Best ( cost effective !! ) field flattener for 80mm f5 refractor ??

[Craney]

(originally posted in Eyepieces.... maybe better under "scopes" )

 

Hello there,

I am a new member to these shores and although have studied the stars for many years  I  have only recently dipped my toe into some  low grade semi-serious astro-photography.

Mainly because the modern equipment is so much more productive than the wobbly scope and tank like Practika film camera I had 30 years ago.

I have a SW HEQ5 and recently bought an Opticstar AR80mm Gold  f5 (400mmFL) refractor. I took this picture of NGC 7000. I have noticed a bit of distortion on the top left of the image.  ( The image has been cropped a bit to centralise the nebula, but you can see the effect).

Is there an easy solution.  Could anybody recommend a cheapish device that could correct this.  

I have seen a SW field flattener at FLO

https://www.firstlightoptics.com/reducersflatteners/skywatcher-field-flattener.html

Would this work ?  (even though it is recommended f5.5 and above).

Malcolm at FLO suggested the Hotech device would be the better version, but it is over twice the price.

I was wondering if any experienced "short" refractor buffs could point me in the right direction.

Cheers,

 

Sean.

 

[ollypenrice]

An F5 achromat, whatever they say in the advert (which I've just visited) is never going to be ideal for imaging. It's pretty hard to get an F5 apochromat to do what it says on the tin. I think those who wrote the advert should be asked to provide the answer. I find the ad rather disgraceful. Sorry.

Olly

[Craney]

Thanks Olly.  I'm new to the more technical side of astronomy and I am quickly learning how much of a money pit it can become.    I bought the F5 refractor as a GOTO scope initially as it was small, compact  and came with a decent focuser option. Then I considered it may then work as a future guide scope if I bought a C-8 or c-9.25 etc.... so it is not 'unfit' for purpose, it just shows it limitations quite quickly.

Just wondered if anybody else had the same problem and had solved it with a £5 accessory from Maplins....... ;0)

Cheers

Sean.