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How can I set the aperture on my DSLR when it's attached to a telescope instead of a lens?

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I would like to use my Nikon D3100 for astrophotography. I have attached the camera to my telescope with a T-ring, after which the camera recognized the absence of the lens, which is perfectly normal. However, without the lens on, I am unable to adjust the aperture, which is extremely important for astrophotography. I can set the ISO, the shutter speed, and some other, minor things but not the Aperture.

I’m using the camera in manual mode.

Is setting the aperture without the lens even possible?

dslr camera-settings astrophotography

share|improve this question

edited 3 hours ago

Michael C

135k7154384

asked 7 hours ago

Gergely KovacsGergely Kovacs

1083

New contributor

Gergely Kovacs is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

add a comment | 

1

1

I would like to use my Nikon D3100 for astrophotography. I have attached the camera to my telescope with a T-ring, after which the camera recognized the absence of the lens, which is perfectly normal. However, without the lens on, I am unable to adjust the aperture, which is extremely important for astrophotography. I can set the ISO, the shutter speed, and some other, minor things but not the Aperture.

I’m using the camera in manual mode.

Is setting the aperture without the lens even possible?

dslr camera-settings astrophotography

share|improve this question

edited 3 hours ago

Michael C

135k7154384

asked 7 hours ago

Gergely KovacsGergely Kovacs

1083

New contributor

Gergely Kovacs is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

add a comment | 

I would like to use my Nikon D3100 for astrophotography. I have attached the camera to my telescope with a T-ring, after which the camera recognized the absence of the lens, which is perfectly normal. However, without the lens on, I am unable to adjust the aperture, which is extremely important for astrophotography. I can set the ISO, the shutter speed, and some other, minor things but not the Aperture.

I’m using the camera in manual mode.

Is setting the aperture without the lens even possible?

dslr camera-settings astrophotography

share|improve this question

edited 3 hours ago

Michael C

135k7154384

asked 7 hours ago

Gergely KovacsGergely Kovacs

1083

New contributor

Gergely Kovacs is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

share|improve this question

edited 3 hours ago

Michael C

135k7154384

asked 7 hours ago

Gergely KovacsGergely Kovacs

1083

New contributor

Gergely Kovacs is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

share|improve this question

edited 3 hours ago

Michael C

135k7154384

asked 7 hours ago

Gergely KovacsGergely Kovacs

1083

New contributor

Gergely Kovacs is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

edited 3 hours ago

Michael C

135k7154384

edited 3 hours ago

Michael C

135k7154384

asked 7 hours ago

Gergely KovacsGergely Kovacs

1083

New contributor

Gergely Kovacs is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

asked 7 hours ago

Gergely KovacsGergely Kovacs

1083

2 Answers
2

active

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8

Is setting the aperture without the lens even possible?

Considering that the aperture is a part of the lens, not the camera body, no, it is not possible.

Telescopes do not typically have variable apertures — there's no need to stop down to limit incoming light (which is absolutely the opposite of what is wanted for star photography), and depth of field control is meaningless when all objects are no closer than the moon.

The aperture of the telescope is the diameter of the front element. In ƒ-number terms, it is the ratio of the focal length of the telescope divided by the diameter of the front element. Be sure to use the same units (i.e., inches, or mm/cm/m).

share|improve this answer

edited 6 hours ago

answered 7 hours ago

scottbbscottbb

21k75896

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I'm not sure about OP's camera - but I know some may refuse to shoot when no aperture is selected in certain modes. Do you know if this affects the D3100?
  
  – Hueco
  4 hours ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @Hueco not sure precisely. It never occurred to me to use a t-mounted camera in anything other than manual mode. I had no problems shooting manual with a D90 mounted on a telescope, nor with my D800E on a scope.
  
  – scottbb
  3 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  This is not entirely true--you could use an additional aperture inline between the objective and the flange.
  
  – chrylis
  50 mins ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @chrylis Well, I did use the weasel phrase "telescopes do not typically have variable apertures"... =) But regardless, the bigger point is that apertures are not a part of the camera.
  
  – scottbb
  46 mins ago
  

  
  
  
  

add a comment | 

3

Check your telescope manual and find the telescope's aperture. Assuming no telescope eyepiece is utilized, the camera is said to be at the "prime focus" position. Find the scope's diameter. Find the scope's focal length. Divide focal length by diameter. The results of this math is the working f number of the system. Example: 1000mm focal length 4 inch diameter. Convert all units to millimeters. Inches to millimeters conversion is 25.4. Thus 1000 / (4 X 25.4) = 1000 / 101.6 = 9.8. Round to f/10. By the way, f/10 is typical of most systems.

share|improve this answer

answered 5 hours ago

Alan MarcusAlan Marcus

26k23060

add a comment | 

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8

Is setting the aperture without the lens even possible?

Considering that the aperture is a part of the lens, not the camera body, no, it is not possible.

Telescopes do not typically have variable apertures — there's no need to stop down to limit incoming light (which is absolutely the opposite of what is wanted for star photography), and depth of field control is meaningless when all objects are no closer than the moon.

The aperture of the telescope is the diameter of the front element. In ƒ-number terms, it is the ratio of the focal length of the telescope divided by the diameter of the front element. Be sure to use the same units (i.e., inches, or mm/cm/m).

share|improve this answer

edited 6 hours ago

answered 7 hours ago

scottbbscottbb

21k75896

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I'm not sure about OP's camera - but I know some may refuse to shoot when no aperture is selected in certain modes. Do you know if this affects the D3100?
  
  – Hueco
  4 hours ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @Hueco not sure precisely. It never occurred to me to use a t-mounted camera in anything other than manual mode. I had no problems shooting manual with a D90 mounted on a telescope, nor with my D800E on a scope.
  
  – scottbb
  3 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  This is not entirely true--you could use an additional aperture inline between the objective and the flange.
  
  – chrylis
  50 mins ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @chrylis Well, I did use the weasel phrase "telescopes do not typically have variable apertures"... =) But regardless, the bigger point is that apertures are not a part of the camera.
  
  – scottbb
  46 mins ago
  

  
  
  
  

add a comment | 

8

Is setting the aperture without the lens even possible?

Considering that the aperture is a part of the lens, not the camera body, no, it is not possible.

Telescopes do not typically have variable apertures — there's no need to stop down to limit incoming light (which is absolutely the opposite of what is wanted for star photography), and depth of field control is meaningless when all objects are no closer than the moon.

The aperture of the telescope is the diameter of the front element. In ƒ-number terms, it is the ratio of the focal length of the telescope divided by the diameter of the front element. Be sure to use the same units (i.e., inches, or mm/cm/m).

share|improve this answer

edited 6 hours ago

answered 7 hours ago

scottbbscottbb

21k75896

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I'm not sure about OP's camera - but I know some may refuse to shoot when no aperture is selected in certain modes. Do you know if this affects the D3100?
  
  – Hueco
  4 hours ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @Hueco not sure precisely. It never occurred to me to use a t-mounted camera in anything other than manual mode. I had no problems shooting manual with a D90 mounted on a telescope, nor with my D800E on a scope.
  
  – scottbb
  3 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  This is not entirely true--you could use an additional aperture inline between the objective and the flange.
  
  – chrylis
  50 mins ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @chrylis Well, I did use the weasel phrase "telescopes do not typically have variable apertures"... =) But regardless, the bigger point is that apertures are not a part of the camera.
  
  – scottbb
  46 mins ago
  

  
  
  
  

add a comment | 

Is setting the aperture without the lens even possible?

Considering that the aperture is a part of the lens, not the camera body, no, it is not possible.

Telescopes do not typically have variable apertures — there's no need to stop down to limit incoming light (which is absolutely the opposite of what is wanted for star photography), and depth of field control is meaningless when all objects are no closer than the moon.

The aperture of the telescope is the diameter of the front element. In ƒ-number terms, it is the ratio of the focal length of the telescope divided by the diameter of the front element. Be sure to use the same units (i.e., inches, or mm/cm/m).

share|improve this answer

edited 6 hours ago

answered 7 hours ago

scottbbscottbb

21k75896

share|improve this answer

edited 6 hours ago

answered 7 hours ago

scottbbscottbb

21k75896

answered 7 hours ago

scottbbscottbb

21k75896

answered 7 hours ago

scottbbscottbb

21k75896

3

Check your telescope manual and find the telescope's aperture. Assuming no telescope eyepiece is utilized, the camera is said to be at the "prime focus" position. Find the scope's diameter. Find the scope's focal length. Divide focal length by diameter. The results of this math is the working f number of the system. Example: 1000mm focal length 4 inch diameter. Convert all units to millimeters. Inches to millimeters conversion is 25.4. Thus 1000 / (4 X 25.4) = 1000 / 101.6 = 9.8. Round to f/10. By the way, f/10 is typical of most systems.

share|improve this answer

answered 5 hours ago

Alan MarcusAlan Marcus

26k23060

add a comment | 

3

Check your telescope manual and find the telescope's aperture. Assuming no telescope eyepiece is utilized, the camera is said to be at the "prime focus" position. Find the scope's diameter. Find the scope's focal length. Divide focal length by diameter. The results of this math is the working f number of the system. Example: 1000mm focal length 4 inch diameter. Convert all units to millimeters. Inches to millimeters conversion is 25.4. Thus 1000 / (4 X 25.4) = 1000 / 101.6 = 9.8. Round to f/10. By the way, f/10 is typical of most systems.

share|improve this answer

answered 5 hours ago

Alan MarcusAlan Marcus

26k23060

add a comment | 

Check your telescope manual and find the telescope's aperture. Assuming no telescope eyepiece is utilized, the camera is said to be at the "prime focus" position. Find the scope's diameter. Find the scope's focal length. Divide focal length by diameter. The results of this math is the working f number of the system. Example: 1000mm focal length 4 inch diameter. Convert all units to millimeters. Inches to millimeters conversion is 25.4. Thus 1000 / (4 X 25.4) = 1000 / 101.6 = 9.8. Round to f/10. By the way, f/10 is typical of most systems.

share|improve this answer

answered 5 hours ago

Alan MarcusAlan Marcus

26k23060

share|improve this answer

answered 5 hours ago

Alan MarcusAlan Marcus

26k23060

answered 5 hours ago

Alan MarcusAlan Marcus

26k23060

answered 5 hours ago

Alan MarcusAlan Marcus

26k23060