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08-10-2013, 07:34 PM   #16
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QuoteOriginally posted by nater Quote
In that review it says under Specifications "other features 1:1 macro adapter", which is why people are saying to make sure to get this lens with the matching diopter.
This is very true, though the lens itself is spec'ed at 1:2 and Klaus tested it without the diopter attached. Adding the auxiliary close-up diopter will indeed allow closer focus to 1:1 in much the same way that adding the Raynox adapter will allow a close-focus zoom to support 1:1 or greater magnification. I would expect that the Cosina diopter will provide similar functionality on the Pentax-M 100/4 (another 1:2 macro lens) or any other 1:2 macro lens having 49mm filter threads. The nice thing about a diopter is that you get magnification without loss of speed. The not-so-nice thing is that there is potential for a quality hit.

If a 1:2 with the option of 1:1 with adapter is acceptable, I would suggest the Pentax-M 100/4 Macro, Pentax-M 50/4 Macro or the older version Tamron (1:2) 90/2.8 Macro with its matched doubler. All are available at the same price point or lower than a new Cosina, but with somewhat better build. Auxiliary close-up lenses to boost the magnification to 1:1 are readily available or a simple short extension tube (the more common solution back-in-the-day) will also do.

Here is the link again to RioRico's excellent "cheap macro" article. He gives a quick summary regarding auxiliary closeup lenses.

https://www.pentaxforums.com/forums/pentax-lens-articles/152336-cheap-macro-b...lose-work.html


Steve


FWIW, I have a set of Hoya close-up filters capable of doing a +7 diopter stack. They are great fun and yield a quite workable image.


Last edited by stevebrot; 08-10-2013 at 08:45 PM.
08-10-2013, 10:52 PM   #17
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My word! It looks like I've opened up a hornet's nest here - my head is spinning with all the technical stuff you guys are dishing out!

I didn't realise that there were so many variables in choosing a macro lens. I now need to assess what I want to do with a macro lens, i.e. flowers or bugs. If it's primarily bugs, then my understanding is that I need to get a lens not shorter than about 100mm and with 1:1 magnification. Is that correct?
08-10-2013, 11:11 PM   #18
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Nothing is absolute but I prefer 100mm it gives you more room to work. If you want to get serious Pentax made a 200mm macro that can occasionally be found
08-10-2013, 11:28 PM   #19
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Too bad Tanner (Yeatzee) is no longer active here. He was the king of shooting bugs and I believe that he did so using relatively pedestrian gear. His last post was in February and his Flickr account is similarly dormant. He is good about providing full information on his shots. Check out his Flickr stream...

Flickr: yeatzee (Officially an adult, but still learning)'s Photostream

...and scroll down past the truck pictures.


Steve

08-10-2013, 11:40 PM   #20
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QuoteOriginally posted by Neville Quote
I am expecting delivery of my K5II and 18-135mm combo any day now, and I am thinking of also getting a macro lens to add to my collection.

I already have the following Pentax lenses: 35-80mm, 18-55mm, 100-300mm, which I have been using with my *ist DL.

Any recommendations of which macro lens to get?
Hi,

A friend of mine has a Tamron SP AF 90mm f2.8, Macro 1:1 lens for sale if you are interested.

Regards.
08-10-2013, 11:43 PM   #21
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QuoteOriginally posted by gordon_l34 Quote
Hi,

A friend of mine has a Tamron SP AF 90mm f2.8, Macro 1:1 lens for sale if you are interested.

Regards.
Thanks Gordon.

What does your friend want for it, taking into account that it will need to be shipped to South Africa?
08-11-2013, 01:35 PM   #22
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If you are new to macro--I would think what you would also use the lens forother things. Imagine walking with couple of lenses--and want to do macro (that's my scenario when backpacking). If you want a wide angle and a normal/minor telephoto--then a 50mm f/4 or f/2.8 macro (if it's Pentax). If you would like a good telephoto: lots of nice 9 mm + macros. But then it a question of a smaller/cheaper vs faster/heavy lens. Point is it is often best to have few lenses that do lot's of things well vs. the ultimate lens that only does 1 thing really well. an exxageration but I hope you get the point
08-11-2013, 05:53 PM   #23
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QuoteOriginally posted by stevebrot Quote
Too bad Tanner (Yeatzee) is no longer active here. He was the king of shooting bugs and I believe that he did so using relatively pedestrian gear.
With patience, understanding of insect behavior, and effort, it is indeed possible to photograph insects with very short working distances. Another good example is Thomas Shahan, who uses a reversed lens on extension:

Thomas Shahan!



08-11-2013, 08:16 PM   #24
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QuoteOriginally posted by stevebrot Quote
Here is the link again to RioRico's excellent "cheap macro" article. He gives a quick summary regarding auxiliary closeup lenses.

https://www.pentaxforums.com/forums/pentax-lens-articles/152336-cheap-macro-b...lose-work.html
My understanding is that matched diopters take into account the optical formula of the lens they are bundled with, and are always preferable to a generic diopter. In that article, RioRico points out the cons to generic or general-purpose diopters: "CON: Imperfect image quality; not flatfield sharp; can be quite acceptable."

I can say that when I owned the Voigtlander 40mm f/2 SLII lens (another Cosina lens) that the matched diopter it came with worked very well and had none of the downsides RioRico describes for general purpose diopters.
08-12-2013, 05:05 AM   #25
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QuoteOriginally posted by nater Quote
My understanding is that matched diopters take into account the optical formula of the lens they are bundled with, and are always preferable to a generic diopter.
They are... and the Cosina's is a matched adapter.
08-12-2013, 02:33 PM   #26
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QuoteOriginally posted by nater Quote
My understanding is that matched diopters
My understanding is that a "matched" single-element diopter is still a simple meniscus (magnifying glass). The extra magnification is accomplished at the price of the parent lens' optical correction. Perhaps one of this site's optical gurus could step in at this point?


Steve

FWIW...If it were possible to make a single element matched diopter without penalty, they would be the standard for 1:2 macro lenses. With a few exceptions, this has not been the case. When a matched adapter has been offered, it usually is in the form of a 2x converter that mounts between the lens and camera.
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