Screw Mount Extension Tubes vs Bellows

Hi!
Just got a nice bellows for my Spotmatic collection. Before I actually film stuff, I thought I'd ask your advice on a few things.

My biggest problem with the tubes was the constant, scary, screwing and unscrewing to find the (close to) ideal length. This never left the lens in the correct orientation with the barrel readouts all over the place. Bellows solves this nicely and safely.

The only downside of the bellows that I can see so far, is that extension begins at 1". I have some tubes that allow for less. On the upside, it would be dificult for tubes to generate up to 5".

Now, the seller reminded in in a very nice note he included with the shipment to not forget the "bellows factor" when determining exposure.

I have a 55mm 1.8 Super Takunar on it presently and, at max extension I see no vignetting or major light loss. I'm using TTL metering and am trying for more DOF (any DOF?) by stopping down as much as possible. Will my meter give me somewhat accurate readings, or should I open up by some graduated amount to compensate for bellows length?

Thank's in advance for your opinions!

Cheers

Hi Mac,
I thought you would know by know the best place to look first is www.pentax-manuals.com

If you look on the M42 page ( http://pentax-manuals.com/manuals/m42/m42manuals.htm ) you can get the operating manual for most of the closeup equipment including the bellows complete with all the data tables. I have just got the manual for the Bellows II and slide copier and will be adding this in the next week or so as soon as I get it scanned. I also have the manual for the Auto bellows on it's way and that should also be up in a week.

PS. The short answer is that TTL metering will take account of the exposure factor. You only reallly need this for non TTL cameras such as the SL and earlier.

Kim

Kim,

Shoulda known you would even have manuals for stuff other than cameras andr lenses.

Keep the door open, here I come...

Thanks!

When TTL metering first came in it said it was the answer to all metering problems! No more calculating exposure factors for bellows extension etc. ;well, the first time I used bellows on flowers the pics were very UNDEREXPOSED ! The Pentax sellers did not remind people you still had to be careful about the TONES you were photographing ie if you were taking a white flower you need MORE, a dark flower or subject you need LESS exposure, just as in normal photography.

Peter,

I suspect you'll find that metering systems have moved on a bit since thirty years ago. Along with a few other things.

George
........................................................................................
Got computerised twenty years ago and digitised five years ago. (Thankfully).

Turns out the $5.00 M42 Bellows I got on eBay is in fact, the real McCoy - Pentax. Kim C's manual provides all the data for this unit with all my Takumar lenses mounted on it. The manual also contains all the equations and formulae to explain how tubes and bellows work.

We all thank Kim very much, as this information has headed-off a zillion silly questions from