Long exposure artifacts. IQ250

[postman]

Can anybody tell me why I am getting the elliptical artifacts that occur in this image. The clearest is just to the left of the cooling tower, though there are many many of them. This was a 24m exposure using a 6 stop (big stopper), IQ 250, XF and a Mamiya 105-210 set at 180mm.



Thanks in advance.

 

[Boinger]

Are you talking about that eleptical shaped smoke? could you circle what you are talking about as I am unclear to what you are reffering.

 

[dchew]

If you mean the long skinny vertical lines, I think that looks like lens flare.

Dave

 

[MrSmith]

I see plenty of lens flares which are situated more or less opposite the point sources of light from the centre of the lens, is there something else? I’m looking on my iPad though so maybe missing something?

 

[postman]

Thanks for responses so far.

I circled the artifacts in green. I have also added an image that was taken with a 60 second exposure without the little stopper.

I used a 0.9 soft transition neutral grad on the foreground that was being lit by lights behind me, and then closest to the lens was a little stopper (6 stops). f5 for 25m.

 

[dchew]

I bet the big stopper added reflections that created the flare.

 

[postman]

I see plenty of lens flares which are situated more or less opposite the point sources of light from the centre of the lens, is there something else? I’m looking on my iPad though so maybe missing something?

The far left light in the 25m exposure using the little stopper (6 stops) does not show flare, but a 30m exposure I did using a big stopper (10stops) does have a flare in that location.

I am trying to determine if this is a IQ250 Long Exp. Artifact. A Mamiya 105-210 artifact or a Lee filters artifact. I am really just trying to figure out how to prevent them in the future.

I added a new image in a post below, that doesn't seem to have any artifacts but it is a 60s exposure.

 

[Paul2660]

A few thoughts, by any chance was it cool out? and did the lens happen to slightly fog on the front? I have seen similar flare (that is what your artifacts are for sure) due to slight fogging on the front of a lens, especially with bright lighting like you have (mine was sunrise flare).

Still blows me away just how clean the IQ250 sensor is. Phase did a wonderful job on that one. I noticed this from the day the camera was announced. I have not seen as clean a shadow recovery with the IQ150, 3100 or IQ4. And I don't believe that Fuji's 50S can get quite that clean. The recovery on the grass is impressive, not that in this case you would want it.

It's still a mistake that P1 did not enable the E shutter on this back. That would have made a amazingly powerful solution. The fact that both Fuji and Hasselblad did on their solutions using this same chip show that it both can be done and done very well.

Paul C

 

[postman]

A few thoughts, by any chance was it cool out? and did the lens happen to slightly fog on the front? I have seen similar flare (that is what your artifacts are for sure) due to slight fogging on the front of a lens, especially with bright lighting like you have (mine was sunrise flare).

Still blows me away just how clean the IQ250 sensor is. Phase did a wonderful job on that one. I noticed this from the day the camera was announced. I have not seen as clean a shadow recovery with the IQ150, 3100 or IQ4. And I don't believe that Fuji's 50S can get quite that clean. The recovery on the grass is impressive, not that in this case you would want it.

It's still a mistake that P1 did not enable the E shutter on this back. That would have made a amazingly powerful solution. The fact that both Fuji and Hasselblad did on their solutions using this same chip show that it both can be done and done very well.

Paul C

It was bloody cold out! and I spent a lot of time cursing the LENR phase. The IQ250 is a great back. I am not a fan of it being less than full frame and I was upset that I lost the use of my Rodenstock 35mm (Arca R Mount), I am thinking about getting a 40R for the wide angle and just starting my research on how well the 40R will work on the IQ250.

 

[postman]

Reading an FAQ at Lee Filters support site this morning they mention that all light must be prevented through the view-finder. I did not have the prism-finder on the XF, I had the waist-level finder (closed). I wonder if it allowed light to leak into the camera.

Has anybody ever noticed light leak with the waist-level finder?

 

[tcdeveau]

Any particular reason you used f5 and a stopper instead of stopping the lens down?

Could be reflections from the filters as other have mentioned. Id start my troubleshooting by doing a test with the filter and the wider aperture, and then remove the filter and stop down and see what happens.

I usually just stop down for longer exposures at night instead of using filters. Especially considering you’re dealing with the LENR of the IQ250, the less variables the better IMHO.

I also carry quick dry towels in my shooting bag, and for any exposures longer than a couple minutes throw one of those over my whole setup to reduce chance of light leaks (as long as the wind is low).

 

[Paul2660]

It was bloody cold out! and I spent a lot of time cursing the LENR phase. The IQ250 is a great back. I am not a fan of it being less than full frame and I was upset that I lost the use of my Rodenstock 35mm (Arca R Mount), I am thinking about getting a 40R for the wide angle and just starting my research on how well the 40R will work on the IQ250]

The 40 will do very well. 20mm of shift horizontal.

There is no excuse that P1 could or would not turn off the mandatory dark frame.
On both the 3100 and all 50mp backs.

Everyone else using this chip figured out a way to do it just fine.

Paul C

 

[Gerd]

.......................

Has anybody ever noticed light leak with the waist-level finder?

The waist-level finder must be closed, then no light comes in.


Greeting Gerd

 

[postman]

The waist-level finder must be closed, then no light comes in.


Greeting Gerd

Closed it was. So I’ll see what Lee Filters has to say and do a little more testing.