[Clinton]

Greetings all, I'm wondering if anyone can help me with this puzzle.

I picked up a Pentax Reflex 1000mm, and I'm wondering if a filter can in fact be mounted to the threads on the front of it.

Bojidar Dimitrov's site says it has no threads: K 1000/11 Reflex

However looking at the front of the lens, it has threads and they measure to be around 105mm. I'd love to pick up a uv protective filter to keep this lens in pristine condition, but I don't want to take a stab in the dark and be wrong...

Does anyone have more info they could share?

[rfortson]

Greetings all, I'm wondering if anyone can help me with this puzzle.

I picked up a Pentax Reflex 1000mm, and I'm wondering if a filter can in fact be mounted to the threads on the front of it.

Bojidar Dimitrov's site says it has no threads: K 1000/11 Reflex

However looking at the front of the lens, it has threads and they measure to be around 105mm. I'd love to pick up a uv protective filter to keep this lens in pristine condition, but I don't want to take a stab in the dark and be wrong...

Does anyone have more info they could share?

Just a guess, but does it use rear-mounted filters? It's rare that a lens doesn't accept any filters. Of course, that doesn't serve your lens protection purpose.

That being said, buy a 105mm filter and try it out. If you buy from a reputable place, I'm sure they'd let you swap it out in case it's not an exact fit.

[Ole]

The K 1000mm f/11 takes 52mm filters at the rear.
- that's probably the way to go.

[SteveM]

It looks like it will take a rear filter (there should be a section that lifts up). Here are the sizes;

Filter Sizes for Pentax Lenses (and Filter Response Characteristics of Pentax Filters) - Mark Roberts Photography

Great news about the K1000...looking forward to seeing some shots of it and the shots you take. Have you thought of what you will use for a tripod?

[Clinton]

Yup, I can confirm you can rear mount filters. However in this case I'm thinking of protecting the front of the lens. I tried out one photography shop here in town and they didn't have any filters this big. The Sigma ex dg 105mm is around $100 in amazon, which would be fine if I knew it would fit, but the hassle of a return seems like a drag.

[Ben_Edict]

Yup, I can confirm you can rear mount filters. However in this case I'm thinking of protecting the front of the lens. I tried out one photography shop here in town and they didn't have any filters this big. The Sigma ex dg 105mm is around $100 in amazon, which would be fine if I knew it would fit, but the hassle of a return seems like a drag.

I would not use a front filter with that lens. Catadioptrics are prone to flare and have low contrast anyway and a filter will only add more IQ loss. Instead there should be a substantial lens hood in place. For a 1000mm lens, the lens hood is very long and offers more than adequate protection. And the lens hood is needed anyway, as otherwise the flareing would be way too pronounced with sucha lens.

Ben

[SteveM]

I'm not sure if the front of that lens is threaded? My larger lenses are not....so it's not possible to add anything to the front of the lens....

[gofour3]

As previously mentioned, this lens has built-in filters and also accepts rear mounted 52mm filters.

Here is a link to the lens manual:

http://www.pentax.ca/pdf/o_manuals/om_SMC500MM1000MMREFLEX_e.pdf

Phil.

[Laurentiu Cristofor]

Instead there should be a substantial lens hood in place. For a 1000mm lens, the lens hood is very long and offers more than adequate protection. And the lens hood is needed anyway, as otherwise the flareing would be way too pronounced with sucha lens.

Maybe that's what the filter was for, but the hood was missing from the package?

[Clinton]

Maybe that's what the filter was for, but the hood was missing from the package?

No, the built in hood is also there, it's just not likely to stay in place.

[Ben_Edict]

No, the built in hood is also there, it's just not likely to stay in place.

To use the hood is eesential with catadioptric lenses. If it is loose, shim some aluminium foil or paper between the hood and the lens tube and that should suffice to hold it in place.

Ben

[Clinton]

So I took a gamble, and bought a super cheap (read junk) $12 105mm filter from someone on ebay to see if it would fit.

It wont fit. I expect if I wanted a lens cap, this size would work but the threading isn't correct for a filter.

If you're looking at this post, there's no need to waste your money.

[Ben_Edict]

So I took a gamble, and bought a super cheap (read junk) $12 105mm filter from someone on ebay to see if it would fit.

It wont fit. I expect if I wanted a lens cap, this size would work but the threading isn't correct for a filter.

If you're looking at this post, there's no need to waste your money.

I would guess than, that the front threads are only there to screw in the retainer ring for the front lens and they may not be of metric size, then.

Ben

[Clinton]

I would guess than, that the front threads are only there to screw in the retainer ring for the front lens and they may not be of metric size, then.

Ben

Or just baffling to reduce reflection and lens flare while providing some extension to protect the front element.

[Ben_Edict]

Or just baffling to reduce reflection and lens flare while providing some extension to protect the front element.

It's way too short to provide any baffling, you'll need a long hood for this. But the retainer ring needs the thread.

Ben