I can't afford anything!

You should be able to get a male to male adapter, or stacking ring, from Jessops but you will have to know the filter sizes of the two lenses you intend to stack.

Extension tubes are another method of producing macro images. Usually sold in sets of three tubes of differing lengths. These are usually 12, 20, and 30mm'ish and can be used singly or in any combination of 1, 2, or 3 tubes to give varying magnification. To keep things very simple, the use of extension tubes emulates the function of a macro lens, but a bit more fiddly. they are placed between the camera body and the lens to create an air gap or . . . extension.

With regard to protecting the contacts: Get hold of one of the older push-on Pentax rear caps. Cut out the centre and mount it on the reversed lens so that the contacts and mechanics are protected.You can do this with the hard caps as well but the soft ones are easier to cut.

Many many thanks.

Guess what I'll be doing this weekend!

Where ?

Well it was on the way up a hill near Lochinver in the West of Scotland
and I was trying to take a picture of a local "Munro". But you can't tell from the "Bee".

Here's the hill


http://web.mac.com/john_md/iWeb/Site/Mostly%20North%20Scotland.html

picture No.5

Now that's a difficult one, let me think . . . .

Which lenses do you intend to use?

The SMCP-F 70-210 and the SMCP-F 50 both happen to have 49mm filter threads so a stacking ring was easy to find. Ideally they should both be the same. If you have a zoom with a large filter thread, and a 49mm threaded 50mm lens for instance, you will get vignetting. But your favourite editing software can fix that.

BTW: Macro is much more rewarding with a digital body beccause you can see your results much faster and make necessary adjustments. Not so with film.

Have fun.

Erm...

Well, here's a confession, I don't have a Pentax.

I have a Samsung GX10. The 2 lenses I have are a Schneider D-XENON 18-55mm + 50-200mm.

Before my forum account is banned, they are the same camera built in the same factory. Ten feet away from the door the conveyor belt splits into two.

It's all right, Drewster. Imitation is the sincerest form of flattery.

Perhaps I can interest you in a nice Pentax macro lens that I am selling?
SMC Pentax-A 1:2.8 50mm, lovely condition, sharp as a razor, and it's certainly not "anything", so you CAN afford it.

And then you'll be a true Pentax user.

G

Those two lenses are not best suited to stacking together but you could certainly get hold of a SMC Pentax 50mm 1:1.7 lens reasonably cheaply. Then fix it to the front of your 50-200mm zoom.

BTW, I don't think your account will be banned. Ridiculed, you might be. Belittled, occasionally. But banned . . . probably not, as long as you display some first class results here.

Oooh! Yes, please tell me more!

What does the numbers mean before the mm? i.e. 1:2.8. Are these the max apperture values?

I have an 18-55mm. Now I thought the mm signified whether it was a wide angle/normal/telephoto. Like a 17mm, must be a super macro Macro, right? But I've seen Macros such as the Sigma 70mm F2.8 EX DG Macro. This is a 70mm lens, but capable of getting in closer then my 18-55mm. So the question I'm really asking is what differenciates a Macro from say a normal 18-55mm lens.

And one last Q, why do the new ones cost £200 +, when I can pick up an old one for cheaper (a lot cheaper, aye George!).

Many thanks!

Drew

1:2.8 means a maximum aperture of f/2.8

Macro means the ability to focus very close, properly used with specialised lenses focusing to give magnifications of half life size (1:2) or life size (1:1). In the latter case, for example, this means an object 1cm long would be 1cm long on the film/CCD.

The focal length in mm relates to whether the lens is a wide angle design (get a lot in, low mm number) or a telephoto (magnify distant objects, high mm number).

So a 18-55mm zoom covers from a wide angle to normal focal length on digital. A similar lens for film would have to be a 27-137.5mm to give the same angle of view.

I realise this is a lot of numbers, so I suggest a basic book on photography would assist in understanding the various bits of terminology.

not meaning to nitpick John, but shouldn't that be 27-83.5?


I'm not sure if this is still possible since K mount lens prices have gone mad on ebay in the last few weeks, but I got my Tamron 90mm F2.5 Macro with a matched 2x flat field teleconverter for £50 on ebay.

It is a bit basic and has no auto features whatever unless you can get hold of the elusive PKA adaptall 2 mount, but it works well and has taken me some pretty good shots both closeup and long distance as a fairly fast short telephoto prime.

You are quite right, whatever happened to my mathematics? I think I did a 2.5x conversion there instead of 1.5x. I'll just go and reboot my brain.

Pentax lenses are fetching some very decent prices on eBay at the moment. Decent for sellers, that is, but with fewer bargains for buyers.

People who buy and sell lenses prefer to call them by exactly the same name as the manufacturer, in order to avoid confusion. So what I said is what is written on the lens.

Translation

SMC - Super multi coating. This is Pentax's superior 7-coat lens coating system, which was jointly developed with Contax, and explains why Contax and Pentax lenses offered superior flare resistance, contrast, light transmission, colour fidelity, etc..

Pentax - I think you know

-A On a Pentax lens, the suffix relates to the mechanical/electrical/focussing technology in use. An "A" indicates a lens which transmits aperture information to the body, and which can have its aperture controlled by the body. Focussing is manual.

1:2.8 - This is the maximum aperture in optologist-speak. F2.8 to you or me.

50mm - The focal length, which determines the angle of view. On a film camera, it approximates to that of the human eye, on a digital camera it becomes a short telephoto, good for portraits.

The focal length has nothing to do with macro, which is primarily a question of the lens being able to focus on objects which are very close, and which therefore are magnified when you look at the printed picture.

The problem with macro lenses is that in order to get them to focus on near objects, the lens has to be moved much further from the body. This increases size, weight, and cost.

That said, the 50mm is not a big lens by any means.

And why does anything lose half its value when taken out of a shop? This is not a phenomenon unique to lenses.

My lens is manual focus, and 20 years old. So it's not worth as much as
a new one.

Here it is - or at least a similar one. Note how it extends.

http://www.bdimitrov.de/kmp/lenses/primes/normal/A50f2.8-Macro.html

G

True, but the quality will be just as good as a new one.

For mounting on the front of the 50-200 backwards... Yes it should be very good.

I have an old SMC A 50 1.7 (might be an A50 2.0 or 1.4, not looked at it in a while and it is not with me for me to check) which I hope to use on my K10D (when it arrives(approx 10-day countdown )).

Zoom lenses are not as easy to use for reverse coupled macro work as they are more fiddly and normally don't have as large an aperture.

I was tempted by the Samsung GX-10, especially as it comes with two lenses for the same price as the K10D with one lens. I couldn't miss out on the SMC coating as I shoot outdoors most of the time and glare is a problem on my current digital camera.


Was browsing through the K-mount listings and came across this:

http://www.bdimitrov.de/kmp/lenses/primes/normal/K50f1.2-Gold.html

What a waste of money...