Close-Up Sharpness Problem

[plantynut]

Please be gentle. I have lurked for a while while weighing the pros and cons of a camera choice. I see there are many bright Nikonians here and it's my first time coming to you with a question.

I am a new first time DSLR owner ( D5000). I am a long time amature With decent knowledge of aperture and DOF. And for years I have done a very good job with my point and shoots. Most recently the Sony H50.

But now I find myself totally flummoxed.

I am having a hard time getting good focus on close-ups.

Ignoring the lighting since that was not my area of concentration for these tests, I photographed this African Violet plant with the camera on a tripod.

Using an 18-55mm lens set at 35mm, ISO 400, F32 1.6 seconds



Now I have been told a lens won't give it's sharpest image at it's smallest aperture
so I shot at 35mm, ISO 400, F18 1/2 sec.



It looked very similar if not identical at F20 to my eyes.

In the viewfinder it all looked good. Even on the playback.
What am I doing wrong?

So my questions:
1. What is the sweet spot with this lens?
How close can I be to the subject?
2. What focal length should I be using for close-ups.

I have no problems with photos of things further away. Only close-ups.
Except for a few that actually did come out good.
This was ISO 200, 55mm, F20, 1/50 sec. Hand held.
I consider it a lucky shot since the majority are not this sharp.



Then there was this one which looked fine on live view and through the view finder.

Same settings as the rose except the aperture was F8. So clearly not a good setting for good DOF for this type of photo.



I am eager for your feedback because I am very frustrated.
Arlene

 

[noreast]

Consult the lens review for the aperture/focal-length combination you used in your pictures: http://www.dpreview.com/lensreviews/nikon_18-55_3p5-5p6_vr_n15/page3.asp

There are no measurements at F18 or F20 but you can extrapolate between the measurements for F16 and F22.

the other thing to consider is the minimum focus distance, are you sure your object was at least as far as the minimum distance for the lens?

Did you switch VR off for tripod use? Did you use a remote shutter release or the self timer to avoid motion blur that may happen when you release the shutter manually?

 

[plantynut]

the other thing to consider is the minimum focus distance, are you sure your object was at least as far as the minimum distance for the lens?

No since I have no idea what it is.

Ok after reading the link you provided I see the minimum distance from lens to subject is about 7 inches(11mm) if I read that correctly.

Did you switch VR off for tripod use?

No but I had the same problem when I hand held it for the last picture in my post.
Did you use a remote shutter release or the self timer
to avoid motion blur that may happen when you release the shutter manually?

No

I did forget about shutting off the VR for tripod use although I don't understand why that needs to be done. And I am willing to admit to causing camera shake for those long exposures at the smaller apertures. I considered re shooting but got lazy.

I realize I have a lot of learning to do.
Anyway, thanks for your reply.
Arlene

 

[Snapshott]

Start by making sure you are not less that the minimum focus distance. If you can't get the green focus dot in the viewfinder to light you are too close. Start by moving back and then get closer and make sure you can still get the focus dot to light up.

Work with f11 of f8 for now as refraction can start to degrade the sharpness after about f13 bit I never notice it until f22 or higher.

On the tripod turn VR off and us a remote shutter release or the self timer. Turning on the shutter delay mode will also help.

--
Snapshott

 

[noreast]

I realize I have a lot of learning to do

Welcome to the club

Every lens has a minimal focus distance that is part of its specifications. The lens can not focus on an object closer than that distance unless mounted on extension tubes or bellows (and for those experts out there, please help educate me as well in this area).

VR stabilizes the picture for hand held shots by introducing vibrations that oppose hand movement. When mounted on a tripod, these vibrations "bounce" back and cause camera shake.

Finally, when shooting on a tripod and especially for long exposures, it is recommended to use the self timer to release the shutter since no matter how careful you are, when you press the shutter release button, you are likely to move the camera a little and introduce motion blur.

 

[plantynut]

On the tripod turn VR off and us a remote shutter release or the self timer. Turning on the shutter delay mode will also help.

I put a turn off VR lable on the tripod where the camera sits. Now I won't forget.

Thanks Snapshott.

--
Snapshott

 

[plantynut]

VR stabilizes the picture for hand held shots by introducing vibrations that oppose hand movement. When mounted on a tripod, these vibrations "bounce" back and cause camera shake.

Aha, so that's why. Thanks for that tidbit.

Finally, when shooting on a tripod and especially for long exposures, it is recommended to use the self timer to release the shutter since no matter how careful you are, when you press the shutter release button, you are likely to move the camera a little and introduce motion blur.

Will do.

 

[RAL131504]

Like the others have said, make sure you are not too close. Next, stay away from the f32 for sure and I probably would not go past f16. Your last two shots aren't that bad really. The other thing that will help is to get more light so you can get shorter shutter speeds. Then the big thing is something you may have to get used to compared to your point and shoot. The depth of field is much much bigger on any point and shoot compared to a dslr. The little sensors on point and shoot cameras use very short focal length lenses which lead to almost infinite depth of field. The only way to get any more depth of field on a dslr at f8 to f11 is to go to shorter focal lengths on your zoom. You will have more depth of field at 18mm than you will at 35mm. Many think this is a plus to be able to isolate backgrounds, but you can do that in other ways also, but you just can't hardly do anything to make the depth of field nearly as large as a p&s.

 

[GaryDeM]

you are using a kit lens for your macro work. any lens, other than a true macro lens, has a specified limit as to how close it will focus. check the specs for your lens. even at that distance the size in a macro pic is not going to be that large. it is not like your p&s lens at all. a true dslr macro lens can get to a true 1:1 magnification ratio.

next- any dslr lens, or any other lens, has a diffraction limit. this is the fstop beyond which the image quality degrades or distorts due to diffraction. diffraction is happens to light when it passes through a small hole. for a dslr it begins at any fstop beyond f11.0. at your f18-20-32 you are well into difraction and the image quality is going down. yes at higher fstop you get more dof, but it is at the price of distorsion. i shoot macro too but i automatically do not use a fstop higher than f11.0 because of diffraction. also, because of the higher magnification your shutter speed and the need to stop your motion plays a part. the higher the maginification the more you need a higher shutter speed to stop your own motion. i get plenty of handheld macro shots but i also up the iso to 800 to force a higher shutter speed.

so get rid of the super high fstops, go to f11.0 and you will find yourself using a shutter speed that is very handholdable. if not up the iso to 800. remember this is a dslr not a p&s. the dslr can take the higher isos with no loss of image quality.

if your kit lens cannot focus and give a big enough image. then that simply means that you will have to get some kind of macro lens or macro attachment. a macro lens is the best but so is the price the highest.

below are macro images. all ar shot at iso higher than the base and are handheld. all but the butterflys are at iso 800. the butterflys is at iso 1600. all images shot with a macro lens.















any questions. please ask. gary.

 

[dumbo]

I am having a hard time getting good focus on close-ups.

Ignoring the lighting since that was not my area of concentration for these tests, I photographed this African Violet plant with the camera on a tripod.

Using an 18-55mm lens set at 35mm, ISO 400, F32 1.6 seconds

As you indicate yourself small appertures are not the best for getting absolute sharpness. Most lenses have their sweet spot somewhere in between f/5.6 and f/8. Sometimes, though, you need DOF larger than f/8 give you and then, of course, stopping down is the only thing you can do. I would think twice before stopping down further than f/16 though. After that you will see quite strong degradation of IQ.

Also, shutterspeed might have an impact on sharpness. I don't know about the conditions where these where taken, but with a shutter speed of 1.6 seconds, for example, you will have blurriness if it's the least windy. Also you mustuse the self timer or remote release at such shutter speeds, if you didn't do that.

So my questions:
1. What is the sweet spot with this lens?

See above.

How close can I be to the subject?

The closest focusing distance with the 18-55 is 280mm. This is measured from the film plane, so you have to subtract the length of the lens (varies by the focal lentgh and focusing distance) and the distance between the lens and the film plane (about 45mm). That would be approx. 155mm from the front element with the lens at it's shortest setting.

2. What focal length should I be using for close-ups.

You will have larger magnification at 55 and also the background will be more pleasing. So that is what I would use with that lens.

VR should be disabled on tripod because if the lens is still the algorithm that controls the VR might start compensate for it's own movement and starts to oscillate and actually CAUSE blur insted of helping in not getting it.

Same settings as the rose except the aperture was F8. So clearly not a good setting for good DOF for this type of photo.
http://pic20.picturetrail.com/VOL18/606199/6823748/376293425.jpg

I don't necessarily agree that f/8 and wider isn't good for flowers. Then, that would depend a little on the type of shot you're after.But mostly it's about putting focus in the right spot. I mostly use wide apertures for flowers. Pics below might not be the best for a "spices portrait" though...
50mm@f/1.8:



35mm@f/1.8:



90mm@f/5.6:



50mm@f/1.8:

 

[GaryDeM]

note- the above images were all shot with a dslr that does not have a shake reduction syatem on the lens or body.

 

[GaryDeM]

almost forgot- all images were shot with a 105mm macro lens.

 

[James Sherman]

This was shot using a hand held D90 and a 70-300VR at f/8 and 300mm. The closer you get, the thinner your DOF.

 

[plantynut]

Like the others have said, make sure you are not too close. Next, stay away from the f32 for sure and I probably would not go past f16.

Yes, I am learning this.

Then the big thing is something you may have to get used to compared to your point and shoot. The depth of field is much much bigger on any point and shoot compared to a dslr. The little sensors on point and shoot cameras use very short focal length lenses which lead to almost infinite depth of field.

This will be a big change for me but I will get used to it eventually. I've been on training wheels for so long.

The only way to get any more depth of field on a dslr at f8 to f11 is to go to shorter focal lengths on your zoom. You will have more depth of field at 18mm than you will at 35mm.
I'll have to experiment with this.

Many think this is a plus to be able to isolate backgrounds, but you can do that in other ways also, but you just can't hardly do anything to make the depth of field nearly as large as a p&s.
I've been spoiled by those easy cameras.

 

[WineO]

With a zoom lens you will definatelly lose sharpnes from above f16 as diffraction will come in. How noticable this is depends on the lens. Prime lenses can be used with far less noticable diffraction above f16. Because of the smaller sensor size the DOF on a point and shoot is wider at the same distance and aperture. What it boils down to is that the lens you have is not ideal for close-ups and certainly won't do as a macro lens. Hope this helps.
Claude

 

[plantynut]

Gary you were very helpful. I am learning a lot with thee responses.

I do a lot od macro with my flowers so I think that will have to be my next purchase.

I did not know the DSLR nac handle a higher useable ISO than the p&s so that is another factor to get used to although a good one.

I like your pictures. Particularly the butterfly and 3 3 white flowers.

I see there are different sizes of macro lens. What are the advantages of one over the other?

Dumbo (how did you get stuck with that one. That's how I feel now) Your photos are lovely. Especially the last one. You've made some very good points. I am absorbing.

Thank you James. I will back up when I can with a longer lens. That's what I often did with the H50. Zoomed in and backed up. I got great results. Nice shot btw.

Thank you Claude. You're so right.

Arlene

 

[1PhotoFan]

Arlene,

If you are shooting the African Violets with your tripod on a carpet you will always have a problem with focus at long shutter speeds. Your camera will move when the shutter opens (even though this isn't visually perceptible as you watch the camera).

Dale

--
Living the dream ... cleverly disguised as a responsible adult.

 

[GaryDeM]

Gary you were very helpful. I am learning a lot with thee responses.

I do a lot od macro with my flowers so I think that will have to be my next purchase.

I did not know the DSLR nac handle a higher useable ISO than the p&s so that is another factor to get used to although a good one.

I like your pictures. Particularly the butterfly and 3 3 white flowers.

I see there are different sizes of macro lens. What are the advantages of one over the other?

depending on the maker, you can get a macro at or near the following sizes in mm. the 35mm, the 60mm, the 90-105mm(i have the sigma 105mm, very satisfied. the pics that you saw were shot with that lens.), and the 150-200m. all will go to 1:1. but what is different is the working distance. that is the distance from the front of the lens to the subject at any magnification. the 90-105mm is generally considered the miduse most sold type. for it will do all jobs fairly well. if however you were to go in for a special type of macro shooting then the mm really msatters. i am thinking of insect or other small critter pics. you then would want as large a working distance as posible so as to not scare your own subject and make it move. as said the 90-105 is the do all lens. it will do most jobs fairly well. the big macros the 150-200 require a lot technique due to size and the distance from the subject.

Dumbo (how did you get stuck with that one. That's how I feel now) Your photos are lovely. Especially the last one. You've made some very good points. I am absorbing.

Thank you James. I will back up when I can with a longer lens. That's what I often did with the H50. Zoomed in and backed up. I got great results. Nice shot btw.

Thank you Claude. You're so right.

Arlene

other macro shots-









finally do not think that you absolutely need a dslr with a macro lens to get a good macro image. below was shot by a pentax S5i, a p&s.





any questrions. please ask. gary.

 

[plantynut]

Thank you Gary. That orange zininia is awesome.

 

[plantynut]

Dale the tripod was on carpet. Interesting.