Pentax M 100mm f4 Macro


Lingevres

Link Posted 05/02/2016 - 20:57
Hi, I've just bought one of these lenses and am really pleased with it's image quality, sharp enough for me anyway, but it only reproduces at half life size so not a true macro really. Anyone use one of these? and how do they find the best way to get 1:1 macro reproduction with it. Thanks.

John

johnriley

Link Posted 05/02/2016 - 23:02
An extension tune will do the trick. Alternatively, a 2x converter, but that may add some optical compromise. Pentax made a suitable converter, the Rear Converter K T6-2X.
Best regards, John

davidwozhere

Link Posted 06/02/2016 - 00:54
I find that a short extension tube does the job nicely. On the other hand, it is sharp enough as it stands to make major crops quite feasible. What it is not much good for (unlike the 50mm version) is normal, non-macro everyday shots.
Both the *istDS and the K5 are incurably addicted to old glass

My page on Photocrowd - link

Lingevres

Link Posted 06/02/2016 - 08:36
Hi, thanks for replying, I was hoping someone would say a 'short' extension tube as the lens is quite long at full magnification and I didn't want it to become cumbersome. I will also look into the converter which I assume is matched to this lens.Thanks again.

John

johnriley

Link Posted 06/02/2016 - 09:16
The converter is not matched to one lens, but designed for most Pentax lenses of the era up to the shorter telephotos. I think up to 300mm IIRC.
Best regards, John

redbusa99

Link Posted 06/02/2016 - 12:35
with a converter you could lose image quality as it is another piece of glass with an extension tube you just lose a bit of light which you can compensate for also there is probably a calculation as what length tube will give you 1:1. with my Tamron Adaptall 90mm the 1:1 adaptor is a 43mm ext tube they made for it,so not a standard length but don't know what would be needed for 100mm.
K3 II and the odd lens or 2

Flickr
Last Edited by redbusa99 on 06/02/2016 - 12:37

davidwozhere

Link Posted 07/02/2016 - 01:18
I have the 'A' version of that converter -"Rear converter A 2xS", where the S stands for "short" = lenses up to 300mm (short??)
The IQ is very good indeed so if you want to take that route, don't worry about image degradation unless you are after perfection.
I've never used it on the 100mm macro but I shall now just to see what happens .....

I also put a severely cropped image of a hyacynth flower on the gallery. The lack of 1:1 doesn't seen to be a problem there!
Both the *istDS and the K5 are incurably addicted to old glass

My page on Photocrowd - link
Last Edited by davidwozhere on 07/02/2016 - 01:21

LennyBloke

Link Posted 07/02/2016 - 12:00
davidwozhere wrote:
I have the 'A' version of that converter -"Rear converter A 2xS", where the S stands for "short" = lenses up to 300mm (short??)
The IQ is very good indeed so if you want to take that route, don't worry about image degradation unless you are after perfection.

I'll second that - all of the Pentax A converters are very, very good - there will be some minor degradation, but if you're stopping down a little you're unlikely to notice!


LennyBloke
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