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03-16-2008, 06:46 PM   #1
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About to purchase help

in the next few hours......either
ASAHI,PENTAX,SMC,K Pentax-M 100mm f4 Macro AA+

Sigma MACRO 105mm F2.8 EX DG Lens for Pentax

PENTAX 100MM F4 MACRO SMC M LENS - GREAT SHAPE

Out of the 3 which will give me the best photos? thanks, at least I have it narrowed down to 3 now, LOL

03-16-2008, 07:50 PM   #2
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Are the 2 Pentax lenses identical? It looks as if both of them are Pentax-M 100/F4 macro lenses. I don't have experience with either lens, but the Pentax has some pretty good reviews. The Sigma seems to be well received as well. Tough choice....hopefully someone will chime in here.
03-16-2008, 08:01 PM   #3
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QuoteOriginally posted by maxwell1295 Quote
Are the 2 Pentax lenses identical? It looks as if both of them are Pentax-M 100/F4 macro lenses. I don't have experience with either lens, but the Pentax has some pretty good reviews. The Sigma seems to be well received as well. Tough choice....hopefully someone will chime in here.
It does look as if the 2 pentax lenses are the same. I put a bid on the sigma and it closes in about 40 mins. So we will see if anyone has anything to add here in time
03-16-2008, 08:07 PM   #4
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Not much in the way of reviews here, but there are a few in the database.

Pentax
Pentax Lens Review Database - 100mm F4 Macro

Sigma
PentaxForums.com Third-Party Pentax Lens Review Database - 105mm F2.8 EX DG (AF Lens)

I doubt you'll go wrong with either one. Good luck!

03-16-2008, 08:11 PM   #5
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QuoteOriginally posted by maxwell1295 Quote
Not much in the way of reviews here, but there are a few in the database.

Pentax
Pentax Lens Review Database - 100mm F4 Macro

Sigma
PentaxForums.com Third-Party Pentax Lens Review Database - 105mm F2.8 EX DG (AF Lens)

I doubt you'll go wrong with either one. Good luck!
Thanks I had found the review about the 100 f4 but not the other one. I appreciate your help. If things keep going the way they are now I will be the happy owner of a Sigma 105 macro! we will see how much more the price goes up
03-16-2008, 08:59 PM   #6
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I lost the bid on the used Sigma but at the price it went for if the person had done some research they could have gotten it new for 5.00 more dollars! So now need to make the decision about getting the new sigma or bidding on the pentax 100 F4
03-16-2008, 09:04 PM   #7
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QuoteOriginally posted by rmtagg Quote
I lost the bid on the used Sigma but at the price it went for if the person had done some research they could have gotten it new for 5.00 more dollars! So now need to make the decision about getting the new sigma or bidding on the pentax 100 F4
I am extremely happy with my 100/4 M series Pentax. I use it with the camera in AF.S mode a lot, which gives me snap in focus. I even use snap-in-focus for flower shots in the wild. I set the magnification factor on the lens (they are engraved on the barrel) and hold down the shutter release while very slowly sneaking up on the flower, usually with the stamens under the center focus point (the only one that is active with an M lens). Magically, Mr. Pentax takes a perfectly focused shot for me. Well, most of the time anyway.
03-16-2008, 09:10 PM   #8
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QuoteOriginally posted by Canada_Rockies Quote
I am extremely happy with my 100/4 M series Pentax. I use it with the camera in AF.S mode a lot, which gives me snap in focus. I even use snap-in-focus for flower shots in the wild. I set the magnification factor on the lens (they are engraved on the barrel) and hold down the shutter release while very slowly sneaking up on the flower, usually with the stamens under the center focus point (the only one that is active with an M lens). Magically, Mr. Pentax takes a perfectly focused shot for me. Well, most of the time anyway.
I am wondering how is does in a little bit lower light setting being an F4 as apposed to a F2.8?????

03-16-2008, 09:17 PM   #9
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QuoteOriginally posted by rmtagg Quote
I am wondering how is does in a little bit lower light setting being an F4 as apposed to a F2.8?????
There is a lot more concern about depth of field than aperture, believe me. At f/4 a 100mm macro seems to have no depth of field. It snaps focus quite nicely in any light that I can see the subject well enough to place the focus point. It does get a bit dicey if I try to do 1:1 with the 50mm tube on the back, but even then, it seems to snap once I put it in just the right spot.

I did forget to mention that it only goes to 1:2 without extension tubes. The reduced field of view with the dSLR offsets this quite a bit. At 1:2 your field of view is 2/3 the 35mm frame (1 X 1.5 inches) or about 2/3 inch by an inch. If you are mostly into flowers and bugs as big as a butterfly, I don't think this will be a problem.
03-16-2008, 09:59 PM   #10
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I think F/4 is a bit slow for taking macro under shade especially at 1:1. I know that with my Tokina 90mm (no auto aperture), when I used f/4, the AF confirmation wouldn't even fire, and the Katz Eye shows sight out of blacking out. For most of my active bug shots, I usually use f/4 or f/5.6 to nail it, further stopping down might result slow shutter speed.
03-16-2008, 10:07 PM   #11
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QuoteOriginally posted by aegisphan Quote
I think F/4 is a bit slow for taking macro under shade especially at 1:1. I know that with my Tokina 90mm (no auto aperture), when I used f/4, the AF confirmation wouldn't even fire, and the Katz Eye shows sight out of blacking out. For most of my active bug shots, I usually use f/4 or f/5.6 to nail it, further stopping down might result slow shutter speed.
I use manual exposure, and have had no problems with the shutter speed, using ISO 400, which is really quite clean on the K10D, at magnifications up to 1:2. I might get ambitious and try the tube with the lens and see if it will work "in the dark". Using the lens without the tube (up to 1:2), I have had no problems with the AF indicator and snap-in-focus. I seldom need more magnification than 1:2.
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