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08-18-2009, 05:13 PM   #1
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Rikenon P-zoom 1:4-5.4 28-135mm MACRO lens

Hello,
I am using a Pentax K2000 and I just acquired a Rikenon P-zoom 1:4-5:4 28-135mm MACRO lens from my father. The filter attachment is dented, so I can't screw any filters on, but the lens seems to work fine in manual mode. I'd like to learn more about this lens and am hoping that I can find some good information here.

So far all I know is from Robertstech:
QuoteQuote:
Incompatibility Warnings:Avoid Ricoh P-series ("Program") lenses.

You can identify these lenses by a "P" or "(A)P" setting on the aperture ring similar to the A on the A-series Pentax. When the ring is rotated into the "P" (Program) position, it locks in place and you have to depress a small button to get the aperture ring to move again. These lenses have a small ball bearing contact on the rear flange of the lens that will pop right into the hole that holds the AF cam on Pentax autofocus bodies. The result will be that the lens gets locked tight on the body, only halfway mounted.

Early, non-P-Series Ricoh lenses should cause no problem because they have no extra electrical or mechanical contacts.
I didn't have this information before I tried the lens on, but it doesn't seem to experience any of these issues. The lens is easily removable.

What does the p mode on the aperture ring do? (It locks and has a release button).

It performs very well and the macro works nicely, too. The front glass is a little messy, as you can see. What steps should I take to clean it up?

I'm also curious about the value of the lens.

Thanks!

(I took the picture with my Sony cybershot, and I think it focused on the inside of the lens and not the front. Sorry that it isn't a sharper image).

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Last edited by dragonfly; 09-04-2009 at 10:36 PM.
08-18-2009, 05:24 PM   #2
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The P position acts like the A position on Pentax A lenses. However, the lens cannot tell the body that it is in auto-aperture mode. Unless you are using a Ricoh camera, you just use it like an M lens.
08-18-2009, 05:36 PM   #3
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QuoteOriginally posted by alohadave Quote
The P position acts like the A position on Pentax A lenses. However, the lens cannot tell the body that it is in auto-aperture mode. Unless you are using a Ricoh camera, you just use it like an M lens.
Thanks for the snappy reply. When I put the camera in manual mode in the 'P' setting and press the Av button, the camera makes a noise and the display shows what I think is the shutter speed. Is there a way to adjust the aperture in this mode?

Otherwise, I will just use the aperture ring as needed.

Here are a few shots that I took earlier today when I was trying out the lens:

The first is a picture of my dad (thanks for letting me use the lens!) and it shows some strange lines in the bokeh. What is that?!?! There is a mobile dangling in the foreground on the right, but I didn't think that would affect the image like that.

The cactus image turned out better.

I also noticed that the autoISO option is now missing from the menu.
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08-20-2009, 05:55 PM   #4
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I did some photo tests with my new lens today. The camera keeps asking for the focal length, and I keep entering 28mm, since that's what I see on the top of the lens. However, my exif info is showing 35mm equivalent= 42mm.

It seems like the lens won't focus on items that are far away when set at the 28 mm setting (wide open). I try to focus but the lens stops just short of being in focus. When I try to shoot at the 135mm range I get a similar problem (zoom): subjects are not in focus.

When I extend the lens and use the macro mode feature I am able to get sharp images. I'm happy about that, but I'm not taking macro shots all the time.

Am I setting the custom focal length right (28mm)?

08-20-2009, 06:31 PM   #5
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This was posted in the DSLR forum.
Moved to Beginners Q&A.
08-20-2009, 09:07 PM   #6
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QuoteOriginally posted by dragonfly Quote
I did some photo tests with my new lens today. The camera keeps asking for the focal length, and I keep entering 28mm, since that's what I see on the top of the lens. However, my exif info is showing 35mm equivalent= 42mm.
That's correct. 28mm on Pentax D-SLRs is 42mm equiv (28 * 1.5 = 42).

QuoteOriginally posted by dragonfly Quote
It seems like the lens won't focus on items that are far away when set at the 28 mm setting (wide open). I try to focus but the lens stops just short of being in focus. When I try to shoot at the 135mm range I get a similar problem (zoom): subjects are not in focus.
Perhaps something is slightly out of adjustment. I have an old lens that doesn't quite focus to infinity either. I've been meaning to look into that.


QuoteOriginally posted by dragonfly Quote
Am I setting the custom focal length right (28mm)?
Ideallly you would adjust it whenever you zoom. So if you zoom out to 135mm, you would go to the menus and reset the focal length to 135mm. The purpose of this is to optimize the SR (shake reduction). So shooting with the "wrong" setting may make the SR a little less effective, or possibly make the picture slightly worse by over-correcting. It's probably OK to be close but not exact. So if you're shooting at the wide end, you could set it to 35 and probably be OK from 28-50. And if you're at the long end set to 105mm and be happy. You can test to see how well a scheme like this works. Alternatively, if the light is good and you're not shooting at low shutter speeds, just turn SR off and forget about it.
08-20-2009, 10:31 PM   #7
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Thanks for the reply. I went to the farmer's market today to do some more tests. When wide open this lens is only sharp up close. Things that are over 20' away always come out blurry.

When fully zoomed in I am able to get some pics that I wouldn't be able to get otherwise. They're not as sharp as I would like, but at least they weren't all trash. The image of Yoda is the only one that is cropped.

Being a total beginner at this and only having one manual lens for my camera, I don't really know what kind of results to expect. I wanted to think that it was worth trying.
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09-02-2009, 03:32 PM   #8
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Here are a couple more pics from my focus test. It's been tough getting good sharp pics; the focal range of this lens is limited to a certain range which I haven't determined, yet, but it seems to be around 2-6 meters. Objects that are too close or too far just don't come out focused well. I've been using the EV-+ to underexpose the images, and that seems to help get sharper pics.

Also, I've been shooting in 'catch focus' mode. I seem to get more pics that are in focus than in manual focus mode, but this method isn't perfect, either.

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09-04-2009, 09:41 PM   #9
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I managed to get a few decent pics from my last photo shoot. I don't have any data on aperture size, so it's tough to know why any good pics turned out that way. This lens isn't very sharp sometimes, but I manage to get some good pics.





I get discouraged because a lot of my images come out as junk, but I'm starting to learn what this lens is capable of.

BTW, all of these pics were taken in capture-focus mode. I try to capture the focus by taking multiple pics from the far side and the near side to test the focus, but haven't been able to distinguish whether either is preferable. I suppose it depends on the conditions.
09-15-2009, 08:07 PM   #10
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I was taking pictures in the creek today. This image is at full zoom and hand-held at 1/10 sec at about four feet. My goal was to get the water spray in focus. You can see the tiny water droplets flying in the middle of the picture. One nice effect that is captured is a rainbow/prism color effect in the trajectory of the droplets.



This is a crop from another image. It was taken at 1/20 sec. The droplets appear to be strobing, as if they were reflecting a PWM light and not the sun. What is this effect called?
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