Kiron 28-70mm f3.5-4.5 Macro For Reverse Zoom Macro (Images)

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Harold Gough
Posts: 5786
Joined: Sun Mar 09, 2008 2:17 am
Location: Reading, Berkshire, England

Post by Harold Gough »

I now realise that this lens (no manual came with the lens) has a provison which I have not come across before, having used a wide range of lenses. There are two red lines to line up on the aperture ring. One is for wide-angle, the other for telephoto. This means that apertures stated in this topic are correct for 28mm, should be a stop smaller at 70mm and half a stop smaller at 50mm.

Harold
My images are a medium for sharing some of my experiences: they are not me.

Harold Gough
Posts: 5786
Joined: Sun Mar 09, 2008 2:17 am
Location: Reading, Berkshire, England

Post by Harold Gough »

Today is bright overcast. With the lens set at its smallest aperture, reversed on the 110mm extension, I tried locating and focusing on objects through the E-P2 rear screen and through the OM4 optical viewfinder.

The image through the E-P2 was at least a couple of stops brighter. However, whether the subject was in sharp focus or not was much more clearly defined through the OM4. This latter outcome is almost certainly due to the Intensescreen focusing screen fitted versus the poor defintion on the E-P2 screen.

My personal choice is for a subject which is a little more difficult to frame but can be accurately focused.

With supplementary lighting, or on a sunny day, the OM4 should be as easy to use as the E-P2, plus will give more acceptable images due to better accuracy of focusing.

This is about locating the tiny subjects and getting them in focus. Illumination for exposure would be by twin flash.

This test is with the lens on f16, whereas f11 would be my typical choice, giving a brighter viewfinder image.

I have just received one of these LED torches:

https://www.uktoolcentre.co.uk/Shop/p~3 ... Torch.html

Illuminating the subject with it makes the viewfinder image of the OM4 much brighter than the daylight images on the E-P2 with Liveview Boost. Of course it will make locating and framing subjects really easy with the E-P2 but not entirely overcome the dificulty in focusing.

Harold
My images are a medium for sharing some of my experiences: they are not me.

Harold Gough
Posts: 5786
Joined: Sun Mar 09, 2008 2:17 am
Location: Reading, Berkshire, England

Post by Harold Gough »

Update:

I now have a replacement Kiron 28-70mm f3.5-4.5 on the way to me.

Also, I spotted a rare Kiron 35mm f2.8, which is coming by surface mail (4weeks +).

Finally (is it ever :)) I also have a Kiron 28mm f2 due to reach me in a few days.

All of this for £110, including post. Great value for what the lenses enable me to do.

I hope that the faster lenses will be easier to use e.g. for stack series. More important is the possible increase in quality of the primes over the zoom. This will overcome the problem of accidentally changing focal length while shooting, not a major problem.

In the meantime, I have started taking some comparison shots on film. I inserted an Olympus OM x2A TC behind the extension to match the FOV. I have taken some shots on fine-grain ISO 400 but after loading ISO 100 film I found I was out of button cells for my OM4. They will reach me any day now. If worthwhile, I will then copy the transparencies onto digital. That will not be for some weeks yet.

The priority is to continue to test a set-up with a range of magnifications, such that the zoom is first choice. However, if there is significant gain in quality with the primes I will use those when convenient. Because of the subjects, use will be mainly hand-held.

Harold
My images are a medium for sharing some of my experiences: they are not me.

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