[johnha]

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The first review (from Italy 21st June 2019 - 4 star) on this page: Orion 7369 76mm ID Telescope Tube Rings: Amazon.co.uk: Camera & Photo

Not sure which 300mm f/4 it might be though?

Update: The rings arrived today, they fit the 645 A*300/4 well (as previously described by Rick). I'm a bit wary of how tight to tighten the ring around the lens barrel - have to see how solid everything feels when set-up.

Thanks again Rick for this information.

[hatsofe]

It has been half a year since you've received these holding rings now. I was wondering: how did they work? Were they sturdy enough to support the weight of this lens objective with camera mounted ? I just bought this objective on eBay and was going to find an arrangement for mounting it on a tripod before it arrived. Since I can't measure it yet, could you please let me know what's the exact diameter of the area where the mounting ring may hold it? Thanks

[RICHARD L.]

Personally, I have a 67 M* 300 mm f/4, bought new many years ago. I used it on my Pentax 67 II with great success. There is a tripod mount built-in and the lens is quite heavy per se. I'm sure optically it blows away any 645 FA 300 mm offerings though, as it uses only the central portion of the 90 mm diameter illuminated field on a 645Z digital camera.

Regards

[rdenney]

It has been half a year since you've received these holding rings now. I was wondering: how did they work? Were they sturdy enough to support the weight of this lens objective with camera mounted ? I just bought this objective on eBay and was going to find an arrangement for mounting it on a tripod before it arrived. Since I can't measure it yet, could you please let me know what's the exact diameter of the area where the mounting ring may hold it? Thanks

The rings are quite solid—solid enough for time exposures assuming the tripod is—and the diameter is a perfect fit.

I’m not close to the lens to measure the diameter, but the rings shown fit the 645 A* 300/4 perfectly.

Rick “but you have to mess with it to solidly mount a tripod plate” Denney

[rdenney]

Personally, I have a 67 M* 300 mm f/4, bought new many years ago. I used it on my Pentax 67 II with great success. There is a tripod mount built-in and the lens is quite heavy per se. I'm sure optically it blows away any 645 FA 300 mm offerings though, as it uses only the central portion of the 90 mm diameter illuminated field on a 645Z digital camera.

Regards

Richard, do you have real test results to back that up? The 645 A* 300 (then lens discussed in this thread—not the FA) is justifiably famous as one of the best in the line.

Covering a larger image circle doesn’t make a lens sharper in the middle, by the way. In fact, in my experience it’s the reverse.

Rick “who knows what this lens can do” Denney

[RICHARD L.]

Sir, I don't have a 645 300 mm lens to compare to my 67 M* 300 mm f/4 but I've been experimenting lately with 1) the 645 FA 200 mm f/4 VS the 67 M 200 mm f/4 and 2) the 645 FA 55-110 mm f/5.6 VS the 67 M 55-100 mm f/4.5 zooms. In these 2 comparisons, unfortunately the 67 lenses win hands down : sharper, better contrast, true-to-life color palette. I was the first to be astounded by these results, not having used my 12 Pentax 67 lenses for 10 years (lenses which I used with my Pentax 67 II in the "film era"). Last summer, I dusted my 67 M* 300 mm and shot a few pictures with it. It produces magnificent images on the 645Z and a real comparison between a 645 telephoto and an equivalent 67 telephoto would be fun to witness.

Regards

[barondla]

Wonder if 67 lenses have a construction advantage over the autofocus 645 lenses? AF lenses have so many other design considerstions/ compromises. The moving focusing elements must be light and easy to move. This isn't as rigid as those big 67 helicoids. It must be harder to keep an AF lens centered and adjusted properly.

An optical design expert was speaking about lenses. He said the larger the format to be covered, the harder it was to maintain quality over the whole frame. Luckily larger formats are more forgiving.

Thanks,
barondla

[rdenney]

Sir, I don't have a 645 300 mm lens to compare to my 67 M* 300 mm f/4 but I've been experimenting lately with 1) the 645 FA 200 mm f/4 VS the 67 M 200 mm f/4 and 2) the 645 FA 55-110 mm f/5.6 VS the 67 M 55-100 mm f/4.5 zooms. In these 2 comparisons, unfortunately the 67 lenses win hands down : sharper, better contrast, true-to-life color palette. I was the first to be astounded by these results, not having used my 12 Pentax 67 lenses for 10 years (lenses which I used with my Pentax 67 II in the "film era"). Last summer, I dusted my 67 M* 300 mm and shot a few pictures with it. It produces magnificent images on the 645Z and a real comparison between a 645 telephoto and an equivalent 67 telephoto would be fun to witness.

Regards

Well, the 645 A* 300 is in a different category than the 200 FA.

Be careful of assertions without data. Those are the same kinds of assertions that kept you from trying the 33-55 for a time, as I recall.

Rick “whose 67 300 is not the M*, and so not offering assertions one way or the other” Denney

[RICHARD L.]

10 - 4, Sir.

Regards

P.S. I've been "trying" intensively my little 645 FA 33-55 mm f/4.5 since I bought it in the Spring of 2020. I couldn't really find any "positive" reviews on this optic before I took the risk of buying one, so this made me very wary of the performance of this lens. Experience with it all year long has proven it is a high-quality zoom lens with great sharpness, contrast and resistance to flare. It is one of my best lenses with the 645Z nowadays. I wouldn't let it go for anything.

OTOH, the 645 FA 200 mm f/4 is a sweet little lens in its own right :

[hatsofe]

The rings are quite solid—solid enough for time exposures assuming the tripod is—and the diameter is a perfect fit.

I’m not close to the lens to measure the diameter, but the rings shown fit the 645 A* 300/4 perfectly.

Rick “but you have to mess with it to solidly mount a tripod plate” Denney

Thank you for responding. I see. I've ordered the objective and 2-x converter and the "645 to PK" adapter few days ago, planing to use it as 600mm on KP and K5iis. A proper hook -up is a serious matter for this focal length. It looks like , I'll have to build the tripod mount on my own as Amazon.com doesn't ship these rings to where I'm now and that's why I needed the exact diameter of that portion of the lens body.

[johnha]

The rings are quite solid—solid enough for time exposures assuming the tripod is—and the diameter is a perfect fit.

I’m not close to the lens to measure the diameter, but the rings shown fit the 645 A* 300/4 perfectly.

Rick “but you have to mess with it to solidly mount a tripod plate” Denney

I use similar (the same?) rings, I think the given diameter is 76mm (I can't check right now). I haven't tried a tripod plate yet, but balancing it with the D on the back hasn't been a problem using just the ring.

[hatsofe]

I use similar (the same?) rings, I think the given diameter is 76mm (I can't check right now). I haven't tried a tripod plate yet, but balancing it with the D on the back hasn't been a problem using just the ring.

Thanks. I'm going to build the lens and the camera support on a single plate, which will act as a tripod plate; it also makes stabilization of the "lens-camera" easier. Any long enough and heavy lens objective applies pressure at the mounting area of the lens and the camera. I think the proper support is paramount.

[PhilRich]

Since I have the 67 300 M* and tested it quite a while ago I thought it would be good to add to this thread. I've been testing the various lens taking pictures down the street from my front porch. The first picture is the full frame shot while the 2nd is a crop of the same shot, picture taken at f11. As you can see the power pole is in focus, being 150 yards down the street.

_IMG1155 f11

_IMG1155 f11 Crop 3

[barondla]

Since I have the 67 300 M* and tested it quite a while ago I thought it would be good to add to this thread. I've been testing the various lens taking pictures down the street from my front porch. The first picture is the full frame shot while the 2nd is a crop of the same shot, picture taken at f11. As you can see the power pole is in focus, being 150 yards down the street.

_IMG1155 f11

_IMG1155 f11 Crop 3

Impressively sharp! Quite a lens.

Thanks for sharing,
barondla

[RICHARD L.]

I would really like it if someone possessed both the 645 A* 300 mm f/4 and the 67 M* 300 mm f/4 and did a comparison shooting test. My bet would be on the 67 M* ...

Regards