Adjusting the aperture on the Tamron 90mm f/2.8

Pat50

@Moose - Thank you for this wonderful forum where rank beginners like me don't feel so silly asking questions.

I have a Nikon D3100 which I bought a while ago (and which your wonderful cheat sheets will help me conquer), but just recently decided to buy my first prime lens, a Tamron 90mm f/2.8 for macros.

Problem is what I expected isn't happening. I thought that when I got this lens I would dial down my aperture and see f/2.8 on my LCD screen and be ready to shoot.

Oddly it seems as if I still cannot go lower than f/3.5 which is what I was getting with my kit lens 18-55mm. What am I doing wrong? Is the aperture of the lens not all powerful the way I thought it was? Does the camera body itself impose limitations on the aperture?

Sorry to be so dumb about this, but after all my great hopes for a f/2.8 prime lens I am very frustrated and disappointed.

Pat - 63 and still learning

Adelphos

Hey @Pat50 - What mode is your camera in?

If you are in Aperture priority mode you should be able to dial in whatever aperture you want, then the camera will set your shutter speed for you (ISO can be adjusted if photos are too dark).

Checking what mode your camera is set to is the only thing I can think of. I hope it helps.

Pat50

Thanks Adelphos for taking the time to consider this. No, I have it in Manual Mode.

Since I wrote the initial query I have learned that it will go down to f/2.8, but only when I turn the focus ring marker until it is close to the infinity mark. If I have it at the 0.95 mark, then the lowest I can get for aperture is f/5.6.

The lens did not come with any manual or instructions so I really don't understand what is going on. It has not prevented me from taking some lovely photos with my new lens by trial and error and feel, but I'm not sure what is happening or why.

Not having that understanding makes me feel quite insecure about how to gain confidence in using this lens and how to learn to be a better photographer.

Moose

Hey @Pat50 - So sorry for the slow reply, been busy with two baby boys and a bunch of changes here at Camera Tips. It sounds like a rogue setting is throwing thing off.

1. I would start by resetting your shooting options (MENU -> Shooting Menu -> Reset Shooting Options).

2. Next, I would set your ISO to Auto (MENU -> Shooting Menu -> ISO Sensitivity Settings -> Auto ISO Sensitivity -> ON) and in that same menu, set your Max Sensitivity to 3200 and the Minimum Shutter Speed to 1/60.

3. Finally, set your Shooting Mode to Aperture Priority (A on the mode dial). Then using the command dial, rotate it to the left to select an aperture of f/2.8.

Let me know if that helps. All the best!

Pat50

Hi @Moose. Thank you for such a thorough reply. Off to work now, but I will give it a try on my next double day off. Will try to let you know how it goes. Have lots of fun with those kids; time with them trumps everything else.

Moose

@Pat50 - Will do Pat...they are my pride and joy! :)

Pat50

Hi Moose. It has been quite awhile since I posted on your site, but that is probably good news because it means I have been out taking lots of photos. I finally found the answer to what is happening with my lens. The answer was something I just stumbled across on the Nikon site while looking for something else. It was indeed the infinity distance problem, something called the "bellows extension factor". I will post the link here for others to read. Apparently it applies to all prime lenses? Apparently, "A lens' maximum aperture is determined with the lens focused at infinity", so you only get that aperture when you are at infinity.
(see here)