Question about Minolta Rokkor 50mm f3.5 macro lens

[juan_c.]

<p>Hi<br>

I recently got an SRT 102 (LOVE IT!! Ahem.) that came with a Rokkor 50mm 3.5 macro lens. I've been wanting a Minolta macro forever now. Well, it has me a little confused as to what some of the markings on the barrel are, though. When you get into the macro range the markings on the barrel are (4 columns): <br>

Middle left (in orange): 1:1.7 1:1.15 1:1.13 1:1.12 1:1.1 1:1<br>

Middle right (in white): 1:10 1:5 1:4 1:3 1:2.5 1:2<br>

Now, I'm pretty sure those are the magnification ratios for the lens, correct? The one in white is the normal magnification, while the ones in orange are with the dedicated adapter that brings it to a full 1:1. What I don't understand is that on the side of each column, are some fractions: <br>

Far left (in orange): +1/4 +1/2 +3/4 +1<br>

Far Right (in white) +1/4 +1/2 +3/4 +1<br>

Are these exposure adjustments? If that is the case, why are they needed? I thought that since I'm using the lens (without the extension rings), wouldn't it meter anyway and give the correct reading? Or do things change the more magnified they get? <br>

As far as extension rings, I use the Minolta EL rings (I think that is the name). It has 3 rings-- No 1, No 2, and No 3. They have no other names or descriptions. I'm guessing the No 1 (the thinnest) is the one that would bring the macro lens to a full 1:1? Plus, is there any way to estimate the exposure adjustments you have to make with these kinds of extension tubes?</p>

<p>Here is a pic of the lens, if that helps any. Many thanks!!<br>

<a title="DSC_7355 by Valkyrie_VF2X, on Flickr" href="http://www.flickr.com/photos/38387748@N00/5397507170/"><img src="http://farm6.static.flickr.com/5094/5397507170_be3290bc5f_z.jpg" alt="DSC_7355" width="640" height="425" /></a></p>

[craigd]

<p>I think you've correctly understood the markings on the lens. The question is why the exposure adjustments are needed. I'm open to correction on this, but I believe it's because a macro lens moves much farther away from the camera (compared to its infinity position) than other lenses of similar focal length. The aperture seems smaller because it's farther away, and this reduces the effective exposure. The aperture doesn't compensate for the extra distance by opening up.</p>

<p>Nikon had a macro lens with a compensating aperture in the 1960s. It was a helpful feature if you were using a hand-held meter or estimating exposures by the Sunny 16 rule, but they removed the compensating aperture because it confused TTL meters.</p>

<p>So if your camera has a TTL meter, ignore the exposure adjustment numbers. Otherwise, you'll have to add the number of stops indicated to your exposure.</p>

<p>As for the extension rings, if the Minolta rings are of similar sizes to the Nikon and Pentax three-ring sets that I've used, you probably need the widest ring to get to 1:1 magnification. A little experimentation should bear this out; mark off 36mm on a piece of paper and see which extension ring allows you to focus correctly on the markings while they fill the frame from left to right. (Assuming your viewfinder has close to 100% coverage -- I have no idea what the SRT viewfinders are like.)</p>

[tony_lockerbie]

<p>Craig is quite correct, they are magnifacation and exposure adjustment factors, which are irrelavant on the camera shown, as it has TTL metering which automatically compensates. My Macro came with a dedicated tube that takes it to 1:1, hardly ever use it.<br>

The Minolta Macro is a seriously good lens, you will enjoy using it!</p>

[Mattman944]

<p>The exposure adjustment factors would be useful if you were using flash with a camera without TTL flash exposure. Of course, you need a flash meter since guide numbers aren't accurate at close distances.</p>

[jodys]

<p>Rokkor QF lenses pre-dated the (1966) SRT-101, Minolta's first camera featuring TTL metering. This lens, when used on my SR-1 or SR-7, needs those exposure adjustment calculations to work with the camera's internal or add-on meters, which read through a cell to the side of the lens, or from an add-on meter in front of the winding lever. That doesn't mean it's a bad lens; the 50mm 3.5 macro has an excellent reputation I believe.</p>

<p>From this site, your lens was first released on 15 December, 1961: <a href="http://thesybersite.com/minolta/historical/Minolta_Lens_Chronology.htm">http://thesybersite.com/minolta/historical/Minolta_Lens_Chronology.htm</a></p>

<p> </p>

[juan_c.]

<p>Wow, thanks for the great info!! Guess all that is left now is to go nuts taking pics with it :o) <br>

Jody: thanks for the site. Kinda explains why the lens has a stop down lever. HAdn't seen those on Rokkors too often--only have it on an old 135 2.8.</p>

<p>Craig: Never thought of testing it that way. Nice! Will be doing that in the morning when I get some good light in the house. Want to do some serious macro shots with the Minolta :o)</p>

[Mike Gammill]

The MC QF pictured doesn't have to be stopped down to meter on the SRT. The first Rokkor QF, though, was preset. It

came in LTM with a Minolta adapter. Optically the same as later macro Rokkors except for coating. My old QF compares

favorably with my much later Celtic MD macro.