[whwang]

With the GF bodies there isn't even a mirror in the way so there will be some real dust pumping going on.

Probably not. I shoot both 645z and GFX. I do astrophotography, which is highly sensitive to dust (after stacking many exposures to boost weak signals in the image). So far my 645z shots almost always shot dust spots no matter how I clean it, while my GFX shots are almost always clean. I suspect the reason is that there is a cover glass right after the lens mount of GFX and quite far away from the sensor. This cover glass keeps the sensor free from dust, and dust on this cover glass would be almost always out of focus since the glass is far away from the sensor.

[Rondec]

the pentax MF line would not survive such a spinoff. As it stands, I suspect the 645 line is a loss-leader "halo product" for the cheaper consumer pentax gear.

I doubt that Pentax loses money on the 645 line. Whatever R and D costs were put into the 645z were paid off long ago. They have no advertising for it. Basically their expenses are the cost of manufacturing plus distribution and they are getting 5000 dollars per camera. I just can't imagine that they are losing money with that sort of scenario.

If they built a new camera and sunk a lot of cost into it, that could be a different story, but my guess even there is that they would share cost between K-3 III, K-1 III, and 645Z II. If they spun it off, they would be unable to do that.

[awscreo]

Probably not. I shoot both 645z and GFX. I do astrophotography, which is highly sensitive to dust (after stacking many exposures to boost weak signals in the image). So far my 645z shots almost always shot dust spots no matter how I clean it, while my GFX shots are almost always clean. I suspect the reason is that there is a cover glass right after the lens mount of GFX and quite far away from the sensor. This cover glass keeps the sensor free from dust, and dust on this cover glass would be almost always out of focus since the glass is far away from the sensor.

didn't know that there's a cover glass. So the sensor is kind of insulated from the elements?

[SFTphotography]

didn't know that there's a cover glass. So the sensor is kind of insulated from the elements?

Sounds like it.

On another forum I am on a few users mentioned that dust bunnies aren't an issue with that system at all. Indeed any sample images I have seen from these cameras has been dust bunny absent - which is a miracle come to think about it.

I've found the 28-45 really does keep them out - but not the 45-85. Haven't used the 80-160 enough to judge that either. Primes by virtue of not having extending barrels should be better even without weather sealing.

[TDvN57]

Sounds like it.

On another forum I am on a few users mentioned that dust bunnies aren't an issue with that system at all. Indeed any sample images I have seen from these cameras has been dust bunny absent - which is a miracle come to think about it.

I've found the 28-45 really does keep them out - but not the 45-85. Haven't used the 80-160 enough to judge that either. Primes by virtue of not having extending barrels should be better even without weather sealing.

I seem to be fairly lucky then, because I use the 45-85, 80-160, 150-300, 300, 400, 600 and I don't seem to have a dust ingress problem.

When we go on photo trips or hikes I am usually in a lot of dust. When hiking, I usually carry the camera on a sling over my shoulder with the camera at waist level. It gets a lot of dust onto the camera and lens. Sometimes the dust is like a fine talc powder.

I try not to change lenses in strong wind conditions, but other than that I change lenses in the field as needed, with caution of course.

In the six years I've been using the 645z it was mainly outdoors and I only had to clean the sensor perhaps three or four times. My lenses are dust free for all practical purposes.

I do clean my gear fairly thoroughly after I come back inside and then it goes into a dry box, mainly to protect against high humidity. I almost never use a blower and rely on micro fiber cloths and lens wipes. I never use compressed air either.

Either I am very fortunate or I'm doing something different.

[awscreo]

Sounds like it.

On another forum I am on a few users mentioned that dust bunnies aren't an issue with that system at all. Indeed any sample images I have seen from these cameras has been dust bunny absent - which is a miracle come to think about it.

I've found the 28-45 really does keep them out - but not the 45-85. Haven't used the 80-160 enough to judge that either. Primes by virtue of not having extending barrels should be better even without weather sealing.

That's pretty cool! And a clever idea, I guess they use that space they saved not having the mirror well.

[johnha]

That's pretty cool! And a clever idea, I guess they use that space they saved not having the mirror well.

I haven't used the Fujis but another layer of glass is another plane where dust, scratches, moisture or condensation can gather and cleaning the sensor is a lot harder...

[awscreo]

I haven't used the Fujis but another layer of glass is another plane where dust, scratches, moisture or condensation can gather and cleaning the sensor is a lot harder...

Well, I guess it works, otherwise they wouldn't do it?

[normhead]

I haven't used the Fujis but another layer of glass is another plane where dust, scratches, moisture or condensation can gather and cleaning the sensor is a lot harder...

If the camera is sealed behind the glass, then no, there still just one dust collecting plane, and having it not on the sensor is a distinct advantage. And bet I need be, replacing that glass is much cheaper than replacing a sensor if damaged.

he 645 was last updated when a vastly improved sensorr became available, and the 645z actually jumped the que because of that sensor for the development team. When something better becomes available it will probably jump the question again. For Pentax that pretty much means Sony has to make one. There's no guarantee whatever Fuji is using is available to Pentax.

No that I've heard about this Fuji solution, I wish my Pentax bodies had it.

[kaseki]

To first order, a piece of glass in the optical path will delay the light slightly, with the effect that the optical flange focal length will be slightly longer than the physical flange focal length. This is presumably compensated for in Fuji lenses and Pentax to Fuji adapters.

To second order, however, the delays for non parallel rays will vary, and while the effect is slight, I would expect it to be compensated in the Fuji lenses but not in Pentax lenses used with glassless adapters. The effect must be slight, or we would have heard of it by now, but my thinking is that the Pentax lenses will be necessarily less critically sharp in that application than otherwise, particularly with low valued f/numbers (steep ray angles).

[normhead]

To first order, a piece of glass in the optical path will delay the light slightly, with the effect that the optical flange focal length will be slightly longer than the physical flange focal length. This is presumably compensated for in Fuji lenses and Pentax to Fuji adapters.

To second order, however, the delays for non parallel rays will vary, and while the effect is slight, I would expect it to be compensated in the Fuji lenses but not in Pentax lenses used with glassless adapters. The effect must be slight, or we would have heard of it by now, but my thinking is that the Pentax lenses will be necessarily less critically sharp in that application than otherwise, particularly with low valued f/numbers (steep ray angles).

The technical problems will be anticipated and dealt with. The Fuji sensor is so hi res any problems should be apparent. But it goes without saying, if you put in an extra piece of glass, you compensate in your lens or camera design. These guys aren't stupid. They don't' design a system without the glass and then stick the glass in at the last minute.

[kaseki]

The technical problems will be anticipated and dealt with. The Fuji sensor is so hi res any problems should be apparent. But it goes without saying, if you put in an extra piece of glass, you compensate in your lens or camera design. These guys aren't stupid. They don't' design a system without the glass and then stick the glass in at the last minute.

Perhaps I was unclear. I was asserting that Fuji would have compensated for it, but Pentax would not have had to and thus using Pentax lens assemblies with an adapter could show some issue with focus for fast lenses. I have already reported here that the DFA 25mm does not have a good focus -- at the point of best focus -- if the clear glass insert is not in place.

[riffraffselbow]

I haven't used the Fujis but another layer of glass is another plane where dust, scratches, moisture or condensation can gather and cleaning the sensor is a lot harder...

basically every interchangeable-lens camera sensor ever made has a protective glass layer on top of it; this is what you clean with a sensor swab. removing that glass leaves the sensor (and the bayer filter on top of it) extremely vulnerable to permanent damage from almost anything. by moving that glass surface off of "directly in front of the sensor", dust on/scratches to the protective glass filter should affect the image less. All of this is assuming the inner box with the sensor in it is cleanroom-sealed or effectively so (so no dust can get in and on the sensor proper) but that seems likely at the price point etc.

[TDvN57]

Is there a single lens in the Pentax line-up that can operate a, let's say, 150MP 645 FF sensor 100 percent?

@PIXIAC you may want to take a look this thread which is rather old but interesting to read. It relates to your question. I am trying to resurrect the discussion to try to learn some more about the issue.

Resolution of Film vs Digital - PentaxForums.com

[barondla]

While the glass lens mount filter is probably a good idea, there could be disadvantages.

1. Another layer of glass can cause quality loss, however small. This has recently become obvious to me after researching lenses for UV photography. Glass sucks. The fewer elements of glass the better.

2. The glass shield removes a "warning sign" of dirt in the light path. Just because dirt is out of focus, doesn't mean there is no loss of image quality. A lens with dirty front and rear elements impacts image quality...even though the dirt is out of focus.

3. I prefer the Sigma lens mount filter system. It can be easily removed by the user to shoot infrared.


Thanks,

barondla