645D Anyway to Zoom in to Focus ( MF) to make sure Image is in Focus Before taking i

**rollsman4** · 07-14-2018, 07:23 AM

I am trying to Nail MF when Taking Portraits on the persons eye. Is there any way to do this and not just MF the lens till I think its in Focus? Thank you
I was thinking of buying the Split micro prism to make it easier to focus. I saw one for 100.00 plus 16 shipping Not sure if it will do what I want. Thanks Dennis

Adam · 07-14-2018, 01:48 PM

Originally posted by rollsman4

I am trying to Nail MF when Taking Portraits on the persons eye. Is there any way to do this and not just MF the lens till I think its in Focus? Thank you
I was thinking of buying the Split micro prism to make it easier to focus. I saw one for 100.00 plus 16 shipping Not sure if it will do what I want. Thanks Dennis

The 645D has no live view, so you're limited to focusing screens/magnifiers. Things got a lot easier on the 645Z, which does support live view, magnification, and so on.

abruzzi · 07-14-2018, 06:36 PM

In the movie/video world many zoom lenses are parfocal lenses, meaning the focus doesn’t change when zooming. In that world it was common to zoom in to the longest focal length so you can focus, then zooming back out to frame your shot. I don’t know if any of the 645 zoom lenses could work that way.

**pentaxus** · 07-14-2018, 11:04 PM

645 zooms are parfocal. If I were taking portraits, however, I would use the 150mm lens which is not a zoom. The zooms are slow enough that they might be harder to focus anyway and some people might find the 80-160 lens intimidating.

moroccanimager · 07-15-2018, 03:24 AM

I can only speak for working with the 645Z. It's very difficult even using live view and magnification as the subject can often slight shift their position. Working at f2.8 on the 75mm gives a DOF of about 1cm so focus is critical and not possible without the live view, etc. When I have tried to focus through the viewfinder, the results have been poor. I think one option is to stop down to about f10 which gives you about 4cm DOF. This also allows for both eyes to be sharp if the subject is turned slightly. Of course the background will come into play more so you would need to think about that. The link below has been useful.

DOF simulator - Camera depth of field calculator with visual background blur and bokeh simulation.

**rollsman4** · 07-15-2018, 07:43 AM

I appreciate the responses. I just ordered the AA-82 Microprism for the D I hope this will help with my focusing.
Thank you

johnha · 07-15-2018, 02:47 PM

With my P67, I found the viewfinder magnifier really helps (although clunky to use) when using my split-image only screen when the subject doesn't suit the split-image (I much prefer the micro-prism screen). The 645 magnifier seems really expensive though by comparison.

**rdenney** · 07-15-2018, 08:26 PM - **1 Like**

Originally posted by rollsman4

I appreciate the responses. I just ordered the AA-82 Microprism for the D I hope this will help with my focusing.

Thank you

I have found I can focus very accurately with the microprism screen on my 645z.

Rick “more accurate than focus confirmation” Denney

Bob L · 07-16-2018, 12:49 AM

Are the replacement screens typically accurate as a simple "in/out" procedure?. I ask as I've occasionally had to shim the screens on Canon bodiies.

Bob

Sandy Hancock · 07-16-2018, 01:06 AM

Originally posted by rdenney

I have found I can focus very accurately with the microprism screen on my 645z.

I've also had good results just focussing through the viewfinder. Getting the right dioptre correction on the eyepiece is crucial of course.

moroccanimager · 07-16-2018, 02:36 AM

A couple of points spring to mind. Do correct me if I'm wrong. Does the AA-82 Microprism not have a central circle that splits. How would that work if your subject's eyes are not in the centre? Also it's very much miss if you attempt to get sharp images on the eyes with a wide open aperture by just using the viewfinder and standard screen.

**rdenney** · 07-16-2018, 03:34 PM - **1 Like**

Originally posted by Bob L

Are the replacement screens typically accurate as a simple "in/out" procedure?. I ask as I've occasionally had to shim the screens on Canon bodiies.

Bob

Simple install. But I’ve never had to do anything with my Canon bodies, either, and I have a Maxwell screen in my 5D.

Rick “Soviet cameras are a different matter” Denney

---------- Post added 07-16-18 at 03:40 PM ----------

Originally posted by Sandy Hancock

I've also had good results just focussing through the viewfinder. Getting the right dioptre correction on the eyepiece is crucial of course.

On my 645z, the eyepiece is focusable. I think it is on my 645N and NII, also, so I would be surprised if the D is not.

Rick “focus the lines on the screen sharply, then focus the camera” Denney

johnha · 07-16-2018, 04:24 PM

Originally posted by rdenney

On my 645z, the eyepiece is focusable. I think it is on my 645N and NII, also, so I would be surprised if the D is not.

Rick “focus the lines on the screen sharply, then focus the camera” Denney

Yup, the D has dioptre correction from -3.5 to +2. I find the screen on the D is bright enough to use the ground glass for focussing - if shooting quickly it's easier than trying to chase the focus confirmation indicator while framing.

07-14-2018, 07:23 AM	#1
rollsman4 Site Supporter Join Date: Nov 2014 Posts: 459	645D Anyway to Zoom in to Focus ( MF) to make sure Image is in Focus Before taking i I am trying to Nail MF when Taking Portraits on the persons eye. Is there any way to do this and not just MF the lens till I think its in Focus? Thank you I was thinking of buying the Split micro prism to make it easier to focus. I saw one for 100.00 plus 16 shipping Not sure if it will do what I want. Thanks Dennis

07-14-2018, 01:48 PM	#2
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,595	Originally posted by rollsman4 I am trying to Nail MF when Taking Portraits on the persons eye. Is there any way to do this and not just MF the lens till I think its in Focus? Thank you I was thinking of buying the Split micro prism to make it easier to focus. I saw one for 100.00 plus 16 shipping Not sure if it will do what I want. Thanks Dennis The 645D has no live view, so you're limited to focusing screens/magnifiers. Things got a lot easier on the 645Z, which does support live view, magnification, and so on. Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

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07-14-2018, 06:36 PM	#3
abruzzi Veteran Member Join Date: Apr 2017 Location: New Mexico Posts: 788	In the movie/video world many zoom lenses are parfocal lenses, meaning the focus doesn’t change when zooming. In that world it was common to zoom in to the longest focal length so you can focus, then zooming back out to frame your shot. I don’t know if any of the 645 zoom lenses could work that way.

07-14-2018, 11:04 PM	#4
pentaxus Site Supporter Join Date: Jun 2010 Location: Central Coast, CA Posts: 1,313	645 zooms are parfocal. If I were taking portraits, however, I would use the 150mm lens which is not a zoom. The zooms are slow enough that they might be harder to focus anyway and some people might find the 80-160 lens intimidating.

07-15-2018, 03:24 AM	#5
moroccanimager Junior Member Join Date: Jul 2016 Location: Morocco Posts: 47	I can only speak for working with the 645Z. It's very difficult even using live view and magnification as the subject can often slight shift their position. Working at f2.8 on the 75mm gives a DOF of about 1cm so focus is critical and not possible without the live view, etc. When I have tried to focus through the viewfinder, the results have been poor. I think one option is to stop down to about f10 which gives you about 4cm DOF. This also allows for both eyes to be sharp if the subject is turned slightly. Of course the background will come into play more so you would need to think about that. The link below has been useful. DOF simulator - Camera depth of field calculator with visual background blur and bokeh simulation.

07-15-2018, 07:43 AM	#6
rollsman4 Site Supporter Join Date: Nov 2014 Posts: 459 Original Poster	I appreciate the responses. I just ordered the AA-82 Microprism for the D I hope this will help with my focusing. Thank you

07-15-2018, 02:47 PM	#7
johnha Veteran Member Join Date: Apr 2012 Location: Lancashire, UK Photos: Albums Posts: 1,155	With my P67, I found the viewfinder magnifier really helps (although clunky to use) when using my split-image only screen when the subject doesn't suit the split-image (I much prefer the micro-prism screen). The 645 magnifier seems really expensive though by comparison.

07-15-2018, 08:26 PM - 1 Like	#8
rdenney Site Supporter Join Date: Feb 2018 Location: NoVA Posts: 635	Originally posted by rollsman4 I appreciate the responses. I just ordered the AA-82 Microprism for the D I hope this will help with my focusing. Thank you I have found I can focus very accurately with the microprism screen on my 645z. Rick “more accurate than focus confirmation” Denney

07-16-2018, 12:49 AM	#9
Bob L Senior Member Join Date: Mar 2016 Location: La Vienne (86), France Posts: 223	Are the replacement screens typically accurate as a simple "in/out" procedure?. I ask as I've occasionally had to shim the screens on Canon bodiies. Bob

07-16-2018, 01:06 AM	#10
Sandy Hancock Moderator Site Supporter Join Date: Feb 2012 Location: Adelaide Hills, South Australia Photos: Gallery \| Albums Posts: 11,272	Originally posted by rdenney I have found I can focus very accurately with the microprism screen on my 645z. I've also had good results just focussing through the viewfinder. Getting the right dioptre correction on the eyepiece is crucial of course.

07-16-2018, 02:36 AM	#11
moroccanimager Junior Member Join Date: Jul 2016 Location: Morocco Posts: 47	A couple of points spring to mind. Do correct me if I'm wrong. Does the AA-82 Microprism not have a central circle that splits. How would that work if your subject's eyes are not in the centre? Also it's very much miss if you attempt to get sharp images on the eyes with a wide open aperture by just using the viewfinder and standard screen.

07-16-2018, 03:34 PM - 1 Like	#12
rdenney Site Supporter Join Date: Feb 2018 Location: NoVA Posts: 635	Originally posted by Bob L Are the replacement screens typically accurate as a simple "in/out" procedure?. I ask as I've occasionally had to shim the screens on Canon bodiies. Bob Simple install. But I’ve never had to do anything with my Canon bodies, either, and I have a Maxwell screen in my 5D. Rick “Soviet cameras are a different matter” Denney ---------- Post added 07-16-18 at 03:40 PM ---------- Originally posted by Sandy Hancock I've also had good results just focussing through the viewfinder. Getting the right dioptre correction on the eyepiece is crucial of course. On my 645z, the eyepiece is focusable. I think it is on my 645N and NII, also, so I would be surprised if the D is not. Rick “focus the lines on the screen sharply, then focus the camera” Denney

07-16-2018, 04:24 PM	#13
johnha Veteran Member Join Date: Apr 2012 Location: Lancashire, UK Photos: Albums Posts: 1,155	Originally posted by rdenney On my 645z, the eyepiece is focusable. I think it is on my 645N and NII, also, so I would be surprised if the D is not. Rick “focus the lines on the screen sharply, then focus the camera” Denney Yup, the D has dioptre correction from -3.5 to +2. I find the screen on the D is bright enough to use the ground glass for focussing - if shooting quickly it's easier than trying to chase the focus confirmation indicator while framing.