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01-19-2013, 06:11 AM   #1
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Pentax M 28/2.8

Lens used is a version 1 (there were two versions manufactured).
close up, incandescent lighting from below f/2.8 1/500 iso 3200



Linear Polarizer installed. f/5.6 1/15 iso 200



01-19-2013, 01:40 PM   #2
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M 28 F2.8 test pics

ME Super, HP5+ @ box speed, metered manual mode + 1 stop, D76 1+1, MGIV RC Pearl, D72.





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01-27-2013, 02:30 AM - 1 Like   #3
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SMC Pentax M 2.8/28 at f/11 on K7

At f/11 this lens really shows itīs worth (..even though, I blew the light somewhat)

01-27-2013, 02:46 PM   #4
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Also version I:





and reversed onto about 46mm of extension for about 3:1 macro (quick and dirty two-shot focus stack):



01-27-2013, 03:01 PM   #5
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QuoteOriginally posted by baro-nite Quote
Also version I:





and reversed onto about 46mm of extension for about 3:1 macro (quick and dirty two-shot focus stack):
..That first one is amazing..but the second one is mindblowing. The way that that car sticks to the ground. And the way that you got that onto the photo. Well. Congratulatiolations.
02-03-2013, 09:54 AM   #6
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Thanks jt!

More notes about using this lens reversed:

With no extension (other than the reversing ring itself), magnification is approximately 1.7:1. Adding 26.5mm extension (the Helicoid Extension Tube K at minimum) gets approx. 2.7:1. 46.5mm (Helicoid Extension Tube K at full) is approx. 3.5:1.

Pupillary magnification of this lens (i.e., ratio of exit pupil to entrance pupil) is roughly 1.5 with the lens mounted normally, hence 0.67 with the lens reversed.

Effective f-number increases with magnification. This stuff is rather beyond me, but the usual quick-and-dirty formula is effective aperture = nominal aperture * (magnification +1). A slightly more involved formula takes into account the pupillary magnification. Either way, with the lens's aperture ring set to 5.6, a magnification of 1.7:1 (no extension) is already taking you beyond f/11 and well into diffraction territory on APS-C. I say f/5.6 because that is where this lens (version 1, anyway) starts to get sharp, and subjectively I have found it the best aperture to use at 3.5:1 magnification. You might be able to stop it down to f/6.7 or even f/8 on no extension and gain some sharpness, but I haven't tested this yet.

In short, this is a decent lens for reversing at f/5.6, getting you to high magnifications without much extension. But, ideally, find a lens that is sharper at wider apertures.


US 50-cent piece
Nominal aperture f/5.6, 3.5:1 magnification, K-5, uncropped
05-10-2013, 10:19 PM   #7
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This lens is rather sharp and produces fair contrast. But colors are lacking and 28mm isn't that fun on aps-c.

Taken with K10D.













05-11-2013, 05:11 AM   #8
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I must say regardless of any limitations, you have posted some really good photos using the lens. I actually rather like the colors too, so I will consider it a quality. Is yours first or second gen version?
05-11-2013, 08:34 AM   #9
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Mine is a first gen I guess.
06-22-2013, 03:56 PM   #10
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I really love the color rendition of this lens! If only it had AF - would F 28mm f/2.8 or FA 28mm f/2.8 be the answer for my longing?


All taken with K-5

Post processed:

















Built-in HDR-function and PP:




No other post processing than, at most, rotating, cropping and resizing:



06-23-2013, 06:33 PM   #11
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QuoteOriginally posted by komit Quote
I really love the color rendition of this lens! If only it had AF - would F 28mm f/2.8 or FA 28mm f/2.8 be the answer for my longing?
For the history of the optical formula of Pentax 28/2.8 primes, see here:

Pentax Wide-Angle Prime Lenses

Version 2 of the M28/2.8 has the same optical formula (more or less; there is often some minor tweaking between versions with the same basic formula) as the A and F versions. The FA version is completely different.
04-30-2019, 09:05 AM - 3 Likes   #12
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M28/2.8 & K5:













12-27-2019, 12:45 PM   #13
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03-19-2020, 01:22 PM   #14
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07-03-2020, 03:12 PM   #15
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Instead of using my K-1, I used my Sony A7.
I have the F/2.8 and F/3.5 version but the generally spoken less sharp F/2.8 version is still doing a great job in color rendition, and the image is acceptable sharp on a digital body.


Kind regards,
Ron
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