scooter1 wrote:
I was photographing an eagle off my back deck the other day and got some good shots with a 75 to 300. I wanted a closer up shot so I put the telephoto lens, a cheap Opteka, on and all I got was an extremely over exposed shot. Tried everything to darken it up but being an amateur couldn't get it done. Any clues? Shooting with a canon rebel T5. The lens was in a bundle I bought with the camera. Any hints would be greatly appreciated. I'm guessing the telephoto maybe takes in more light? Anyway thanks for any help
I was photographing an eagle off my back deck the ... (
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Without more info, it's a bit hard to say what happened.
The "cheap Opteka" might be a manual focus, manual aperture lens.
chikid68 wrote:
The cheap Opteka lens...will only work properly in full manual mode.
Not true. Yes, you CAN set the exposure fully manually... However there are also limited auto exposure modes that can be used. It's possible to use Aperture Priority (Av) and - probably - Manual (M)
with Auto ISO (if your camera has this mode... most newer ones do, but I'm not sure about the Rebel T5).
Other auto exposure modes WILL NOT work with a manual aperture lens. It IS NOT possible to use full "Auto", or ny of the "scene" modes ("sports", "landscape", "portrait", etc.) or to use Program (P) or Shutter Priority (Tv) with manual aperture lenses. Any mode where the camera needs to control the aperture is unusable.
But you still have at least one AE mode that can be used: Av or Aperture Priority.
Another possibility is that the "cheap Opteka" is an auxiliary lens which screws into the front of your other lens... the 75-300mm. If that's the Canon EF 75-300mm "III", in particular, I wouldn't expect very good image quality when it's combined with an auxiliary lens. The "III" is Canon's least expensive telephoto zoom and doesn't have all that great IQ to begin with (it also lacks image stabilization and uses slower micro motor focus drive)... any shortcomings of the lens will get even worse if used with a lower quality auxiliary lens. OTOH, a slight advantage of an auxiliary lens is that the camera's metering system will work with it and compensate and all the auto exposure modes can be used... so in this case it's more likely that you just had something set incorrectly.
If you post the image here, we might be able to suggest more or even give some guidance recovering it, if that's possible. Just make sure the image EXIF is left intact and be sure to use "store original" when you do the upload.
EDIT: I just did a search for "Opteka 500mm" and see two currently being offered. One is a manual focus, manual aperture 500mm f/8 (under $100) and the other is a more compact 500mm f/6.3 "mirror" lens (under $150). Most mirror lenses do not have a variable aperture. To use them you have to work around their rated aperture (f/6.3 in the case of the Opteka 500mm mirror lens)... OR you can add Neutral Density filters to them to give the same effect on exposure as stopping down (depth of field will not change).
The other "non mirror" lens is a "preset aperture" design, as someone else already noted. Those have an aperture you can adjust manually, but they have two rings... one is used to pre-select (i.e. "preset") the aperture you want to use, but leaves the lens wide open to aid in manual focusing... Then at the moment of exposure you manually stop the lens down using the second aperture control ring. If you had set up your exposure for a smaller aperture, but forget to stop a preset lens down at the last instnat, it would cause over-exposure.
Both of those are "t-mount" lenses. They have an interchangeable mount that allows them to be adapted to work on most film SLRs and DSLRs.
Opteka also offers a cheap "2.2X High Definition Telephoto Lens II" (under $40) which screws into the front of another lens, such as your 75-300mm. If this is what you have, it's an auxiliary lens such as I described above.