What is this Pentax 645 accessory?

Looks like it might fit on the eyepiece. But, if so, I can't figure out the purpose. It's marked "Pentax 645". Thanks.

This one looks like the Pentax Eyecup Large http://www.ebay.com/itm/GENUINE-Pentax-Eyecup-Large-for-645-/311434229441

It's an eyecup.

Pentax 645 cameras had two types of eyecups that I knew about. The large "hard" eyecup and a smaller softer one. I tried both and favored the hard eyecup myself.

If you have bought it then the die is cast but if you are considering it then be aware that my experience of it is that it is so flat that I found it allowed sunlight to penetrate around my eye which was distracting. You can shield with your left hand if the sun is on that side but if it is on the right then you need your right hand to press the trigger.

Some soft foam on the outside of the eyepiece might be enough to prevent penetration of the sun. On the other hand Alan Gales has no problem with it so it might be just me who found it uncomfortable to press my eye hard enough against the hard rubber to prevent ingress of sunlight

pentaxuser

I'm not saying that the large eyecup was perfect but the smaller eyecup was uncomfortable to me. They are cheap enough. Try both and see which you like the best.

macfred said:

This one looks like the Pentax Eyecup Large http://www.ebay.com/itm/GENUINE-Pentax-Eyecup-Large-for-645-/311434229441

Click to expand...

Yep, that looks like it. What struck me as odd was that it was flat and hard.

Alan Gales said:

It's an eyecup. Pentax 645 cameras had two types of eyecups that I knew about. The large "hard" eyecup and a smaller softer one. I tried both and favored the hard eyecup myself.

Click to expand...

It would seem to allow you to get your eye close the the finder and to block out light around it. I found this in a box of misc accessories I had. I did have a Pentex 645 a while ago.

Thanks everyone for the info.