Just got a Minolta f8 500mm reflex, and...

Started 2 months ago | Discussions
Tim Crammond Contributing Member • Posts: 835
Just got a Minolta f8 500mm reflex, and...

...and naturally it has the ND filter, but not the 'clear' one.

I don't see any likely way of getting this part at a not utterly insane price, so can I just tape over the drop-in filter slot, or is the clear filter required for exact focus?  It was overcast today and hard to get enough light to really test it, but it it seemed to be producing more or less in focus images handheld, albeit at very high ISO and shutter speeds (it's a bit hard to imagine it being so bright that you'd need the ND filter at f8 500mm!)

Tim

steelhead3 Veteran Member • Posts: 7,465
Re: Just got a Minolta f8 500mm reflex, and...

You can tape the hole with little penalty.  The ND filter works to increase DOF which is quite narrow on the reflex at f8.

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lehill
lehill Veteran Member • Posts: 4,215
Re: Just got a Minolta f8 500mm reflex, and...

Discussed several times here in the past:
https://www.dpreview.com/forums/post/52640367

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Lance H

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Lensmate
Lensmate Senior Member • Posts: 2,690
Re: Just got a Minolta f8 500mm reflex, and...

Tim Crammond wrote:

...and naturally it has the ND filter, but not the 'clear' one.

I don't see any likely way of getting this part at a not utterly insane price, so can I just tape over the drop-in filter slot, or is the clear filter required for exact focus? It was overcast today and hard to get enough light to really test it, but it it seemed to be producing more or less in focus images handheld, albeit at very high ISO and shutter speeds (it's a bit hard to imagine it being so bright that you'd need the ND filter at f8 500mm!)

Tim

If you are shooting bright sunsets, then the ND filter is needed. But the majority of the time, you will not need it. My clear filter would pop off constantly, and there would be times I would take it out so as to not lose it in the field, and found that there was no difference shooting without it. Keep it covered with tape to keep dust out [or creepy-crawlies]

-Martin P

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OP Tim Crammond Contributing Member • Posts: 835
Re: Just got a Minolta f8 500mm reflex, and...

lehill wrote:

Discussed several times here in the past:
https://www.dpreview.com/forums/post/52640367

Thanks; found a thread, but not that one.

Ralf B
Ralf B Veteran Member • Posts: 8,240
@ steelhead: yes, no, yes but...
4

steelhead3 wrote:

You can tape the hole with little penalty.

Yes.

The ND filter works to increase DOF

No.

which is quite narrow on the reflex at f8.

yes, but ... the ND filter does not change that.
Cheers,
Ralf

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steelhead3 Veteran Member • Posts: 7,465
Re: @ steelhead: yes, no, yes but...

You don't think f16 has a greater DOF than f8?

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Ralf B
Ralf B Veteran Member • Posts: 8,240
Re: @ steelhead: ND filter does not give f 16
6

steelhead3 wrote:

You don't think f16 has a greater DOF than f8?

Of course stopping a lens down by a variable aperture does that just fine.

The DOF is fixed in the lens discussed here as it lacks a variable aperture. As far as I know, that applies to any mirror lens. The ND filter in the Minolta / SAL 500/8 mirror lens does not act like a variable aperture. It can't. It just adds two stops but not by stopping the lens down, only by being darker than the clear filter (or air gap in the light path in case that clear filter is missing as in the OP's case).

Cheers,
Ralf

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steelhead3 Veteran Member • Posts: 7,465
Re: @ steelhead: ND filter does not give f 16

I guess the directions that came with mine about using the ND filter to get to f16 is wrong then.

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Ralf B
Ralf B Veteran Member • Posts: 8,240
Re: @ steelhead: ND filter does not give f 16
1

steelhead3 wrote:

I guess the directions that came with mine about using the ND filter to get to f16 is wrong then.

Did those directions discuss DOF at all? I am sure they discussed exposure. Some more info then:

The ND filter changes the light transmission or T-Stop, but not the F-Stop (or aperture): The aperture is calculated by the ratio of focal length and aperture opening diameter. The ND filter does not change the diameter where it is installed, it has the same diameter as the clear filter. No diameter change - no change in DOF.

A useful link says basically the same:

Quote: The mirror design does not utilize aperture blades, and thus the aperture of the lens is fixed at f/8. Exposure may only be controlled by shutter speed, film or sensor sensitivity, or a rear-mounted neutral density filter.

Cheers,
Ralf

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steelhead3 Veteran Member • Posts: 7,465
Re: @ steelhead: ND filter does not give f 16

You are probably right Ralf...for fun I will test it out today.  I have never used that ND filter except in my 300 f2.8.

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sybersitizen Forum Pro • Posts: 10,863
Re: @ steelhead: ND filter does not give f 16
4

steelhead3 wrote:

You are probably right Ralf...for fun I will test it out today. I have never used that ND filter except in my 300 f2.8.

Ralf is definitely right. ND filters reduce the light intensity. They do not change DOF. Physical aperture changes do that.

Michael Fritzen Veteran Member • Posts: 5,652
Re: @ steelhead: ND filter does not give f 16

steelhead3 wrote:

You are probably right Ralf...for fun I will test it out today. I have never used that ND filter except in my 300 f2.8.

Exactly. On such a fast aperture lens using ND filter allows increasing the exposure time at the same time at the shallow DOF of the fast aperture is kept.

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Cheers,
Michael Fritzen

steelhead3 Veteran Member • Posts: 7,465
Re: @ steelhead: ND filter does not give f 16
1

Just tested...Ralf is right, exposure just changed.  I had that dof thought ever since I bought this lens but had no reason to go to f16 so really never thought it through.  Learn something new keeps the mind working.

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lehill
lehill Veteran Member • Posts: 4,215
Re: @ steelhead: ND filter does not give f 16
1

steelhead3 wrote:

Just tested...Ralf is right, exposure just changed. I had that dof thought ever since I bought this lens but had no reason to go to f16 so really never thought it through. Learn something new keeps the mind working.

You can blame the instructions. It may be that Sony updated the Minolta instructions to unconfuse users and included the last line (italics mine):

"The lens itself has no aperture adjustment.

To adjust the amount of light, attach the supplied normal filter or ND4X filter.

The plug-in filters are component parts of the optical system. Be sure to attached either the normal filter or the ND4X filter when taking pictures.

Use the normal filter generally. When you shoot a bright subject or when you want to slow down the shutter speed, attach the ND4X filter (the amount of light is reduced by 2 stops, which is equivalent to f/16).

• The depth-of field is not affected by attaching the ND4X filter." <- Maybe Sony added this line, it's the only line with a bullet.

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Lance H

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sybersitizen Forum Pro • Posts: 10,863
Re: @ steelhead: ND filter does not give f 16
2

lehill wrote:

steelhead3 wrote:

I guess the directions that came with mine about using the ND filter to get to f16 is wrong then.

You have a document from Minolta that mentions f/16?

Just tested...Ralf is right, exposure just changed. I had that dof thought ever since I bought this lens but had no reason to go to f16 so really never thought it through. Learn something new keeps the mind working.

You can blame the instructions.

I don't see a mention of f/16 or DOF in Minolta's user manual. Only one lens stop is listed in the specs. It's a filter! One would have to infer something that is not there to think the aperture or DOF gets changed:

In case anyone wants to point out the part about the clear filter being an integral part of the optical design, I refer readers again to a detailed explanation about why that text exists and why it can be ignored in this case.

It may be that Sony updated the Minolta instructions to unconfuse users and included the last line (italics mine):

"The lens itself has no aperture adjustment.

To adjust the amount of light, attach the supplied normal filter or ND4X filter.

The plug-in filters are component parts of the optical system. Be sure to attached either the normal filter or the ND4X filter when taking pictures.

Use the normal filter generally. When you shoot a bright subject or when you want to slow down the shutter speed, attach the ND4X filter (the amount of light is reduced by 2 stops, which is equivalent to f/16).

So that's where the f/16 came from! It's equivalent.

• The depth-of field is not affected by attaching the ND4X filter." <- Maybe Sony added this line, it's the only line with a bullet.

Hopefully that would eliminate any erroneous inferences.

Lensmate
Lensmate Senior Member • Posts: 2,690
Re: @ steelhead: ND filter does not give f 16

sybersitizen wrote:

lehill wrote:

steelhead3 wrote:

I guess the directions that came with mine about using the ND filter to get to f16 is wrong then.

You have a document from Minolta that mentions f/16?

Just tested...Ralf is right, exposure just changed. I had that dof thought ever since I bought this lens but had no reason to go to f16 so really never thought it through. Learn something new keeps the mind working.

You can blame the instructions.

I don't see a mention of f/16 or DOF in Minolta's user manual. Only one lens stop is listed in the specs. It's a filter! One would have to infer something that is not there to think the aperture or DOF gets changed:

In case anyone wants to point out the part about the clear filter being an integral part of the optical design, I refer readers again to a detailed explanation about why that text exists and why it can be ignored in this case.

It may be that Sony updated the Minolta instructions to unconfuse users and included the last line (italics mine):

"The lens itself has no aperture adjustment.

To adjust the amount of light, attach the supplied normal filter or ND4X filter.

The plug-in filters are component parts of the optical system. Be sure to attached either the normal filter or the ND4X filter when taking pictures.

Use the normal filter generally. When you shoot a bright subject or when you want to slow down the shutter speed, attach the ND4X filter (the amount of light is reduced by 2 stops, which is equivalent to f/16).

So that's where the f/16 came from! It's equivalent.

• The depth-of field is not affected by attaching the ND4X filter." <- Maybe Sony added this line, it's the only line with a bullet.

Hopefully that would eliminate any erroneous inferences.

Good sleuthing!

-Martin P

https://www.flickr.com/photos/photosauraus_rex/

Steve West Veteran Member • Posts: 5,933
Re: Just got a Minolta f8 500mm reflex, and...

I do love this lens. In fact, it was this lens that convinced me to go with the minolta 7d system. I still love using it to this day with the A99 and A99ii. However, the IQ (and bokeh!) from the 70-400 is considerably better.  The lens is capable of very creamy bokeh if there are no high contrasts in the background. The lens is super light and the AF is very fast. BIF are a hoot with it.

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OP Tim Crammond Contributing Member • Posts: 835
Re: Just got a Minolta f8 500mm reflex, and...

Main issue I'm seeing (and again it was overcast today) is very narrow DOF, even at considerable distances.

Heh - sensor dust shows up as onion rings

Tim

QuietOC
QuietOC Senior Member • Posts: 2,318
Re: Just got a Minolta f8 500mm reflex, and...

Tim Crammond wrote:

Main issue I'm seeing (and again it was overcast today) is very narrow DOF, even at considerable distances.

Yes, I have the Sigma 600mm F8, and I've tried Samyang 800mm F8's. It makes me wonder how useful long F2.8 lenses are really for example the Sigma 200-500mm F2.8.

It seems like F5.6 for the AF sensors is plenty. The new Sony FE 400mm F2.8 doesn't make much sense to me. None of the E-mount cameras have even a single F2.8 AF sensor. Though it does seem like the on-sensor AF points somehow benefit from brighter lenses while dedicated AF sensors mostly do not.

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