problems with D90

**Roadrunner** · 25th January 2010, 05:36 PM

Also have a Soligor 70-210 2.8-4
F22 and background not sharp.

**dmdigital** · 25th January 2010, 05:42 PM

Given up Matt or have you confirmed the aperture is not actually working as per what it's telling you?

Not much around $500. The 18-50 is a kit lens, very plasticy.

**Roadrunner** · 25th January 2010, 06:15 PM

I just don't understand it. If I choose f22 shouldn't that give me the max focus depth ? So in my past shots with 2 different lenses and f22 objects 30cm behind the focus object are not sharp. Does that make sense ?

Thanks for your help.

Matt

**dmdigital** · 25th January 2010, 06:38 PM

It depends on the hyperfocal distance.

Also I just realised something, this is a DX camera and so you are effectively shooting f/16 when at f/22 from the point of view of hyperfocal distance. This is because the you are effectively looking at a smaller circle of confusion or in simple terms a magnified image (remember the 1.5x crop factor of DX).

Am I making sense?

**Roadrunner** · 25th January 2010, 06:43 PM

Might be making sense but you're pushing my limits

So what is a good lense for the D90 ? The whole point was that I could use my old lenses.
Just seen this one Tamron 17-50mm f/2.8 XR Di II Lens is around $700 imported. I think 17-70 would be good as it covers a lot.

Matt

**dmdigital** · 25th January 2010, 07:01 PM

OK, glad I didn't just add to the confusion.

The Tamron lens is a Di which means it is designed for the DX size sensor, just like the DX lenses from Nikon.

Basically any lens designed for digital cameras is going to be OK, some will be better lenses than others. A lot has to do with the ability to focus the light straight to the sensor which was something that wasn't as important on film. This is to do with the photosites on the sensor and the microlens technology employed to direct the light on to them.

**Bushie** · 25th January 2010, 09:21 PM

Plug some figures into this and see what it gives you, as a comparison

Depth of field calculator

Martyn

miky · 25th January 2010, 09:35 PM

Originally Posted by Roadrunner

Might be making sense but you're pushing my limits

So what is a good lense for the D90 ? The whole point was that I could use my old lenses.
Just seen this one Tamron 17-50mm f/2.8 XR Di II Lens is around $700 imported. I think 17-70 would be good as it covers a lot.

Matt

It's the old story Roadrunner - it depends.

I find the 18 - 200 a good all round lens.
Edit: Disclaimer - The page is just to show the lens. Not advertising the company.

Mike

**Roadrunner** · 25th January 2010, 10:22 PM

So when I type in 52mm f22 also I will only get f16 with f22

and distance 1.5m I get total depth 77cm

So how do you take a picture where the person in the front is sharp and everything behind that person ?? f64 will give me 3.8m

When I take my little point and shoot Canon and have F8 everything gets focused.

Matt

**Taz** · 25th January 2010, 11:50 PM

Originally Posted by Roadrunner

So when I type in 52mm f22 also I will only get f16 with f22

and distance 1.5m I get total depth 77cm

There maybe some confusion here. Smaller sensors have greater depth of field for the same aperture. So if we take a 'full frame' (ie 35mm) sensor as the reference, your APS-C sized sensor (1.5 or 1.6 crop factor) will have greater depth of field at the same aperture. So, in order to match F16 on your camera, a full frame camera would need F22 to achieve the same depth of field (everything else being equal).

Originally Posted by Roadrunner

So how do you take a picture where the person in the front is sharp and everything behind that person ?? f64 will give me 3.8m

Get a wide angle lens or stand further away with your existing lens on its smallest aperture setting (F22) and use hyperfocal focus. For example, I know that I can get everything tack sharp from 2-3ft to infinity using my 24mm lens set to F22 on my 35mm camera.

I think you may be expecting a little too much from F22 on your camera with the apparent close range of some of your shots.

Originally Posted by Roadrunner

When I take my little point and shoot Canon and have F8 everything gets focused.

These point-n-shoots have tiny sensors. Tiny sensors = huge depth of field. Hence the reason why you dont see focusing on mobile phone cameras - they dont need it

Perhaps if I can also add... when it comes to portraits, the ones I like the best are the ones where the subject is seperated from their background using very short depths of field.

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