Extension tube with the 150mm on 645
Pentax K-1 + K-5 and some other stuff
Algi
The maths to work out the far point is D = (F+E x F)/E where
D is distant limit
E is extention length
F is lens focal length
so for a 13mm tube on a 150mm lens the far distance would be reduced from infinity to 1880mm. The near point will depend on the amount of adjustment thaat the lens travels through
regards
Bernard
I'm still looking for the #1 tube - I know Pentax make some good two element diopters for the MF system, but I think I'd prefer the tube since it adds no extra glass to the system.
Thanks for the additional info everyone
We recently had a discussion about tubes versus close up filters in the Pentax 645 group on Facebook and the conclusion was that the filter can be a bit soft on the wider apertures compared to using a tube. I picked up my Pentax 645 Auto Extension Tube for £30 at one of the online shops that normally don't even offer Pentax goods.
Gallery: Hans ter Horst Photography
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540 posts
15 years
I've got the 150mm f3.5 for my 645, and while it's a lovely lens, I'd like it to focus closer for tight head shots. I'm guessing the extension tube set is what I need? Looking around, I think just the tube #1 at 13mm or so should give me enough additional magnification. Has anyone any experience with this setup?