Thinking about your suggestion, George, you are so right.
Even with the tripod locked down hard I find when manually focusing on my bird feeders with my finger on the button half pressed, that as soon as I take my hand from the camera the focus moves. It is a minute movement but just enough to make a difference.
I suspect that, with a lens collar, or mount, set so the balance of the set up is mid distance, that this small movemeent would be eliminated.

Will go talk to my clever friend and see if he can adapt the set up.
Will post any results.

regards Thoramay.

Thaanks for the link, George. I had read this before but my memory failed when trying to recall where. A lot of interesting info and I do have a friend that is capaable of producing a good copy.

Thoramay.

I am hovering on a decision. However, I recall reading one of the many forums regarding using 6x7 on 35mm that the effective range of the lens is halved. Now, I could have read it wrong. Does a 300mm on 35mm become only 150mm?

I don't want to plunge and discover it is not what I expected. Can anyone help me with this, please.

regards thoramay.

I fgear I might just have this problem. Can it be cleaned professionally or is it a loss?

regards Thoramay

Thanks for the comeback. I guess there are purists that check the performance of a lens using a banknote, but am I being obstinate in thinking that there is little reference between a banknote and a wildlife shot. Unless it is cast in concrete or dead, there will always be an element of movement and a greater depth of field to consider.

I have been snapping the birds at my feeder for seveal years and been disappointed with the results using my Tamron 75-300. It could be me or it could be the lens but the results using the medium format lens is far better than previously. Maybe not to the staandard of the best snappers but they satisfy me, for the moment. You can be a judge when I post to the Gallery in the morning.

I guess, as always, that is down to the individual. We all see things differently and are satisfied in many different ways.

I shall continue to trial the medium format on my K10. I shall continue to search for the elusive 300 4.5. As my dad always told me. It is not the winning that you should enjoy the most. It is the chase itself.

regards thoramay

Algi. I have failed to upload a pic on here. I have resorted to placing it in the Gallery.

The pic is of a clemetis flower taken with a Mamiya 150mm lens on my K10.
I have also tried a 2x and my 1.7 converter behind this lens. Will upload one of these on the gallery tommorow.

I thought you might be interested in how successful it can be using medium lens of the dslr's

I still want to go the Pentax route. I cannot decide between the 165 or the 300 6x7 lens.

regards Thoramay.

Hi, John. I have read somewhere that Cannon made a tripod collar that will fit the 300 but I cannot find it again.

My other concern with this 300mm is the close focus ability. The Sigma does look to be the better bet in this respect. I have a bird feeding area that is close to the house and will require a lens with a close focusing ability.

Again, so much to think about.

regards thoramay.

Hi, Algi. I am also following these threads. Those pics are real stunners. There are more stunning pics with this set up in the '300mm plus' thread on this site. There are, of course 300mm 6x7 lens and the '300mm plus' thread has results from using these on dslr's.

My reservation is not actually being able to compare the set up. 6x7 lens in my living area are just not found. I have no comprehension of relevant size difference between the Pentax 300mm and 6x7 lens.

I have tried using a Mamiya lens via an adapter and this has proved interesting. I have a borrowed 150mm lens. There is also a 500mm lens available. I shall have to twist arms to try that out.

regards thoramay

Thanks for the offer, John. The K300 is the one without a tripod mount. I have very shaky hands now and would need a lens with a tripod mount ability.

I have read considerably the cons and pros of the 6x7 adaption and have also seen some stunning pics taken with this combo.

Those that have gone this route mostly already have 6x7 lens and so it is a means to put these lens to use. There are issues using centre weighted and issues with incorrect metering which kinda stops me in my tracks.

Maybe my thinking in using the 1.7 converter on a 300mm is flawed and a 400mm then being a better bet which then possibly makes the converter redundant.

Just how close I could focus with a 400mm is another issue to resolve.

Lots to think about. I do appreciate your input. Thanks.

regards thoramay.

It is all very tempting, but.... I would still like to stay Pentax. It's a loyalty thing.

Also, still contemplating adapting to the 6x7 system. Adapter plus 300 lens for little over £300. I have raised this before and had a mixed reaction, yet might just do it for the hell of it. Guess a 300 F4.5 will become available as soon as I go the other route.

Any thoughts!!!

regards thoramay