I know I am going around in circles...please bear with me and hear me out
But first, thank you for the vivitar macro lens advice. It is around 50% of the cost of new pentax 100/f2.8. The savings in cost is great.
If putting extension tube on the 50/f1.4 will not increase the working distance, how about putting the extension tube on the 50-200mm? I am also referring to another post in this forum about fake macro (
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/9517-fake-macro-50-200-a.html)
Then I did some search on youtube and this video came out:
YouTube - Intro to macro
In essence, the video is about taking macro shots on a leaf using a canon 50-200mm and the guy say it is also acceptable to use an extension tube for the job.
Hence, I am looking at this in this aspect:
1) If I use the DA 50-200mm and set to 100mm, the working distance should be the same as a pentax 100/f2.8, no?
2) If I put extension tube on the DA 50-200mm, chances are that I might find it difficult to focus (as suggested by another thread) and the DA 50-200mm will then act as a manual focus lens - exactly like the vivitar series 1 105mm macro, no? If I can get back my AF, then this is a bonus.
3) The combination of extension tube with DA 50-200mm will solve my desire for point 1 and point 2 as previously mentioned, no?
Thanks again!!