I have one of those auto dark lense sheilds from harbor freight,works just fine & never had a flash from it ,I bought it to just try it out & found out for the price its a hellavu deal.
I know several ironworkers,pipefitters & boilermakers who use them at work all the time now because if you drop & break it you didnt lose much money compared to a 300.00 miller speedglass
I have the miller speedglass i use for xray welds on boiler tubes,nuclear power plant welding etc & TIG welding but have found the cheapy works just as good
All types of lenses & sheilds & safety glasses have to meet the OSHA Z81 standard before being offered to the public for sale & the HF sheild meets these standards,it is a 1/25000 millisecond change,the miller speedglass is a 1/16000 millisecond
One thing i dont suggest wasting your money on is the sheild lense that look like a mirrored gold or chrome,I know from experience if its scratched the SLIGHTEST bit you will get weld flash & the thing is you dont even know youve lost the protection from it because the scratch can be so slight you dont even see it unless looking very closely
Always wear at least a pair of clear lense safety glasses behind your sheild,you wouldnt think it gives any protection from the UV rays but it does,very slight but it does
When im welding in the outside in the sunlight of day i use a lighter lense & wear dark safety glasses behind it just for the fact when were on the jobsite we have to wear safety glasses 100% of the time
On the adjustments on an auto always remember if what you are welding at the time if the puddle looks like a big bright light its not dark enough,the proper darkness is when you can actualy see the ripples in the weld puddle itself
Another thing to consider is a cheater lense,its like a pair of reading glasses behind the weld lense,as we all get older we need reading glasses to read a newspaper or book,this also apllies when welding,if you dont see the puddle & it seems to be just big glob of blurry light.maybe you should try a cheater lense,can get them at any weld supplier