macro lens help please

[spigwell]

Hi,

First time poster so please be gentle with me

I have a Pentax K10D camera with a Tamron AF 18-250mm F/3.5-6.3 lens (it says on the box LD Aspherical (IF) Macro). It has a great zoom facility and I have taken lots of pictures with it that I am happy with. The reason I chose this lens was the fact that I thought it would also do some really good macro shots. (not been doing photography for long). I have tried to take some macro shots with this lens of close up jewellery (diamond, emerald, opal etc) and have had very very poor results, I just seem unable to get the lens to focus close up.

Is this due to the way I take macro images? ( I move close to the subject and manually focus I also use a lightbox) or is this lens not a good macro lens? If it is the way I take the photo does anyone have any handy tips that maybe I should use? Or if it is indeed a poor lens to take close up shots with does anyone have any recommendations that I could use with this camera?

Many thanks for reading this, and any help no matter how small is a big help to me

Thanks
Gary

 

[d_pipa]

get some extension tubes P

 

[pete-c]

I agree extension tubes are the answer.

Pete

 

[StewartR]

The specifications for this lens state that it has a minimum focussing distance of 45cm and a maximum macro magnification ratio of 1:3.5. To achieve this ratio you'd need to be using the 250mm end of the focal length range and focussed at the minimum possible distance.

The sensor on your camera measures 23.5mm x 15.7mm. Put that together with the 1:3.5 magnification ratio and it emans that the best "macro" image you can achieve would have an object that is 82mm x 55mm filling the frame. That's almost exactly the size of a credit card.

So ... it's not a great lens if you want to do real close-up work. If you want to photograph objects which are only say 10mm or smaller, then they'll only take up a very small amount of the image and you'll have to crop very heavily.

Does that help you understand what you might have been doing wrong? If it doesn't, I suggest you post a sample picture for us to look at, with a detailed description of how you took it.