm to decide what fov combination you would prefer?

[steppenwolf]

The optics in the 100mm are good but the extra focal length will put more demands on your mount. Many deep sky objects are pretty large so a shorter focal length (wider field of view) may be a better choice. I'd be tempted to go for the 80mm option.

[ianaiken]

I went for the 100, but I wanted to do visual as well. If its purely imaging you want, then the 80 with a flattener for sure.

Personally I use my Camera lens for any faster imaging work although the optics are not as good as the SW scope but for me it was pointless getting an 80 since I could achieve that with my lens, and would not be able to do as much visual. Being my first scope, I do not expect it to be my last, not one scope is perfect for everything.

[ollypenrice]

For imaging, certainly the 80 for its F ratio. For imaging with a DSLR, certainly certainly the 80 because thermal noise limits your exposure time and consequently DSLRs perform better and better the faster the scope that's feeding them light. Reducer/flattener, yes!

Olly

[glowjet]

There is a dedicated reducer/flattener available from FLO that fits both scopes, which would reduce your f9 1OOED to f7.6 and as I understand it this would be passable for some photographic work, but you also have a nice scope for visual use. On the other hand the 80APO seems to be the workhorse for a lot of imagers at f6.25 and 5.3 with the reducer. If your leaning is towards imaging only, then the 80 would be the way to go. I am no expert but if imaging is the route down which you wish to travel, then you will have to take into consideration that a good quality solid mount is also an essential piece of kit, with the CG5 being the very basic and most popular with the smaller scope users

[riklaunim]

There are other 100 mm ED APOs out there that are brighter than the SW. So you can get bigger, but more usable for astrophotography (with the same aperture for visual use).

[ianaiken]

Personally I think the 100 ED is more than passable for imaging with the reducer, but, I fully agree the 80 is better for dedicated imaging. If you got the 100 ED just for imaging you will be left thinking you need faster, without a doubt.

[Uranium235]

The weapon of choice is definietly the ED80 + 0.85x FF/FR, which gives you f6.38. Imaging at f9 would be my vision of hell....lol.

[ianaiken]

100 ED with flattener is 7.65, this is still hell for dedicated imagers :-)