Hi David,
The recessed front element is no problem. I have used the FA 100/2.8 macro, which also has a recessed front element. No problems at all. Don't know if it gives any benefits, though.
The only good way to deal with vignetting is by extension tubes or bellows. You will always get vignetting with wide-angle lenses. I paired the 100mm with an FA*24/2 which has a larger front element than the 100mm, but still got vignetting.
If you use the 50mm reversed before the 90mm, your total magnification will be 1.8x. With the 28, you'll get 3.2x. That's quite a difference...
John Shaw, in the book "Closeups in nature", writes that the best lens he's come across for reversal is a 200/2.8 in combination with various lenses reversed. He recommends a 50mm. He recommends against stacking two macro lenses together.
While John Shaw is a Nikon shooter, I think he's on to something about the focal lengths. Recently I tried to reverse an FA 50/1.4 in front of an A* 200/4 macro, and the result was a lot better than the 24mm/100mm combo.
hth, Jostein
----- Original Message ----- From: "David Zaninovic" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Tuesday, May 10, 2005 5:05 PM
Subject: Re: reverse mounting lenses
> Is F50/1.7 front element large enough to be reverse mounted on > top of
Tamron SP90/2.8 ? SMC-M 28/2.8 works only when Tamron is set
> to f2.8, beyond that I get vignetting. Which lens is recommended > for
reverse mounting ?
It all depends on thread size. Just use step-up/step-down rings to make
them mate.
mating is not a problem I have plenty of duct tape.
if you get vignetting, you need to add extension tubes between the camera
body and the prime lens. this will eliminate it.
>
> I see that it helps if I focus the Tamron as close as possible > but not by
much. Is it good or bad the fact that Tamron has deeply
> recessed front element ?
You should always focus as close as possible.
yes, that seems to help but not as much as I would like. I think that front element on the 28/2.8 is just to small. I will get
F50/1.7 in a few days and will try with that lens.
Again, extension tubes are a big help.
Tamron is already a 1:1 macro lens so it has its own extension tube which is very long. I noticed that there is not so much
difference if I focus at infinity or as close as possible, there is a difference but not more that few f-stops before it starts to
vignette. So If I add even more extension I don't think it will help much as I could end up with ridiculously long tube. Or adding
extension is something different from what the Tamron is already doing, it is possible as rear element on Tamron is fixed and it is
right at the end of the lens.
It shouldn't matter that the tamron has a recessed front element.
Strange that it does not make any difference.
Check out John Shaw's "Closeups in Nature" A great book with all kinds of
techniques for macro.
That is the only photography book I have. :)
I guess I should take a look if there is anything that could help me, I did not think of that. :)
