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04-17-2008, 07:44 AM   #1
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Pentax 50mm f/2,8 macro - reversed?

Does anybody know if it's possible to use the macro lens also in a reversed way.

Plonsky - Macrophotography Article
In this article M. Plonsky uses a Pentax 50mm f/1,4 as a reverse macro, so could the Pentax ordinary 50mm f/2,8 macro also be used in a reversed way to gain more magnification?

For this I would also need the macro coupling ring and lensmate adapter? Will these fit in my K10D? I assume that the autofocus does not work anymore in DSLR with this kind of setup?


Or is it better just to use the 50mm macro lense the right way and stack Pentax teleconverters? But they are so expensive ....

04-17-2008, 10:20 AM   #2
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Long winded way to say - don't bother reversing a macro

QuoteOriginally posted by hippo Quote
Does anybody know if it's possible to use the macro lens also in a reversed way.

Plonsky - Macrophotography Article
In this article M. Plonsky uses a Pentax 50mm f/1,4 as a reverse macro, so could the Pentax ordinary 50mm f/2,8 macro also be used in a reversed way to gain more magnification?

For this I would also need the macro coupling ring and lensmate adapter? Will these fit in my K10D? I assume that the autofocus does not work anymore in DSLR with this kind of setup?


Or is it better just to use the 50mm macro lense the right way and stack Pentax teleconverters? But they are so expensive ....
To get magnifications greater than 1:1, you could mount the 50 macro reversed on the front of something else of longer focal length, but you would get even better image quality with extension tubes, and maintain the exposure control. Extension tubes have no glass in them, so they are much less costly than teleconverters. Just make sure that the tubes you buy maintain the A coupling, that is they have the electrical contacts to transmit exposure information to the camera body. Don't even look for AF tubes that might have the drive coupling - you will be using manual focus anyway.

The reversed lens is used commonly to avoid the expense of a true macro lens, or with a wide angle lens to get high magnification. The downside is the working room, which is the distance from the lens mount to the sensor - call it an inch, and the contacts and levers and so forth sticking out in the middle of nowhere to be damaged.

Your 50 macro goes to 1:1, a photo of something 16x24 mm in size fills the sensor, and your working room should be at least 4 inches.

Add a 50mm tube to your 50, and you should come out somewhere around 1.5X, a photo of an object 10X16mm would pretty well fill the sensor. That's pretty small and you would still have greater working room in front than the reversed lens.

If you need the working room, such as for insect pictures, a 2x teleconverter would maintain your working room while giving you 2X on the sensor/film. If you get a good teleconverter, the loss in image quality will still be much less than with the reversed lens technique. The problem with the reversed lens technique is that the image quality relies on the primary lens.
04-17-2008, 11:04 AM   #3
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QuoteOriginally posted by Canada_Rockies Quote
To get magnifications greater than 1:1, you could mount the 50 macro reversed on the front of something else of longer focal length, but you would get even better image quality with extension tubes, and maintain the exposure control. Extension tubes have no glass in them, so they are much less costly than teleconverters. Just make sure that the tubes you buy maintain the A coupling, that is they have the electrical contacts to transmit exposure information to the camera body. Don't even look for AF tubes that might have the drive coupling - you will be using manual focus anyway.

The reversed lens is used commonly to avoid the expense of a true macro lens, or with a wide angle lens to get high magnification. The downside is the working room, which is the distance from the lens mount to the sensor - call it an inch, and the contacts and levers and so forth sticking out in the middle of nowhere to be damaged.

Your 50 macro goes to 1:1, a photo of something 16x24 mm in size fills the sensor, and your working room should be at least 4 inches.

Add a 50mm tube to your 50, and you should come out somewhere around 1.5X, a photo of an object 10X16mm would pretty well fill the sensor. That's pretty small and you would still have greater working room in front than the reversed lens.

If you need the working room, such as for insect pictures, a 2x teleconverter would maintain your working room while giving you 2X on the sensor/film. If you get a good teleconverter, the loss in image quality will still be much less than with the reversed lens technique. The problem with the reversed lens technique is that the image quality relies on the primary lens.

Thank you for the help!

Is it possible to stack tubes? I wonder what is the magnification for example in this picture:

http://www.mplonsky.com/photo/6IMG_1888s.JPG

Is this kind of magnification possible with extension tubes... I guess there are practical limits if you stack something like 10 tubes?

Those really detailed pictures from bugs got me inspired to try it my self too, just wondering what would be the best way because it seems that there are many ways to achieve "ultra macro". And yes I agree that the lense reversing is a bit troublesome.
04-17-2008, 11:43 AM   #4
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QuoteOriginally posted by hippo Quote
Thank you for the help!

Is it possible to stack tubes? I wonder what is the magnification for example in this picture:

http://www.mplonsky.com/photo/6IMG_1888s.JPG

Is this kind of magnification possible with extension tubes... I guess there are practical limits if you stack something like 10 tubes?

Those really detailed pictures from bugs got me inspired to try it my self too, just wondering what would be the best way because it seems that there are many ways to achieve "ultra macro". And yes I agree that the lense reversing is a bit troublesome.
That's most likely a work from a bellows. The fly was definitely dead so you can set up properly to take that kind of shot. It seems he also did several focus stacking shots, need to take that into consideration too.

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