Strange vignetting with telepinhole tube

Malibu

A
Malibu

  • 1
  • 1
  • 42
Rockwood Park-4

A
Rockwood Park-4

  • 0
  • 0
  • 46
Enamored

A
Enamored

  • 0
  • 0
  • 106
Kea'au Bike Flower

A
Kea'au Bike Flower

  • 3
  • 1
  • 159

Recent Classifieds

Forum statistics

Threads
180,518
Messages
2,490,978
Members
95,091
Latest member
gigidamico
Recent bookmarks
0

Uncleleo

Member
Joined
Apr 2, 2022
Messages
4
Location
Russia
Shooter
Traditional
Can anyone help me with this strange vignetting? Why i have it?

Here is my gear.https://dfh.es/en/producto/extensible-plastic-drawing-tube-to-keep-and-transport-plans-posters-etc/

Shooted at 1250mm focal distance with 0.9mm and 3mm hole. Used different shutters, weather, focal distances. Vignette always exists.

133.jpg

fghh.jpg
 

Sirius Glass

Subscriber
Joined
Jan 18, 2007
Messages
42,528
Location
Southern California
Shooter
Multi Format
The vignetting could be corrected with a few added correction lenses.
 

cramej

Subscriber
Joined
Dec 29, 2009
Messages
1,155
Shooter
Multi Format
You already have vignetting from using a pinhole and then you have the inverse square law for light so you're compounding the issue with the meter+ distance from pinhole to film plane.
 
OP
OP

Uncleleo

Member
Joined
Apr 2, 2022
Messages
4
Location
Russia
Shooter
Traditional
You already have vignetting from using a pinhole and then you have the inverse square law for light so you're compounding the issue with the meter+ distance from pinhole to film plane.
Thanks. My сathetus on tube axis (tube length) is 720mm. Radius of the tube 55mm. Maximum hypotenuse from hole to edge of the frame is 722mm. So why this diference between light paths 722mm and 720mm makes so huge vignette?

I have same size vignette with 720mm and 1250mm focal length.
 
Last edited:

cramej

Subscriber
Joined
Dec 29, 2009
Messages
1,155
Shooter
Multi Format
@Uncleleo Now the questions are beyond my knowledge :smile: . Wish I could help more!
 

Dan Fromm

Member
Joined
Mar 23, 2005
Messages
6,293
Shooter
Multi Format
Thanks. My сathetus on tube axis (tube length) is 720mm. Radius of the tube 55mm. Maximum hypotenuse from hole to edge of the frame is 722mm. So why this diference between light paths 722mm and 720mm makes so huge vignette?

I have same size vignette with 720mm and 1250mm focal length.

Hmm. Tube length 720 mm, tube radius 55 mm, The dimensions in the product description don't match your description.

Still, accepting your description, if the pinhole is centered at the subject end of the tube the diameter of the circle covered at the end of the tube will be 110 mm. What's the size of the film you're using and how far is the film end of the tube from the film?
 

Light Capture

Advertiser
Joined
Feb 5, 2008
Messages
128
Location
Norwich, Ontario
Shooter
Multi Format
Can anyone help me with this strange vignetting? Why i have it?

Here is my gear.https://dfh.es/en/producto/extensible-plastic-drawing-tube-to-keep-and-transport-plans-posters-etc/

Shooted at 1250mm focal distance with 0.9mm and 3mm hole. Used different shutters, weather, focal distances. Vignette always exists.

View attachment 302004
View attachment 302003

Looks like it could be some serious flare. Is the inside of the tube shiny and reflective?
If it is, flat paint or flocking should take care of it.
It seems that image is formed all the way to the corners of your negatives so there shouldn't be any mechanical vignetting.
 

NedL

Subscriber
Joined
Aug 23, 2012
Messages
3,204
Location
Sonoma County, California
Shooter
Multi Format
Looks like it could be some serious flare. Is the inside of the tube shiny and reflective?
If it is, flat paint or flocking should take care of it.
It seems that image is formed all the way to the corners of your negatives so there shouldn't be any mechanical vignetting.
that's my thought too, can't think of anything else that makes sense.
 

DWThomas

Subscriber
Joined
Jun 13, 2006
Messages
4,337
Location
SE Pennsylvania
Shooter
Multi Format
What is the actual pinhole like physically -- I have seen vignetting from attempting to use a hole drilled in a thick plate. The plate containing the pinhole should be very thin, on the order of 0.1 mm or so.

Are the shutters mentioned actual camera shutters -- leaf? Focal plane? I once tracked down a problem in a pinhole rig by drawing a very precise cross section with all my mechanical parts carefully scaled to size and position, then looked at simple ray tracing. The relatively long focal length you are attempting would have a very narrow angle of view which should minimize the problem, but perhaps there is a ring or collar somewhere that constricts the light path?

Are you putting this tube on some sort of film holding back, or substituting it for a camera lens on a camera body?
How large are the film pieces we see above?
I also agree with those above that if he tube has a glossy inner surface it might provoke some serious flare.

(Yes a lot of questions, but the more we know the better the chance of someone having a moment of revelation. :smile:)
 

AgX

Member
Joined
Apr 5, 2007
Messages
30,010
Location
Germany
Shooter
Multi Format
Hmm. Tube length 720 mm, tube radius 55 mm, The dimensions in the product description don't match your description.
Likely this tube comes in different sizes and the OP got a different model than linked to, which indeed can be extended to about 1,2m.
 
OP
OP

Uncleleo

Member
Joined
Apr 2, 2022
Messages
4
Location
Russia
Shooter
Traditional
Likely this tube comes in different sizes and the OP got a different model than linked to, which indeed can be extended to about 1,2m.
Yes, sorry, i checked site information. I have different tube same brand with sizes from 720mm to 1250mm.

My photos are 31x44mm (127x178 cut at half and again cut at half).

I drilled another hole at the edge of radus and now my vignette at least at the edges of the photos.
jhjh.jpg



I'm using replacement holes from closing parts.

photo_2022-04-03_15-39-55.jpg
 

AgX

Member
Joined
Apr 5, 2007
Messages
30,010
Location
Germany
Shooter
Multi Format
In your original set up no vignetting is to be expected, and I do not see it, but to be expected is lot of stray light.

I would paint a sheet of cardboard with matte black paint, or chalkboard paint, or use black cardboard, and roll such sheet and install it in that tube.
 
Last edited:

Dan Fromm

Member
Joined
Mar 23, 2005
Messages
6,293
Shooter
Multi Format
In your original set up no vignetting is to be expected, and I do not see it, but to be expected is lot of stray light.

I would paint a sheet of cardboard with matte black paint, or chalkboard paint, or use black cardboard, and roll such sheet and install it in that tube.

Given the focal length -- 1250 mm -- and film format -- 31 x 44 mm -- cos^4 fall off will be negligible. We agree on that.

If the OP is showing us negatives then the black areas are heavily overexposed. This is the opposite of vignetting and I agree that stray light is the culprit.
 

cramej

Subscriber
Joined
Dec 29, 2009
Messages
1,155
Shooter
Multi Format
Yes, sorry, i checked site information. I have different tube same brand with sizes from 720mm to 1250mm.

My photos are 31x44mm (127x178 cut at half and again cut at half).

I drilled another hole at the edge of radus and now my vignette at least at the edges of the photos.
View attachment 302075


I'm using replacement holes from closing parts.

View attachment 302074

This may be your problem. Ideally, as stated above, the pinhole should be very thin. I've used soda cans in the past with good results. Those grommets are really thick!
 
OP
OP

Uncleleo

Member
Joined
Apr 2, 2022
Messages
4
Location
Russia
Shooter
Traditional
In your original set up no vignetting is to be expected, and I do not see it, but to be expected is lot of stray light.

I would paint a sheet of cardboard with matte black paint, or chalkboard paint, or use black cardboard, and roll such sheet and install it in that tube.
Thank you all! After adding black sheet of paper the flare have dissapeared!

photo_2022-04-04_14-22-57.jpg fgfhgh.jpg
 

ciniframe

Member
Joined
Jul 3, 2014
Messages
807
Shooter
Sub 35mm
If the OP wants to experiment with very long focal length then a +1 (1000mm) close up lens could be used to improve the image quantity quite a bit. I would use a 10mm drill to make a f100 stop in a flatened out aluminum drinks can. For fixed focus you would need to rig some kind of ground glass, or a thin sheet of textured plastic to confirm focus wide open with what ever size close up lens you can obtain. When I experiment with home made rigs I usually use photo paper as a negative because it is cheap, can be handled under safelight, and is so slow, 3-6 ISO usually, that exposures are all several seconds even in sunlight.
 

europanorama

Member
Joined
Aug 10, 2004
Messages
352
Location
Basel-CH
Shooter
Large Format Pan
Musou darkest black paint. problems improved heavily. they also have similar velvet. google. dont expect low prices.
 
Photrio.com contains affiliate links to products. We may receive a commission for purchases made through these links.
To read our full affiliate disclosure statement please click Here.

PHOTRIO PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Ilford ADOX Freestyle Photographic Stearman Press Weldon Color Lab
Top Bottom