So baciscly with what frame should you farm ?
Well of course you can do it with every warframe but there's one difference in high/fast DMG frames against low/slow DMG frames they have lower pull of focus.


Places:
T1 Survival , Ceres: Interception//Draco

First of all 100 000 EXTRA focus can be earned per day.
Max per mission: 55 000 extra focus.

Lets begin with Saryn.

Saryn is high dmg frame with very easy combo(2 1 2 4 or 1 3 4)










Her build is not complicated.If you don't have Primed Continuity add normal continuity and try to buy cheap Primed one D:(it will be hard belive me or not xD)
With her you can get around37,000 in first long round inDraco.

Mesa as Saryn is high but not fast(not at all shh don't hate)dmg frame ~ Her 4th ability need to "warmup" before fast shooting :p
This build for Mesa is very old so please don't judge.At old time it was very high recommended now even thou my friend(Mesa main) said that this build is very good but he rather replace Flow with Prime Continuity and add 3rd forma for Coaction Drift because enemies got reduced armor by 30% and with this dirft 37%

As i said up later i played as Mesa veeeeeeery long time ago so i dunno how many focus she can get(i do shh) but i was informed by my friends that she can get 25 000 - 30 000 per mission so its good score as for a slow/high dmg frame ^-^

Excalibur is fast/high dmg frame only thing that i like most than in Saryn as Exca is that he is spamming 3 and 3 is doing more dmg than full combo of Saryn(wtf moment)Yeah you heard well EXCALIBUR IS THE STRONGEST WARFRAME EVER and of course most ballanced XD
Note - This is a 3 Forma build(Excalibur Prime) and 5 forma(Excalibur standard)
Excalibur gains 35 000 - 45 000 focus in one Draco round

As for Exca and Saryn , Ash is very powerful warframe ~
His High and ultra fast DMG from Blade storm makes him 2nd strongest warframe in game.


This build requires 1 forma on Ash prime and 3 forma's on normal Ash.


I recommend taking Tipedo on ASH beacuse its fastest weapon in game + His 4th ability is faster with Attack speed :P(it was tested many times belive me or not but just DO IT)

Hope I helped you a little bit guys ! ^-^
Remember that Focus limit is 100k per day.

Mesa,Saryn,Excalibur Prime pictures are from -> www.warframe.wikia.com
Excalibur Umbra and Prime are made by -> http://marshallvex.deviantart.com/gallery/52662166/Warframe