Thanks John & David - I was just trying them out under the conditions available - that was window light, handholding, SR on, and my aperture was limited by acceptable ISO & shutter speeds. I'm happy with the 'closeness' and sharpness, so I guess thats the main thing. Obviously I'm going to struggle with shutter speeds at ISO 100 even in brighter light, and a tripod doesn't help with subject movement.

Bye the way, does anyone know if there is any effective light loss with tubes - not in the normal sense as there's no elements involved, but does the extra length make any difference? I imagine it would be very small if it did, as the light is still just travelling straight in from the rear element of the lens.

John, in relation to the question about magnification - I think I'm just looking for some reassurance that its all working as it should - based on the lens focal length and the 3 stacked tubes - that this is the sort of result that is expected. It sounds like all is OK from what you have both said, so I am pleased with that. Now I just have to learn how to get the damn mounting ring off the lens !- back to the other thread ....

Thanks for looking David, you may have misunderstood me - Its the first time I've used tubes, so I want to know if they seem to have been used correctly in relation to the lens and the magnification performance. More specifically, is this the expected magnification with 3 tubes together on a 150 mm lens - does this setup seem to be working properly based on these test images? Aperture was f6.7.

You're not going to see any macro live subjects from me! I'm not at all interested in insects or scary bug shots I am interested in getting good detail close-ups of flowers though (as I was asking about in the 'Pixels or Glass' thread) - I guess the magnification I'm getting with this tube set-up would be plenty for flowers?

Do you think the DOF effect and IQ you can see (bearing in mind thes are at ISO 800 on the K7) is good, and is to the level that can generaly be expected with such a lens and tubes? Sorry to be so specific in the questions!

Just experimenting with new extension tubes - which then got stuck!! (see troubleshooter thread) - but I got a few shots.

Just looking for general feedback on the close-up aspects to see if the tubes are the way to go. The lens is the Pentax 'M' 75-150 f4.0, on the K7. ISOs were 800 or 1600, so pushing it a a bit on the K7, but it was just a try out.

Are these shots actually real 'close-focus'? - Is this the sort of performance I should expect from tubes ? Its not 1:1 macro, but not too far off I think? Would appreciate any technical thoughts and feedback re the close-up / macro effect. Many thanks!


























Thanks for looking and any thoughts

Relax, nothing off-topic or personal here! Its about stuck extension tubes . Following some of the advice I got on the thread asking about 'Pixels or Glass', wanting to take closer focused images, I got a set of 'Neewel' tubes from Amazon. First time with anything like this, so it was bound to go wrong

There the good and the bad - the good is that I was able to get shots very closely focused ans I think the quality is OK - I'll put a few shots us on another thread soon .... bad news is that one the mount rings has become stuck onto my 'M' 75-150 zoom - totally jammed.

Pictures below, but there are two mount rings, one with a small screw at the side which is the one I attached to the lens - the screw makes no difference. The aperture still works on the lens, although not 'auto-diaphragm - the lens remains fixed at the aperture on the ring and does not jump back to full open. So no 'stop down' metering, although I still get accurate readings via the green button, just a dark viewfinder at smaller apertures.

Is this functioning normal with extension tubes?


Heres the set, minus the jammed ring :





And heres the lens with the mount ring jammed :















I'm not panicking - the camera is fine (and the other ring goes on and of the camera OK) - and I can use the lens for the close-ups .... but its a nice lens and I would really like to have it back for normal shots! Any ideas very gratefully received.

Yes, a good improvement I think ... It has a softer look that is not jarring like the first version, and the crop is better as well. Just goes to show that its always worth having a fresh look and always worth keeping a basic 'master' form of the original to go back to. Thanks for showing the photo and giving us the chance to look critically at it.

OK then - I'll try and give a balanced response ! I like the idea behind the shot - to show the bird in a wider context, and the DOF control adds a sense of 3D space to the image that works very well, with parts of the foliage coming into focus as well as the subject.

I'm not convinced by the center placement of the bird though - perhaps a crop that places it off-centre would improve the composition?

And I do have to agree with Steve regarding the sharpening & exposure - easy solution to the exposure in processing - I would cut the exposure by 0.5 a stop and reduce the contrast a little, either with a contrast slider or maybe levels in PS. This will help to avoid the far background going too dark and becoming distracting.

The over - sharpening shows up even at full size here on the birds feathers and around the edges of the in-focus foliage - looking a bit 'artifacty'. You'd have to go back to a master version and re-process I guess - it could be that the sharpening amount has been increased automatically by whatever method you used to make the web-sized version?

Should I take a look for the deciding opinion?

Its the 'them and us' bit that's starting to become a bit fuzzy now ... Hee hee

I wonder what they like to talk about over there now ...

I am surprised, but as always 'Intensely relaxed' (thanks Mr Mandelson) about being wrong. I am surprised to hear that DOF result was from the lens alone,... I havn't seen such a limited field of focus even on my 14mm. Either way it works well!