Hoya HMC HD2 Questions

[MIB]

Thinking of trying one of these as my Planar 7010 from 7' projecting a 65" image is very bright - the whites are a little overpowering.

Is this the right filter?

Hoya 72mm HMC NDX2 (744) - Warehouse Express

The Planar isn't threaded so I assume I'd have to go for a slightly larger filter and secure with blu-tack? The lens measures 72mm so would I be best going for the 77mm or could I go for a smaller (and cheaper) filter and secure inside the lens housing, or would that interfere with the light path?

[jacko5]

Originally Posted by MIB

Thinking of trying one of these as my Planar 7010 from 7' projecting a 65" image is very bright - the whites are a little overpowering.

Is this the right filter?

Hoya 72mm HMC NDX2 (744) - Warehouse Express

The Planar isn't threaded so I assume I'd have to go for a slightly larger filter and secure with blu-tack? The lens measures 72mm so would I be best going for the 77mm or could I go for a smaller (and cheaper) filter and secure inside the lens housing, or would that interfere with the light path?

Yes, that is the quality of filter to use. I would go for a smaller one, preferably one which is slightly smaller than the rim diameter so that it can be fitted snugly inside. Quite often the glass lens is quite a bit smaller than the barrel housing it so it can be quite a bit smaller than the rim size without obstructing the full image. It,s just a question of the easiest way of securing it.
Remember that although the ND2 cuts the light output by half, the eye/brain perceives it as a roughly 20% reduction. So if your image is really bright you may need an ND4 filter to start with and perhaps go down to an ND2 when the lamp has a few hundred hours on it.

[MIB]

Thanks Jacko

The rim measures approx 67mm on the inside so would you recommend the 58 or 62 filter. Are the Hoya filters wider than the stated size, ie is a 58 actually 60+mm?

Looking on projector central the light output on my setup is very high so the ND4 might be the best option. Is their any downsides to the ND4?

[jacko5]

Originally Posted by MIB

Thanks Jacko

The rim measures approx 67mm on the inside so would you recommend the 58 or 62 filter. Are the Hoya filters wider than the stated size, ie is a 58 actually 60+mm?

Looking on projector central the light output on my setup is very high so the ND4 might be the best option. Is their any downsides to the ND4?

The size is the actual thread diameter, so I would use the 62mm which will give you a 2.5mm gap to fill all round. Four little beads of BluTak should do the trick. The ND4 will improve your black levels but at the same time will tame down your whites, which after all is what you want to achieve.
Filters are said to reduce the ansi contrast, but I didn't have any complaints using an ND2 on my PJ.

PS Kelvin S1965 uses an ND4 filter, I am sure he will advise you if you send him a PM.

[MIB]

Originally Posted by jacko5

The size is the actual thread diameter, so I would use the 62mm which will give you a 2.5mm gap to fill all round. Four little beads of BluTak should do the trick.

Sorry if I am being thick but if the thread is 62mm then isn't there some extra material which the thread is cut into making the outside diameter greater than 62mm? Wouldn't want to get the 62mm to find it didn't fit.

[DrugstoreCowboy]

Buy a couple of cheap filters first and test, you may find an ND4 more suitable.

My 68" screen benefited more from an ND4.

[KelvinS1965]

Originally Posted by jacko5

PS Kelvin S1965 uses an ND4 filter, I am sure he will advise you if you send him a PM.

I've been using an ND4 filter in combination with a high gain screen (1.8) as I'd bought the screen before getting the PJ. I've had to really improve my room with regard to reflections and light walls, by using lots of black cloth & velvet that can be taken down afterwards (it's our living room), but the filter helps give blacks that I'm happy with. I think that I'll be changing over to the ND2 filter soon though as I think the initial brightness of my lamp has settled down (at 200 hours approx).

Some say about ND filters reducing contrast, but I tried comparing a paused dark scene and held the filter in front of my eye rather than have it on the PJ (same effective brightness hitting my eye). This should have taken the contrast reducing effect out of the equation due to the light being partly reflected back into the PJ, but TBH I couldn't see any improvement. Just make sure that you buy a good brand once you've tested out a cheap one as the resin type created halos and other strange effects on my PJ. I use the Hoya HMC type as in your subject header.

There is another thread that suggests there is a 'right' way round to use these filters incase the antireflection coating is only on one side, but I've looked at mine outside in bright sunlight and any reflection on the filter surface seems equal to me. I will try it 'the other way round' next film night though, just incase.

EDIT: The one in your first post is exaclty the type I have....but they've gone up a bit in price since last year.

[MIB]

Originally Posted by KelvinS1965

I've been using an ND4 filter in combination with a high gain screen (1.8) as I'd bought the screen before getting the PJ. I've had to really improve my room with regard to reflections and light walls, by using lots of black cloth & velvet that can be taken down afterwards (it's our living room), but the filter helps give blacks that I'm happy with. I think that I'll be changing over to the ND2 filter soon though as I think the initial brightness of my lamp has settled down (at 200 hours approx).

Some say about ND filters reducing contrast, but I tried comparing a paused dark scene and held the filter in front of my eye rather than have it on the PJ (same effective brightness hitting my eye). This should have taken the contrast reducing effect out of the equation due to the light being partly reflected back into the PJ, but TBH I couldn't see any improvement. Just make sure that you buy a good brand once you've tested out a cheap one as the resin type created halos and other strange effects on my PJ. I use the Hoya HMC type as in your subject header.

There is another thread that suggests there is a 'right' way round to use these filters incase the antireflection coating is only on one side, but I've looked at mine outside in bright sunlight and any reflection on the filter surface seems equal to me. I will try it 'the other way round' next film night though, just incase.

EDIT: The one in your first post is exaclty the type I have....but they've gone up a bit in price since last year.

Thanks for the advise

Don't really want to pay out for 2 filters so think I'll go for the HMC ND2 62mm, cheaper than the 77mm but still £31 inc P&P

Hoya 62mm HMC NDX4 (717) - Warehouse Express

[jacko5]

Originally Posted by MIB

Sorry if I am being thick but if the thread is 62mm then isn't there some extra material which the thread is cut into making the outside diameter greater than 62mm? Wouldn't want to get the 62mm to find it didn't fit.

The diameter of the threaded part is 62mm and the overall diameter is 64mm appx.
I am not familiar with the lens setup on your PJ. Have a look at it and measure up and decide how you will fit the filter to it. Remember that most PJs don't have a threaded lens barrel so there is no such thing as an exact fit. Decide if it is easier to fit it, by using BluTak or tape, just inside the front edge of the lens housing, or deeper into the barrel if the glass lens is deeper inside. Whichever you consider most convenient. Then decide which size of filter to get.

[MIB]

Originally Posted by jacko5

The diameter of the threaded part is 62mm and the overall diameter is 64mm appx.
I am not familiar with the lens setup on your PJ. Have a look at it and measure up and decide how you will fit the filter to it. Remember that most PJs don't have a threaded lens barrel so there is no such thing as an exact fit. Decide if it is easier to fit it, by using BluTak or tape, just inside the front edge of the lens housing, or deeper into the barrel if the glass lens is deeper inside. Whichever you consider most convenient. Then decide which size of filter to get.

Thanks Jacko

The inside measure of the barrel is approx 67mm so the 64mm should fit snug inside with a bit of blu-tac. No thread on my Planar.

Now need to read the 'Which way round thread' so I hopefully know what to do with it

[MIB]

Filter arrived and fits snug inside the barrel with a few blobs of blutac. Very happy with the improvements, the fierce white's have been tamed