macro lens for ist DS

What would be a good macro lens for a ist DS?
The price of a pentax lens is a little to steep and I was bidding on a Sigma 50mm f2.8 macro lens on ebay, but the prices there are allmost rivalling the in store price for a new one, so not interesting.

http://www.sigma-benelux.nl/products/lens/product.php?pid=46

I can get the same lens for 259 Euro's from an online store. The price on ebay is allmost 170 Euro's now for a used one... I'll bet it can continue to 200 Euro's or more which is a little to high for a used lens...

How do you select the right focal length for macro shots? is a 50mm a wise choice or is a 90 or 105mm a better choice. It will mainly be nature shots and technical subjects (damaged pH electrodes for example).

The 100mm lenses are preferred by some because they place the subject a bit further away. Useful if it's a scorpion, or, conversely, if it's something that's feeling a bit nervous about you.

The best macros in the world are reckoned to be the Pentax 200mm macros, but they're not cheap. (For language scholars, that's an example of British understatement.)

Around the 100mm mark, you might find a Pentax M or A series lens that you can afford, or the Tamron SP 90mm, all of which are highly regarded.

The Pentax F and FA 100mm macros are great but perhaps outside your budget.

Recently I picked up a Pentax-A 50mm 1:2.8 for just under £40.00, and if you are quick you will see a K 1:1.4 being sold on Ebay by a member of this list. It's a good lens from a good seller, but because of his reputation the price is already more than I paid for mine.

Avoid the temptation to buy a so-called "macro zoom".

I don't have experierience of other makes' macros, but don't dismiss them, even Sigma. Many are good.

G

I picked up one of the manual focus 55mm Vivitar macro lenses for under £30 on Ebay. I've been impressed by the results using it with my DS:




It seems to be the case that pretty much all proper (i.e. prime) macro lenses are optically pretty good.

Knockout photo, niblue. Amazing detail. ON the Pentax side, I must agree with George. The Asahi 100mm macro is one of the finest macros ever made, at least based on photos taken with my ST in M42, which I would dearly love to have back today.

As for fitting stuff onto a *ist DS, this afternoon I photographed some Olympus cameras for a recently deceased friend's widow to sell on ebay. She has no use for them and prefers her Rolleiflex. First I used the kit 18-55, then removed it, installed the Pentax M42/K adapter, and fitted an old M42 SMC 1.8/55. The results with the old lens seemed, at least to my aging eyes, a bit sharper. Am I hallucinating, or is that, in fact, the case?

I'd always expect a decent prime to be sharper than a cheap consumer zoom. The only way your 55mm F1.8 wouldn't outperform the 18-55 would be if it was broken!

The old lens has plenty of life left in it yet - it will be sharper and will have excellent freedom from distortion. Modern zooms are sharp enough (or at least the higher priced ones are) but the designers do let the distortion creep in a bit.

However, not all older lenses make the grade. This may be due to variation in individual samples, but I had a SMC Pentax-M 50mm f2 that was not as sharp as the 18-55mm until it was stopped dpwm to about f11.

So testing our own lenses for ourselves can be a good idea.

regarding de sigma lens I mentioned in the opening post,

I see that the one that I can buy is the version introduced in 1998 which is the EX version of the Sigma lens. Now there is a new version called the DG version which according to the marketing blurb on the website optimized for use on digital camera's. Is a digital SLR more picky on lenses than a film SLR?

[sales blurb]
Sigma launched first standard 50mm Macro lens in 1990. This was succeeded by the 50mm F2.8 EX Macro in 1998 which proved even more popular with photographers, benefiting from improved build and optical quality.
The advent of digital SLR's requires optimum lens performance and therefore the very latest optical technology has been incorporated in the production of the New Macro 50mm F2.8 EX DG. This ideal standard lens sets the benchmark for digital SLR cameras.
[/sales blurb]

What they have to see about the DG lenses is the following:
DG (DG Lens)
These are large-aperture lenses with wide angles and short minimum focusing distances. With an abundance of peripheral illumination, they are ideal lenses for Digital SLR Cameras whilst retaining suitability for traditional 35mm SLRs.

I see no real difference in the spec sheets of the old and new lens:
Both are F2.8

old:
new:
The short distance required isn't a real problem for the tasks I have at hand for it. 9 out of 10 times it will be not moving objects. Or would a 100 or 105 mm macro lens be a better choice for a allround macro lens. As an extra note, I possibly can get a 50mm smc pentax-a f1.7 manual focus lens as well. Would this be something to take in consideration when selecting a macro lens?

There are two factors in particular that are relevant to designing lenses for digital SLRs.

The first is that the CCD is highly reflective and can reflect light onto the rear element of the lens. If this is not to be a problem then the rear element needs particularly good coatings. I would expect the SMC coating of pentax lenses. to be good enough to start with, but maybe even there additional layers may have been used.

The second is that CCDs like the light to fall on them at 90 degrees, and to achieve this lens makers use a telecentric design principle. This is new to digital lenses.

In both these cases film does not have the same problems, so film camera lenses were not specifically designed with these requirements in mind. Nevertheless, there are lots of film camera lenses that give superb results on digital!

This afternoon I took my SMCP-M 1:5.6 400mm down to the river to play with it. I haven't really had a chance to do so since getting it late last year.

It performs well enough most of the time, but give it some extreme light conditions, like the reflection off this pub sign, and the CA goes wild.




When the light isn't too contrasty, it's fine:




So my question is, why is it that this lens performs badly on digital, given that the rear element is so far from the sensor that the light path must be almost vertical?

G

I'm not convinced that "cromatic abberation" is a digital sensor issue.
Usually with digital you get a purple bluish cast....
I'm thinking that the lighting angle and red abberations are attribitable to late afternoon sunlight (already warm) being colored more by the reflective gold, creating a red cast to normal lens flare.

Don,

I suspect you are right.

Incidentally, this lens is an example of how best to use (some) K and M lenses on a DSLR.

I just leave it on f5.6 all the time, and shoot in Av mode.

G

since I will be getting my Pentax-A 50mm f1.7 shortly I will be on the lookout for a nice 100 or 105mm macro lens. Manual focus will not be a problem, most of the time you got enough time to focus manually when doing macro.

Just started playing with a set of extension tubes I picked up on ebay (NOT the £1.20 ones!)




This was taken with my SMC 50mm 1:1.7 lens and all three tubes (36,20 and 12 mm) 1 sec at f5.6 and ISO200, Tungsten white balance on the DS. The field of view is 16mm

Now I need a set of focusing rails! It never ends

A bit of experimenting with my FA 100/f2.8 Macro and a tungsten desk light covered with baking foil with a small hole about 1/4" dia (poor man's snoot )




Costume jewellery Bracelet, 30sec @ F32, Raw to Tiff to Jpeg, no adjustments or cropping, just the use of Matts sharpening action.

just playing around, but maybe with some more experiments this could work.
28-70 f4 with cokin filter adapter.
50mm 1.4 with cokin filter adapter.
reverse mount the 50mm to the camera mounted 28-70 with a piece of electric tape (on the filter rings not the lenses themselves.)
http://homepage.mac.com/lightexpressions/macro/macro.html