Pentax Adapter Q for K-mount Lenses in stock.

Started Nov 27, 2012 | Discussions thread
snostorm Senior Member • Posts: 2,044
Re: Pentax Adapter Q for K-mount Lenses in stock.

GeoffNS wrote:

Have you experiences situations where the shutter in the adapter was an important advantage?

Hi Geoff,

I don't have the Pentax adapter yet, so I can't say from an experienced standpoint. There are some very long shots that I've made with the JR adapter that I have that might be showing some rolling shutter effect (what should have been straight lines that were slightly wavy) even though the shutter speed was relatively high, but I can't confirm this without taking a similar shot with the Pentax adapter and comparing them. This is just nit picking though as I was really looking for problems. . . and probably 99.9% of people looking at the shots wouldn't have noticed. I really don't think there will be much advantage for super tele shooting with the Q.

I'll ramble a little here. . .The area where the shutter in the adapter will make a significant difference for me is in macro shooting with adapted lenses and flash. I like to shoot very small critters handheld with flash. The Q with adapted dedicated macro lenses is, on paper, made for this. The crop factor gives an apparent 3.6x magnification advantage over APS-C (the magnification is the same 1:1, but the 3.6x crop advantage fills the frame with a much smaller subject, so printed at the same size, the Q image looks close to a what a 4:1 shot would from an APS-C camera with the same lens. This is a big advantage in a number of ways. I can either shoot at MFD and get a greater apparent magnification, or I can shoot from farther away, get the same apparent magnification as 1:1 on APS-C, but deeper DOF (DOF increases as subject distance increases) andhave the additional advantages that longer working distances give -- less subject intimidation and less extreme angles (and more options) for on-camera flash. The Q + adapter + my D FA 100/2.8 Macro weighs about the same as my K-5 body alone, and the whole Q package is obviously smaller. Handheld critter macro shooting usually puts me in very awkward positions, and the smaller lighter gear will make a big difference (as will the LCD VF with Focus Peaking). I'll also be shooting the Q at larger apertures because the lens will become diffraction limited at much faster apertures than with my K-5 (soon to be a K-5 IIs ) This will allow me to use much less powerful flash (read smaller and lighter also)

The problem, that I can't solve practically with 3rd party adapters, is the default to electronic shutter. This causes the flash sync to go to 1/13 sec. It's virtually impossible to make the flash dominate the exposure outdoors in daylight at 1/13. Freezing camera shake and subject motion are the main reasons to use flash in macro shooting, and to achieve these benefits, the flash has to become the dominant light source so I get an effective shutter speed of faster than 1/1000 (the flash duration). With my K-5, I can use ISO 80, f16, and the max flash sync speed (1/180) to counter the ambient light, but at ISO 125, and diffraction limiting at f8, and 1/13, I'd need about another 3 stops to accomplish this with the Q. I've tried f16, and the images are very soft and the LCD/EVF was too dark to be very useful for the required critical MF. The same problem presented itself when I tried ND filters to make up the difference. -- So it could be done, but not practically.

With the shutter in the Pentax adapter, I should be able to use up to 1/250 with external flash, and the max 1/1000 with the pop up. This should make it easy. . .and worth the extra cost of the Pentax adapter -- for me, of course -- YMMV.

Sorry for the long post.


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