Yes..... am aware of the differences and again appreciate the post - especially about the vignetting. I was going to ask but didn't since I couldn't see any in your images. I wasn't trying to say that the Pentax 150mm was in any way superior but that it was/is an unbelievable bargain at the price I paid for it and that, maybe, you should look into it as part of your arsenal. I probably would not opt for the Sigma 135 but instead would seriously think about the Sony 135 that could also be used on my A7R5 assuming I could find a great copy. That always seems to be the issue...without vignetting ...
Best.....
Victor B.
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