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Post by revolver on Mar 10, 2007 23:14:39 GMT -5
I have a Tamron 70-300MM Di macro zoom lens that I am using on my Pentax K100D.nice lens and all but i was wondering what the effect of a doubler would be.
I understand that it would make the lens a 600MM lens but I am more concerned with the quality of the pictures.
will the doubler decrease the quality of the photos?
would there be anyless clarity than if using a 600MM lens
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Post by kiev4a on Mar 11, 2007 0:13:39 GMT -5
Any doubler has some effect on photo quality. Also the doubler will knock a couple of f-stops off the lens which would probably put it up in the f8 range maximum aperture which may make it hard for the camera to autofocus. If the lens is a true 70-300 just putting it on a camera with a 1.5x factor will make it a 450mm on the telephoto end and a doubler would kick it to 900mm (at least as far as angle of view is concerned) But you will probably have a pretty dark viewfinder. Definately a tripod-only setup.
I've never been much of a fan of extenders, even though modern ones are much better than the early models (multi-coating and multiple elements have helped a lot).
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Post by revolver on Mar 11, 2007 9:29:23 GMT -5
I figured there would be some deterioration of the photos using a tool such as a tele converter.
I just converted MM into feet and see my dilema.
300 MM is less than 100 feet.
the subject that disapointed me was a woodpecker about 50-80 feet away.
i also messed around with the white ballance on some other photos of squirels later on that I had better results with.
I figured a bird on a tree would come out good since my moon shots looked so big.
I guess I have lots to learn about focal lengths as well
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Post by nikonbob on Mar 11, 2007 9:47:45 GMT -5
I use a TC201 2X teleconverter with my 180/2.8 ED Nikkor lens with decent results. The lens has sharpness to spare and is fast to start with but it still needs to be tripod mounted or bean bagged for best results. The VF becomes very dim, equivalent to having a 5.6 lens on, with that combo and focusing a bit difficult. I don't think that I would use one on a zoom that is slow to begin with and you would likely have AF trouble with that slow an aperature. You would be taking a 5.6 lens and turning it into an F11 effective aperture. You really need patience with birds and small animals and let them come to you so they are close enough to fill the frame. Not an easy type of photography.
Bob
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Post by revolver on Mar 11, 2007 11:25:15 GMT -5
I use a TC201 2X teleconverter with my 180/2.8 ED Nikkor lens with decent results. The lens has sharpness to spare and is fast to start with but it still needs to be tripod mounted or bean bagged for best results. The VF becomes very dim, equivalent to having a 5.6 lens on, with that combo and focusing a bit difficult. I don't think that I would use one on a zoom that is slow to begin with and you would likely have AF trouble with that slow an aperature. You would be taking a 5.6 lens and turning it into an F11 effective aperture. You really need patience with birds and small animals and let them come to you so they are close enough to fill the frame. Not an easy type of photography. Bob that doesnt seem like a good idea then. I tell them to hold still but they wont listen! lol |
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Post by nikonbob on Mar 11, 2007 11:45:14 GMT -5
revolver
Personally I don't think that it is a good idea. You could try setting up a blind outdoors and wait for the little critters or shoot from in the house at a nearby perch that you have made for birds to land on. There are alternatives to that really long, heavy and expensive birding lens.
Bob
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Post by Rachel on Mar 13, 2007 8:08:30 GMT -5
Tamron did make a 2x converter for it's lenses. A flat-field converter was how they described it although I don't know what it means. It fits between the lens and the Adaptall mount. I have one but I've never used it.
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Post by kiev4a on Mar 13, 2007 8:31:28 GMT -5
I've got a four-element 2x Kiron extender (Nikon mount) I've used it a couple of times just as a test. It wasn't too bad -- better than the two element extenders--but certainly not as good as a prime lens. I'm not big on long telephotos anyway.
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