Greetings, I have a Canon EOS Rebel T5 which is in excellent condition. I mated it up with a recently acquired Sigma 70~300mm 1:4~5.6mm APO Macro Lens. Please bare with me because I am trying to describe my problem. The lens fits perfectly, no problem there. I should also mention that I have a Sunpak external flash, made exclusively for my T5. It also is in excellent condition. When practicing to learn how these two guys get along, I noticed something very peculiar. Here are my settings: 1/125s, F/4.0, ISO 100 and shooting in Manual Mode. I should mention that I have never had a problem with this flash, in fact I like it better than some of the speedlights that Canon offers. Okay, at these settings, my photographs came out a little underexposed, again using the external flash. Now, here is the weird part. The more I shut down the lens, the more overexposed the photographs turned out. I increased the number for the f/stop setting all the way down to f/25 and again, grossly overexposed. Then I decided to increase the shutter speed to 1/800s, and left the other settings alone. When looking through the viewfinder, I noticed the shutter speed automatically adjusted itself to 1/200s and at this speed, the flash would not flash. I reset the shutter speed to 1/160s, the flash worked but the image was horrible. I then decided that perhaps I was too close to the subject and I then moved farther back. There was a little change, but nothing to write home about. The flash unit does have a diffuser which I did use and it turned out alright. The question is of course, why are the exposure settings changed prior to taking the photo? I can upload the photos here which will show the EXIF data. I do like the images I get with the Sigma lens. The auto-focus is very accurate, however it is slow so just a minor inconvenience. Thanks for the help. The batteries are all fully charged and I did clean all the contacts. Also, why are the lens settings working backwards? Tony
Now this made me go hmmm...I would pay attention to the guide number, and with the camera in manual mode perhap is the flash also in manual mode? Perhaps it was in ETL mode? What was the distance to your subject?
Hi Porkphoto, yes my Canon is always in Manual Mode. As for the Sunpak Flash, it is in one mode only. Since I rarely do any low light or night time photography, I will not worry about it much. The camera and lens function quite well outdoors in daylight. Thanks a bunch for your input. Tony
Actually, upon further use, I have noticed that the lens completely differently indoors than outdoors. Outdoors, it is a wonderful lens as it produces excellent photos. Indoors, well that is a horse of a different color. Everything works in reverse when shooting indoors. When I open up the lens to the smallest number, the image is way underexposed and when I stop down the lens to its largest number, the image is way overexposed. I wonder if the meter is reacting differently indoors and producing erroneous info to the processor. Any ideas and suggestions will be very much appreciated. Thanks, Tony