[atlnq9]

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Hi All,

I'm a little late to the party regarding the drop in polarizer for the Pentax 645 A* 600mm f5.6 lens. I had given up looking for one like most here about 9 months ago and then suddenly yesterday I saw one appear for sale, so I quickly grabbed it. I guess it's still pouring rain . Although I often use polarizers with certain lenses and subjects, I wasn't quite sure how often I'd find myself in circumstances where I'd find the drop in polarizer for this lens necessary or a distinct advnatage without then faing the ussual stability and loss of image sharpness with this lens. Time will tell.

The reason I haven't added a test report to my posted comprehensive list of tested Pentax 645 lenses on the 645D, is simply I wanted to get more of a feel of the lens's performance out in the field with a wide range of subjects and at various distances. What everyone here has already written about this lens has certainly been accurate.

It's been interesting to hear/read that the 67 M* 400mm lens has optical performance that can equal the 600mm f5.6 lens, especially when the 400mm is used with the 1.4x. This certainly gives food for thought, espcially that it provides two different focal lengths out in the field as mentioned.

I haven't participated recently in these forums, simply due to an enormously busy schedule but hopefully that will change somewhat. Always great postings here on Pentax!

Dave (DandA)

Dave,
I think one thing really helping the 67 M* 400mm is the 645 image circle; only using the center of the lens...

My main quibble about it is that it is ergonomically light years behind the 645 A* 600mm. I haven't been using the 67 400 much lately. Considering at some point letting it go and getting a 645 FA 400mm 5.6. Of course then I have consider size and weight of everything as I travel a lot. The 67 400mm +1.4x is similar in weight to the 645 600mm. So if I went in preference of the 645 FA 400 I would then be carrying that and the 600mm... Probably just keep them all to choose how light I want to travel. I am starting to collect too many lenses though. I need to get rid of this massive k mount kit I have and get a canon or nikon ff and some tilt/shift lenses and something like the sigma 120-300 2.8 or the new canon zoom with the built in 1.4x converter. I find myself wanting tilt/shift a lot now.

[Thomas]

Dave,
I think one thing really helping the 67 M* 400mm is the 645 image circle; only using the center of the lens...

My main quibble about it is that it is ergonomically light years behind the 645 A* 600mm. I haven't been using the 67 400 much lately. Considering at some point letting it go and getting a 645 FA 400mm 5.6. Of course then I have consider size and weight of everything as I travel a lot. The 67 400mm +1.4x is similar in weight to the 645 600mm. So if I went in preference of the 645 FA 400 I would then be carrying that and the 600mm... Probably just keep them all to choose how light I want to travel. I am starting to collect too many lenses though. I need to get rid of this massive k mount kit I have and get a canon or nikon ff and some tilt/shift lenses and something like the sigma 120-300 2.8 or the new canon zoom with the built in 1.4x converter. I find myself wanting tilt/shift a lot now.

You won't be disappointed in the 645 400mm, it's light, has AF and of excellent quality; as much as I like the 600mm, it's much more difficult to use.

[Paul MaudDib]

Each lens design is different. The simple design of the 560mm means that the lens has to physically be longer, and there are fewer ED elements, which will result in more fringing. However, it's also sharper because it has fewer elements.

Fewer elements usually means it's less sharp (or more generally, less corrected). More elements means more opportunities to correct the incoming light to get a sharp image. The historical tradeoff was that more elements meant more air-glass interfaces, which in the days before coatings meant less contrast. Thus the Planar, the father of modern normal lenses, was sharp but somewhat low-contrast, compared to its contemporaries like the Sonnar or Tessar. Not such a big deal anymore now that coatings are up to such high levels of transmission.

[seventhdr]

atlnq9, not sure if you noticed ,but a second polarizer appeared. When it rains it pours.

Pentax 645 Drop in C PL Filter for A 600mm F 5 6 Lens Mint | eBay

Just to let people know that two polarising filters for the 645 600mm lens have just made it to eBay. The seller is agfacamera.

I've got no relationship with them. Just spotted them this morning.

Regards

Chris