Older Model Sigma 50mm Macro lens

[Fotocorn]

I am thinking of buying a macro lens and have borrowed a Sigma 50mm f2,8 EX DG Macro lens from a friend. It has a separate manual aperture ring. I have been looking at the write-ups on the newer models but none of them seem to have this manual aperture facility.

This lens, with the manual feature, was discussed on this forum in 2006. This has been the only reference to this particular model that I have found, despite spending a fair amount of time researching it on the web.

I have five questions that I hope some-one out there can answer for me.

• in what year was that particular model launched, it must be prior to 2006
• why would you need a manual aperture control when you can use manual mode on the camera.
• How do you use it, what happens if you manually set one aperture and then set another via the camera. I don't want to try in case I cause a problem on a lens that does not belong to me. My friend bought the lens new and has had the lens for years. He has never used the manual facility, nor does he know how to use it, nor when/why it should be used!! He can't remember when he bought it, but he hardly ever uses it.
• I want to photograph small insects at 1:1 and find the very short subject to lens distance on the 50mm to be very limiting. Also the fact that the barrel of the lens extends is a nuisance when setting up. Is there an affordable, non extending lens with similar quality glass available?
• I was thinking of going for 110mm to get extra subject to lens distance but I suppose the trade-off is that I would loose low light capability and would have to use lower shutter speeds.

 

[D Cox]

You would use the manual aperture if you put the lens on a bellows or on extension tubes without electronic contacts.

The Sigma 105mm f/2.8 DG Macro is a very useful lens. Focus is rather slow, but for your small insects you will want to use the manual focus option anyway. This lens doesn't have an aperture ring and I haven't needed it.

 

[Fotocorn]

Thank you,

Just as a point of interest the only macro I could find with internal focus was the Canon, is this the only one?

 

[bclaff]

• ...I want to photograph small insects at 1:1 and find the very short subject to lens distance on the 50mm to be very limiting. Also the fact that the barrel of the lens extends is a nuisance when setting up. Is there an affordable, non extending lens with similar quality glass available?

FYI, the distance to the subject from the front of the lens is called working distance.

The total distance from subject to sensor at 1x is approximately 4 * f where f is the focal length. So all 50mm lenses will be roughly the same. To get more distance (including working distance) you generally nneed to go to a longer focal length.

Another option is a teleconverter (which increases the focal length).

• I was thinking of going for 110mm to get extra subject to lens distance but I suppose the trade-off is that I would loose low light capability and would have to use lower shutter speeds.

I don't understand how you would lose "low light capability".

 

[bclaff]

Thank you,

Just as a point of interest the only macro I could find with internal focus was the Canon, is this the only one?

An internal focus lens almost certain drops focal length as you focus close so it probably has an even shorter working distance.

 

[BBbuilder467]

I am thinking of buying a macro lens and have borrowed a Sigma 50mm f2,8 EX DG Macro lens from a friend. It has a separate manual aperture ring. I have been looking at the write-ups on the newer models but none of them seem to have this manual aperture facility.

This lens, with the manual feature, was discussed on this forum in 2006. This has been the only reference to this particular model that I have found, despite spending a fair amount of time researching it on the web.

I have five questions that I hope some-one out there can answer for me.

• in what year was that particular model launched, it must be prior to 2006
• why would you need a manual aperture control when you can use manual mode on the camera.
• How do you use it, what happens if you manually set one aperture and then set another via the camera. I don't want to try in case I cause a problem on a lens that does not belong to me. My friend bought the lens new and has had the lens for years. He has never used the manual facility, nor does he know how to use it, nor when/why it should be used!! He can't remember when he bought it, but he hardly ever uses it.
• I want to photograph small insects at 1:1 and find the very short subject to lens distance on the 50mm to be very limiting. Also the fact that the barrel of the lens extends is a nuisance when setting up. Is there an affordable, non extending lens with similar quality glass available?
• I was thinking of going for 110mm to get extra subject to lens distance but I suppose the trade-off is that I would loose low light capability and would have to use lower shutter speeds.

I don't know what you have, but 50mm is often used for close-ups of flowers and nature subjects, where you might rarely go beyond 1:2 and having a manual aperture ring makes it easier to refine the dof from shot to shot. Don't need maximum dof like insects. Hand-held, the extending lens wouldn't matter. A lot of the 50mm macros were 1:2 and needed extension tubes to reach 1:1.

For insects, you'll stop down to the minimum for dof, so you'll lose shutter speed regardless of the focal length. If your primary interest is insects, you're better off with something in the 90mm to 105mm range. They seem to be a better match when adding extension tubes to reach 2:1 that's common for insects. To avoid camera shake and motion blur, it's common to use flash.

A lot of people on the Macro Forum use Nikon. They can probably suggest a good starting point.

 

[Gerry Winterbourne]

I am thinking of buying a macro lens and have borrowed a Sigma 50mm f2,8 EX DG Macro lens from a friend. It has a separate manual aperture ring. I have been looking at the write-ups on the newer models but none of them seem to have this manual aperture facility.

The aperture ring was essential in the days before f-number could be set electronically on the camera. Doing away with it simplifies (and therefore reduces the price) of lenses so today it's rare.

This lens, with the manual feature, was discussed on this forum in 2006. This has been the only reference to this particular model that I have found, despite spending a fair amount of time researching it on the web.

I have five questions that I hope some-one out there can answer for me.

• in what year was that particular model launched, it must be prior to 2006

No idea.

• why would you need a manual aperture control when you can use manual mode on the camera.

As already mentioned, it is useful when the lens isn't attached directly to the camera. One example - you can buy cheap extension tubes for about £/$10 that have no electronic contacts; automatic tubes with contacts can cost well over £/$100, so having an aperture ring can be a useful economy measure.

• How do you use it, what happens if you manually set one aperture and then set another via the camera.

You don't do that. If you want to use the aperture ring you set f-number on the ring; alternatively you set the ring to A and set f-number on the camera. The camera knows which method you are using and disables the other.

• I don't want to try in case I cause a problem on a lens that does not belong to me. My friend bought the lens new and has had the lens for years. He has never used the manual facility, nor does he know how to use it, nor when/why it should be used!! He can't remember when he bought it, but he hardly ever uses it.

You can't hurt the lens - see above.

• I want to photograph small insects at 1:1 and find the very short subject to lens distance on the 50mm to be very limiting. Also the fact that the barrel of the lens extends is a nuisance when setting up. Is there an affordable, non extending lens with similar quality glass available?

As already noted, you need a longer lens if you want more working distance. That's just a fact of life. Internal focus, even if you find such a lens, won't help much.

• I was thinking of going for 110mm to get extra subject to lens distance

There are several lenses at 90, 100 and 105mm that will give you more working distance; I don't know of any at 110mm

• but I suppose the trade-off is that I would loose low light capability

No. You'll get the same light at a given f-number regardless of focal length.

• and would have to use lower shutter speeds

However, whatever focal length you use the depth of field at macro distances is tiny so you'll need to stop down a long way. It's that that requires slower shutter speed so macro work often entails using flash.

Even at 105mm the lens can cast a shadow on the subject. A simple (no-cost) diffuser like this solves that problem and avoids harsh shadows. You can use it with a hotshoe flash if you want to.

--
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Gerry
________________________________________________________________________
I'm happy for anyone to edit any of my photos and display the results
_________________________________________________________________________
First camera 1953, first Pentax 1985, first DSLR 2006

Galleries by Gerry Winterbourne

www.pbase.com

[email protected]

 

[FrancoD]

I think yours is from 2004

https://www.dpreview.com/articles/4679302227/sigmalenses

The previous version (I think) was called DG Macro (no EX)

http://www.coinimaging.com/sigma_50.html

 

[Fotocorn]

Hi bclaff,

Thank you for the information.

I have always been under the impression that, the longer the lens the lower the shutter speed for the same exposure at the same f stop.

 

[Fotocorn]

Thanks BBbuilder467,

The Sigma 50mm I have on loan has 1:1, I never realized that I could attach it to my extension tubes to get 2:1

Thanks for the information,

 

[Fotocorn]

Thanks Gerry,

I appreciate your taking the time to give me such a comprehensive reply.

This forum is a mine of knowledge!!! I love it.

 

[Fotocorn]

Thanks Franco.

It seems it is pretty unique in having the manual f stop ring.

 

[Gerry Winterbourne]

Hi bclaff,

Thank you for the information.

I have always been under the impression that, the longer the lens the lower the shutter speed for the same exposure at the same f stop.

No, that's wrong. Indeed, f-stop - the ratio of aperture size to focal length - is used precisely because it keeps exposure parameters the same.

 

[Gerry Winterbourne]

Thanks Franco.

It seems it is pretty unique in having the manual f stop ring.

Not unique at all. Until about 2005 just about every lens was made that way.

 

[FrancoD]

Thanks Franco.

It seems it is pretty unique in having the manual f stop ring.

Not unique at all. Until about 2005 just about every lens was made that way.

The problem here is that most photos have the Minolta/Sony or Canon mount, neither of those have a manual ring.

 

[bclaff]

Hi bclaff,

Thank you for the information.

I have always been under the impression that, the longer the lens the lower the shutter speed for the same exposure at the same f stop.

No.

Ignoring pupil magnification, at the same magnification the exposure time will be the same.

 

[bclaff]

Hi bclaff,

Thank you for the information.

I have always been under the impression that, the longer the lens the lower the shutter speed for the same exposure at the same f stop.

No, that's wrong. Indeed, f-stop - the ratio of aperture size to focal length - is used precisely because it keeps exposure parameters the same.

Gerry,

He's probably referring to effective f-number but since the factor is (1 + m) those would also be the same at the same magnification.

 

[Fotocorn]

Thanks Bclaff,

My rational was that, as you increase the focal length so the field of view is reduced and therefore less light enters the camera and is "spread" over the same sensor area. This reduces the light intensity on the sensor.

Less light intensity means less exposure, hence more exposure time is required to compensate.

Now I think I understand, I was only halfway through the thought process.

Since the f stop is a ratio of focal length to area of the lens, the area of lens used to produce the same f stop increases with increasing focal length.

This lets in more light to compensate for the reduced field of view, producing the same light intensity on the sensor.

59 years of photography to understand a basic principle. Wow!!!

 

[FrancoD]

Thanks Bclaff,

My rational was that, as you increase the focal length so the field of view is reduced and therefore less light enters the camera and is "spread" over the same sensor area. This reduces the light intensity on the sensor.

Less light intensity means less exposure, hence more exposure time is required to compensate.

Now I think I understand, I was only halfway through the thought process.

Since the f stop is a ratio of focal length to area of the lens, the area of lens used to produce the same f stop increases with increasing focal length.

This lets in more light to compensate for the reduced field of view, producing the same light intensity on the sensor.

59 years of photography to understand a basic principle. Wow!!!

Honestly I think you got confused by the comments made by some members here.

If you have the correct "exposure" by using a 50mm macro at 100ISO, f/2.8 , 1/100th , the same settings on a 100mm will give the same .

As I have pointed before, see if you can find a light meter that has a focal lenght or sensor size setting. This was true in the film days, it hasn't changed now apart from the convoluted reasoning some try to preach here .

 

[Fotocorn]

Thanks Franco,

Just to make sure my understanding is now correct;

• a 50mm lens set at say 1/100 f/5,6 would give the same exposure as 100mm lens with the same settings.
• the area of the iris of the 100mm lens would be double that of the 50mm at the same f stop setting?

Excuse my naivety, even though I have been into photography for nearly 60 years, I am a rank beginner at the magic art of Macro.

If the requirement for more DoF in Macro require smaller apertures, and f8 is probably the widest aperture used, why do we need such expensive fast glass in the lenses ?

Surely it would be cheaper, and the lenses would be smaller and lighter, if say f/5,6 lenses were used with a” sweet spot” at f/8.

Since working in the 1:1 environment probably requires use of a tripod, shutter speed is not an issue.

Am I missing something?