Quantaray brand lenses are made by Sigma, branded as Quantaray and sold thru Ritz Cameras. Here is this lens on Sigma's site. Or it may be this lens
. (Sigma makes 2 70-300 lenses with different lens coatings.)
Unfortunately, neither Sigma nor Ritz makes their lens manuals available online as pdfs, unlike Canon and other major camera and lens manufacturers. Sigma's downloads
are limited to just a few of their cameras, and to the brochure for their lenses.
You will need to get your hands on a paper copy of the user manual for this lens. I suggest you go to a Ritz Camera store in person, at a time when they aren't busy (when they first open is usually a slow time). First, ask for a UV or polarizing filter for this lens (or a similar item you might need) - this makes you a "paying customer" so they will be more likely to help you with your next request. Then ask to see the lens, and the owner's manual. Then ask if they can photocopy the manual for you. They are more likely to help if you are asking them to do a favor for you when you are also buying something (the filter) than if you weren't buying anything.
If they aren't willing to photocopy the owner's manual, you can also consider purchasing the lens "as a gift", photocopy the manual yourself, and then after 12/25 return it "because the recipeint already has one". Check their return policy to make sure you can get a refund, not just store credit.