[fwcetus]

OK, for anyone who has, or had, or otherwise has experience with, the M* 300/4 or A* 300/4 and also the M* 300/4 accessory hood (which, of course, despite its name fits the A* 300/4 just fine), here's a question:

Does the accessory hood also mount in a reversed position, screwed into the filter threads on the lens (using the internal threads inside the base of the hood), over the outside of the built-in sliding hood (which would be retracted of course, at the time)?

[ I did notice that the M* 300/4 accessory hood was not mentioned in this thread: https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/175697-lens...300-f-4-a.html ]

Thanks.

[seventhdr]

Actually it does!!!

I've got my A* 300mm f4 on the desk in front of me, with its SMC Pentax-M* 1:4 300mm lens hood reversed on it.

The hood has 77mm threads on both sides of the lens hood. It reverses easily over the build in hood and screws into the 77mm filter threads.

The built in hood extends 20mm when extended. The M* lens hood extends this by a further 30mm for 50mm of light shielding.

Regards

Chris

[fwcetus]

Actually it does!!! I've got my A* 300mm f4 on the desk in front of me, with its SMC Pentax-M* 1:4 300mm lens hood reversed on it. The hood has 77mm threads on both sides of the lens hood. It reverses easily over the build in hood and screws into the 77mm filter threads. The built in hood extends 20mm when extended. The M* lens hood extends this by a further 30mm for 50mm of light shielding. Regards Chris

Thanks for your very helpful reply, Chris.

I had already known that the M* 300/4 hood had "internal" as well as "external" 77mm threads -- in fact, I have even used one of the M* 300/4 hoods at one time not too long ago on my Tokina AT-X 100-300/4, on which it could mount either "regularly" or "reversed". [I did eventually obtain the proper Tokina metal hood - almost exactly the same size as the M* hood - for the AT-X zoom (and that hood, by the way, also is "double-threaded" and mounts in both directions).]

The problem was (and this was my reason for posting originally) that it has been several years since I had either the M* or the A* 300/4 -- I did have both of them previously, (M* first, A* second) at separate (but slightly overlapping) times, before eventually replacing the A* 400/4 with an F* 300/4.5. So, now I am looking at selling my two unused M* hoods, and I had started making a list of advantages for having an accessory hood for lenses that already had built-in hoods. And that brought me to my thread question:

I couldn't say for sure (due to foggy memory - some of my lenses are sharper than I am) that the M* hood did fit in the reversed position over the built-in hood, although I assumed that it did (otherwise, why would Pentax make it "double-threaded). So, I was looking for verification of my assumption, and your post did that, and more (since it also provided specifics on the difference in shading, which I knew about, but which I didn't have any measurements for) - Thanks!

[I still suspect that it might have been somewhat unusual for a lens maker to make a dedicated accessory hood for a lens that was already equipped with a built-in sliding hood (as with the M* and A* 300/4).]

So, anyhoo, here is my current list of advantages for Pentax offering an accessory hood for the nifty little M*/A* 300/4, even though Pentax had already equipped the lens design with a built-in sliding hood:

1. The accessory hood screws into the filter threads at the front of the lens, so that it becomes much more secure to use an M* or A* 300/4 lens in the field -- the accessory hood is not easily dislodged, unlike the built-in sliding hood, which can easily be inadvertently pushed back, exposing the front lens element to damage.

2. The felt bushing that lines the built-in sliding hood's base can tend to become worn or compressed over time, so that the built-in hood can become "sloppy" or "droopy" on some older lenses -- obviously, the screw-in hood would improve on that, since it will instead mount quite solidly to the front of the lens.

3. The appearance of the two hoods (i.e., the built-in hood and the accessory hood) from the side might make it seem as if they are approximately the same in length. However, because the built-in hood cannot extend all the way out (or it would fall off), in effect the built-in hood is actually considerably shorter (by over an inch) -- therefore the accessory screw-in hood will better shield the front of the lens from stray light, making for higher contrast images in many lighting conditions.

4. The accessory hood is actually "double-threaded" - i.e., it has the usual threads used to mount it on the lens in a forward-facing position, but it also has internal threads that allow the hood to be mounted on the lens in a reversed position for storage, fitting over the built-in hood.

5. Because the accessory hood is slightly wider than the built-in hood, it allows for the use of certain polarizing filters that might otherwise not be able to be used with the built-in sliding hood extended -- the built-in hood cannot be extended if there is a polarizing filter equipped with an "adjustment grip" already in place.

6. The dedicated M* 300/4 accessory hood was sold separately from the lens, so probably not too many users bothered to obtain it (since the lens did, after all, come with a built-in hood already), which might be the reason why Pentax never bothered releasing a re-marked A* hood for the newer lens version. Therefore the M* accessory hood, besides being quite functional, could also be a desirable (and collectible) accessory for many owners of the M* and A* 300/4 lenses.

Well, that's my list, expanded with info that you've provided, Chris, so I do thank you once again.

[jcdoss]

Thanks Chris! I have the hood and never noticed it was reversible. I just checked and you're 100% correct!

[Kerrowdown]

I have the hood and never noticed it was reversible

Can anyone post a picture of this hood as...

1) I didn't know it even existed.

2) I can't get my head round how it screws on when reversed.

Thanks in advance.

[fwcetus]

Can anyone post a picture of this hood as...

1) I didn't know it even existed.

2) I can't get my head round how it screws on when reversed.

Thanks in advance.

I hope I explained that (sort of) OK...

[Kerrowdown]

I hope I explained that (sort of) OK...

Wow... how cool is that, gonna have to get me one of those, wouldn't happen to have Pentax Part Number? as even Bojidar Dimitrov's page has no mention of such a hood.

[fwcetus]

Wow... how cool is that, gonna have to get me one of those, wouldn't happen to have Pentax Part Number? as even Bojidar Dimitrov's page has no mention of such a hood.

Nothin' but the best for your "Duchess", eh?



I did double-check the part number in an old loose-leaf binder Pentax dealer catalog that I have, and the sticker on the box ~is~ the same as the part number in the catalog.

[Kerrowdown]

Nothin' but the best for your "Duchess", eh?

Thanks very much indeed, I'll get right on the trail of one of these right now.

When the "Duchess" issues a decree nothing else matters.