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07-20-2011, 03:48 AM   #1
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Reverse adapter advice

Hello Experts,
I have a Pentax K10D. I was thinking of experimenting with some macro photoraphy. So instead of buying a new lens I was considering the option of inverting the lkit-ens for macro-shots.

Now the lens has the following text on it. "18-55mm 52mm"

So now, this is a 52mm lens or a 55mm lens. I need this information for placing the order for the lense inversion adapter.

Do enlighten me on this.

Thanks in advance.
~Roy

07-20-2011, 04:50 AM   #2
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The "52mm" should refer to the filter diameter/size which is what you need to select the correct reversing adapter. This sounds right if the lens is one of the DA 18-55mm versions... See HERE.

Mike
07-20-2011, 06:06 AM   #3
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QuoteOriginally posted by roykurian Quote

Now the lens has the following text on it. "18-55mm 52mm"
You will be disappointed using the kit lens in reversed mode. Because it doesn't have an aperture ring you cannot control the aperture and it will only shoot wide open.

This results in a razor thin DOF, which makes shooting a meaningful macro very difficult.

Find any old lens that has an aperture ring really, doesn't even have to be a Pentax lens.

You'll get much better results and be much happier in the long run.
07-20-2011, 07:05 AM   #4
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Use a 52mm - PK reverse adapter. You can control the kit lens aperture as shown below:


Friction between the flex tubing slipped over the aperture lever and the aperture lever shield holds the aperture in position.

The photo strips below the lens are of a laptop screen and are of good quality; "clearance" is the working distance between the lens and subject - it is sufficient for many situations.

This scheme works well and is an easy intro to macro. Don't worry much about the exact aperture - wide open will result in about maximum sharpness - closed somewhat will increase depth of field.


Last edited by newarts; 07-20-2011 at 07:11 AM.
07-20-2011, 03:07 PM   #5
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newarts' suggestion is very good. I recommend that you set the focal length between 24mm and 55mm for macro shooting. Shorter than 24mm, the exposed rear element could catch stray light that can cause flare and loss of contrast. At 24mm and above, the rear element recesses far enough that the body acts as a lens hood. Be aware that your working distance will be very close, around 2-3 inches.

Yes, the DA18-55 has a 52mm front thread, so you will want a 52mm-PK mount-reversal adapter. Search eBay for PENTAX 52MM REVERS* and you will find some for under US$3.50 shipped. Have fun!
07-20-2011, 05:13 PM   #6
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Well… I stand corrected! Well done newarts.
07-20-2011, 10:52 PM   #7
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QuoteOriginally posted by bimjo Quote
You will be disappointed using the kit lens in reversed mode. Because it doesn't have an aperture ring you cannot control the...
...You'll get much better results and be much happier in the long run.
Thank you for the feedback.

Looks like luck is on my side. I have some old 52mm manual lens from Vivitar.
A 70-210 actually. You think it will work well?

~Roy
07-20-2011, 10:55 PM   #8
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QuoteOriginally posted by newarts Quote
Use a 52mm - PK reverse adapter. You can control the kit lens aperture as shown below.......
...
wide open will result in about maximum sharpness - closed somewhat will increase depth of field.
Thats indeed great! I am eagerly awaiting my adapter to come in.

~Roy

07-21-2011, 06:21 AM   #9
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QuoteOriginally posted by roykurian Quote
Thank you for the feedback.

Looks like luck is on my side. I have some old 52mm manual lens from Vivitar.
A 70-210 actually. You think it will work well?

~Roy
It may work at the short end but may not.

All reversing a lens on camera does is to move the lens away from the camera a bit - this has the effect of increasing magnification. But with longer focal length lenses reversal doesn't move the lens enough.

You could buy yourself a used manual 28mm lens to get a lot of magnification with reversal or with inexpensive extension tubes.
07-21-2011, 06:59 AM   #10
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QuoteOriginally posted by roykurian Quote
I have some old 52mm manual lens from Vivitar.
A 70-210 actually. You think it will work well?
Yes, it will work, sort of. No, it will not work well. I just reversed a 70-210 on my K20D. At 70mm I get about 1:1.67 (0.6x) magnification at a working distance of about 14cm. At 105mm it focuses to infinity and can't get a useful closeup. Longer than 105mm is impossible. I have reversed a 35-80 zoom; 28-80 and 18-55 will work also; but 70-210 is much too long for close (non-macro) shooting except at around 70mm. Try it and see. Just flip the lens around and hold it against the camera.

Simply reversing a lens does not produce magnification. What you gain are flatfield sharpness, because the end that normally projects a flat-sharp image onto the camera frame (film or sensor) is now capturing the image; and a closer working distance. That working distance varies with a zoom; short zooms can work in the 2-6 inch range, and at 80mm can focus past infinity. With a prime, the working distance is fixed at the lens register, which for Pentax is under 2 inches, 45.46mm. So you are forced very close; but for magnification, you need extension.

The 18-55 with its aperture jammed open as per newarts' picture above, reversed, would be a good place to start. In the 18-35mm range you'll have over 2x magnification at working distances of around 2 inches.
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