Crazy bokeh from the A 100/4 macro

Crazy bokeh from the A 100/4 macro · 02:42 PM

Most of the times, this lens has a pleasant bokeh.

But sometimes, it freaks....! Anybody who can explain this pattern? Specs of dust? And if so, where?

And yes, that is my own finger...

Peter Zack · 08-05-2009, 02:56 PM

That looks like moisture to me. Was it humid or wet at all?

bdery · 08-05-2009, 03:05 PM

I agree about moisture. Does it vary with aperture?

**Rense** · 08-05-2009, 03:10 PM

Yes, there is a fen/pond in the background. But I did not mean the hexagons, that is caused by the reflections in the water i.c. with a rather small aperture (f/10). I ment the dots in the hexagons. What are they?

**Lowell Goudge** · 08-05-2009, 03:31 PM

I think it is dust or a spot on the front element, and stopping down has highlighted it

Steinback · 08-05-2009, 03:53 PM

I agree with Lowell that there is likely a mark one of the lens elements, I have a lens with a marked element that makes similar patterns.

**dcmsox2004** · 08-05-2009, 04:23 PM

i kind of like this bokeh.... i've seen some offbeat postings about folks who take black paper, cut out a design in the front, slap on the front of the lens, and you get some funky design artifacts..
how did you train this creature??? i took me a while to train my dog to sit on command...

nate · 08-05-2009, 06:33 PM

Even the first image exhibits the hexagons albeit fainter. I think it may be reflections from the highlights on the eyes (similar shape). This is an older lens without the newer digital coatings. I have seen similar reflections with an old A70-210. Perhaps the structure of the eye provides different reflections and that is your spots. ??

newarts · 08-06-2009, 01:44 AM

Originally posted by Rense

Yes, there is a fen/pond in the background. But I did not mean the hexagons, that is caused by the reflections in the water i.c. with a rather small aperture (f/10). I ment the dots in the hexagons. What are they?

The dots with circles around them are diffraction patterns cast by dust on a lens or filter I'll bet. The small f-stop used combined with the point sources of light from water droplets results in light that allows the effect to be seen.

The two hexagons in the lower right side of the last photo contain identical diffraction patterns; therefore they resulted from the same dust. The fact they appear in different locations on the photo means they must have been reflected more than once at some distance from the sensor (if due only to dust on the hot mirror they could not be separated so far on the sensor, nor be so large compared to the hexagonal image of the aperture I think.)

Dave in Iowa

PS it is possible that specular reflections from the insect's individual hexagonal eye facets are involved. Does your lens' aperture have six leaves?

**Rense** · 08-06-2009, 06:17 AM

Thank you all, I guess you're right about dust somewhere remote from the sensor....

**Ash** · 08-06-2009, 06:37 AM

Sure thing about dust affecting the bokeh here, but what did you do to the wings of this poor insect Rense?!?

adriano210 · 08-06-2009, 06:42 AM

thats cool, why they don't run away ? how you did it?

**Rense** · 08-06-2009, 08:14 AM

Originally posted by Ash

Sure thing about dust affecting the bokeh here, but what did you do to the wings of this poor insect Rense?!?

I had to do something to let him sit still

No, it's a very fresh specimen, who just saw life as adult. The feins of his wings are not yet filled with air, so they look like they have to be ironed,

Originally posted by adriano210

thats cool, why they don't run away ? how you did it?

... and that is the reason he did not fly away, but waited calmly until I shot my photos

Wildnsyko · 08-06-2009, 12:27 PM

Did you name him??

**Rense** · 08-07-2009, 08:02 AM

Originally posted by Wildnsyko

Did you name him??

Nope. Did not think of that

Rense
	View full profile
	Contact via private message
	Find other posts by Rense
	Find threads started by Rense
	Find threads in which Rense has posted

08-05-2009, 06:33 PM	#8
nate Inactive Account Join Date: Sep 2006 Location: mid-Missouri, U.S.A. Photos: Gallery Posts: 64	Eyes? Even the first image exhibits the hexagons albeit fainter. I think it may be reflections from the highlights on the eyes (similar shape). This is an older lens without the newer digital coatings. I have seen similar reflections with an old A70-210. Perhaps the structure of the eye provides different reflections and that is your spots. ??

08-06-2009, 01:44 AM	#9
newarts Inactive Account Join Date: Dec 2008 Location: Ames, Iowa, USA Photos: Albums Posts: 2,965	Originally posted by Rense Yes, there is a fen/pond in the background. But I did not mean the hexagons, that is caused by the reflections in the water i.c. with a rather small aperture (f/10). I ment the dots in the hexagons. What are they? The dots with circles around them are diffraction patterns cast by dust on a lens or filter I'll bet. The small f-stop used combined with the point sources of light from water droplets results in light that allows the effect to be seen. The two hexagons in the lower right side of the last photo contain identical diffraction patterns; therefore they resulted from the same dust. The fact they appear in different locations on the photo means they must have been reflected more than once at some distance from the sensor (if due only to dust on the hot mirror they could not be separated so far on the sensor, nor be so large compared to the hexagonal image of the aperture I think.) Dave in Iowa PS it is possible that specular reflections from the insect's individual hexagonal eye facets are involved. Does your lens' aperture have six leaves? Last edited by newarts; 08-06-2009 at 01:55 AM.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Pentax 100 WR macro vs Sigma 105 macro	GSk	Pentax SLR Lens Discussion	7	03-22-2010 04:23 PM
Nature Autumn, fungi, Pentax-A 100/4 macro, and striate bokeh	Rense	Post Your Photos!	15	10-30-2009 11:13 PM
Crazy looking weed macro	yeatzee	Post Your Photos!	17	07-01-2009 01:40 PM
Bokeh crazy with Super-Tak 135/3.5	-kb-	Post Your Photos!	4	02-16-2009 01:20 AM

08-05-2009, 02:56 PM	#2
Peter Zack Pentaxian Moderator Emeritus Join Date: May 2007 Location: Edmonton Alberta, Canada Photos: Gallery \| Albums Posts: 10,643	That looks like moisture to me. Was it humid or wet at all?

08-05-2009, 03:05 PM	#3
bdery Pentaxian Join Date: Mar 2008 Location: Quebec city, Canada Photos: Gallery Posts: 9,357	I agree about moisture. Does it vary with aperture?

08-05-2009, 03:10 PM	#4
Rense Site Supporter Join Date: Dec 2008 Location: Zetten - The Netherlands Photos: Gallery \| Albums Posts: 9,050 Original Poster	Yes, there is a fen/pond in the background. But I did not mean the hexagons, that is caused by the reflections in the water i.c. with a rather small aperture (f/10). I ment the dots in the hexagons. What are they?

08-05-2009, 03:31 PM	#5
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,887	I think it is dust or a spot on the front element, and stopping down has highlighted it

08-05-2009, 03:53 PM	#6
Steinback Veteran Member Join Date: Jan 2008 Location: GTA, ON, Canada Photos: Gallery \| Albums Posts: 1,673	I agree with Lowell that there is likely a mark one of the lens elements, I have a lens with a marked element that makes similar patterns.

08-05-2009, 04:23 PM	#7
dcmsox2004 Site Supporter Join Date: Apr 2008 Location: rhode island Photos: Gallery \| Albums Posts: 7,522	i kind of like this bokeh.... i've seen some offbeat postings about folks who take black paper, cut out a design in the front, slap on the front of the lens, and you get some funky design artifacts.. how did you train this creature??? i took me a while to train my dog to sit on command...

08-06-2009, 06:17 AM	#10
Rense Site Supporter Join Date: Dec 2008 Location: Zetten - The Netherlands Photos: Gallery \| Albums Posts: 9,050 Original Poster	Thank you all, I guess you're right about dust somewhere remote from the sensor....

08-06-2009, 06:37 AM	#11
Ash Loyal Site Supporter Join Date: Mar 2007 Location: Toowoomba, Queensland Photos: Gallery \| Albums Posts: 23,920	Sure thing about dust affecting the bokeh here, but what did you do to the wings of this poor insect Rense?!?

08-06-2009, 06:42 AM	#12
adriano210 Forum Member Join Date: Jul 2009 Location: Dublin Posts: 60	thats cool, why they don't run away ? how you did it?

08-06-2009, 08:14 AM	#13
Rense Site Supporter Join Date: Dec 2008 Location: Zetten - The Netherlands Photos: Gallery \| Albums Posts: 9,050 Original Poster	Originally posted by Ash Sure thing about dust affecting the bokeh here, but what did you do to the wings of this poor insect Rense?!? I had to do something to let him sit still No, it's a very fresh specimen, who just saw life as adult. The feins of his wings are not yet filled with air, so they look like they have to be ironed, Originally posted by adriano210 thats cool, why they don't run away ? how you did it? ... and that is the reason he did not fly away, but waited calmly until I shot my photos

08-06-2009, 12:27 PM	#14
Wildnsyko Inactive Account Join Date: Oct 2008 Location: Southeast MO Photos: Gallery Posts: 366	Did you name him??

08-07-2009, 08:02 AM	#15
Rense Site Supporter Join Date: Dec 2008 Location: Zetten - The Netherlands Photos: Gallery \| Albums Posts: 9,050 Original Poster	Originally posted by Wildnsyko Did you name him?? Nope. Did not think of that