Having a few issues with a rare variant of Pentax 645 I just got

Hey guys,

So I just received an excellent condition Pentax 645 I got off of eBay and I already seem to be struggling with it, that or it has a few issues with it that I'm not aware of.

I bought the original 645 instead of the 645n because of a better manual focus screen with split image, microprism and matte. Unfortunately the screen in mine has been switched out with a matte only one which is very frustrating because it didn't mention this in the listing and I can't find an original one anywhere, there's only a super expensive one from Italy on eBay right now. Not a huge deal though, this is a problem I at least know how to fix.

First thing I did was sit down and read the whole manual to get a grasp on the camera. Second strange thing I noticed about the camera is that in the manual it shows the dial on the back left as a S/C switch, but mine is an EF compensation wheel. I searched everywhere on the internet and only found one person mention anything about this, just that it is a rare factory custom feature for chrome shooters who wanted EF steps more precise than 1 and didn't mind giving up S/C mode. No big deal, I don't mind missing out on S/C for a more accurate EF compensation. However now that there are two ways to change EF on the camera I'm not sure if one overrides the other or if they add together, any ideas?

Upon putting batteries in the camera grip the LCD display turned on without even switching the camera on and it always remains active even when the camera switch is set to off. Is this normal? I understand there is also an internal battery but I'm not sure what the different battery sources power.

My biggest problem so far has been trying to get the camera to just get into manual mode. The modes go from B to 60 (which I assume is 1/60 shutter no battery required). From there with the mode button held down it goes to M 8 (no clue what this means) but when I release the mode button it changes to M 1000. Then the next Mode is auto but upon releasing the mode button it turns back to M 1000 which makes sense because I don't think you can go into Auto mode without film inserted. So this makes me think M 1000 is Manual mode with a shutter set to 1000, however, I can't figure out how to change the shutter at all, the up and down arrows don't change the number at all no matter what I do. Also I was under the impression that the viewfinder displays shutter speed and EV value when in manual mode, while mine does show 1000 as the shutter speed it displays an aperture of F16 no matter what aperture the lens is actually set at with no EV value in sight. Any ideas?

I'm still playing with the camera and trying to figure it out but any help would be greatly appreciated. I hope there's something very obvious that I'm missing because I'd rather not have to go through the hassle of returning the package.

Thanks in advance.

I don't have this camera and never even "played" with it at a shop, but I can read a manual.
You didn't read the manual properly.
Read again a few times, but pay attention to what you missed like the bottom of page 33 or pages 42 and 43.
I'll suggest you use a used film roll, just using the paper to practice.

Alright sorry for wasting everyones time, this can be deleted.

Nah, you didn't.
I now know how the Pentax 645 works. I wouldn't have read its manual if it wasn't for this thread.

Yes, re-reading the manual should answer your mode questions.

With AA batteries in the camera and no film, the top LCD is always on, even with the power switch off, and reads M1000. With an empty film holder, holding the Mode button only allows you to toggle to the different modes. For manual modes, make sure the lens is not set to A. With film or with a rear body cap attached, you hold down the Mode button to get into a Mode and then with the Mode button released you can change the settings within that Mode.

The lithium battery (CR1220) is a backup battery so you don't lose settings if the main (AA) batteries die when shooting; it preserves the film count, ISO, mode, etc. The manual says this battery should be replaced every 5 years by Pentax but you can replace it yourself. A pair of snap ring pliers (that have pointy tips) can be used to remove the small circular battery cover on the bottom of the camera. Do this when you know the AA batteries are good. It would be worth removing it and replacing it; or you could check the voltage and continue to use it if it's at full voltage. In my experience, the battery has been at full voltage well past 5 years.

If the EF wheel provides finer exposure compensation (1/3 or 1/2 stop) I would think this is what you would use and not the EF button.

Good luck. I've used mine for 10 years now and I think they're great cameras and lenses.

Thanks for the info mklw, I think I'll replace the lithium just to be safe. I'm really excited to start using this camera it seems like a lot of fun to use.

I think my oversight with the modes was thinking the film cartridge would act the same as the rear body cap, and I just panicked when the camera wasn't working when I thought it absolutely should be.

After playing around with the camera some more I figured out that both the EF wheel and EF buttons can be used separately or together. The wheel is only 0 to +-.5 and +-1 so really just for fine tuning I suppose.

I do have one more issue with the camera though

I've been playing with the diopter to try and get the perfect setting. I read a good way to set the diopter is to point the camera out of focus at a flat bright subject and to turn it until the circle on the focusing screen is sharpest. So I did this (with my matte-only screen) and it seems to never get quite perfectly sharp but it seems like it gets very close on one end. I also noticed a slight split-image thing happening on the perimeter of the central circle, is this normal? It never changes while I shift the focus, it looks just slightly split. I'm not sure if this central circle is slightly magnified or not, I can't easily tell.

I also tried just setting the camera to infinity and setting the diopter that way but things at infinity did not appear to be perfectly in focus at any point. Is it possible that because the screen has been switched out on my camera the new one might not have been properly installed? Could it possibly not be inserted back in all the way or maybe upside down? Tomorrow I'm going to check it out but I see you need some special tweezers to take the screen out. Will any tweezers do?

Thanks again.

I use 1/3 stop exposure compensation by changing the ISO. But you have to remember to set it back to your film speed when not needed because there's no indication in the viewfinder like there is when using EF.

For diopter adjustment, I simply rotate the diopter control until the viewfinder outside the center focus circle is in focus. I don't consider the center focus circle in doing this. For me, no + or - is needed. As I shoot, sometimes the diopter control shifts a little towards - and I have to adjust it to zero again (no big deal). The viewfinder focusing circle has always been sharp so maybe you do have a screen issue; unfortunately, I cannot advise on what to use to check or remove/replace the screen as I've never had to deal with that. Maybe do a search or ask the question here on APUG, photo.net, or pentaxuser.com.