Wide field OTA

[Simon Dunsmore]

Hi Folks, 

I was wondering if anyone could suggest a wide field OTA for around £150? I presently use a Skywatcher 130pds for imaging DSOs but I would like to consider a wide field scope also for astrophotography for use with a DSLR.  Budget very limited to £150 or very close. 

Thanks for your help 

Simon 

[vlaiv]

I don't think there is anything in that price range.

Why don't you use 130PDS as wide field scope - or wider field scope?

All you need to do is learn how to shoot mosaics and bin your data.

Want scope that is about 325mm in FL? Shoot 2x2 mosaic - use 1/4 of the time on each panel (that you would otherwise use on whole target with actual 325mm scope) and bin each panel 2x2. That will give you approximately the same result as using 325mm F/5 scope, with difference being in slight overlap between panels that you must make in order to stitch mosaic together and very slightly different SNR - which you can offset by altering your exposures (but you don't have to - it is very small difference indeed - with longer FL scope impact of read noise is just a bit larger than with shorter FL scope - but if you use same rule - that single exposure swamps read noise with either LP noise or thermal noise - you are ok and need not worry about it).

Similarly want to shoot at about 217mm - shoot 3x3 mosaic, use 1/9th of time on each panel and bin each panel 3x3 in software while still linear prior to stitching.

Only drawback is added difficulty and processing time, although with right software - it can be automated (I think that APP can do automatic stacking and stitching of mosaics, but not sure if it can software bin).

[Simon Dunsmore]

Hi Thanks for your comments and the detailed explanation. I'll give it some thought.  Cheers!!! 

[happy-kat]

Why not something like the canon nifty fithty 50mm f1.8 (stopped down) or similar for what ever DSLR you are using.

[Simon Dunsmore]

10 hours ago, happy-kat said:

Why not something like the canon nifty fithty 50mm f1.8 (stopped down) or similar for what ever DSLR you are using.

Hi, Thanks, good idea. I hadn't thought of just using a camera lense! 

[happy-kat]

Could look at searching images on astrobin

The samyang 135mm f2 is another lens and has a dedicated thread on here but you'd have to look out for a second hand one. 

[Space Oddities]

If you're on a budget, it's hard to beat old film lenses!   

The Pentax Super Takumar 200mm f/4 (M42 mount) can be found used for less than 100€. I think I bought one for 70€ on Ebay. It's a good lens for the price, and easy to mount on any DSLR with the right adapter. 

If you want something a bit more wide field, there are some good vintage 135mm f/2.8 or f/3.5 lenses out there too. I haven't used any, since I have the more modern Samyang for that focal length, but I often see people shooting with these. Maybe someone here can recommend a good one!

For even wider field, the Canon 50mm has indeed good reputation!

[happy-kat]

Or of you have any lenses already might be worth a go with one of them.

[Simon Dunsmore]

1 hour ago, happy-kat said:

Or of you have any lenses already might be worth a go with one of them.

Hi and thanks for all the suggestions. The camera came with a Tamron SP 10-24mm 1:3.5 - 4.5 DiII lense. Maybe I'll give that a try first