80mm F/5 refractor

[Maged]

Hi,

I'm thinking about buying a 80mm F/5 refractor instead of my 4" F/8 scope in order to start astrophotography of DSOs.

I wanted advice on weather the 80mm will be good for astrophotography considering the f/5? or 80mm is too small for light gathering?

thanks,

[Earl]

80mm f5 is great however how good is the colour correction as that does not come in cheap.

[DaveS]

Indeed.

I think this is about as cheap as triplet apos get, but it only has a Crayford focuser, with no option for a R&P

http://www.firstlightoptics.com/esprit-professional-refractors/skywatcher-esprit-ed-80-pro-triplet.html

Budget another £119 for the matched flattener.

Unless, of course, you can budget for a Tak baby Q

[Maged]

80mm f5 is great however how good is the colour correction as that does not come in cheap.

I don't think colour correction is that good its an achromatic lens with coating

[Earl]

I don't think colour correction is that good its an achromatic lens with coating

What scope you have in mind as there are 80mm f5 apo's available.

for example.

http://www.firstlightoptics.com/sky-watcher-spring-sale/skywatcher-esprit-ed-80-pro-triplet.html

[lensman57]

Hi,

I'm thinking about buying a 80mm F/5 refractor instead of my 4" F/8 scope in order to start astrophotography of DSOs.

I wanted advice on weather the 80mm will be good for astrophotography considering the f/5? or 80mm is too small for light gathering?

thanks,

If by the 80mm F5 you mean an Achromatic scope then for imaging it is a waste of time. I won't go into the details as to why. For imaging you'd need at least an ED scope,  an 80mm F5 Apo will cost you a quite a bit of money, an F6 or F7 ED is a lot more affordable. If your budget does not stretch to those scopes another option is a 130PDS which is a native F5 but does need tweaking to get the best out of it.

A.G

[nmoushon]

If by the 80mm F5 you mean an Achromatic scope then for imaging it is a waste of time. I won't go into the details as to why. For imaging you'd need at least an ED scope,  an 80mm F5 Apo will cost you a quite a bit of money, an F6 or F7 ED is a lot more affordable. If your budget does not stretch to those scopes another option is a 130PDS which is a native F5 but does need tweaking to get the best out of it.

A.G

Also to note that though the cheaper scopes are F6/7 at their native FL you can always get a reducer which will bring them closer to F/5. So if you cant afford a triplet then you will want a slower doublet. But as other have said you do not want to image with an achro.

[ollypenrice]

There is nothing wrong with 80mm for imaging. There is nothing wrong with F5 either. But if you want F5 at imaging quality it will be very expensive. Cheap F5 will not do.

Olly