Calling on the fraccers! Evostar 80ED VS Esprit ED80

[Sonicfishcake42]

I'm more or less ready to pull the trigger on an imaging set up. I've got my mount chosen and ready to go so now it's just the case of some glass to sit on top of said mount! 

I've thus far only used an SCT for visual and I'd love to get started with imaging, I'm in the process of saving up my pennies for the OTA. I'm keen to learn the differences between the Esprit and the Evostar models and if the benefits warrants saving a little extra for the Esprit?

I'm limited to around £1000 for the OTA, anything over and I'll have a VERY angry other half! Convincing her my first scope was worth the pennies was easy.... A second 'scope is a little trickier! (I've not even mentioned the need of a dedicated camera....yet) - One hurdle at a time eh?

In addition to the above, I would like to know if buying the Evostar 120ED over the Esprit 80ED would have any advantage? For me, visually anyway, bigger means better however in the fandangled world of imaging I understand this is not necessarily the case.

Any information would be appreciated as always  

[ChrisLX200]

A camera does what your eye cannot - it accumulates light the longer the exposure. For visual then aperture rules, for imaging optical excellence rules. So no, you don't need a large aperture scope for imaging (but it helps of course if it can collect photons more quickly) but what you do want is the best quality you can afford - pin-point stars across a wide, flat field, and a relatively fast focal ratio. For that reason I would recommend you consider the Star71 astrograph. It is by no means the only option but that particular OTA is designed for the job and offers the exact qualities you're looking for. The Esprit is good too, but will need field flattener. Lots of choices.

ChrisH

[Sonicfishcake42]

I'm absolutely open to suggestions! (Provided they are within budget). To be honest I've not even thought about WO, I assumed they'd be out of my price range! I don't/wont need the scope for visual use at all so dedicated astrographs are definitely a consideration! 

[swag72]

.....In addition to the above, I would like to know if buying the Evostar 120ED over the Esprit 80ED would have any advantage? For me, visually anyway, bigger means better however in the fandangled world of imaging I understand this is not necessarily the case.

Any information would be appreciated as always

On this note - a 120ED over an 80ED ............. I categorically say no way! I started off with a 120ED as my imaging scope. I had no idea what I wanted to image and was totally green around the gills. To this end, I was recommended the 120ED by a retailer and it became apparent over time that it was a mistake for me. The 80ED has a shorter focal length and this is beneficial for many of the nebula's. The focal length of the 120ED at around 900mm I found very much a betwix and between - Not good for the bigger nebula's and not good for the small stuff either.

When I changed the 120ED for a 75mm scope it became even more apparent what a mistake I'd made. 

The 80mm scope is the basis for many peoples imaging rig and for good reason....... If you look at the fov calculators out there, then you can out in various scope and camera combo's and look at the sort of stuff that particularly interests you for imaging.

Hope that helps

[MattJenko]

The Esprit is a triplet, so better corrected (although the ED80 doublet is very well corrected anyway) and faster, but will need a flattener as well. It is also heavier with a better focuser. At that kind of money, other makes of 80mm refractors come into play, TS and AA ones are worth considering too.

[ollypenrice]

When you choose a scope for imaging you need to follow some kind of checklist system. Here's my order but it could perfectly well vary somewhat. 

1) Focal length.  a) Determines FOV. What do you want to fit on the chip? b ) Determines pixel scale. Below an arcsec per pixel is getting difficult to guide and resolution may be wiped out by the seeing. 2 is sweet. Up to about 3.5 is OK. c) Shorter FL is easier to guide, as just said.

2) Focal ratio. Fast is good but is also demanding on the optics which means expensive.

3) Colour correction. Blue bloat affects most refractors to some extent, but how badly? Decide on a scope by scope basis rather than on the theory that doublets are worse then triplets. This requires all things to be equal to be true and they aren't.

4) Corrected circle. Large corrected circles are usually expensive but will cover bigger chips.

5) Will you need to replace the focuser? Many standard Crayfords are awful.

I agree with Chris that the WO Star 71 is remarkable.

Olly

[nicoscy]

80mm is the best place to be when embarking on the treacherous path of imaging. Does it have to be a Skywatcher telescope? Shipping from Germany should be about 40 pounds max, leaving 960 pounds or 1,300 euros to spend.

TS has the following within your budget:

http://www.teleskop-express.de/shop/product_info.php/info/p7224_TS-80mm-f-4-4-Imaging-Star-APO-Astrograph---aperture-80mm---focal-length-352mm.html

or this and add a field flattener/reducer (not necessarily a TS flattener/reducer) and some money left on the side for the camera budget:

http://www.teleskop-express.de/shop/product_info.php/info/p5193_TS-PHOTOLINE-80-480mm-F-6-Triplet-APO-FPL-53---3--Focuser.html