Closest I can get with a Lens kit?

[Daisy14'sDH]

What is the closest you figure I can get to an object?
Equipment; using a lightbox, tripod on a 3 second delay with remote
Pentax k-x

Choice of

DAL 18-55 kit lens
DA 50-200
A 50mm f2.0

Which lens will get me the sharpest pics? At what distance? I've been playing with it trying to get some pics of some "flat" objects, so DOF isn't a huge issue. Everything looks grainy to me still...

 

[JoeDif]

Depends on the lenses closest focusing distance which varies on each lens. A macro lens will allow you to get within inches of the object where other lenses only allow the closest distance to be 9 - 12 inches or so to achieve focus.

I'm not sure if you are trying to do macro work but if not another option is to use the 50 -200 and zoom in close.

I'm sure some of our Pentax people can assist with those lenses

 

[Daisy14'sDH]

I was about 6 inches away for this shot. It doesnt seem very focused or sharp in the lower portion of the frame.

 

[pjacobi]

You only have a fraction of an inch DOF at 42mm focal length at 6 inches, even at f/10. The photo is shot at an angle which is why the lower portion is out of focus. See DOF calculator:

http://www.dofmaster.com/dofjs.html


Exposure was 1/5 second, so camera shake could also be an issue.


-Paul

 

[Daisy14'sDH]

That shot there I didn't use the delay with the remote, just the remote. I will try to resimulate that shot again tonight once the kiddies are in bed...

I used my Gorilla Pod instead of the Tripod there, thats why there is an angle. The Tripod puts the camera to high over the area, but maybe I can attach the Gorilla Pod to the Tripod...

 

[Daisy14'sDH]

BTW thats my new favourite online resource...

 

[AndrewWG]

You are also for some reason, shooting at ISO 200. I would try this shot at ISO 100 or lower (provided the camera has it) and at a smaller aperture like f16 on a tripod with the shutter release. Even then, I think that your depth of field at 6 inches or so is going to be an issue. Maybe not. Never know till you try I suppose.

Now, if you could glue all those Mickey heads to something and take the pic straight on (or somehow get the camera DIRECTLY above them) DOF would not be an issue.

 

[Daisy14'sDH]

K-x only allows a minimum of ISO 200, unless of course there is a trick to get it lower...

 

[Daisy14'sDH]

I guess my lightbox needs some work, I got the GorillaPod attached to the Tripod and got it directly over the mickeys about 10 inches away. But I ended up with a large area that is very dark in comparism. I guess I could either pull the camera back further or strengthen the light intensity in the box (which BTW is my Pool table light with a sheet around it!)

Maybe if I added 2 more light fixtures one on either side that would give a large area with tons of light.

Back to the drawing board I guess...

 

[disneyboy2003]

You only have a fraction of an inch DOF at 42mm focal length at 6 inches, even at f/10. The photo is shot at an angle which is why the lower portion is out of focus. See DOF calculator:

http://www.dofmaster.com/dofjs.html


Exposure was 1/5 second, so camera shake could also be an issue.


-Paul

Wow! I'm SHOCKED that the Depth of Field (DOF) is only 0.14 inches with the above settings!

At first glance, I would have thought that a small aperture like f/10 would have been good enough to keep much of the photo in-focus. But using that DOF calculator really opened my eyes to how much I need to pay attention to the other variables of DOF.

I guess that also helps to explain why macro photography is so hard. You still get razor-thin DOF, despite using small apertures!

 

[pjacobi]

a smaller aperture like f16

f/16 is too small! At f/16, diffraction will become a problem and images will be less sharp. Use a maximum of about f/8.

f/16 is good for film or full-frame, but too small for crop cameras.


-Paul

 

[AndrewWG]

f/16 is too small! At f/16, diffraction will become a problem and images will be less sharp. Use a maximum of about f/8.

f/16 is good for film or full-frame, but too small for crop cameras.


-Paul

I have never tried it on a pic like this but on that angle they will need the most DOF they can get I would think. They are already at f10 in this pic so I was just taking a guess. I don't get the whole diffraction thing. I will have to look that up.

 

[disneyboy2003]

I have never tried it on a pic like this but on that angle they will need the most DOF they can get I would think. They are already at f10 in this pic so I was just taking a guess. I don't get the whole diffraction thing. I will have to look that up.

According to the DOF calculator, at f/16 the depth of field is still only 0.23 inches!!! (using the same settings of focal length 42mm and subject distance 6 inches)

There are a couple of very good Web sites that describe the concept of diffraction. Although at times they might be a little technical, I think the sample pictures they show clearly illustrate how very small apertures can affect the sharpness of your photos due to diffraction:

• Cambridge in Colour: Diffraction & Photography
• Luminous Landscape: Understanding Lens Diffraction

 

[YesDear]

OP I agree with everything you have been told so far. First let me say that you are not shooting a flat object. Staked flat objects are not flat.

If this shot is something that is critical for you, you might try renting a macro lens. You would still have the same issues as previously discussed but the lens would be designed for what you are trying to do. The issues would not be as stark. I did a quick search online and found there are one or two places that will rent pentax mount lens. $30 would get you a macro lens for 4 days.

Also see if you have any photo friends or a school that has a light stand. That would assure your camera is perpendicular to your subject and would help greatly. You may not want to spend any money to get the shot, but you are spending a good amount of time. Sometimes it does take the right equipment to get what you want.

The specs on your camera says you can go to ISO 100 in manual. FYI

 

[Daisy14'sDH]

No the shot isn't critical. Its just me playing with the camera and annoying DW lol. I'm just really trying to get the most out of my camera and learn new things every time I use it.

The settings on the camera will only allow a minimum of ISO 200

 

[AndrewWG]

The settings on the camera will only allow a minimum of ISO 200

Some of the Pentaxians in here can probably help with this. I don't think that you are losing a lot of sharpness with ISO 200 but usually your lowest ISO is best.

 

[disneyboy2003]

No the shot isn't critical. Its just me playing with the camera and annoying DW lol. I'm just really trying to get the most out of my camera and learn new things every time I use it.

The settings on the camera will only allow a minimum of ISO 200

I double-checked a couple sources, and looks like the minimum ISO on the Pentax K-x is ISO 200.

It's on p. 298 of the Pentax K-x's user manual (link).

Also, dpreview.com confirms this, too. (link)

However, sounds like you can artificially expand the sensitivity range, and bring your minimum ISO down to ISO 100. Instructions are on p. 92 of the manual. It's "Custom Setting 1" > "3. Expanded Sensitivity". Turn this feature ON to get ISO 100.

I'll let others chime in on the pros and cons of expanding the ISO sensitivity like this.

I agree that, in general, you should use the lowest ISO possible for a particular picture. Different photos may require higher ISOs, depending on what you're trying to achieve with your photo. However, I don't think the difference between ISO 100 and ISO 200 is really that substantial, except to the very discerning eye.

 

[Daisy14'sDH]

Lol, yes I found it as well sitting at my DD ballet class re-read the section on ISO. I didnt realise that I had to "Expand the Sensitivity" myself when I had it set to AUTO ISO.

Thanks for the heads up!

And there appear to be lots of discerning eyes on the board. Thats why we ask questions!

 

[SelfEmployedDebtFree]

Its just me playing with the camera and annoying DW lol.

I know that feeling.
I have the K-x as well. Nice camera.