Sigma 28 70mm
Sigma Lens or Sony -?

I recently purchased an A100 on craigslist. It came with three lenses, two of which have approximately the same range. I'm thinking sell one of them, and wondered what in his opinion, was the best lens and what would be a fair price to sell one? Sony Lens: 18-70mm f3.5-5.6 Sigma Lens: 28-70mm f2.8, a 72mm Hoya Skylight (1B) Filter I tried to find information online about the Sigma lens, but can not find this specific. I think was originally a 35mm lens because it does not have any markings saying its an EX DG or the lens, as well as abnormal is really heavy! Any advice would be appreciated. Thanks! I appreciate the detailed response. I looked at the Sigma lens again, and I really do not think that's the EX DG. The photos I've seen that lens be different from the lens I have, and the photos show saying the Sigma EX DG lens on the side of the lens, in my not (just says sigma). Is it possible to find a serial number of the lens?

You can see this problem in several ways. First, let's talk $ $ $ to get it out of the way – do you need? The superior optical Sigma 28-70mm f / 2.8 sold in the range of $ 250 to $ 300 used. The number is closer to $ 300 if you include the Hoya Skylight filter. You can get around $ 50-80 for the Sony 18-70mm f/3.5-5.6. If you are tight on cash right now then I suggest you keep them both. The Sony kit lens is probably one of the worst kit lens in terms of quality optical (1, 2). Although the Sigma probably has the best built, best performance, and a fast constant aperture, the lens from Sony includes an additional 10 mm at the wide end. The quick opening steady, better construction and better view is very nice to have, but so is the versatility. You need to decide what is more important for yourself. A way, your Sigma is likely that a Sigma 28-70mm f/2.8 EX DG: http://www.sigmaphoto.com/lenses/lenses_all_details.asp?id=3264&navigator=2 Follow-up: Can you provide a picture of your lens? It seems that a number of Sigma 28-70mm f/2.8 lenses available for the Minolta / Sony mount. Some of them became Minolta for film cameras and have since been suspended. You can find a fairly complete list here complete with user-submitted comments http://www.dyxum.com/lenses/resultsAdv.asp?selLensType=3&txtMinFocal=&hdFormSubmited=Submited&selDLens=sAll&rdbManufacturer=3&selProduction=sAll&selCoverage=sAll&txtMaxFocal=&txtName=&Submit Srto = Search & def = & offset = 20 course, my original statements on the Sigma no longer apply if it is a different objective.