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09-21-2017, 04:20 AM   #1
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Pentax SMC Pentax A 50mm 1.7 for macro photography?

I am quite keen to try out macro photography and I was wondering if, using manual extension rings, the MF Pentax SMC Pentax A 50mm 1.7 lens is a better option than the AF Pentax-DA 50mm 1.8 lens?

Is buying the MF lens redundant if I already have the AF 50 lens?

Also, do you really need a set of AUTO (with contacts) extension tubes or is a full manual set OK?

Using a full manual set and the Pentax SMC Pentax A 50mm 1.7 lens, will the GREEN BUTTON set the correct exposure on a K-3?

Thank you!

Theo


Last edited by Theov39; 04-25-2018 at 08:51 PM.
09-21-2017, 04:25 AM - 2 Likes   #2
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The primary disadvantage is having to use the terrible aperture ring on the A 50/1.7...No PTTL either, but the only affordable ring flashes will only work at full power on a K-3 anyway...
09-21-2017, 04:34 AM - 1 Like   #3
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The DA 50mm f/1.8 does not have an aperture ring. So unless your extension tube has electrical contacts you will not be able to set the aperture.

The A 50mm f/1.7 is a fine choice for macro as it has a very flat field of focus.

Stop down metering in manual mode - green button or Optical DOF preview (activates exposure bar needle match metering) will work. Even better if the tubes have an auto aperture lever.
09-21-2017, 05:02 AM - 2 Likes   #4
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If you get the cheap teleconverter with Pentax-A contacts on it then just remove the glass inside and it will act as ext. tube but you will retain full control of the aperture on your Pentax body and will have full P-TTL metering if flash is on the camera or on extension cord. The SMC Pentax-A50mm F1.7 is excellent lens and can be used in macro photography as well, just remember to take care of thin depth of field when using it (critical focus).

Do not worry what brand teleconverter is as long as it have A-contact will be good and make sure those are working prior purchase. They are around $20 to be found.

This is quick sample taken with SMC Pentax-A 50mm ƒ1.7 lens... I guess it is useful as macro (small rose pictured)




Last edited by RAART; 09-21-2017 at 05:08 AM.
09-21-2017, 05:07 AM - 1 Like   #5
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Or you could do what I did and spend years searching online auction sites to find a set of Kenko AF extension tubes at a good price

09-21-2017, 05:17 AM - 2 Likes   #6
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as for the second option DA50mm F1.8 is also useful if you get teleconverter and then remove the glass. It needs to have electrical contacts, speak Pentax-A contacts, in order to work or as @boriscleto suggested those Kenko ext. tubes equipped with electrical contacts. They are more expensive as the teleconverter, deglassed but gives you also the choice of different magnification. You will loose only AF but everything else will work.

This is quick example taken with DA50mm F1.8 lens. Hope this will help with your decision...

09-21-2017, 05:19 AM - 1 Like   #7
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I thought it was more fun to start with a reversal ring on a manual lens, rather than mucking with extension tubes.

09-21-2017, 05:34 AM   #8
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QuoteOriginally posted by RAART Quote
as for the second option DA50mm F1.8 is also useful if you get teleconverter and then remove the glass. It needs to have electrical contacts, speak Pentax-A contacts, in order to work or as @boriscleto suggested those Kenko ext. tubes equipped with electrical contacts. They are more expensive as the teleconverter, deglassed but gives you also the choice of different magnification. You will loose only AF but everything else will work.

This is quick example taken with DA50mm F1.8 lens. Hope this will help with your decision...
Thank you very much. Really shows the possibilities either way. The reason why I was asking about the DA-50 as I already have that lens but I'm willing to buy the Pentax-A 50 if required. It seems like a nice lens in any case.

Regarding deglassing an old AUTO TC, doesn't a TC in effect act like a close up lens anyway if used with a 50mm lens? If so, it may be useful even NOT de-glassed.
09-21-2017, 05:52 AM - 1 Like   #9
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It will act also as teleconverter if you do not remove glass of course but the minimum distance to subject will increase as well and if you need to get close by (for magnification sake) you will need to remove glass. I used old Takumar-A teleconverter for this and removing glass is non-destructive. It just unscrew the retainer and remove glass, later you can put it back if needed but do not know about quality of the used glass in teleconverters.

EDIT: while you have DA50mm already then logical choice, at least for me, is to get the teleconverter.
09-21-2017, 06:01 AM - 1 Like   #10
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I have used the A 50/1.7 with the Vivitar 2X macro-focusing TC -- find one of those with the KA contacts (they are not rare), and you can avoid using the fidgety (and brittle) A 50/1.7 aperture ring - leave the aperture ring set on A and set the aperture using the DSLR body. [And do ~not~ punch out the glass elements on that Vivitar 2X macro-focusing TC - LOL.] The A 50/1.7 is a really fine ~flat-field~ lens for macro use(better in this regard than the two faster A 50's) (and the manual focusing is likely ~much~ better than with any of the AF 50's).
09-21-2017, 06:10 AM   #11
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QuoteOriginally posted by RAART Quote
It will act also as teleconverter if you do not remove glass of course but the minimum distance to subject will increase as well and if you need to get close by (for magnification sake) you will need to remove glass. I used old Takumar-A teleconverter for this and removing glass is non-destructive. It just unscrew the retainer and remove glass, later you can put it back if needed but do not know about quality of the used glass in teleconverters.

EDIT: while you have DA50mm already then logical choice, at least for me, is to get the teleconverter.
That makes sense. Thanks for the tips. Much appreciated.

---------- Post added 09-21-17 at 06:15 AM ----------

QuoteOriginally posted by fwcetus Quote
I have used the A 50/1.7 with the Vivitar 2X macro-focusing TC -- find one of those with the KA contacts (they are not rare), and you can avoid using the fidgety (and brittle) A 50/1.7 aperture ring - leave the aperture ring set on A and set the aperture using the DSLR body. [And do ~not~ punch out the glass elements on that Vivitar 2X macro-focusing TC - LOL.] The A 50/1.7 is a really fine ~flat-field~ lens for macro use(better in this regard than the two faster A 50's) (and the manual focusing is likely ~much~ better than with any of the AF 50's).
Great tip. I used to have a Vivitar 2X macro-focusing TC back in my Nikon days but never really used it as I wasn't interested in macro photography back then.

Will see if i can pick up a PK version but they are pretty rare in Australia. Even the more common Nikon version I had to order from KEH!

Last edited by Theov39; 09-21-2017 at 06:16 AM.
09-21-2017, 06:52 AM   #12
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QuoteOriginally posted by dcshooter Quote
It's probably a bit of a stretch to categorically state the KA version of the VIV converter is "not rare." More like "rarish" or "uncommon."

Another option that some here have had a lot of success with is pairing the DA50mm 1.8 with a Raynox 250 closeup lens. I'm not generally a fan of front-mount closeup lenses, but this combo seems to really shine together, and it retains AF and in-camera aperture control with the DA lens.

At 60 bucks, it's also a bit cheaper than a nice condition sample of the Viv.

The Raynox Macro club - PentaxForums.com
It is amazing to see the quality the Raynox 250 closeup lens can produce. Never took that lens seriously before but might be worth having a look at.
09-21-2017, 09:41 AM - 1 Like   #13
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QuoteOriginally posted by boriscleto Quote
The primary disadvantage is having to use the terrible aperture ring on the A 50/1.7...
How common is the shoddy ring problem? I have one that came with a film camera with the busted ring. It's kind of a hassle so it's been sitting in a drawer until I get around to a repair (Pentax-A 50mm f1.7 Aperture ring repair - PentaxForums.com).


I went with an SMC Pentax-A 28mm/2.8 for use on tubes or reversing (onto another lens or tubes). For it's price, it's pretty decent, and it takes less extension than a 50mm to get a given magnification.

I'm a fan of the Raynox DCR250, it also pairs nicely with a dedicated macro should you eventually go that route.
09-21-2017, 12:12 PM - 1 Like   #14
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QuoteOriginally posted by dcshooter Quote
It's probably a bit of a stretch to categorically state the KA version of the VIV converter is "not rare." More like "rarish" or "uncommon."

OK, I stand corrected then... (Or maybe then I ~sit~ corrected...)
09-21-2017, 01:45 PM   #15
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If you get a reversing ring, you can use any manual 50mm lens, not just Pentax. Shorter focal lengths will give greater magnification and less working distance. Reversing on tubes or a TC gives you more options as well. You're losing aperture automation and auto diaphragm, of course, but still a valid option.This is one of the of set-ups that Thomas Shahan uses. I've tried it myself and the results can be quite excellent, even with a no-name 4 element TC. Playing about with odd bits and pieces is a great way to work in macro. I'll also link to two excellent resorces that have given me a lot of good ideas: https://www.pentaxforums.com/forums/54-pentax-lens-articles/152336-cheap-mac...lose-work.html

and http://extreme-macro.co.uk/

Last edited by Thagomizer; 09-21-2017 at 01:52 PM. Reason: Links added
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